And yet another OVERHEATING thread . . .
08-25-2012, 07:50 PM
#1
Thread Starter
Join Date: May 2012
Location: Colorado
Posts: 48
And yet another OVERHEATING thread . . .
66 Coupe. Stock 289, 3-speed. Everything is pretty much original on this car.
It's been overheating since I bought it in early June. Here's what I've done:
Had the radiator rodded out
New water pump
New hoses
New thermostat (a couple times)
Added a shroud (not the best fitting, I must admit but it's better than nothing)
Added an overflow tank
New head gaskets (had an oil leak) and YES, the head gaskets are installed correctly and the tabs are visible at the front of the engine.
(An interesting aside: When I had the heads off, I noticed that the #5 piston is installed backwards; that is, the notch is to the rear. A little piston slap doesn't bother me and if it's doing it, I can't hear it anyway, so it's going to stay just as it is until the day comes for a rebuild. I don't know who did the work on the block, when they did it or how many miles are on it like this. But that's not related to my issue, anyway.)
OK. Here's what it does. I can drive it and after about 4 miles or so, the temp gauge comes right up to the center. It stays there for another few miles (just long enough for me to think it's going to be OK); then, after another 4 or 5 miles or so, the temp slowly starts to creep upward again. After a total of 12-15 miles, the temp gauge is right at the top of the safe mark.
I've measured the thermostat housing temp with my infrared thermometer and with the car's temp gauge at the top of its scale, it shows about 230. The car has actually been hot enough to blow steam out of the overflow tank. So it's not just an indication issue. I've measured as good as I can on the front of the intake manifold (water passage out of the heads) and they seem to be about the same temp on each side, and about the same as the t-stat housing.
Yesterday, I looked at the ignition timing. It has WAY too much vacuum advance, so I thought I'd found the issue. It is set at 10 initial (I live at over 6,000'). With the vacuum advance disconnected, it runs out to 18 at 2500 rpm. According to the FSM, this is right on the money for the mechanical advance. With the vacuum advance connected, it peaks at 49 degrees. I tried adjusting the screw in the canister but it didn't alter the vacuum advance, so maybe my vacuum advance is in need of replacement. But just to see if I was on the right track, I took the car for a drive with the vacuum advance unhooked (running just on the mechanical advance). No change. So it's not a timing issue, regardless of the vacuum advance error.
I've put my coolant pressure tester on the radiator and pumped it up to 12 pounds. It held that pressure for 10 minutes, so I don't think I have a combustion leak. Plus, no bubbles in the upper radiator tank when it's running. I haven't actually checked for combustion gasses in the radiator tank, though. I suppose this is still the likely culprit; a flaw small enough that 12 psi won't find it, but combustion pressure can still get through. I want to exhaust other probabilities before pulling the heads again, though.
Yesterday, I flushed the engine for 45 minutes. I clamped the upper radiator hose, heater return and bypass hoses shut and ran the water backwards through the heater core, intake manifold, heads, block, up through the radiator and out the fill neck the whole time. So water is able to flow through the heads (see note above about the head gaskets ARE installed properly). Water ran freely and was very clear after a couple minutes. I let it go 45 minutes anyway.
After flushing the system, I closed it back up and ran the car with the radiator cap off to see if there was water flowing in the upper tank. After the t-stat opened, the water started to move, and was a genuine torrent in there with the engine at 2500 rpm or so. So I think I'm getting plenty of circulation.
After it warmed up, I put my hand and felt around the front of the radiator. At the top, it was warm (hot) on the right and left sides, cool in the center. At the bottom, it was pretty cool all the way across. I don't know why it was so cool at the top center of the radiator. I figure there are 2 causes for this; 1) that the tubes in the center of the radiator are plugged again and there is no water circulating through the center part of the radiator, or 2) that's right in front of the fan and maybe it should be cool. I just don't know.
My next thought is to set up a home-made manometer to measure the air flow through the radiator. Basically, a differential pressure test between the front and back sides of the radiator. I've heard of some folks having trouble with air getting under the front of the car and essentially equalizing the pressures on the front and rear sides of the radiator, which would mean no airflow through the radiator (or worse, air would flow the opposite way). My rear springs are pretty weak and the car does sit a bit low in back. If that's the cause, I could try blocking some of the air from the bottom with some cardboard to see if that helps before I plan on a more permanent fix. I suppose I could also put some shackles (1970s tech) to get the back end a little higher. Somehow, I doubt airflow is my problem so I'm reluctant to start down that road.
