I need to remove the heads off of a newly rebuilt engine (4-cylinder) I built (never run). They have already been torqued. Are the head gaskets and gasket between the cylinder and block, compression gaskets that should be thrown away (i.e., replaced with new one) after I untorque the heads?

The head gaskets will be easy to replace. But I'd have to pull the cylinders to replace the ones between them and the block.

i would not disturb the base gaskets and you can anneal head gaskets and reuse.

The bottom are shims and should not compress.

The head sealing rings are designed to compress as and need to be replaced.

If you are cheap you can anneal them and hope for the best. They will return to there press installed softness but not shape.

Bigger question: WHY are you using head gaskets?

I think he's talking about head gaskets, not copper ex. gaskets. Copper ex gaskets you can anneal. Unless he's switched to an aftermarket copper head gasket the head gaskets are laminated aluminum. Never heard of anyone annealing them.

They should not be used in the first place.

But if you do choose not to use the gaskets, you increase your compression ratio if you don't put equally thick barrel spacers under the jugs.

You also reduce your deck ht by the thickness of the gaskets, which new is ~.75mm.

If you have 1mm or more deck ht in your cylinders and you are happy with the bump in comression then no need for barrel spacers.

If the engine was never run you should be able to retorque the gaskets if you want to reuse them. I would try to put them back in the same positions, though.

The VW tech bulletin everyone seems to refer to when this subject comes up does not apply to the 914 motors. People like Jake Raby have a machine shop that can make the cylinders fit into the heads perfectly, thus making sure they seal correctly. I don't have that ability, and the factory engineers designed them into the motor. And I suspect that those German Engineers are a lot smarter than any of us (Including Jake) when it comes to these motors. So I use them in every engine I build. And I don't have any problems with them blowing out.

And you won't notice the gain more HP by increasing the compression .01%.

At one point, at least, there were also copper head gaskets/sealing rings that were available for the VW Type IV engine. They did compress, and required you to periodically re-torque the heads. They were not favorably viewed by a lot of people for that reason--it's a PITA to re-torque the heads on the Type IV engine while installed in our cars!!

--DD

My thoughts exactly. I will change the head gaskets just to be safe. I just didn't feel like taking the cylinders back off to change the base gaskets. They are out of the Victor Reinz gasket set. I was hoping someone might know if they are compression or not.

The base gaskets will be fine.

Clay, it may be in a Porsche car but it's still a VW engine. The 1.7 and 1.8 heads and cylinders are identical but even the 2.0 heads, tweaked a bit by Porsche, didn't change the head to cylinder sealing surfaces, shape, dimensions or torque. It's still all VW. And the VW bulletin wasn't factory, it was addressed to rebuilders, so in the same situation that we are.

That being said unless I was that engine's builder and knew the clearances I'd just replace the head gaskets and put it back together the way it was rather than risking too tight deck height.

i know which gaskets op was referring to. mine are copper and reused them with no issue. as stated earlier, the people who designed the engine thought enough to include them, so i do too. mine dont leak and i sincerely doubt there is any performance to be gained by omitting them. the only only aircooled engines i have seen that run without a headgasket are english 500cc engines of the 1930's. they had a cast in spigot or "firewall" to seal them, but heads had to be lapped in like a valve. also, headbolts are supposed to be retorqued after heat cycling a few times anyway, i dont see that copper gaskets are in anyway inferior to the steel gaskets in the retorqueing area.

The last time I used any gaskets between the cylinder, and the head was in 1995. One more thing to fail, and I never trust 3 pieces of .007" aluminum formed together to hold cylinder pressures.

The gasket thats not there, can't fail.

The engineers of the Galaxy Note 7 thought it a good idea to include a 3500 mAh Li-Ion battery to a 8mm thick phone too.
Is that somehow evidence that they are infallible?

one generation of that phone, not ten years of production, so yeah in this case, as opposed to the phone.

For those in the "No Gasket" world, do you lap the cylinder barrels to the heads?

