The Stovebolt Site Forums The Shop Area Engine Shop 350 Engine got hot, might be toast

I installed a GM 350 crate engine in a 72 over a year ago for a friend. His 16 year old son has been driving it to school. New everything, radiator, trans, brakes, exhaust, etc. He heard a noise and pulled over on the freeway and said steam was rolling out from under the hood. At this point I have only done some preliminary checks. I filled it with water and found no external leaks so the presumption is that the thermostat stuck. It turns over but sounds like it has no compression and will not start. It also has a distinctive clunk when trying to start. It has no water in the oil, however the cooling system was dry so that may change after it sits a couple of days. I got a 50 Olds hot back in my youth and the rings collapsed on several cylinders. That could be a possibility here, but clunks are also never good. I'm going to check the compression and do some further investigation. Any suggestions would be appreciated.
Fred

Do a dry, then a wet compression test. If there's a noticeable difference, 15% or more, you've probably got collapsed rings. Also, try a cylinder leakdown test with air pressure applied to cylinders at top dead center compression, and listen for leaks at the intake, exhaust, and crankcase. Also look for bubbles in the radiator during the leak test. The knocking noise sounds like a collapsed piston or other nasty situation. If you rehab it, don't trust the pistons- - - -they're probably distorted in the skirt area below the wrist pins and they will have too much skirt clearance.
Jerry

sounds like a blown head gasket to me

Smell the oil, if it smells cooked, you have a boat anchor and I would start with a different engine.
Scott

It's history. I was able to check it out saturday. It sat for a couple of days with water in the cooling system. It is now in the crankcase and the cylinders. The compression is between 15 and 30 lbs and still has the clank. The owner is ordering another engine. It's amazing that a $10 part failure can take out a $1700 engine but stuff happens.
Fred

Did it not have a temperature guage or at least a warning light? I've lost a couple of motors to overheating over the years. The only case where I was the driver when it happened I was also falling asleep and probably should not have been behind the wheel.

If I had been alert and paying attention I would have seen the temp increase and would have stopped to figure out why before the motor became junk.

A friend of mine has lost a couple motors to running out of oil. Those failures occurred in cars his kids drove and should have been caught by watching the gauges and checking the dip stick from time to time.

I suspect this is less a $10 part failure and more operator error. If the driver and owner blame the part and not the operator they risk it happening again.

It has an idiot light which was working when I finished the project. Of course it can be contributed in a large part to the operator. A 17 year old with one year driving experience and probably had the radio turned up to the pain level. However, he was on the freeway and depending on the traffic flow there may have been a critical point when he realized he had a problem and was unable to get over to the side. A few minutes may have made the difference. I think the driver and the dad understand the gravity of the situation and are not pointing fingers at anyone. We are going to install a set of gauges for the next go around. I encountered several overheated engines when I worked in various shops in the past and some we could save and some not.
However,I don't think the newer engines will take as much abuse as some of the older stuff.
Fred

I wonder where the term "idot light " came from??

Some one should make a over temp switch that shuts off the radio,than just maybe they would pay attention


Pete

IMO the one and only redeeming factor for "Idiot lights" is that if there is a problem they are on, and in your face. Only an idiot would ignore them. That's why I've had thoughts of running both. I watch my gauges, but by no means is my attention fixed on them. They would be nice for those long night drives. As an example I had a head crack on the 327 in 68 C20. It happened that quick that if it hadn't been for a traffic problem I wouldn't have noticed. There was no indication of excessive heat under the hood. There was an indication of heat by the time I got off the freeway. It did collapse a piston, but I was able to drive it till I found a replacement, did sound real good.

Larry