I suppose another, easier method might be to take the hood off and drive it.
So I'm throwing this out for you folks to chew on. Any ideas? If this car turns into one that I have to work on every weekend, I'm going to sell the damned thing. If I wanted a project car, I would have bought a project car.
Thanks in advance.
It's been overheating since I bought it in early June. Here's what I've done:
Had the radiator rodded out
New water pump
New hoses
New thermostat (a couple times)
Added a shroud (not the best fitting, I must admit but it's better than nothing)
Added an overflow tank
New head gaskets (had an oil leak) and YES, the head gaskets are installed correctly and the tabs are visible at the front of the engine.
(An interesting aside: When I had the heads off, I noticed that the #5 piston is installed backwards; that is, the notch is to the rear. A little piston slap doesn't bother me and if it's doing it, I can't hear it anyway, so it's going to stay just as it is until the day comes for a rebuild. I don't know who did the work on the block, when they did it or how many miles are on it like this. But that's not related to my issue, anyway.)
OK. Here's what it does. I can drive it and after about 4 miles or so, the temp gauge comes right up to the center. It stays there for another few miles (just long enough for me to think it's going to be OK); then, after another 4 or 5 miles or so, the temp slowly starts to creep upward again. After a total of 12-15 miles, the temp gauge is right at the top of the safe mark.
I've measured the thermostat housing temp with my infrared thermometer and with the car's temp gauge at the top of its scale, it shows about 230. The car has actually been hot enough to blow steam out of the overflow tank. So it's not just an indication issue. I've measured as good as I can on the front of the intake manifold (water passage out of the heads) and they seem to be about the same temp on each side, and about the same as the t-stat housing.
Yesterday, I looked at the ignition timing. It has WAY too much vacuum advance, so I thought I'd found the issue. It is set at 10 initial (I live at over 6,000'). With the vacuum advance disconnected, it runs out to 18 at 2500 rpm. According to the FSM, this is right on the money for the mechanical advance. With the vacuum advance connected, it peaks at 49 degrees. I tried adjusting the screw in the canister but it didn't alter the vacuum advance, so maybe my vacuum advance is in need of replacement. But just to see if I was on the right track, I took the car for a drive with the vacuum advance unhooked (running just on the mechanical advance). No change. So it's not a timing issue, regardless of the vacuum advance error.
I've put my coolant pressure tester on the radiator and pumped it up to 12 pounds. It held that pressure for 10 minutes, so I don't think I have a combustion leak. Plus, no bubbles in the upper radiator tank when it's running. I haven't actually checked for combustion gasses in the radiator tank, though. I suppose this is still the likely culprit; a flaw small enough that 12 psi won't find it, but combustion pressure can still get through. I want to exhaust other probabilities before pulling the heads again, though.
Yesterday, I flushed the engine for 45 minutes. I clamped the upper radiator hose, heater return and bypass hoses shut and ran the water backwards through the heater core, intake manifold, heads, block, up through the radiator and out the fill neck the whole time. So water is able to flow through the heads (see note above about the head gaskets ARE installed properly). Water ran freely and was very clear after a couple minutes. I let it go 45 minutes anyway.
After flushing the system, I closed it back up and ran the car with the radiator cap off to see if there was water flowing in the upper tank. After the t-stat opened, the water started to move, and was a genuine torrent in there with the engine at 2500 rpm or so. So I think I'm getting plenty of circulation.
After it warmed up, I put my hand and felt around the front of the radiator. At the top, it was warm (hot) on the right and left sides, cool in the center. At the bottom, it was pretty cool all the way across. I don't know why it was so cool at the top center of the radiator. I figure there are 2 causes for this; 1) that the tubes in the center of the radiator are plugged again and there is no water circulating through the center part of the radiator, or 2) that's right in front of the fan and maybe it should be cool. I just don't know.
