MYTOYOTA

Good morning gents. I have a 22re cylinder head with pitting on the #2 cylinder. The location of the pitting is on the matting face between the water jacket and the combustion chamber. Here is a couple pics to help explain.

INDEX:
Blue = Mark where metallic ring on head gasket sealed the combustion chamber.
Light Red = Pitting (not yet sure from what).
Green = Simulation of coolant entering my combustion chamber!
DARK ROJO = MY ANGER AND FRUSTRATION!




Same thing just a different angle.




So anyways there it is. I have heard many people say this is usually caused by electrolysis between the steel block and the aluminum head. This apparently happens when the head and block do not have a sufficient ground, or in my case the block has two grounds with the head having none (didn't notice when I purchased the rig).
The second theory I here is that the aluminum head can corrode when in contact with water over time.
The last theory I usually hear is that most coolants contain levels of Phosphorous too high for the type of aluminum used in the casting of the heads. Toyota sells a specific coolant mixture just for this reason (so I have been told)


If you guys have any clue that would help me come to a conclusion on how this might have happened please inform me. I can't avoid this in the future if I don't understand the cause.

Thanks for your time.

MYTOYOTA

Bumping

jeetS

Old coolant turns acidic and eats aluminum.

Coolant doesn't last forever that's why you gotta change it.

4x4climber

I would attribute it to a couple things. These heads are designed very thin right there. Bad idea. The Engnbldr head i got had beefier channels right there.

I would MOSTLY attribute this to the green coolant your using and bad grounding on the head. Especially if that green coolant has been in there a while and gotten old.. My solution would be to buy a NEW head. use RED coolant from Toyota, and add some groundage. Make sure you have one on the intake manifold and maybe even put another one near the back of the head. It never hurts to ground your motor a bit better in different places.

That is my .02$ I don't see any reason for you to do anything else...

MYTOYOTA

I did not know that. Scary info I cant remember how many rigs i have ran old coolant in. Thank you.

So true very cheap fix. Well at least the ground is cheap as far as the head goes I'm ordering a new one from engnbldr.com asap. Probably in the next two weeks I'll send the order in. You say you bought a head from them as well, did the thicker material come as a feature on their stock built heads?

4x4climber

I don't know if it is a feature. It might be considering I know these heads were cast a higher volume and beefier in MANY critical areas. Beefier in critical areas know to corrode, eat thru, or crack.. they made it beefier. At least it is said to be... From what i saw it was.Maybe it is one of those AREAS... I know they are cast slightly different.

It was just one of the couple little things i noticed. Since I compared them RIGHT NEXT to each other to see the differences..When you look at it from the bottom side its not Exactly the same... I wish i still had my head off... cuz i dont think i have pictures.

Bob_T

I recently pulled the head off of my very neglected and mistreated 22R. The headgasket was leaking but there was no pitting on the head. This is after 277,000 miles of never changing the coolant and using green coolant or whatever was laying around. So go figure.

I'm not sure of the grounding theories. I do know a couple of electrical guys and I'll see what they think.

But I think jeetS is right that it was probably acidic coolant in your case. I think what happens is that a pocket of stagnant coolant gets trapped between the gasket and head and turns acidic, eventually eating it's way through to the combustion chamber. I was just lucky for some reason. I can kick myself for disrespecting my old beater truck and not taking proper care of it. I let the coolant get real low and seriously overheated it. Probably would have gone 300,000 or more if not for my neglect.

I'm curious, how many miles are on your engine? I am having a case of remorse over my decision to rebuild my motor with so many miles on it. Keep discovering more issues and sort of think I'd be better off if I had gone to a later model engine and abandoned the old old 22R.

Good luck with the new head!

Bob

MYTOYOTA

Please do ask around in your circle cause I would like to know if anyone else has experienced this first hand and has evidence that the ground is the issue....if that is even possible. Also I'm not sure how many miles are on the engine because I bought it second hand, and it wasn't until I got a closer look at it did I notice the junkyard chalk writing on it so I assume its a rebuilt. The truck itself has 167,000 miles on it but is in awesome shape!

Thanks for the reply's guys I really do appreciate it. Makes me feel like I have a buddy right in my shop lol.

Bob_T

Well, I talked to my electrical engineer friend, he's a very practical real world engineer, not one of the clueless stereotype engineers. He said that in his opinion the head is completely and totally electrically connected to the block by the head bolts and not having an additional ground strap on the head will not cause corrosion since it's very effectively connected through the head bolts to the block.

GuitarMike

I gotta agree with that (not that I'm an engineer, but still...). Think of where you would hook up a jumper cable....it's all grounded. Any metal that is grounded connecting to other metal IS grounded; it would take miles of metal for one end to be considered 'not' grounded and the other to be.
The 'electrical' theory has some merit, but I would lean towards gasket failure/cheap coolant/neglect/casting issue/oddball phenomenon long before I'd get into it being some block grounding problem.
Crap happens....as long as one part of your block is grounded, IMHO (and it IS humble), you should be fine.

Bob_T

What's interesting to me, based on what little I think I know about corrosion is that in order for those pits to start, they had to begin with a tiny amount of coolant working it's way between the gasket and the head (corrosion requires moisture, right?). Once it got there, it started chewing away at the aluminum head, like tooth decay. As the pit got bigger, more coolant got in, more corrosion, until we get the result that MYTOYOTA posted.

Here's where I wonder about the conventional wisdom that we shouldn't use a gasket sealant on head gaskets. I think part of the theory is that aluminum and cast iron expand at different rates when hot and a sealant will prevent then necessary small amount of relative movement between the head, gasket and block? I think the clamping force of the head bolts is immense and the thermal expansion forces are more than immense and any resistance due to a very thin layer of spray on non-hardening sealant is not going to make much difference in the small amount of relative movement.

I've also read the theory that copper coat spray gasket sealants will promote galvanic corrosion due to the copper. But the copper particles are encased in the non-hardening 'glue' and should not make any contact with moisture. And the moisture should not be there to begin with due to the sealant.

I think this is a little bit of a drift from MYTOYOTA's thread here, but I hope it's still very much related to the topic and OK.

Appreciate any comments or rebuttals about the gasket sealant use.

Bob