Inliners International Forums General Discussion Engines Overheated engine

Hi guys,

My '78 GM 250 overheated the other day and won't start now. I'd had problems with overheating in the past, but only on long, slow hill climbs or in bumper-to-bumper traffic. On the other hand, it was a pretty hot day when the incident occurred, so I don't know if the problem was due to the existing lack of cooling capacity or if a new problem was responsible. Anyway, as I was getting the rig off the freeway, the engine changed sound and the power dropped. After that, I couldn't start it.

When I got it home, I did a compression check. The results were: 170 30 155 122 160 65 -- very odd. Adding a teaspoon of oil to #2 didn't change the reading. I adjusted the valve lash on #1 and #2 and the compression changed to 120 on #1 and 0 on #2 (it's the first time I've done it, so it's possible I made the adjustment incorrectly). BUT, then I loosened the rocker arms on #2 so that the valves wouldn't open at all and checked the compression. I got one good compression stroke to 120psi, so it doesn't seem like the cylinder is leaking afterall. I also noticed that in the distributor, the points were opening about halfway in between the wire posts. So it seems like the timing has changed drastically and that's what's screwed up the compression as well as the ignition.

So the question is what can cause these symptoms? What is the order of things I should check (from easy to hard)? I'm a novice mechanic, but I do want to give a shot at fixing this myself before I get professional help.

Also, anyone have tips for cranking the engine by hand? I can't get it to budge, though it spins normally with the starter.

Thanks for any help,
Joe

If the overheating was as you say a prexisting condition then it should have been fixed some time ago.

The whole story kinda sounds like driver neglegence.

Get a new engine put in for $75.00 maybe you can find one at the crushers, after all the ones being crushed are in better shape then yours.

Joe,You can purchase for less then $20 a plate that will bolt on to the crank end that allows you to attach a long handled socket wrench such as a extension bar with a socket pivot end that will greatly ease turning the crank to set the valves.Remove the spark plugs when you do this for easier rotating of the crank.However, with all you have experienced maybe yoy should just pull the cylinder head to get a look inside for gasket damage or piston and valve condition.Follow a manual if you have one.

The engine is a transplant into a Land Rover. I found out after I bought the truck that this particular conversion has been known to have overheating issues. Around town it had never overheated before.

I will try the plate, which should allow me to adjust the valves properly, I couldn't get TDC aligned precisely enough using the starter. And then I'll go from there. I'd rather not tear the engine apart unless I have to.

Thanks,
Joe