My next thought is to set up a home-made manometer to measure the air flow through the radiator. Basically, a differential pressure test between the front and back sides of the radiator. I've heard of some folks having trouble with air getting under the front of the car and essentially equalizing the pressures on the front and rear sides of the radiator, which would mean no airflow through the radiator (or worse, air would flow the opposite way). My rear springs are pretty weak and the car does sit a bit low in back. If that's the cause, I could try blocking some of the air from the bottom with some cardboard to see if that helps before I plan on a more permanent fix. I suppose I could also put some shackles (1970s tech) to get the back end a little higher. Somehow, I doubt airflow is my problem so I'm reluctant to start down that road.
I suppose another, easier method might be to take the hood off and drive it.
So I'm throwing this out for you folks to chew on. Any ideas? If this car turns into one that I have to work on every weekend, I'm going to sell the damned thing. If I wanted a project car, I would have bought a project car.
Thanks in advance.
Last edited by dklistul; 08-25-2012 at 08:08 PM.
08-26-2012, 04:06 AM
#2
I did everything you did when I was having cooling problems, and nothing seemed to help. I suspected that debris or something had clogged up the motor somewhere. Motor got rebuilt, but in the tear down behind the freezer plugs was lots of crud and so I'm assuming more was hidden elsewhere. First I would try using some of the chemical flushes to hopefully break some of the debris free (if that is the problem). 230 degrees is pushing it for sure. However a radiator problem would also explain the issues.
08-26-2012, 08:37 AM
#5
Thread Starter
Join Date: May 2012
Location: Colorado
Posts: 48
Yeah, this ain't my first rodeo. T-stat is installed correctly. Like I said, there was lots of circulation through the radiator AFTER the T-stat opened (and very little when it was cold). Circulation through the system is fine. It's just building more heat than I can dispose of.
What I'm trying to figure out is whether it's too little cooling capacity (as in low airflow or clogged radiator tubes) or excessive heat (as in combustion gas in the coolant). The radiator is not my first suspect, since I can see so much flow in the top tank with the engine running at a good clip. But I know these cars had marginal cooling to begin with and maybe a 25% or so blockage could cause my trouble and still show good circulation.
And before anyone suggests it, I tried running it without any T-stat at all and that didn't help, either.
What I'm trying to figure out is whether it's too little cooling capacity (as in low airflow or clogged radiator tubes) or excessive heat (as in combustion gas in the coolant). The radiator is not my first suspect, since I can see so much flow in the top tank with the engine running at a good clip. But I know these cars had marginal cooling to begin with and maybe a 25% or so blockage could cause my trouble and still show good circulation.
And before anyone suggests it, I tried running it without any T-stat at all and that didn't help, either.
Last edited by dklistul; 08-26-2012 at 08:50 AM.
08-27-2012, 03:04 AM
#6
Flow doesn't always accurately indicate if it's your radiator or not, but if the engine hasn't been rebuilt for a long time I'm betting there is all sorts of crud behind those freeze plugs. I'm unsure if they can be pulled out with the engine still in though. I would think if their was a mixing of combustion gas and coolant that you would run low on water very quick, and perhaps even smell or see something like oily steam.
08-27-2012, 06:31 AM
#7
2nd Gear Member
Join Date: Nov 2006
Location:
Posts: 356
Hi,
A couple of thoughts,....
If you can rule out the fact you're confident the rad is circulating fine, (shoot various quadrants, side to side and top to bottom), Have you checked the accuracy of the temp gauge with a mechanical unit?
Also, are you running a coolant recovery tank? I'm big fan of these as, after a few heating a cooling cycles, they will purge any air in the system. So, you have maximum cooling capacity.
I think we've all learned the mustangs rads were not very efficient, but, I don't recall my OEM rad being that in-efficient that it couldn't reduce the temps such as you are experiencing.
Keep us posted and good luck!
A couple of thoughts,....
If you can rule out the fact you're confident the rad is circulating fine, (shoot various quadrants, side to side and top to bottom), Have you checked the accuracy of the temp gauge with a mechanical unit?
Also, are you running a coolant recovery tank? I'm big fan of these as, after a few heating a cooling cycles, they will purge any air in the system. So, you have maximum cooling capacity.
I think we've all learned the mustangs rads were not very efficient, but, I don't recall my OEM rad being that in-efficient that it couldn't reduce the temps such as you are experiencing.
Keep us posted and good luck!
