I am currently rebuilding engine. In order not to tire everyone with a lot of newbie questions I have been searching the forum (thanks for the tip Cap´n).

There has been a lot of debate about using or not using head gaskets. Is this the VW tech bulletin which has been referred to in some of the post recommending not to use the head gaskets? VW Tech bulletin head gasket

David

that is the basic explaination.

I would suggest you assemble the motor dry and measure your deck height (top of piston to top of cylinder) to determine your compression ratio first.

then you can use a combination of a head gasket (if you chose) and a cylinder base shim to set your CR properly.

Those measurements stated in the bulletin may not even be close to what you really need.

FAT Performance uses head gaskets. European Motorworks uses head gaskets. As it turns out, so do I.

You use lots of things that maybe only you would use

A three letter acronym of a certain substance that smears all over the place.....
Things like that ....

I don't use them, new AMC heads have a big red warning tag telling you not to use them.

But I do check CR and use cylinder shims.

That's it. Applies ONLY to certain VW Bus engines, NOT 914s.

The Cap'n

I haven't built a single engine with head gaskets since 1997. I've never had an engine come back to me with a head leak, either.

The key to keeping the heads sealed off is controlling expansion, and the key to controlling expansion, is directly related to thermal control.

To me, the part thats not there, can't fail... I'd pull them out even if I never saw the VW bulletin.

Do something for me, Cap'n. Look at the date on that bulletin. Manufacturers are required to support their products for ten years, meaning Volkswagen had an obligation to issue that bulletin while Porsche, who had stopped selling cars with those engines more than ten years previously, had no obligation. But they're the same engine if installed in a Volkswagen or a Porsche, aren't they? So why would VW's advice be any different if their engines were installed in Porsche cars or VW's?

The problem VW was addressing was the tendency of their head gaskets to fail and burn through the gaskets, usually but not always on high mileage engines. Aircooled engines run hot and the VW design sandwiches an iron cylinder between an aluminum case and an aluminum head, where the heat cycles from normal use repeatedly compress the head gasket, eventually consuming all its flexibility and ability to seal. Combustion will eventually erode through a head gasket, and usually take the head with it. You may have never had the problem, I don't know, but Volkswagen did, and they had it a lot. They didn't issue that bulletin frivolously, defective products are a very hard and expensive thing for any car company to admit. It's not an imagined problem, there was a good reason.

Nothing in that bulletin addresses the 914.

I haven't built a engine with head gaskets in at least 15 years, I've only ever had one engine failure and it was the last head gasket I used. Blow torched right through it.

Even Porsche eliminated head gaskets on the 3.2, but I guess that's OK because the factory did it.

worked well on the 3.6....which they ended up putting the head gasket back in under a TSB after a few years of problems.

On a type 4, I do not run them.
I also dont plan to see 100k miles on any of my type 4 motors before I die...
I am far to ADHD to wait that long, so I change the motor around anyways every once in a while.
My latest rebuild lasted (in my head) about 1 hour...now I MUST change the camshaft not due to any breakage, I just chose the wrong camshaft for my goals.

I would not use one, Like Jake said, its one less variable that you have to worry about.

Rich

When I worked on my motor I searched all the threads on head gasket usage and noticed people only talk about head gasket failure.

For those of you in favor of using the head gasket, what's the failure when no head gasket is used? Has anyone experienced a head seal or overheat issue because of no head gasket?

The Porsche six cylinder engines aren't really comparable. First because they have individual heads, so get more uniform clamping, and they have aluminum cylinders between aluminum heads and case, all similar metals. The cast iron cylinders in the VW T4 motors are the real problem because they react differently in the heat expansion/contraction cycles than the aluminum heads and case.

The 911T had iron cylinders.

Sorry. So Porsche sixes "generally" use aluminum cylinders, but point's the same, they aren't a good comparison.

The "blowtorch effect" is made worse with the headgaskets because it creates a sandwich of dissimilar materials. Once a leak occurs with the gasket, the heads are usually toast. I think the copper in the gasket makes it worse.
If a leak occurs without a gasket, there is a greater chance of saving the head.

I have not used the gaskets since my first type IV rebuild in ~89.
Since that was almost before the internet, I have no idea where I even learned to NOT use them.

Never had a blowout either.

"But they're the same engine if installed in a Volkswagen or a Porsche, aren't they? " No, they're not. The head design on the 2.0 914 is substantially different from that of the Bus. "Supporting" the engines means supplying parts, NOT fixing them or addressing problems beyond the written warranty period. You see Porsche supplying a "fix" for the smogged up 2.7 ten years down the road? Or, beyond defective valve guide replacement, even during the warranty period? I think not. You'll note the changes under discussion affect only certain original and factory remanufactured engines, hence the statement: "These changes effect Engine codes: GD, GE, CV." Note the elimination of head gaskets goes along with piston lubrication, increased piston to cylinder clearances, and replacement of the paper base gaskets.

I know Jake doesn't use head gaskets, and we've had discussions to that effect. He does a lot more engines than I, and he doesn't just "rebuild" them. EVERY case is selected and remanufactured according to strict guidelines he has established for his work. Few, if any, are what you would call "routine rebuilds". Most, in fact, are what you could call "modified for performance purposes". Some cost a lot more than the cars they're going into.

If you're willing to put the kind of basic prep work into your engine that Jake does, the absence of head gaskets is probably not going to be a bad thing. How many folks here have the cases checked for warpage, and corrected both at the bore AND the deck? People on this forum complain about the cost of a rebuild, and they don't even do a proper "remanufacture". Most just do the minimum and forget it until something fails prematurely. Not so Jake, and not so me.

