6.5 or 6.2 head gaskets???

[Ratkilr]

I am going to install 6.5 heads-intake-exhaust manifolds on a 86 6.2. Which head gaskets should I use? I understand there is a water passage difference between the two. but I am unclear on which gasket I should use. I have read that there can be a external coolant leak if the right one is not used.

 

[WarWagon]

Use the 6.5 head gaskets. Supposedly they are better for turbo applications. I have seen some weird shaped gaskets come off surplus 6.2 military engines. Regardless using 6.5 head gaskets on 1985 6.2 diesels worked fine for me. Careful as some of the old (pre-1991) 6.2 gaskets contained asbestos. The rumor of an external coolant leak is simply a krap install job. What difference does it make when the bore size is the only difference between a 6.2 and punched out 6.2 aka 6.5? Yeah, None.

Do not use gaskets on the exhaust manifolds. They are warped if soot (that these engines generate plenty of) doesn't seal them up. Gaskets blow out or walk out leaving a hole bigger than soot can seal up.

 

[Will L.]

What’s the best brand of gaskets to go with. The go to has been Felpro or VictorReinz.

But recently VictorReinz is now under the label of Mahle. While Mahle has a good reputation for the metal products they make, idk about their gaskets. And are they different, or they same high quality gaskets just with new company ties.

I would (and by time I do mine will if no one else has by then) call and clarify about the situation.

Go to Felpro just to be safe? But I have heard of 3 blown headgasket possibilities recently and the people had 6.5 with arp studs too- and not leaking past the threads as a blame to the only known disadvantage of studs vs tty bolts.

2 of the 3 possible headgasket failure issues are guys from this forum. I don’t want to air peoples laundry, but if they are willing to talk it out here on could it be brand failure issue- I think that may be a conversion worth having. Often someone thinks they are the only one and later many find common issue.

I have no clue who I will use at this point, and even want to dig up the conversation about cometics. I had problems with them years ago on two 6.5 engines. One was very questionable if the gasket was the issue. The other I and a few others that looked at it all blamed gasket failure. Then I read about 2 other people that had descent 6.5 reputations say no cometics, and that closed my mind to them for years. But since then have heard others say they prefer them.

Anyone with experience on any failures, please speak up on Felpro, Victor Reinz, our cometics.

@Ratkilr if this is going sidetrack from what you are after, sorry and lmk- I will edit this out and start seperate thread.

If anyone has any theory of heat/pressure testing them, I would buy and ship one of each to whoever has a way to test.

 

[Ratkilr]

I was just under the appresion that ether the 6.5 head or the 6.2 block “I think” has a small peanut shaped water passage on the ends of the block or heads mating surface the will interfere with the wrong gasket if used??

 

[Will L.]

The water passage is larger on 6.5, so use 6.5 gasket.
Also like WW mention they are designed for more heat and pressure.