You must have also missed where two of the most knowledgeable type IV engine experts (possibly in the world) just said (above) that you should not use gaskets.

yeah i saw that, i also see the manual, haynes, vw/porsche say to use them. they have come each engine gasket kit i have gotten from renz. the world famous engine builders dont say how they prep head or cylinders. so i am going with the engineer who designed the engine and use the gaskets in my stock street applications on my cars.

Cool, but I wouldn't depend on Haynes as gospel, and if you're going to defer to the engineer who designed the engine then you need to eliminate those gaskets. Here, the last word from VW on that subject:

http://www.ratwell.com/mirror/www.dolphins...m/techbull.html

My own experience is that the failure rate is very small, maybe a percent or two and after a lot of miles, but those are still failures and there's no need for it. I know some builders still use gaskets, so it's not certain death or anything, and of course you can do anything you want with your own engines.

The tech bulletin specifically calls out

"Models(s): Type II/Vanagon 1975 - 83 MY Date: May 31, 1990"

I don't see Type IV anywhere in the listing, much less the 914.

you DO realize that the engine is exactly the same (with respect to the head sealing interface) as the 914 don't you?

If you want head gaskets in one of my T4 engines find another engine builder.

I hear GEX offer good prices....

You are the one who builds the motor. You have to stand behind your work. So do what you feel is right.

I will do the same.

I didn't mean to invite a debate. This issue has been widely discussed. Everybody can make their own decisions for their engines. For me, I will use a head gasket on a street engine. And I will suffer the consequences if it blows out. I was just curious if the head gasket, and base basket, are compression-style gaskets, needing to be replaced after untorquing.

New T4 AMC heads come with a big warning card in every box "Do Not use head gaskets".

BTW I just tossed out a couple dozen new head gasket sets.

You can lead a human to knowledge, but you can't make them think.

Words to ponder

No one's led us to knowledge yet, they've just said 'do what I say'. I was hoping someone might address that question of whether the head and cylinders need to be lapped together. Can I do it by hand? Depending on the tools required, gaskets might be the option I can afford.

^well said. my experience would lead me to lap the cylinders into the head with grinding paste to get a uniform surface. on a 1930's norton 500 single, easy to do without upsetting the cylinders and rings. on a type IV, not so much as you would have to remove cylinders and lap them into the head to get a uniform surface. i use the gasket because it is easier to get a tight mating surface without disturbing the ringland. on a blueprinted, heavily modified engine with lots of aftermarket components and custom machine work, i can see it. a stock street motor not so much.

The reason VW said to stop using the head gaskets is, the differences in expansion rates of the bi-metal relationship between the heads and jugs combined with the inevitable shuffling (relative movement between the heads and jugs) during operation causes the laminated aluminum gaskets to delaminate. That buletin was not written with performance engines in mind, but stock.

Once they start delaminating, they allow combustion gasses to escape, which quickly etches a big path that very often leads to serious damage to the head.

Here's the reality about lapping jugs into heads: If the finish in the heads from the flycutting is rough the lapping will smooth it, but if the surface is so rough that it needs that then how much confidence do you have in the machine works accuracy with regard to both chambers being the same height AND on the same plane. Also, lapping will remove metal from the heads, but do little if anything to ensure the jugs are flat.

If you choose to lap, make a paste out of ajax and count your revolutions so you can use the same technique on each postion. If a light lap doesn't clean up the both surfaces, time for a trip to the machine shop.

Many engine builders toss the gaskets and spray the heads with aerosol coppercoat a few minutes before assembly. Overspray will not hurt anything.

That's the low down on gaskets. Proceed with your engines as you wish.

Head gaskets installed on my current torn apart motor, pics below show deformation of gaskets and damage to head. Pro built motor, not a lot of miles based on how clean the motor was inside and outside under the tin.

(had a flat cam, the reason for the teardown)

Top pic shows one gasket that has deformed.
Other pictures show head damage, luckily caught before gasket failed completely allowing gases to escape and burning small ridges into head as they leave.

