overheating damage

[garylau]

As some of you know, since I have asked several questions about it already, I have a '97 Lumina I'm going to be replacing the heads on. I've been thinking about it I'm beginning to wonder if I should just be replacing the whole motor. The car overheated causing a gasket to go and possibly caused the heads to warp, but the block doesn't seem to be cracked. There is antifreeze in the oil and the car has been sitting for three months. Can letting it sit with that dilluted oil in it cause any corrosion or damage inside the motor? Is it a bad idea to use a motor that overheated to that point anyway? I'm not sure how well these engines handle high heat like that and I'm worried that the metal is overly heat-stressed and prone to future failure.

[john_V63400]

I over heated my first GA 3400, and I after I fixed it it ran, it was very drivable but it never was the same, power and just all around engine performance was never like it used too. So yeah if you have the money and the time, and the resources, replace the block....But it all depends on how bad and how long it was over heated, if the heads are warped, replace them or resurface them and your good, Oil+ antifreeze in engine...Prolly do a thurough engine flush and check your oil pan for corrosion. If theres no corrosion there prolly no corrosion in your engine. But good luck its your call, new block..or new heads with old block, depending on how bad it is.

[garylau]

Unfortunately my heads are junk. Besides probably being warped they sound terrible, so resufacing is pointless. I have replacement heads coming, though. The original plan was to replace the heads for now and swap the engine out for a 3400 next spring, but I guess I'll have to see how it looks when I start teardown. If yours was still useable I feel a little reassured that I'll be okay at least for the winter.

[Joseph Upson]

Unfortunately my heads are junk. Besides probably being warped they sound terrible, so resufacing is pointless. I have replacement heads coming, though. The original plan was to replace the heads for now and swap the engine out for a 3400 next spring, but I guess I'll have to see how it looks when I start teardown. If yours was still useable I feel a little reassured that I'll be okay at least for the winter.

Heads don't sound terrible, the valve train does when it's not getting enough oil. If the heads are visibly cracked that's another story. If the engine was run hot enough you may very well have bearing damage. Blown head gaskets and leaking intake gaskets have a different immediate result. When you get the engine hot enough to blow the head gasket it also suggests the oil pressure may have dropped low enough to ruin the mains.

I did it on a 2.8L iron head motor except I blew the radiator instead of the head gasket, I didn't have enough coolant to hit the sensor and register an over heat until it was too late. The little ticking noise I thought were rod bearings developed, I changed the rod bearings with the engine in the car and can you believe it, didn't even bother to check one single main bearing. Cranked it up and the noise was still there, when oil pressure finally dropped closer and closer to the danger zone many miles of driving later, I pulled the engine and found grooves in the main journals on the crank as much as .040" thick and nearly .250" wide and I'm not exagerrating.