Long-term Head/Cylinder/Case Sealing?

[donbarnes]

Starting to rebuild a 1600 Mexi AS41 to stock specs with new Mahle kit and wondering what is the best option for sealing between the cylinder and case, then between the cylinder and head? Not so much worried about deck height and compression/performance- Just want it to sit there as long as possible without leaking? It came apart with paper gasket between jug/case, and metal shim between jug/head. Fel-Pro still sells a head gasket set that has copper shims they claim aid in long term sealing, any thoughts on that? thanks...(and yes I have a Muir book, but wondered what everybody does nowadays)..

[KTPhil]

No copper seals have been part of the VW engine since the clean-air models came in about '65. And typically cylinder shims go between the case and cylinders, not between the cylinders and head.

Grind the cylinders into the head with valve compound.

The paper gaskets don't work well at the case. I used them with a smear of high-temp silicone; or if I have metal shims for CR control, on the shims themselves.

[anthracitedub]

X2 on lapping the cylinder into its respective resting place on the cylinder head. I always used gasket shellac along with the little paper gaskets on the case/cylinder fitment.

[slalombuggy]

As long as you don't over heat the motor you won't need anything to seal the cyl/head. As for the base gaskets. I used to use av gasket shelac and paper gaskets on stock motors, now I just use Right Stuff silicone and never worry about leaks on all my motors, big or stock. Use it sparingly, just a thin bead will do.

brad

[johnnypan]

use this cylinder to case,toss the paper gaskets...what KT says about cylinder to head...

[babyblue69]

KT

What do you exactly mean about "Grind the cylinders into the head with valve compound." Grind is what I am not sure of.

I am going to be building a 1776 motor and want to seal it up nice and tight.

[anthracitedub]

Use some light valve lapping compound, put a little on the rim the cylinder then, insert the cylinder into the head and rotate it back and fourth, the grit will seat the cylinder into the head…you don't have to go all hog nutz crazy with it, just a little…and be certain that you clean all that stuff out of there once your done.

I never used to do this procedure, but an old school dubber was doing it in a shop I worked at many moons ago…he said it was a little peace of mind type thing and I agree…may not be needed but I started doing it after that…could be an OCD type thing.

[babyblue69]

I have never used Valve Compound. After you grind the head and cylinder how much time do you have to mount them?
Or do you half mount a cylinder, grind it, finish mounting it and them move to the other cylinder repeat and apply before the compound hardens up?

Half mount a cylinder = piston on the rod, jug over piston and slid over the head studs but not enough so they do not stick through so you can rotate the head on the cylinder.

[djkeev]

Johnnypan and I are beginning to have an on going lack of agreement! but I would advise AGAINST using any silicone sealer anywhere on your air cooled engine. I know that the likelihood of any hardened globs making it into you lubrication passages from this application are quite slim, but really, why take the risk no matter how small??
My advice on silicone sealant and air cooled engines is to forget that such a product was ever invented! Save it for your water pumpers.

Use as others have advised or another good product is Hylomar. It is a non hardening sealer which is ideal for the aircooled motor applications.

Dave
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[anthracitedub]

[KTPhil]

[babyblue69]

Okay. thanks anthracitedub and KTPhil, my retarted mind has got it now.

Thanks for all of the help.
I will be back with more questions during my build

[KTPhil]

Take it slowly, and expect to have to redo everything at least once-- that's standard practice to get it right. Ask a million questions. Read the Muir and Fisher books for two extremes on the rebuilding methods and tools needed.

[babyblue69]

Re-do's I am REALLY good at.
the only thing that has me a little overwelmed is the rocker arm geometry. I have been doing alot of reading and think I know enought to start asking qualified questions not to sound like a goober.

[KTPhil]

With a stock rebuild you have little to worry about with rocker geometry. At most you may need to add shim washers to make the adjusting stud contact the valve tip in the right spot.

Maybe I'mm just very lucky, but all of my rebuilds have worked out fine without adding shims. But then they have all been stock.

[john7]

i build alot engines, all the time. im sure i am way into the hundreds but i never kept track. my sealers of choice for a leak free engine are

case haves -Yamabond or 3 bond 1104 (same stuff)

ultra black RTV on - cylinders to case

ultra black rtv- under the 6 main case half washers, the 2 washers on the case studs above and below the cam plug, under the washer on the case stud just over the oil pump.

ultra black RTV- between the oil pump and the case

Kuril K2- on oil pump cover gasket

nothing on the push rod tube seals with stock tubes, if you are using spring loaded tubes ultra black on the seals

super weatherstrip adhesive on the valve cover to the gasket (never put anything on the head side)

factory sealing nuts on the oil pump cover, use no washer and red side towards the pump cover (other wise dont even bother using them if you dont use them correctly)

oil sump plate gets german gaskets with copper crush rings & factory cap nut (i had rubber gaskets made and they work awesome, no seepage or anything)

i clean everything 3 times or until my white shop rags stay white (even the washers). this is a place most people skimp and if not totally clean it doesnt matter what sealer you use it will leak

thats about $50 in different sealers when you buy them but the tube of 1104 will last about 10 engines, the tub of kuril K2 will last years, the tube of super weatherstrip adhesive will last a long long time and the rtv will go the quickest
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[babyblue69]

I can see after all of that sealant you do not leak.

factory sealing nuts on the oil pump cover, use no washer and red side towards the pump cover (other wise dont even bother using them if you dont use them correctly)

I have been lucky on my other engines I believe I put the red on the out side and I did not leak. It has been 10+ years since I have built a VW motor, I could be wrong on the nuts but I do remember no leaks.[/quote]

[KTPhil]

There is a difference between sealing nuts (with the red plastic on the face of the nut towards the cover), and locking nuts (with the plastic on the outside, though a little countersunk into the thread area). The first is used to seal, the second to avoid coming loose. Many people confuse the two.

[john7]

KTPhil is right they are often confused.

oh and i dont use any gasket between the case and the deep sump. only Toyota Oil Pan sealant (it is not the same as black rtv)
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[donbarnes]

Whats the difference between Hylomar Aero and Hylomar Blue or Racing? And there seems to be different makers of "Hylomar", I've seen it listed under Permatex and Valco? I used to be a fan of Permatex Aviation (still have a tub of it) until I put a Mopar show car engine together with it and within a couple of years the engine was dirty and seeping in mutiple places, almost like the Aviation dissolved or broke down, had to pull it back out and reseal the whole engine