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How much pitting is too much for a head gasket to cope with? I bought this truck with a known bad HG, but the pitting on the block was a surprise. It's right at the spot where the head gasket blew, but that couldn't have happened quickly.
I'm not in a spot where I can easily pull the block so I'm debating filling it in with JB Weld. It's at least flat, there's no where on the block a .003" feeler gauge will slip through.
Man, tough to say what I'd do. I might be tempted to try the tiniest amount of JB. Now just how in the heck did that pit like that unless you were running saltwater through it! In old cadillac v8s the FSM recommended using that walnut shell sealer stuff in the coolant, so you might put a tube of that in the coolant after the H/G job.
Just picked up the heads and the guy at the machine shop suggested something similar. "Add some stop leak and don't worry about it." I might add some copper gasket sealant also for peace of mind, but I'm leaning against the JB Weld. At least the sealant wouldn't make it worse.
The truck is 20 years old, 140k miles, and had the original timing belt. I'm going to guess the coolant was never changed either.
That's the way they all look when you pull the heads off. I have a bottle of that copper gasket seal. Stuff works wonders, even on head gaskets. I definitely recommend it.
I don't know the 5VZ but that is about what I find on the 22r motors. The head gasket should fill that void fine I would think. The factory "1" in the picture looks deeper then the pitting by the picture to me. I know it is way off from the leak you had.
Just curious but when you removed the head on your motor, how was the head bolts? Reason I ask is on the 22 motor, I have seen several blown head gaskets that I feel was the result of the head bolts backing out and not necessarily the gasket failing.
Also going from my experience it seems the head bolts that loosen is on the exhaust side more often and really don't think I have seen a head bolt on the intake side loose. Just offering some suggestions and my experience is on a completely different motor.
Now anytime I have a valve cover off, I re-torque the head bolts to about 10 pounds below recommended specs which is high enough for me to discover any loose bolts but not so tight that it might disturb the head or gasket. You would be surprised at how many loose ones I have found that way in the past and am sure I have prevented a few head gaskets from blowing.
Loose head bolts may possibly be a reason yours blew and not necessarily the pitting in my opinion.
If I remember right, the intake side head bolts were a little looser than the exhaust side. Enough to be noticeable, but still reasonably tight. Pretty sure overheating killed this head gasket though. The truck has a new radiator and dried coolant covering the engine bay.
Also, when I pulled the heads my eyes went right to the deteriorated part of the head gasket between the center cylinder and the coolant channel. But looking back over the pictures, that's not actually where it blew:
The gasket is deformed around cylinder #5, probably where the head warped. The shop said they had to take 15 thou off it to get it flat again. The block surface feels slightly rough around that point too, but nothing compared to the pitting near the coolant channel.
That's interesting, Terry. During assembly in Japan, were the head bolt hand torqued, or machine? Just for my own curiosity.
Hello vasinvictor..I am not sure how they are torqued at the factory. A friend of mine that works on these more then I do seems to think some head bolts do loosen and cause the 22 motor to blow head gaskets as well.
Another thing we have discussed is how the aluminum heads and steel blocks expand and contract at different rates and wonder if that causes them to loosen or to put stress on the head gasket.
Something we have wondered is why doesn't someone make a reproduction head out of steel instead of aluminum. I am sure it due to some weight and heat issue but I cant see it adding that much more weight on a 22 motor.
As far as I am aware most if not all Toyota motors are steel block and aluminum head/s. To me the 3.4 seems to be the most stable of the motors I am most familiar.
I talked to another guy in my area and he too had a loose head bolt on his 22 motor that blew the head gasket. I try to catch someone that has a blown head gasket and see if they think that what could of caused theirs to blow.
On any of the truck motors that we deal with here on Yotatech, I would think the exhaust side would expand and contract the most. It has been a while but I asked a member on here if he suspected loose head bolts and he did have 2 loose bolts. It was on a V6 motor just don't recall which one it was. He liked the suggestion of tightening head bolts when having the covers off.
This is a back yard test but I wonder how many others may have dealt with this issue and blamed the gasket. I dont think torqueing to 10 pounds less then actual torque would hurt anything but still tight enough to find loose bolts.
Hello incendui... I was interested in hearing that you may have had loose bolts. We will never know if that is what caused it to blow but it might make some aware of this being a possibility. I would like to hear others discoveries when they work on their motors and what results they find.
The main difference being 22R(T)(E) head bolts are tightened to a specified torque, and REQUIRE retorquing after the initial install. Whereas VZ engine head bolts have a totally different tightening procedure, and DO NOT require retorquing. There's practically no way that they could ever come loose if they were properly tightened to begin with. They're tightened to roughly 2x the final torque as R series head bolts. I've recorded readings around 120 ft.lbs. on the last 90° turn.
That's good to hear. I just had the valve covers off my 3.4 a couple months ago and was starting to think I missed an opportunity to re-torque my head bolts
I forgot to mention the paint marks on the bolt heads. If the bolts have moved since they were installed, the paint marks used to reference the final 180° of turn(90° + 90°) won't be facing the rear of the engine anymore. Assuming they're still visible, and were placed correctly facing the front of the engine to begin with.
02-28-2016, 06:39 PM
