1988 Jeep Cherokee won't start after over heating?

[HokieJeep]

My 1988 Cherokee over heated and shut off a few days ago. The last time this happened, I let it sit for awhile and it started up again. Now, it will start for a second and shut right off. I can give it gas and hear the engine revving. It just will not keep running. What may be the problem? Solution?

 

[cpmcjr]

I am afraid I have some very bad news for you. You are going to be going car shopping soon.

The last time you did this you were lucky and there was no engine damage just a loss of power. Once the engine cooled, you were off and running again. This time it sounds as if you were not so lucky. You may have one of many problems, unfortunately they all lead back to you need to have your engine rebuilt as it is blown. A car at that age, most likely going to be best to just scrap it. Here is some more information on specific damage that occurs when an engine overheats:

CONSEQUENCES OF OVERHEATING

If the engine overheats, the first thing that will happen is a gasoline engine will start to detonate. The engine will ping and start to lose power under load as the combination of heat and pressure exceed the octane rating of the fuel. If the detonation problem persists, the hammer-like blows may damage the rings, pistons or rod bearings.

Overheating can also cause preignition. Hot spots develop inside the combustion chamber that become a source of ignition for the fuel. The erratic combustion can cause detonation as well as engine run-on in older vehicles with carburetors. Hot spots can also be very damaging and burn holes right through the top of pistons.

Another consequence of overheating may be a blown head gasket. Heat makes aluminum swell almost three times faster than cast iron. The resulting stress can distort the head and make it swell in areas that are hottest like those between exhaust valves in adjoining cylinders, and areas that have restricted coolant flow like the narrow area that separates the cylinders. The typical aluminum head swells most in the middle, which can crush the head gasket if the head gets hot enough. This will cause a loss of torque in the gasket allowing coolant and combustion leaks to occur when the head cools.

Overheating is also a common cause of OHC cam seizure and breakage.

Wait, there's more. If the coolant gets hot enough to boil, it may cause old hoses or an age-weakened radiator to burst under the increased pressure. Pistons may swell up and scuff or seize in their bores, causing serious engine damage. Exhaust valve stems may stick or scuff in their guides. This, in turn, may cause valves to hang open which can damage pistons, valves and other valvetrain components. And if coolant gets into the crankcase, you can kiss the bearings and bottom end of the engine goodbye.

A HOT warning lamp should never be ignored. Though a few high tech cars like Cadillacs with the Northstar engine can disable cylinders to "air-cool" the engine and keep it running at reduced power in the event of coolant loss, most engines will suffer serious damage if they overheat. So advise your customers to stop driving at the first sign of overheating. Turn the engine off, let it cool down and try to find and fix the cause before risking further travel.