Third head gasket job- why are they failing?

[Red Top Engine]

I rebuilt my engine nearly 5 yrs ago. Had the heads, block, etc checked and replaced everything that could be replaced. Runs and drives great, no coolant loss etc. 2 years later, head gasket failure symptoms presented themselves. so I took it apart thinking the head-bolt threads are wearing out, re-threaded block using NS300L tool, and re-installed heads with new bolts, gaskets etc. 2 years later to the date, leak down test confirms coolant being displaced primarily on cylinder 7, and slightly on 5. I purchased my gaskets from AB, which I believe are OEM. Are there are other gaskets out there that are above OEM specs? What exactly causes these gaskets to fail?

 

[greiswig]

Heads decked and all mating surfaces flat? Is there a retorque procedure that's supposed to happen after thermal cycling the engine or anything like that?

 

[Rover Range]

There's no requirement to retorque the head bolts after installation.

The head gaskets leak due to not enough head bolts and little material between the cylinders.
IMO. A long block is truly the best long-term fix.

 

[greiswig]

A) It's really great to have someone like @Rover Range who can weigh in on threads like this with real knowledge. Thank you!

B) A friend had a diesel engine that had trouble with head gaskets, too. On the advice of an old German mechanic, I got a spray can of some blue stuff made by Rolls Royce for their aircraft engines. I believe it's a high-temp polyurethane. We sprayed a thin coat on both sides of the head gasket and assembled as usual. He's gone at least 100k more without further symptoms.

 

[Red Top Engine]

Appreciate the quick feedback. Pretty sure the matting surfaces are flat across all angles, but will double check. In all the head gasket jobs I've done (on many other models too), I was told to install dry. This Rolls Royce spray can has be intrigued and I will look into it. In speaking to AB 2 years ago, they have not had any complaints on failing new gaskets. But then again, not everyone who experiences this complains. I suspect a brief cross state trip of running the engine with low oil may have been the cause, but truly not sure. The cause of that oil leak was found by a missing VVT cover bolt I must have missed. The last two head bolts along firewall side of cylinder 7 I could not rethread due to lack of space, took chance on torquing to spec in original state. Those are the only anomalies I could think of. Should I purchase my 3rd headgasket from AB? Do they differ from the OEM?

 

[Rover Range]

Go with OEM head gaskets.

 

[greiswig]

This Rolls Royce spray can has be intrigued and I will look into it. In speaking to AB 2 years ago, they have not had any complaints on failing new gaskets.

I would treat this spray as a “last resort” kind of solution, and really check the heads and block for trueness. The spray is tenacious, and will be hard to remove from anything you get it on. But my friend was in exactly that situation, where he was about to get rid of the vehicle because he couldn’t keep it running. It’s still running now.

 

[scapistron]

Just want to reiterate that the best long term solution is going to be a long block. That said the engineer in me couldn't let the Rolls-Royce adhesive thing go. Hylomar makes a number of non-setting jointing compounds. They are blue, from a UK company, and one even carries Rolls-Royce approval (PL32A).

Your truck, your choice.

 

[Red Top Engine]

The temp specs on the PL32A has me hesitant to to move forward with it for now. I'm leaning on installing OEM gasket with new head bolts, and pray it surpasses the 2 year cycle for now.

 

[itsaguything]

FWIW, at 170,000 kms I’m on the original head gasket. OE is the way to go.

There is sometimes a difference between OE and OEM…

Cheers!