08-27-2012, 09:11 AM
#8
Join Date: Oct 2011
Location: Texas
Posts: 12
66 Coupe. Stock 289, 3-speed. Everything is pretty much original on this car.
It's been overheating since I bought it in early June. Here's what I've done:
Had the radiator rodded out
New water pump
New hoses
New thermostat (a couple times)
Added a shroud (not the best fitting, I must admit but it's better than nothing)
Added an overflow tank
New head gaskets (had an oil leak) and YES, the head gaskets are installed correctly and the tabs are visible at the front of the engine.
(An interesting aside: When I had the heads off, I noticed that the #5 piston is installed backwards; that is, the notch is to the rear. A little piston slap doesn't bother me and if it's doing it, I can't hear it anyway, so it's going to stay just as it is until the day comes for a rebuild. I don't know who did the work on the block, when they did it or how many miles are on it like this. But that's not related to my issue, anyway.)
OK. Here's what it does. I can drive it and after about 4 miles or so, the temp gauge comes right up to the center. It stays there for another few miles (just long enough for me to think it's going to be OK); then, after another 4 or 5 miles or so, the temp slowly starts to creep upward again. After a total of 12-15 miles, the temp gauge is right at the top of the safe mark.
I've measured the thermostat housing temp with my infrared thermometer and with the car's temp gauge at the top of its scale, it shows about 230. The car has actually been hot enough to blow steam out of the overflow tank. So it's not just an indication issue. I've measured as good as I can on the front of the intake manifold (water passage out of the heads) and they seem to be about the same temp on each side, and about the same as the t-stat housing.
Yesterday, I looked at the ignition timing. It has WAY too much vacuum advance, so I thought I'd found the issue. It is set at 10 initial (I live at over 6,000'). With the vacuum advance disconnected, it runs out to 18 at 2500 rpm. According to the FSM, this is right on the money for the mechanical advance. With the vacuum advance connected, it peaks at 49 degrees. I tried adjusting the screw in the canister but it didn't alter the vacuum advance, so maybe my vacuum advance is in need of replacement. But just to see if I was on the right track, I took the car for a drive with the vacuum advance unhooked (running just on the mechanical advance). No change. So it's not a timing issue, regardless of the vacuum advance error.
I've put my coolant pressure tester on the radiator and pumped it up to 12 pounds. It held that pressure for 10 minutes, so I don't think I have a combustion leak. Plus, no bubbles in the upper radiator tank when it's running. I haven't actually checked for combustion gasses in the radiator tank, though. I suppose this is still the likely culprit; a flaw small enough that 12 psi won't find it, but combustion pressure can still get through. I want to exhaust other probabilities before pulling the heads again, though.
Yesterday, I flushed the engine for 45 minutes. I clamped the upper radiator hose, heater return and bypass hoses shut and ran the water backwards through the heater core, intake manifold, heads, block, up through the radiator and out the fill neck the whole time. So water is able to flow through the heads (see note above about the head gaskets ARE installed properly). Water ran freely and was very clear after a couple minutes. I let it go 45 minutes anyway.
After flushing the system, I closed it back up and ran the car with the radiator cap off to see if there was water flowing in the upper tank. After the t-stat opened, the water started to move, and was a genuine torrent in there with the engine at 2500 rpm or so. So I think I'm getting plenty of circulation.
After it warmed up, I put my hand and felt around the front of the radiator. At the top, it was warm (hot) on the right and left sides, cool in the center. At the bottom, it was pretty cool all the way across. I don't know why it was so cool at the top center of the radiator. I figure there are 2 causes for this; 1) that the tubes in the center of the radiator are plugged again and there is no water circulating through the center part of the radiator, or 2) that's right in front of the fan and maybe it should be cool. I just don't know.
My next thought is to set up a home-made manometer to measure the air flow through the radiator. Basically, a differential pressure test between the front and back sides of the radiator. I've heard of some folks having trouble with air getting under the front of the car and essentially equalizing the pressures on the front and rear sides of the radiator, which would mean no airflow through the radiator (or worse, air would flow the opposite way). My rear springs are pretty weak and the car does sit a bit low in back. If that's the cause, I could try blocking some of the air from the bottom with some cardboard to see if that helps before I plan on a more permanent fix. I suppose I could also put some shackles (1970s tech) to get the back end a little higher. Somehow, I doubt airflow is my problem so I'm reluctant to start down that road.