I will now have to make a flycutter to fix the head.

i could be wrong but what i see is a deformed gasket from improper torquing sequence, not a gasket failure. looks like one side was over tightened causing the gasket to deform. you can see the result.

pretty good eyes to see improper torque

Look pal, DIY's come here for advise. There are a host of professionals in various specific fields that apply directly to some of these questions who help our fellow 914 lovers.

In this particular case the O.P.'s question related to a very specific apect of an engine build. This issue was addressed by VW 40 years ago. It's actually settled technology.

And as if that weren't enough, at least 3 engine professionals - myself included -with well over 50 years of combined T4 engine experience chimed in to help advise the O.P.

I have no problem with your disagreeing with me. I really don't care. But you do a diservice to the O.P. and others tryiing to learn when you argue from a position of ignorance.

You've done this on other threads as well and have exhibited the kind of behavior that contributes to the spread of misinformation that the internet has, sadly, become famous for.

I know a lot of professional aircooled VW engine builders, and not a single one of them uses head gaskets on a typical build. Are you the one professional exception, or just an internet troll? That's a rhetorical question. Based on your technical postitions, I already know the answer.

So, it sounds like I need to consider not using head gaskets. I researched this some time ago, but, it seems that the consensus here is not to use them. Maybe somebody could post the process that needs to be performed to leave them out? Can this be done by a "garage mechanic" like myself?

i do use the gaskets, i think you mean aircooled vw engine builders, sorry i dont worship at your altar, that does seem to bother you and i aint your pal.

There seems to be a difference of opinion here and it is not going to be solved over the internet.


Do what you think is right, and I will do what I think is right.

My lapping procedure is actually quite simple.

I use valve grinding compound, not because I think it's the best, but because I have a huge can of it that was given to me. I put an even coat on the sealing surface of the cylinder, place it in the head and turn it a couple times (no pressure)complete turns, then check to see that I have an even coat.
I then turn it so it facing the direction it will be installed. I grab it with both hands and rotate back and forth the limits of my wrists, I put slight downward pressure to make sure the head doesn't lift or cock in the bore.
As I start I look at the clock, I keep a steady cadence and I do the same amount of time on each cylinder. The amount of time will depend on your compound, mine is fairly aggressive and I only have to do 1-2 minutes each bore. Once I have a clear, even lap it's done.
I mark every cylinder and bore so they stay in order, very important.
Cleaning has to be spotless, again very important.

If you are doing a real good job you should also have your case bores surfaced/decked, I do this as a part of every build now, as I find many are out of spec.

The last detail is do a freaking CR check, (plus deck height) and shim it for a correct CR.
Google engine calculator and plug in the numbers, I can do the math, I don't need a calculator.
Head CC you can buy the plate kit or make one out of 1/4" clear plexi, you can get a CC syringe from a drugstore, just tell them what you want it for, tell them you don't want the needle and you want the biggest they have. PITA because 10cc is likely the biggest they have, but in a pinch it works. Just don't lose count. Oil will kill the rubber stopper, you can use water, but put a drop of Dawn dish soap in it to break the surface tension.
You can get custom shims made by RIMCO and EMW keeps a stock of shims. You can use up to 3 of the thin factory shims but no more. They must be shimed exactly the same.

That's it, I've never seen the need to go full rotations. Many years ago I talked to a swiss trained master machinist friend about my procedure and he agreed with it, BTW same guy who gave me the big can of lapping compound.
My heads never leak, at least not till it's time that they should be rebuilt anyways.
Been doing it this way for years.

For those of us watching from the side lines, I think this captures the question.

If you buy a typical set of cylinders and don't have access to have the top surface re-machined, and you heads are freshly done by a competent (but probably not a specialist) machine shop, are you more or less likely to have issues with or without head gaskets.

And if you are leaving the head gaskets out, do you have any additional prep required??

To roll all the way back to the OP, if his engine was built with head gaskets, what is the chance he can reseat the heads without them?

