Okay, my 1969 351W runs fine as long as there is airflow passing thru the grill. Got stuck in a traffic jam on the interstate a few days ago and had to pull over to let the car cool down (it was 75-80 degrees outside) When I couldn't hear the "boiling" from the radiator anymore I removed the cap and put in a thermometer, it was 210.. and this was after it had cooled a bit. Once the car has been warmed up a bit, It only takes about 10-15 minutes for the temperature to increase to a high level while at idle (needle gets to the right edge of the "M" on the "TEMP" gauge). I assume this isn't normal. It runs cooler as long as I'm going at least 25mph. I'm trying to get some ideas of anything I can try before ponying up for an aluminum radiator.

Here are some details about my engine: 351w 4-v, stock radiator, 6 bladed fan with shroud, and a makeshift overflow reservoir. I have no info about the thermostat (what temp its rated at). The engine itself is getting old, dunno if it's ever been rebuilt, but if it has it was at least 20 years ago. Still runs fantastic though, although it does burn oil (about 2 qts every 3000 miles). With the radiator cap off and the engine running I can definitely see that the liquid is "gurgling".

Also, I recently switched to a synthetic blend oil (Valvoline SYD-Power 10w-30 apparantly for "high powered engines") about 800 miles ago.. the car had always ran with normal non-syn 10w-30 beforehand. Could this in anyway be contributing to the problem? I do notice that the oil pressure runs a bit higher with the synthetic oil. Could switching back to normal oil possibly solve the problem? Thanks for any input.

 

With the engine at idle, when you place your hand infront of the radiator how much air can you feel flowing past your hand? can you see light through the fins okay?
When the water level is just below core level can you see any deposits in top of the cores?

Gun

 

The "stock radiator" is more than likely your problem. It's only a 2-row and it's pushing 40 years old. Don't waste your time cleaning it; it'll still just be a 2-row! Buy a brand new 4-row. Replace that thermostat while you're at it. Go with a 160 degree...

 

Gun Jam, I put the thing away for the day, but I'll let you know tomorrow. And actually, I have an aftermarket a/c unit, and the condenser is right in front of the radiator, and there is no way to put my hand in between the two to feel for air flow. Similarly there is no way to see thru the radiator cuz the condensor is blocking it. I didnt notice any deposits, but I'd have to look again to make sure.

Dan, actually I shouldnt have made the comment "stock radiator" because I really don't know what the actual stock radiator looks like, I'm just assuming that it is because the rest of the engine is pretty much stock, and it definitely isn't aluminum. How can I tell if it has two or four rows?

Thanks for the quick replies guys.

 

Pull the rad cap off and look into the hole. Count how many rows of holes you see, if its stock you should see two. I just replaced mine with a 3 row (was a 2 row) and it runs nice and cool. When I let it idle for 15 - 20 min, it will not get much higher then 185 deg. I'm also running a 180 deg stat....

 

Try a new thermostat for starters, 180 at most id say. And a 6 blade flex fan. They move alot more air then the old stamped steel fans. you may just need a new radiator. I had cooling problems a while ago. turns out it was just the radiator was old and clogged up. I put in a new 3 core and I have no problems now.

 

Yeah my stock radiator was starting to give me problems too. In the summer the air temp can get to 105-110 here no problem with road surfaces in the 135+ range (burns your hand if you touch the road) The temp had been creeping up to the high side so we got an aluminum radiator for it and that solved the problem real well also running a black magic electric fan. On my old radiator you could see what looked like little pieces of gravel in the core openings when the fluid was down below them.

Gun

 

i'm going through the same thing cooling problems...i have a new 3 row radiator and shraode, when it warms up it stays around 180-195 idle and also when driveing...my problem is temp will raise up to 230 []and i would pull over and turn the stang off and let temp drop...then drive it again and temperature will drop while running...i think the thermostat getting stuck and the new thermostat is Stant brand name,from advace auto...but will change the thermostat to a 160 and see if any changes...and i'm thinking about installing a electric fan...i've gotta get this fix before spring or summer when temps are higher...this is all happening at 36 degrees weather like today here...

 

When I was younger, here is what I used to do. I would take out the radiator and cap off the top and bottom. Take a diluted mixture of muratic acid and water and fill the radiator 2/3. Stick it in a wheel barell and rock it back and forth sloshing the solution. Let it sit. After about 30 minutes drain and flush with a hose. Works like a charm and looks brand new inside. When I had leaks I would take an old bicycle inner tube and cut it in half. Clamp it to the top and bottom outlets and pressurize with air. Take a spray bottle of soapy water and spray. Look for bubbles. Mark your leaks and clean the area with a torch and flux. Use the torch, flux and 50/50 solder to fix the problem. You can also flush your engine before doing any of this to break up all the crap in the block. Before spending a bunch of money on a new radiaor, try this becasue it is mainly time and a little money. Hope this helps.

 

howsit im a newbie from south africa and ive got a v6 4 core rad that was in there and have just had it recored will it be enough