RedFox91

Trying to diagnose issues on this project car. Compression test came out to 80-90 psi across all cylinders. Most were in the 85-88psi range. I realize this is quite low, but it was consistent. The car does start and run easily enough, but has somewhat of a rough idle and seems low on power.

Previous owner thought it had a bad headgasket. It smoked like crazy out the pipe (thick white sweet smoke) the day I bought it, but has not done that since. There is a hint of smoke from the drivers side tailpipe, has that sweet coolant smell. No sign of oil in coolant. When I changed the oil it was runny (watery, not thick). Chocolatey color though. There are no bubbles in the radiator. Pretty sure the water pump is leaking also. I have not lost a noticeable amount of water but the car has only been run briefly since I got it. I have driven it around the neighborhood but shut it down when the gauge reaches 1/2 (gauge actually is jumping between 1/4 and 1/2 way up the scale).

The back of the engine looks wet but I cleaned it a little and have not seen any new fluid coming from it. Most of the spark plugs are black or dark grey except for Cyl #3, which was a light tan (not quite white). #6 and #8 were wet, looked like a combo of oil and fuel. #8 had a greenish tint as well (the leak in the back seems to be right above plug #8).

Previous owner had changed intakes and possibly screwed up the job, I dont think they drove the car at all after the swap. The timing was messed up and it would hardly run before I got that straightened out (thanks to tech article).

TrimDrip

Sounds like the intake gasket is leaking. Regardless of that, I would save my self the trouble and try to find a low mileage gt40 or gt40p engine to replace it if the motor is stock and your compression gauge is correct. If it isn't running hot then the intake gasket would be a good fix but, if your gauge is correct, you need an engine. Can you tell if the car has blow-by?

Also, an intake gasket alone shouldn't run the car hot until it runs out of water. Also watch your oil, you can wash a bearing out and ruin a motor with water in the crankcase.

stdyhand

If there is no coolant in the oil I'd simply by a head gasket set and replace all the gaskets. I had another car which had low compression. After replacing the gaskets it ran so much smoother and compression jumped from about 90 psi up to 140 on all cylinders.

The white smoke from the exhaust sounds like a bad head gasket. It may have quit but will likely start again at some point. I'd replace it now to prevent any further problems down the road.

RedFox91

I'm not sure if there is coolant in the oil or not. There is no oil in coolant that I can see. When I changed the oil, it was the milk chocolate color but it didnt seem thick, it actually was more watery. I let it sit in a clear container to see if it was separating and didn't seem to. When I poured the oil into another pan, there was a little bit of thicker residue on the bottom of the container.

Are there other tests I can use to help pinpoint the problem? I want to be sure its a headgasket issue before I start that job (never changed a headgasket before). Would changing just the intake gasket have anything to do with the white smoke or low compression numbers?

I do have a complete engine gasket set for the car, I figured I would have to do the head but was hoping it would turn out to be something simpler.

stdyhand

If the compression is low, chances are the head gaskets are old. The low compression and coolant loss would be common signs of such a problem. The intake gasket would have no direct effect on your compression or coolant loss. If coolant is getting into the cylinders you've either got a bad head gasket or a cracked head. It's likely the gasket though unless it overheated.

Replacing a head gasket isn't rocket science. If you don't mind a little sweat and blood (I always seem to bust a knuckle or two when bolts break loose :P) and have the time it isn't too hard. Thats the best part about the older 5.0's. They are a lot easier to work on.

If you already got the gaskets you might as well do it. You will probably want to get some new head bolts though for when you torque them. You can probably get them at a local autozone and they should be able to give you the torque specs.

It isn't the easiest job but it's far from the worst. You need some good sockets, maybe some extensions, and a torque wrench. If you don't have one you might be able to rent one from autozone. I actually bought mine at AZ for like $20.

The worst part I think is breaking loose bolts that haven't been broke free in years. The exhaust manifold bolts can sometimes be a real pain. Other than that it's really as simple as lining up gaskets and getting the bolts to the proper torque.

.boB

That engine is sick, and probably terminal.

Your description of the oil sounds like water. Is the level well above the Full mark on the dipstick?

Smelling coolant at the tail pipe means there's coolant behind the exhaust valve. Usually in the cylinder, too. But a cracked head through the exhaust port is also a possibility. Pull the spark plugs, and see if there's coolant in any of the cylinders.

NAPA sells a test kit for the coolant. It detects by products of combustion. If that is positive, it's usually a head gasket.

Go to Autozone, and borrow their coolant test kit. They'll charge you $80, but you get it back when you return the kit. Follow the instructions that come with the kit.

When you did the compression check, did you repeat the test with a little oil added? If so, did the numbers go up? If they did, that's usually bad rings. But bad rings generally don't all go at once, and at the same amount. Usually you see a lot of variability from one cylinder to another.

