2.0 Cylinder Gaskets, Should they be used? Options

[Bleyseng]

On any type 4 engine don't use the freaking cylinder to head metal gaskets as they leak. VW who actually built these engines came out later and said "No".

Do you base your opinion on what "everyone" says to do, or do you base your opinion on personal experience? How many Type IV motors have you built? Have you ever seen any issues with the head gaskets? Have you seen any issues because the head gaskets were left out?

My personal experience is I have seen more leaks in the sealing surface because the gaskets were left out. And I have probably built around 200 or so Type IV motors.

10 engines and I follow Raby’s and Len’s advice on this as they have plenty of experience too besides VW coming out with that service notice not to use them as they leak

[Mark Henry]

You should measure the combustion chamber volume as well as the deck height and calculate your compression ratio.

Deck height is not measured based on the wear marks in the cylinder wall.
Measure to the top of the piston to the top of the cylinder.
The wear marks in the cylinder are normally created by the piston rings not the piston.

I don't use the head gaskets and in my 20 years as a mechanic I never had a leak without the gaskets. The expansion and contraction cycles as the engine heats and cools cause the gaskets to squirm around and sometimes fail.
The AMC heads I put on my 78 bus said not to use head gaskets with their heads. I don't recall an explanation for the instructions.

Good luck with the engine!

Take care
Jim

(IMG:style_emoticons/default/agree.gif)

I don't use head gaskets and I always measure CR (IMG:style_emoticons/default/biggrin.gif)

My 102mm nickies T4 and all the 96mm performance engines I build have no head gaskets. I've been at this 30 years and I haven't used head gaskets in the last 20 years. But every set of heads I use is a fresh fly cut.
BTW Every head gasket solution that you can think of including copper gaskets has been tried.

[HAM Inc]

I understand that the laminated metal gasket can be problematic but what is so unique about VW Type 4 heads that makes them fail? Laminated metal gasket is commonly used on water cooled engines all the time.

Maybe the fact that heads run so much hotter than a water pumper?

Then I wonder, why not use a different material like copper? Norton Commando's use a copper head gasket and they are air cooled. I think some other Brit bikes used copper as well.

I suspect that in the end the aluminum head is soft enough vs. the steel jug to deform and basically form it's own seal and account for a 0.0005" - 0.001" inconsistency between any of the mating surfaces. Sort of odd that air cooled 911 heads use a head seal though?

Like other's I haven't used laminated gaskets but as I read this thread I'm wondering what the real development history behind it was.

Excellent question, and the answer hits at the heart of the problem.

For the laminated gaskets to stay laminated they have to have even crush, all the way around. For that to happen the case spigots have to be deadnuts level and exactly on the same plane, the jugs have to be deadnuts the same ht., and the heads have to have the same level of precision as the case. Having decked over 150 cases over the years and seen how wildly uneven the spigots have been all but one (a low mileage 911 case) I can tell you the likelyhood of success of all 4 laminated gaskets on an old, undecked case (or an improperly decked case) is bleak.

Next, at operating temps the clamping has to be perfectly even and the expansion of of both chambers in each head has to be the same for that to happen. This is rarely the case.
Shuffling of the heads on the jugs frets the gaskets.

Frankly I consider it a miracle that any of them make it. I feel like Clay's success probably stems from careful builds, good tuning and frankly speaking some luck, unless he did all his machine work, too. (IMG:style_emoticons/default/biggrin.gif)

[Superhawk996]

@HAM Inc

Thank you for taking the time to post the explanation. That helps satisfy the engineer in me.

When you think of all the tolerance stacks in VW/Porsche motors it seems like a bit of miracle that they work so well and have proven to be so durable.

[jack20]

I just wanted to thank everyone for responding to my post on whether or not to use head gaskets when I put my heads back on.

The consensus is not to use the gaskets. I don’t know how many miles the existing gaskets have on them and since I now know they’re laminated I would want to replace them. I would rather just buy new base gaskets and eliminate a potential problem.

I’ve done some measurements and determined that my engine is totally stock. Bore and stroke match the engine specs found on the Pelican site.
The German pistons are dished.
The head gasket is ~ .8 and the base gasket is .2mm equaling 1mm of total deck height.

So my choices are to replace the laminated gaskets and substitute a 1mm base shim for the .2mm shim or to buy new .8mm laminated gaskets and re-use the .2mm shim.

Some of you suggested I measure the volume of the combustion chamber to determine the compression ratio. If I do that I will also need to pull a piston to get the dish volume. The heads are stock and the pistons are stock. I can’t imagine I would find much deviation from the stock comp ratio of 7:6 if I do either of the suggested options.

I believe I’m down to these two choices but I tend to over-think things that are new to me.

Please let me know if my logic is flawed. In the meantime, thanks again for all your input. I really appreciate it.

Jack

[Superhawk996]

Some of you suggested I measure the volume of the combustion chamber to determine the compression ratio. If I do that I will also need to pull a piston to get the dish volume. The heads are stock and the pistons are stock. I can’t imagine I would find much deviation from the stock comp ratio of 7:6 if I do either of the suggested options.


Jack

I know I'm going to get blasted for having said this (IMG:style_emoticons/default/stirthepot.gif) (IMG:style_emoticons/default/happy11.gif) but if you can't measure CR and you're staying stock and have very near to stock deck height, you will be fine.

Is it best practice to CC the heads and even things out. Absolutely. All manufactured componets have nominal tolerances that were designed to yield a perfectly functional engine regarless of how the parts intermixed at the time of assembly. Did some engines come with a litle higher CR and/or a bit more Horsepower than the next one? Yup. Did some come with a little lower CR and maybe down a smidge on power. Yup.

Did the factory build them without CC'ing heads and perfectly matching CR cylinder to cylinder. You betcha.

Depending on the dish of the pistons, if they are stock pistons as you mention someone can post the standard CC volume. You could use that and still CC the heads if you were curious.

CC'ing and equalizing CR is all part of the game if you're trying to build the best possible engine you can with the parts you have. Basically working in the vain of "blueprinting" the engine. However, that is not the way mass production assembly lines work.

As a side note, I should mention that deck height is important for for other reasons beyond Compression Ratio. You don't want to go too tight on deck height. If I couldn't measure all components and do CR calculation, I'd make sure to err on having just a bit more deck and a slightly lower compression ratio.

[jack20]

You won’t get blasted by me. I appreciate the perspective you laid out.
I could go to the trouble of buying the components to CC the heads and frankly I’d like to do it but given what I’m trying to accomplish, I don’t think I’d really gain anything. This project started out as a pushrod tube seal replacement. I pulled the heads to check the carbon buildup on the pistons and combustion chamber on this ~50,000 mile engine. That’s when I noticed the head gaskets. My 356 doesn’t have head gaskets and that’s why I asked the question about the need for them. My research before posting caused me to think they should be eliminated. This engine runs well so all I want to do is de-carbon, lap the valves, change the tube seals, either replace the head gaskets or eliminate them by creating 1mm of deck height at the base.
Everyone has weighed in with very valuable info and I have learned a lot.
This forum is superior to any car or motorcycle forum I’ve experienced.