I suppose another, easier method might be to take the hood off and drive it.
So I'm throwing this out for you folks to chew on. Any ideas? If this car turns into one that I have to work on every weekend, I'm going to sell the damned thing. If I wanted a project car, I would have bought a project car.
Thanks in advance.
It's been overheating since I bought it in early June. Here's what I've done:
Had the radiator rodded out
New water pump
New hoses
New thermostat (a couple times)
Added a shroud (not the best fitting, I must admit but it's better than nothing)
Added an overflow tank
New head gaskets (had an oil leak) and YES, the head gaskets are installed correctly and the tabs are visible at the front of the engine.
(An interesting aside: When I had the heads off, I noticed that the #5 piston is installed backwards; that is, the notch is to the rear. A little piston slap doesn't bother me and if it's doing it, I can't hear it anyway, so it's going to stay just as it is until the day comes for a rebuild. I don't know who did the work on the block, when they did it or how many miles are on it like this. But that's not related to my issue, anyway.)
OK. Here's what it does. I can drive it and after about 4 miles or so, the temp gauge comes right up to the center. It stays there for another few miles (just long enough for me to think it's going to be OK); then, after another 4 or 5 miles or so, the temp slowly starts to creep upward again. After a total of 12-15 miles, the temp gauge is right at the top of the safe mark.
I've measured the thermostat housing temp with my infrared thermometer and with the car's temp gauge at the top of its scale, it shows about 230. The car has actually been hot enough to blow steam out of the overflow tank. So it's not just an indication issue. I've measured as good as I can on the front of the intake manifold (water passage out of the heads) and they seem to be about the same temp on each side, and about the same as the t-stat housing.
Yesterday, I looked at the ignition timing. It has WAY too much vacuum advance, so I thought I'd found the issue. It is set at 10 initial (I live at over 6,000'). With the vacuum advance disconnected, it runs out to 18 at 2500 rpm. According to the FSM, this is right on the money for the mechanical advance. With the vacuum advance connected, it peaks at 49 degrees. I tried adjusting the screw in the canister but it didn't alter the vacuum advance, so maybe my vacuum advance is in need of replacement. But just to see if I was on the right track, I took the car for a drive with the vacuum advance unhooked (running just on the mechanical advance). No change. So it's not a timing issue, regardless of the vacuum advance error.
I've put my coolant pressure tester on the radiator and pumped it up to 12 pounds. It held that pressure for 10 minutes, so I don't think I have a combustion leak. Plus, no bubbles in the upper radiator tank when it's running. I haven't actually checked for combustion gasses in the radiator tank, though. I suppose this is still the likely culprit; a flaw small enough that 12 psi won't find it, but combustion pressure can still get through. I want to exhaust other probabilities before pulling the heads again, though.
Yesterday, I flushed the engine for 45 minutes. I clamped the upper radiator hose, heater return and bypass hoses shut and ran the water backwards through the heater core, intake manifold, heads, block, up through the radiator and out the fill neck the whole time. So water is able to flow through the heads (see note above about the head gaskets ARE installed properly). Water ran freely and was very clear after a couple minutes. I let it go 45 minutes anyway.
After flushing the system, I closed it back up and ran the car with the radiator cap off to see if there was water flowing in the upper tank. After the t-stat opened, the water started to move, and was a genuine torrent in there with the engine at 2500 rpm or so. So I think I'm getting plenty of circulation.
After it warmed up, I put my hand and felt around the front of the radiator. At the top, it was warm (hot) on the right and left sides, cool in the center. At the bottom, it was pretty cool all the way across. I don't know why it was so cool at the top center of the radiator. I figure there are 2 causes for this; 1) that the tubes in the center of the radiator are plugged again and there is no water circulating through the center part of the radiator, or 2) that's right in front of the fan and maybe it should be cool. I just don't know.