How much risk is there due to the slight increase in compression and/or the slight decrease in effective deck height?

Exactly. Leaving them out is not as simple as . . . well, just leaving them out. And the proper process needed to leave them out is beyond the scope of my expertise and tools, in this area. I have built quite a few street engines over the years, always put them in, and never had a problem. Also, as I understand it, most of the problems that have arisen using them, have occurred after quite some miles (tens of thousands). Most of us aren't putting that many miles on our 914s these days, unless it is a daily driver.

Having said that, there seems to be a large enough of a concensus that they should be left out to cause me to want to reconsider my traditional choice. I respect the learned engine builders here, and certainly want to benefit from their expertise.

I found one at a farm supply in the "veterinary/medicine" department.
It was ....wait for it...... 60ccs.

In my area the store is Murdoch's I don't know what you have in the GWN.

Vets will have larger syringes as they get used for hand feeding small animals.

I've never had to find one, wife works at a hospital.

I thought that too, however that deformed part is on the hotter exhaust side.

I'll see if I have the pictures of the other gaskets.

^that makes sense to me, in that the the exhaust side runs much hotter, (hence, the the sodium filled exhaust valves or nmeumonic exhaust valves, to disisapate heat more efficiently reside.) if the deformation was in that area, the exhaust stroke will reek the havok you see by a faulty seal. but iam sure HAM,INC, has a well reasoned explanation as to why i am full of shit and you need a set of new $2,000.00 heads.




6

You're a special kind of stupid aren't you.

Would you like me to count the the number mistakes and misinformation you've made in this thread alone?
Because bud you've made plenty.
You are nowhere near an expert on this subject, in fact you're a piss poor amateur.

"nmeumonic exhaust valves" What? Are you saying nmeumonic is a material?

Thoughts!

Lapping barrels to heads:

Since the materials are significantly different in resistance to abrasion (what lapping is doing) most all the wear (lapping, polishing) will be on the softer material of the head.

Lapping valve makes sense because the materials are of similar hardness, and they rotate in operation so you ant a surface the seals at any position in the rotation.

So lets take three different assumptions.

1) Machine marks in the sealing surface of the barrel are concentric.

Lapping the head slightly polishes the barrel, while shaping the matting surface to match these concentric marks. - Yielding an
improved seal.

2) Machine marks are not concentric; perpendicular, axial, or even random.

Lapping the head polishes the mating surface to near flat (average of random barrel surface), and slightly polishes the barrel, yielding a slightly improved seal.

3) Machine marks are radial or spiral but not concentric;

Lapping again polishes the head to near flat depending on the degrees of rotation. Example, machining with a slow spiral pattern and a relatively small rotation (less than 1/4) would actually cut matching groves into the head. In this case the seal is only improved if the head and barrel are assembled near the mid point of the lapping rotational arc.

(Not arguing, just thinking)

Obviously gaskets have their own issues, especially with the high temperatures and relative motion (Difference's in expansion, of heads barrels and studs, etc.)

I wonder what would happen if you machined a slight grove into the top of the barrel (decreasing the surface area and therefore increasing the contact force) and use a o-ring shaped deformable gasket to make a secondary seal?

Porsche totally deleted the head gasket/ring by the 3.2... OMG the 3.2 /6 has no head gasket! The horror!
Must be their worst engine.

Mark, thanks for that procedure above, that's what I was hoping for.

You seem to miss the point that "designing in" or "designing out" a head gasket is a DESIGN issue.

Machining, materials, and assembly specifications all come into play.

EDIT:
This takes me back to working in a chemistry analytics lab at school.
We had machines that needed very high and very low pressure seals at very high and very low temperatures.
Most common seal was two machined flat surfaces and a gold wire as an o-ring. (That, and lots of bolts for even tension.)
Some has a grove for the wire, some did not. (all specified a real gold wire o-ring, but the school was cheaping out.)

Picture "borrowed" from brand new post on the 914 Facebook page.

Gasket failure,

Click to view attachment