Has the engine ever been rebuilt or modified? A big cam in a stock engine will run rough, and have low compression numbers across the board. Especially at high altitude.

stdyhand

bob brought up a great point about adding the oil to the cylinders. Adding a teaspoon of oil to the cylinder and testing your compression would be a great way to rule out bad rings. As he mentioned though your compression likley wouldn't be so similar across all cylinders. It would be a good thing to check though just to eliminate that possibility.

If the rings are good however your problem is likely in your gaskets or heads. Since you said your compression is about the same with all 8 I wouldn't suspect a cracked head as much as the gasket.

Also you said your gauge was jumping between 1/4 and 1/2. Are you referring to the water temp or oil pressure? Just want to make sure I understood you correctly.

RedFox91

Thanks for the feedback so far.

The oil level on the dipstick was just under the full level. When I changed it the amount of oil that came out of the pan seemed about right (didn't measure it but I know it was less than 6 quarts, probably closer to 4). But I think it was recently changed by the previous owner, so may not have been driven enough to indicate much.

I didn't test compression with oil, mainly because I forgot to but also found it strange that all of the cylinders were equally low.

The gauge that was jumping was the water temp gauge. It would stay at the bottom when I first drove, about 3 minutes later when I got back to my house it would pop up to 1/4 and then oscillate between 1/4 and 1/2. I don't know what else has been messed with, as far as the thermostat, temp gauge, sensor, etc.

I didn't see any fluid come out of the cylinders during the compression test. The front of the engine is cleaner and dry, the back (by Cyl #8) had a lot of grimy residue indicative of a fluid leak. This appears to have been coming from above the spark plug holes on the drivers side only. I couldn't tell if it was oil or coolant, the grime was thick and dirty though.

I dont know if the engine has been modified, it has probably had many owners. I doubt it has much performance parts, I found a timeslip from the kid who I got it from and it was slow (can't remember for sure but it was at least 14, maybe 15 sec 1/4). This at 5,000+ ft altitude. Is there an easy way to check the cam, heads, etc to see if they are not stock?

I will do the block test and hopefully a coolant pressure test as soon as I can.

Would both side gaskets need to be replaced? The smoke was only coming from the drivers side tailpipe, and only the drivers side has signs of fluid leakage.

If I end up changing the headgaskets, should I expect this car to be OK? I bought it with plans of selling it anyway, but don't want to pass it off as good if its junk.

Thanks again for all the helpful responses.

RedFox91

Thanks for the feedback so far.

The oil level on the dipstick was just under the full level. When I changed it the amount of oil that came out of the pan seemed about right (didn't measure it but I know it was less than 6 quarts, probably closer to 4). But I think it was recently changed by the previous owner, so may not have been driven enough to indicate much.

I didn't test compression with oil, mainly because I forgot to but also found it strange that all of the cylinders were equally low.

The gauge that was jumping was the water temp gauge. It would stay at the bottom when I first drove, about 3 minutes later when I got back to my house it would pop up to 1/4 and then oscillate between 1/4 and 1/2. I don't know what else has been messed with, as far as the thermostat, temp gauge, sensor, etc.

I didn't see any fluid come out of the cylinders during the compression test. The front of the engine is cleaner and dry, the back (by Cyl #8) had a lot of grimy residue indicative of a fluid leak. This appears to have been coming from above the spark plug holes on the drivers side only. I couldn't tell if it was oil or coolant, the grime was thick and dirty though.

I dont know if the engine has been modified, it has probably had many owners. I doubt it has much performance parts, I found a timeslip from the kid who I got it from and it was slow (can't remember for sure but it was at least 14, maybe 15 sec 1/4). This at 5,000+ ft altitude. Is there an easy way to check the cam, heads, etc to see if they are not stock?

I will do the block test and hopefully a coolant pressure test as soon as I can.

Would both side gaskets need to be replaced? The smoke was only coming from the drivers side tailpipe, and only the drivers side has signs of fluid leakage.

If I end up changing the headgaskets, should I expect this car to be OK? I bought it with plans of selling it anyway, but don't want to pass it off as good if its junk.

Thanks again for all the helpful responses.

stdyhand

If it were mine I'd tear into it. The leaking from cylinder 8 plus the smoke from that exhaust pipe is evidence enough that something is bad, whether it be the gasket or head.

No matter which one it is, it isn't that bad. Worst case would be if the rings were bad. As long as your short block is good you don't have anything you can't do in a few hours, even if you've never done it before.

The head gasket would be the cheapest route but even if the head were cracked you may be able to find another one at a salvage yard or get a rebuilt one from the parts store for a couple hundred.

If you do pull the head off chances are if you inspect the gasket back around cylinder 8 you'll notice the seal or ring around the cylinder is wore flat somewhere and that is allowing coolant through.

You said the last owner thought it was a head gasket. Chances are it is and he sold it thinking the job would be too hard to do. I've gotten some good cars like that because the previous owner thought a job would be real difficult.