My next thought is to set up a home-made manometer to measure the air flow through the radiator. Basically, a differential pressure test between the front and back sides of the radiator. I've heard of some folks having trouble with air getting under the front of the car and essentially equalizing the pressures on the front and rear sides of the radiator, which would mean no airflow through the radiator (or worse, air would flow the opposite way). My rear springs are pretty weak and the car does sit a bit low in back. If that's the cause, I could try blocking some of the air from the bottom with some cardboard to see if that helps before I plan on a more permanent fix. I suppose I could also put some shackles (1970s tech) to get the back end a little higher. Somehow, I doubt airflow is my problem so I'm reluctant to start down that road.
I suppose another, easier method might be to take the hood off and drive it.
So I'm throwing this out for you folks to chew on. Any ideas? If this car turns into one that I have to work on every weekend, I'm going to sell the damned thing. If I wanted a project car, I would have bought a project car.
Thanks in advance.
NOT to be critical...just a thought. They did NOT overheat out of the box, so you've overlooked something, however, please keep in mind that all of the newer cars run as follows:
The stock water temp gauge on the Miata in a way is linear. It's just that between 180°-210°F, it will stick to that 11AM position. If you ever climb over 210°F, you will notice the needle will climb up slowly. At about 210°-220°F, it will sit at the 12 oclock position. At 230°F, you can see the gauge start to move to the 1/2 oclock position. Many here will probably never see it move, but if it does, be sure you stop and cool the car. Also, not all guages are calibrated, so it everything checks out, don't start going down a bunny trail for nothing. HTH
08-27-2012, 08:48 PM
#9
Thread Starter
Join Date: May 2012
Location: Colorado
Posts: 48
I think I'm closing in on the problem. Today I managed to go over 20 miles and the needle never climbed above the center of the "M" in the word TEMP on the gauge (well, except while idling, then it goes up a ways still). Just like I prefer to see.
Here's what I've done over the last 2 days:
Yesterday, I needed to do something besides work on the dadburned deck again, so I thought I'd give it another whack. I opened the radiator and saw some chunks of rusty scale directly below the filler neck. I stuck my magnet in there and pulled out some pretty nasty looking chunks. Hmmmm.
I put the magnet on a flexible steel "stick" and fished it around in the top tank and came out with quite a bit more crap. OK. So I removed the radiator, flipped it upside down and let the water run through it for 20 minutes or so, sloshing things around at the same time.
Then, I put the hose to the flush fitting in my heater hose and let the water run through the block for another 30 minutes.
Put it all back together, filled it up and took it for a drive. This time (this was yesterday), I managed to get almost 20 miles before the temp gauge was at the top of the normal range (I live in a pretty remote area and "around the block" is 6 miles). So that was an improvement, but the problem was still there.
At that point, I was a little pissed so I walked away from it.
Today, when I was done with work, I went out to the car, opened the radiator and guess what? More chunks in the top tank. OK, this crap is coming from the heads or block (I already knew that). Probably got knocked loose when I had the heads off.
So I stuck my magnet in there again and fished around until I wasn't getting any more crud. I put the hose on the flush fitting again and this time used a strainer to catch the debris coming out of the radiator. Got some more in the strainer. I ran the hose until no more chunks were coming out.
Then, I pulled the T-stat housing and started the block flush again, this time running the water in the NORMAL direction. I put my 16 pound magnet in the water coming out of the manifold to detect anything that might be coming out. I got a little bit of "stuff" but nothing major.
So it appears that the crap in the block and heads is migrating to the radiator, but probably less and less after each flush session. I fashioned a strainer to put in the upper radiator hose to keep the crud out of the radiator, then filled it up and went for a ride.
This time, I went over 20 miles and like I said at the top, the temp stayed right in the center! HooRah! It still climbs up to about 3/4 scale at idle, but unlike before, it now cools off again as the RPM increases.
I also have a jug of cooling system flush chemicals in it right now. I want it to get one more warmup/cooldown cycle before I dump it to look at the strainer in the upper hose. But it looks like we have a winner.
Here's what I think is going on:
After the cooling system flush, the radiator is clear of debris and cools the engine normally. After 5 or 6 miles, enough crap has been loosened from the engine that some of the tubes get blocked. This reduces the cooling capacity of the radiator to just slightly less than what the engine puts into the water, and the temp starts to slowly climb. This also explains why, every time I flush the system, it would act the same way.
