Pulled head. Gasket good. Internal crack????

[Scout23]

Hey to all 3AC motor heads out there. I posted a few months ago about my 1986 Tercel with a 3AC puking coolant back through the radiator. I finally got around to pulling the head thinking it was the head gasket and when I got the head off the gasket looks fine.

I am wondering if anyone knows if it is possible to have internal damage to a 3AC head that would cause it to force the exhaust back through the system that isn't visible to the naked eye. Should I just search for a new head and and replace it or have this head checked. Anyone else experienced this problem??? The bottom of the head also looks fine. I don't want to waste my time and money putting this head back on with a new gasket if it's not going to fix the problem.

Thanks for any suggestions.

Aaron

[Petros]

It is extremely rare to find Toyota heads cracked, I have never seen a 3a head cracked (warped, but never cracked). but looking at the pictures it appears to me that gasket between cyl. one and two look suspect. you will not always see an obvious break, all it takes is to break the seal between head and gasket and it will blow combustion gases into the cooling system.

The car would have to be overheated very badly to crack the head, it would more likely melt before it cracked. Clean off the head surface and take a straight edge to it, if it is flat within .002" chances are there is no crack. It is not even warped.

YOu can dismantel the head further and have it checked for cracks at a shop, it does not cost much. But if it not even warped I would not bother at all. I have only had a toyota head checked for cracks once, found nothing, and I must have replaced/rebuilt/resurfaced Toyota heads (and head gaskets) over 20 times. Never felt it was necessary.

Follow the procedure for cleaning up the surfaces as I outline in the repair guides section, use a new head gasket and install it per the procedure. Your engine should be good to go. Might want to replace the thermostat while you are at it (easy to reach with the head off). And perhaps even the heater hoses.

[smokerx]

No offense, I'm not sure what you expect a blown head gasket to look like. Are any of the cylinders and pistons steam cleaned instead of covered in soot? That only tells you whether coolant was entering the cylinder and not whether exhaust was entering the coolant also. It doesn't have to be obvious where the headgasket is leaking from. it could be a hairline where the gasket lifted away its seal from the block.

Look at the water pump and it's down pipe on the radiator hoses end for sediment from leaky Coolant. That's more likely where hot coolant is seeping then a crack in the block but I still suspect the head gasket even after a visual observation.

[smokerx]

Also If you get it back together and it still purges coolant it is possible you replaced the head gasket wrong and either didn't machine a warp on block or head properly, marred the gasket on install or didn't clean your surfaces. I highly recommend paying tedious attention to these steps. I measured and remeasure for any warp in the head or block(no warp) until I could fit no feeler gauge under my straight edge in any direction the FSM states to measure (required no machining, because there was no warp). and both mating surfaces cleaned and sanded for 3 days until they where meticulous then remeasured. If there was any warp that was thicker than my smaller feeler gauges I would have taken it to the shop to have it cleaned and resurfaced for the $30 or $60 or whatever. It's probably worth it to have them clean the head since they bath it if you're really worried about it and have money just laying around. I would still sand it to get the machining marks off like Petros does.

[Petros]

Use this detailed procedure to install a head gasket. It also has instructions on modifications to improve cooling of the head.

https://tercel4wd.com/forums/viewtopic.php?f=7&t=6059

[kadrian69]

I had the same problem on my 83 tercel and it was a warped head that's most likely what your problem is also