The Head Gasket

[DNK]

On the Wedge, Composite gaskets and the head will be on for a few months with maybe only a mile or so on the odometer after the install.
Should I put something,oil(?) on them to facilitate a speedy and easy removal?

 

[TomMull]

Back when I was a kid, the "old timers" (younger by far than I am now) put grease on them. I don't think it did much, though. Should come right off with no goo at all.
Tom

 

[DNK]

Pretty sure the one I took off that had about 300 miles on it
came right off too.
Just don't want to buy a third

 

[Darrell_Walker]

When I changed mine last year, the consensus was dry.

Do the composite gaskets crush? Not sure I would reuse any head gasket, other that perhaps solid copper.

 

[DNK]

Good point Darrel.
No matter what the usage?

 

[Darrell_Walker]

Good point Darrel.
No matter what the usage?

I would never reuse the steel TR8 head gasket, as it it meant to crush when installed.

The more typical composite-sandwich type may be OK, but given the effort to get the heads off on the TR8, I wouldn't risk having to redo it. I don't think it would try to reuse the valley pan gasket, either (and that was much more expensive than the steel head gaskets).

 

[DNK]

hmmm, Think I remember Woody saying it was OK
He didn't ship me a new one 300-400 on the old one

 

[Darrell_Walker]

hmmm, Think I remember Woody saying it was OK
He didn't ship me a new one 300-400 on the old one

Wow!

 

[DNK]

Miles, Darrell

 

[Darrell_Walker]

Miles, Darrell

Oh, OK.

 

[tr8todd]

I would never reuse a head gasket. A local reputable engine builder had a problem with a stroker Rover V8 he had just built for a buddy of mine. The newly built engine was on the dyno and the gapless rings were causing negative crankcase pressure. He pulled the whole thing apart, bought another set of new forged pistons slightly more oversized, steel rings, and a new set of Cometic head gaskets. Point is the builder wouldn't reuse the gaskets which cost around $250 a set and he was the one standing behind the work and he was footing the bill. Engine has been in the car for a few thousand miles and so far it runs smooth and powerful with no blow by.

 

[TomMull]

the gapless rings were causing negative crankcase pressure.

Hmmm???

A new composite head gasket will certainly give the best chance of sealing properly but I've reused more than my share without incident. Hard to recommend for a mere thirty bucks though.

Tom

 

[tr8todd]

Something about the rings sealing when under pressure but not sealing on the downstroke under negative pressure. I didn't buy that explanation at first either, but the builder rebuilt the engine at his expense and all seems well. The folks from gapless rings told him to go back to steel rings.

 

[TomMull]

Interesting. Perhaps someone can enlighten us. At the risk of straying somewhat off the topic, my 92 BMW is designed to run with negative crankcase pressure. (I cracked the oil pan at a road construction site once and drove the car fifty miles. It didn't leak much at all until I shut it off and then it drained like I pulled the plug.)
Tom

 

[tr8todd]

I would assume your BMW engine has a PCV hooked up to manifold vacuum. This Rover engine had nothing hooked up to it while it was getting broken in on the dyno. At first everyone was like cool no engine blowby. Then they realized the engine was consuming oil and there was actually a small vacuum being created that you could feel when you put your hand over the oil filler. Rover V8s are known to have blowby or positive crankcase pressure. The amount of blowby is determined by who built the engine, how it was built and what parts they used. The engines with really big cams that wash lots of fuel down the cylinder walls at idle seem to fair the worst as the rings never seat well and the crosshatching on the walls gets worn away. Many of the guys with the 4.6L and up engines are using a vacuum pump to draw out excess pressure and also to create vacuum for the brake booster. That is if they are using a big overlap cam that doesn't make much vacuum. Somehow negative crankcase pressure makes more HP, but the biggest advantage is not spitting out oil pan gaskets and dipsticks every time you romp on it.

 

[70herald]

my 92 BMW is designed to run with negative crankcase pressure.
Tom

I don't know for sure but it seem to me that the neg pressure would be created by the PCV valve and there is no reason that the pressure can't be set for whatever the manufacturer thinks is desirable by balancing the amount of air sucked from the crankcase with the total blowby, leaks, outgassing.... if there is more sucked out then the pressure is going to go negative.

 

[DNK]

What was my question again?

 

[TomMull]

What was my question again?

Sorry, had to look it up. But you will admit that a head gasket change is not all that interesting? Good luck with yours. Cheers.

Tom

 

[DNK]

like watching paint dry

 

[tr8todd]

Blowing them up is more fun than putting them back together!!