The Cap'n

The 2.0 heads have a different combustion chamber, sure, but how, exactly, are the sealing surfaces any different? Again, the engine codes cited were the only ones sold by VW in that ten year period, meaning those were they only engines that VW was obligated to address. And the sealing of the heads in those particular engines are no different than any other T4 engine that came before. Only difference is falling within that 1980-1990 period or not.

Those were VW's instructions to re-manufacturers of VW products, so why exactly would it make a difference whether it's a production rebuilder, a local shop, or a home mechanic? VW's only obligation is to detail best practice recommendations, and that's what they did. At this point both Porsche AND VW are out of the picture. You know their best-practice recommendations, whether or not you follow them is your choice.

RTV is NOT an acronym. FAT Performance uses it, European Motorworks uses it and as it turns out, so do I.

I THOUGHT he was talking about 'KY'

I thought he was talking about POO. Not an acronym either, but a funny visual.

I used head gaskets on my engine build.. No problems at all with the engine.....

RTV = room temperature vulcanizing -

I usually do not use head gaskets. I have the heads fly cut and also lap them to the cylinder. However on my last build, I had trouble lapping and as I looked closer, a rim around the combustion chamber on the head was butting against a rim around the cylinder wall. This would keep the cylinder from sealing tight with the head. In this case, a head gasket gave me the clearance I needed.

Ummmm, yes, in fact it is an aconymn.

room temperature vulcanization
RTV Silicone (room temperature vulcanization silicone) is a type of silicone rubber made from a two-component system (base plus curative; A+B) available in a hardness range of very soft to medium - usually from 15 Shore A to 40 Shore.

An acronym is a word. Like radar. (RTV is not a word) A word that is made up of the initial letter, letters or major parts of a compound term. Scuba is a word. You're probably right though. WTF (not an acronym) do I know.

Love grammar debates. Ellyutt is right. RTV is technically an initialism, not an acryonym.


Oh yeah... what were we talking about again?

European told me not to use head gaskets. idk man.

I like.

Of course this whole argument is moot if using 96mm P&C's.



I would expect that, did you by chance buy 96mm from them?

Just a point I would like to make.....


Betty is driving a 914-4 that has 365,000 miles. During that time the engine has always had the head gaskets installed. And it has NEVER experienced a head sealing issue, EVER. The engine has been rebuilt 3 times since she has owned it. The first one at 150,000 miles.

There is nothing in any Porsche manual or bulletin that says not to use them. And I have had excellent results using them.

Look at it this way....


If you use the head gasket, and there is a leak between the head and the jug, you burn a slot in the gasket. You take it off and throw it away.

If you don't use a head gasket, and there is a leak between the head and the jug, you will end up burning a slot in the head or the jug. Repairs to the head will be expensive. The jug will have to be replaced, and that is expensive too.

I consider that cheap insurance.

True, but why is the "Porsche" part even relevant? It's a VW engine in your car and a VW tech bulletin. Is it really prudent to ignore their advice? Their advice about their own engine?


Unfortunately that's not how it works. I've never heard of a gasket failing without damaging the head, unless it was caught in time purely by chance. The material in the crushable head gasket is softer than the aluminum head or the iron cylinders so the flame will indeed burn a slot in the gasket first. But that hot spot in the gasket enlarges every time hot compression gasses get squirted through it, eroding the metal. The slot never gets a chance to cool so very quickly (no shit quickly) it burns a channel into the aluminum head. That's the "blowtorch effect" that's been mentioned. An aircooled engine makes a lot of noise, so unless you know what you're listening for you won't hear it until it's already bad enough to have trenched your head past where it can be fixed with a fly-cut. Once started it can do that damage in one good stretch on the freeway.

For good order's sake it is entirely possible that the same thing could occur if no gasket is used. If it does the damage will be no different, it will trench the head, it's just less likely (according to VW) if there's no soft metal head gasket giving the flame front an easy place for a hot spot to start and then breach.

Other thing, it's not an "OH NO, WE'RE ALL GONNA DIE" thing, it's more like your doctor telling you to cut back on the smoking (or bacon, alcohol, extreme sports, whatever) or bad things could happen. Those bad things are more likely if you don't change your habits, but they aren't inevitable. There are lots of old guys who smoke, just not nearly as many as old guys who smoked as old guys who didn't. You haven't had a problem? Great.

You also don't need to believe VW tech bulletins (or anything else you read on the internet), but the next time you talk to an old-time VW mechanic (once again, that's a VW engine in your car) ask him about head leaks. He'll have a lot of interesting things to say.

EDIT: This horse is way dead and I'm done, but need to clarify that there ARE times when a head gasket is a good idea. When you have questionable machining from a flycut, for example, and lapping won't be enough. Or when have no other way to get deck height, are building a performance engine that will be torn down frequently, things like that. Or even when you just damned well want to, then all means go for it. It's your engine, so do whatever you want with it.

The point that everyone here seems to have missed is VW redesigned the cylinder heads. The Spanish heads are of the redesigned variety. When that happened, the head gaskets were no longer necessary. They DO NOT tell you to leave out the head gaskets on engines not of the specified series. Note, too, that the 914 2.0 is a VW "BASED" engine, and the pistons, cylinders, and heads are different from the 2.0 VW engine.

The Cap'n

Yes i did, Maybe thats the key?
Maybe my reading comprehension is sucking. who knows. I am somewhat new to this.
I did notice when i flooded the motor with fuel and got under it, fuel did leak out of the motor from between the barrel and head. however I was told by a aircooled mechanic thats not uncommon since fuel is thin?
Runs perfect when started and driven. no leaks that ive noticed.

Fuel may be thin, but it's not thinner than air ...

The Cap'n

Right, thats why i said WTF.