So it appears that when I had the heads off, I disturbed some crap in there that is now blocking at least part of the radiator tubes, but am slowly getting rid of it. I know, I should pull the motor, disassemble it and have it cleaned but that leads to machine work, new rotating parts, more machine work, valve work, more machine work and, well, you know the drill. I just don't have the $$ for an engine rebuild right now. Besides, if it comes to that, a crate motor might have to follow me home.
I suspect that the radiator is just barely marginal when it's clear. Once I get the crap out of the circulatory system, I just might invest in a better radiator.
Here's what I've done over the last 2 days:
Yesterday, I needed to do something besides work on the dadburned deck again, so I thought I'd give it another whack. I opened the radiator and saw some chunks of rusty scale directly below the filler neck. I stuck my magnet in there and pulled out some pretty nasty looking chunks. Hmmmm.
I put the magnet on a flexible steel "stick" and fished it around in the top tank and came out with quite a bit more crap. OK. So I removed the radiator, flipped it upside down and let the water run through it for 20 minutes or so, sloshing things around at the same time.
Then, I put the hose to the flush fitting in my heater hose and let the water run through the block for another 30 minutes.
Put it all back together, filled it up and took it for a drive. This time (this was yesterday), I managed to get almost 20 miles before the temp gauge was at the top of the normal range (I live in a pretty remote area and "around the block" is 6 miles). So that was an improvement, but the problem was still there.
At that point, I was a little pissed so I walked away from it.
Today, when I was done with work, I went out to the car, opened the radiator and guess what? More chunks in the top tank. OK, this crap is coming from the heads or block (I already knew that). Probably got knocked loose when I had the heads off.
So I stuck my magnet in there again and fished around until I wasn't getting any more crud. I put the hose on the flush fitting again and this time used a strainer to catch the debris coming out of the radiator. Got some more in the strainer. I ran the hose until no more chunks were coming out.
Then, I pulled the T-stat housing and started the block flush again, this time running the water in the NORMAL direction. I put my 16 pound magnet in the water coming out of the manifold to detect anything that might be coming out. I got a little bit of "stuff" but nothing major.
So it appears that the crap in the block and heads is migrating to the radiator, but probably less and less after each flush session. I fashioned a strainer to put in the upper radiator hose to keep the crud out of the radiator, then filled it up and went for a ride.
This time, I went over 20 miles and like I said at the top, the temp stayed right in the center! HooRah! It still climbs up to about 3/4 scale at idle, but unlike before, it now cools off again as the RPM increases.
I also have a jug of cooling system flush chemicals in it right now. I want it to get one more warmup/cooldown cycle before I dump it to look at the strainer in the upper hose. But it looks like we have a winner.
Here's what I think is going on:
After the cooling system flush, the radiator is clear of debris and cools the engine normally. After 5 or 6 miles, enough crap has been loosened from the engine that some of the tubes get blocked. This reduces the cooling capacity of the radiator to just slightly less than what the engine puts into the water, and the temp starts to slowly climb. This also explains why, every time I flush the system, it would act the same way.
So it appears that when I had the heads off, I disturbed some crap in there that is now blocking at least part of the radiator tubes, but am slowly getting rid of it. I know, I should pull the motor, disassemble it and have it cleaned but that leads to machine work, new rotating parts, more machine work, valve work, more machine work and, well, you know the drill. I just don't have the $$ for an engine rebuild right now. Besides, if it comes to that, a crate motor might have to follow me home.
I suspect that the radiator is just barely marginal when it's clear. Once I get the crap out of the circulatory system, I just might invest in a better radiator.
Last edited by dklistul; 08-27-2012 at 08:53 PM.
08-27-2012, 09:02 PM
#10
2nd Gear Member
Join Date: Nov 2006
Location:
Posts: 356
Hi Again,
OK, so what do you know about this block? Has it ever been pulled and cleaned in it's previous life? I'm running an OEM block. It was first rebuilt in '96 along with the flush, dip, & clean. I have since run a qualified coolant. Thus no crud. Was your block run with pure water as the coolant for some long period prior to your ownership?
OK, so what do you know about this block? Has it ever been pulled and cleaned in it's previous life? I'm running an OEM block. It was first rebuilt in '96 along with the flush, dip, & clean. I have since run a qualified coolant. Thus no crud. Was your block run with pure water as the coolant for some long period prior to your ownership?