2.0 Cylinder Gaskets, Should they be used? Options

[jack20]

Hello,
I had leaking pushrod tube seals and dropped the engine to make the job easier.
I decided to pull the heads to check condition. I’ve done quite a bit of reading about whether or not gaskets should be used between the cylinder and case and between the cylinder and head. Some posters point to a service bulletin stating not to use gaskets.

I have metal spacers/gaskets between the heads and cylinders. I think this engine has been rebuilt once before I got it. It runs well but it’s not as quick as another 914 2.0 I had years ago. Maybe the other car had higher compression and no gasket? I’m wondering if this metal gasket should be there. I haven’t checked for a gasket between the cylinder and case. My 356 has a thin copper gasket between the cylinder and case.

Can anyone shed some light in this?

Thanks in advance,

Jack

[ClayPerrine]

You have opened a can of worms with that question.

Lots of people say to leave the gaskets out because of a technical bulletin issued around 78 or 79 that says to. But the bulletin never mentions the 914 at all. They say to lap them like you would do for valves.

I don't do that. I use the head gaskets. I cannot see how anyone other than a professional engine builder would be able to lap the cylinders into the heads and get the deck height to within .001. You certainly can't do it in a home garage. So one cylinder will be tighter than the other when that side is assembled.

I have never had an issue in the 35 years I have been working on these cars.

Clay

[iankarr]

...and the shims between the cylinders and the case are primarily for setting/adjusting the deck height...

[jack20]

Thanks Clay. I understand what you mean about deck height. Regarding the cylinder to case, is there a gasket in that location? I’m seeing some oil weeping from all four barrels. If no gasket, would it be appropriate to seal the barrels with a narrow bead of Ultra Gray or Curil T?

[jack20]

OK, Cuddy. I haven’t pulled a barrel yet but on my 356 I used Curil T on both sides of the copper shims. That should stop the weeping on this car.

[ClayPerrine]

OK, Cuddy. I haven’t pulled a barrel yet but on my 356 I used Curil T on both sides of the copper shims. That should stop the weeping on this car.

I always use a thin bead of Drei-Bond on both sides of the bottom cylinder gasket to make sure it doesn't leak oil.

[bdstone914]

@ClayPerrine ' date='Apr 9 2020, 12:31 PM' post='2802542']
[quote name='jack20' post='2802528' date='Apr 9 2020, 02:14 PM']
OK, Cuddy. I haven’t pulled a barrel yet but on my 356 I used Curil T on both sides of the copper shims. That should stop the weeping on this car.
[/quote]

I always use a thin bead of Drei-Bond on both sides of the bottom cylinder gasket to make sure it doesn't leak oil.
[/quote]

I hear your argument Clay. But the last two 1.8L engines I torn down had original gaskets that got sucked in at a small area and created a leak. Wish I saved them and look pictures.

Bruce

[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".

[HAM Inc]

Leave out the headgaskets.

They are made of laminated steel. Over time many will delaminate. This leads to the gaskets getting sucked in, as BD reported.

I have seen countless T4 heads over the years, Bus and 914, that did this and the leak was ignored long enough to burn a trough in the head you could stick a finger in. This almost always ruins the jug, too.

Lapping is not needed if the surface finish of the heads is smooth.

Lapping doesn't hurt anything if it's done very carefully with fine grit compound, but the idea of lapping originated in the days of the proliferation of bolt on flycutter's, which in good hands did a fine job, but in the typical hands out there left chatter marks or streaks. These imperfections needed to be lapped down.

Heads that leave our shop do not need to be lapped and we advise our customers not to.

[jack20]

You all have been very helpful. I appreciate it.
So VW put those metal gaskets in to reduce the possibility of oil leaks but cause a potentially bigger problem.
Clay, you were correct about opening a can of worms. I researched many old posts before asking the questions. I wondered what the current thinking is.
Obviously I’m no journeyman mechanic but have done a little of the type of work on other air cooled engines.
If I leave the head gaskets out, will deck height be effected to a point where I will have problems with too high compression or any other problem?

Thanks to all.
Jack

[HAM Inc]

You will need to make sure you have adequate deck ht. No less than 1mm

The headgaskets are ~.8mm thick and do count as deck ht.

If you don't use the headgaskets you may need to put a shim at the base of the jugs to achieve the proper deck ht.

[jack20]

Thanks Len. I do have a shim at the base. Would it be correct to assume that the base shim and the head gasket created a 1mm or less deck height on a stock engine? If so, I will need to calculate how thick the base gasket should be to be under 1mm at the head. Have you been through this? If so what shim thickness did you choose? I’ve read that stacking shims is not the best way to create the needed space.
Thanks for your help.
Jack

[HAM Inc]

Don't stack jug base shims.

A single .8mm shim should get you the 1mm deck minimum since usually you will have at least .2mm without one.

Determining what base shim you need is easy. Just measure what you have without any shim at TDC. Subtract that number from 1mm and that's what you need.

If you need more than 1mm to hit your target CR subtract what you have from what the required deck ht is.

[Superhawk996]

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.

[jack20]

Len,
I just want to run this by you. I checked out some YouTube videos on measuring deck height on a VW engine. What I saw looks nothing like the deck height I appear to have. I just took a photo of my #1 cylinder which shows the extent of piston travel at the head.
I show roughly 6mm of unused surface. Does this look normal to you?

[ClayPerrine]

If you read the tech order from VW, it does NOT mention any type IV motor before 78 or 79. I actually worked for VW in the early 80, and confirmed this tech order does not apply to the older Type IV motors.

I have always run the head gaskets in all of the 914-4 engines I build. Betty's engine has 413,000 miles on it, and I have never had any issues with the head gaskets.


Almost all of the people on this thread are experienced in working on the 914 engines. But we all have different experiences, which gives us each different opinions on what to do. So read the responses, and base your decision on what you think is best.

[ClayPerrine]

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.

[jack20]

Thanks Clay. I certainly intend to do that. Right now I’m looking at what was done when this engine was rebuilt sometime in its life. I just posted a photo that leads me to believe that I could have excess deck height so I need to solve that before putting everything back together.
Jack

[jcd914]

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

[jack20]

Very helpful, Jim!
Thanks very much.