Oil leak between crankcase and #4 cylinder

I had a small oil leak (drips a drop every 7-10 seconds when the engine is warm) between the #4 cylinder and the crankcase. I pulled the cylinder and discovered that there were 2 spacers between the crankcase and the cylinder. Whoever put the engine together used what looks like blue RTV sealant. However, my VW service manual shows a gasket (and I would need 3 since there are 2 spacers). How does everyone seal their cylinders to the crankcase? Thanks.

Paul

Most of the builders I have read up on recommend silicon (RTV). Not certain that I would use blue.....

what you saw (blue goo) was probably permatex.

paul,
Look at the cylinder register surface of the case. If it looks like the barrel has indented it's way into the surface, that could be your leak. Re-gluing it on re-assembly "may" seal it, but the best bet is to have case re-machined. (which means disassembly).
If/when you reseal the barrels, don't use paper gaskets,(They'll squish out if you use any sealant on them) use the steel barrel spacers with rtv, permatex, elring or whatever sealant you prefer to accomodate your deck height. Be sure to check both barrels on that side (if you only have one side torn down)

The other thing to check is:
If you case has case inserts (case-savers)installeld, make sure that they don't stick up high enough for the barrel to rest on them instead of the case.

Greg B

Paul; VW issued a service bulletin many years ago instructing not to use the paper gaskets but use the blue RTV silicone. It looks like your motor was well put together. The spacers you saw there were put in to set up and lower the compression ratio; something very important in these air cooled engines.

Hey everyone! Thanks for the advice. I am glad to hear that everyone uses some sort of sealer vs paper gaskets. That way I can reassemble tomorrow vs waiting for part to arrive in the mail.

Also, thanks for the advice about checking the case savers height and the deck surface. I will be sure to double check those sources of leaks, but it appeared that when the sealer was not well distributed when it was applied so that there was a small gap on the side of the cylinder.

Any tricks to apply the RTV sealer to ensure uniform coverage and minimum thickness? I remember when I was working on V8 valve covers that they recommended a thick bead, waiting until the bead was tacky, loosely tightening the bolts, and then torquing the bolts after 24 hours of curing.

Paul

Paul, No special instructions. I worked in a rebuild shop (vw) and there wasn't any silicone
or rtv in sight, just permatex "aviation sealant", cork vlv covert gaskets and we never had an issue. Double check all the above and realize that this area is splashed by oil but not under the oil level line. That sounds like a very consistent leak via a splash. How many miles on your engine? One other "far fetched" thought. Did your engine leak at the same rate
with the oil filler cap off?

Paul,

How thick are those barrel shims? Are there shims at the base of the other three jugs? Barrel shims are used to alter/adjust deck height or simply reduce the compression ratio in an engine. (They're also used when building a stroked engine to correct and balance the barrel to piston relationship between all four and allow the use of long cylinders or "B" pistons and such.)

Whatever the situation, only one, at the correct thickness, is used. Not two.

The best sealant these days is what they're using at your local Harley dealer. We got a nice assortment of squeeze on and brush on case and barrel sealant from them and it works PISSA.

HOWEVER, the shims are of greater importance right now then the leaks.

"There's something happening here . . . "

Luck,

TC

I've had very good results with Permatex "ultra copper" on VWs and Corvairs. Good heat and oil resistance. Small additional cost over the other "colors", but well worth the result. I would think aircraft grade sealants would be a step up, if they are available to you.

I had leaky barrels with Permatex Aviation Sealant. Switched to the Ultra Copper -- totally dry.

David -- did you do any sailboat racing in SBRA?

Mark

Hey everyone! I put everything back together with Permatex Aviation "Form a Gasket" 3H. Today got everything reconnected and still have leak. I am now suspecting the case savers.

T.C. suggested that the spacers were suspect. I did deburr the spacers which were slightly "buggered" up, especially around the notch where the studs went. Any suggestions on whether I should try to torque the savers down more or try to grind the case saver down. Tonight I am going to take the jugs back off. I am thinking about using a drill to countersink the case saver. Any better ideas? Thanks.

Paul

Paul,
Did you allow some time for the sealant to cure before subjecting it a running engine and hot oil? I usually try to let it cure at least 24 hours before use. Read the tube for suggested cure time. For example, on oil pan gaskets, I don't even put cold oil back into the crankcase until the cure time is complete. It makes a difference!

David,

Yep. I let is cure about 48 hours before even adding oil. Thanks for the suggestion though (I wish it were that simple). The leak did slow down a bit once I resealed everything with the Permatex 3H vs the old blue gunk that was there.

Since I ran my fingers around the mating surface on the engine case and did not feel any burs nor see any marring, I really suspect those case savers are not sufficiently seated/countersunk. Thanks again for the help!

Paul

Well, I don't think it was the case saver inserts. I took a precision ground straight-edge (parallel bar actually) and it is not catching on the inserts.

Is it possible that the oil is leaking from the heads? When I got under the car and watched again, it now looks like the oil might be dripping from the air deflector between the cylinders and/or running down the head stud and pooling at the base of the cylinder.

I already have the head and the #4 cylinder off the car to try again. When I put the head back on, it there any sealer/gasket or anything that I need under the head bolts (there is already a thick washer there). Thanks.

Paul

Maybe use RTV under the washers that go on the head?

Paul; I double checked with the VW Service Manual and funnily enough it says to use high temp. and oil resisting sealer on the four lower washers, nuts and head studs on fuel injection models. That doesn't make much sense to me since apart from a couple of sensors and/or steps in the combustion chambers all heads are basically the same wirth the same inherent problems. I'm pretty sure in your engine the leakage you're experiencing is coming from these areas.

Had a silly idea, but it depends upon your barrel size. Are you running a stock bore, or is the case opened up for larger barrels?

If it's been opened up, and they used shims and all to make things fit, your barrels MIGHT be hitting the ridge inside the barrel opening. We once had a buddy cut a case for us, and it was his first or second or whatever, regardless, he didn't cut deep enough into the casting for the barrel to seat against the case. We had to go into each bore and dremel away some of the material for the barrels to bottom out AND SEAL.

That might be the reason for your shims, and continuing leak. The barrels torgue tight but are bottoming on the ridge NOT the case and leaking. Everything would look right from the outside, but, even with just a tiny amount of space and hot "pressurized " oil, it would leak pretty badly.

If this is the problem, a little mechanic's blue and a dry fit with a quick twist would tell the tale.

Maybe?

Luck,

TC

I've been wrong many times before and I'm sure more to come but I have my doubts about a "constant" drip from that area. The oil isn't
pressurized there. I know stupid suggestion but did you totally rule
out an oil cooler leak running down and around the cyl. base? Not
meaning to be anything other than curious/hopefully helpful.-Bruce

Yup . . . you're wrong.

At any point in time, during operation, the entire case is pressurized to one degree or another, hence all of the breather outlets on the valve cover's, generator stand, oil fill and such. And the increased need in the larger bore engines.

At the level of the barrels, and the leak, is . . . the crank assembly. Rotating and reciprocating masses all bolted together, spinning wildly at 3000 rpm plus and slinging oil, droplets, and vapor all over hell. Building pressure, releasing pressure churning oil in equal amounts into the top, bottom and sides of the case, running up the barrels (the reason for the scraper/oil ring) and against the barrel mounting surface(s).

Hot and agitated, trapped inside a chaotic and dangerous environment, partially pressurized and seeking any and all outlets available, the poor little oil would look for every exit. You would too, if you were oil trapped in a case. Given this situation, the oil leak would certainly be constant. The need for escape primal, and the desire for self-preservation all consuming.

Why in some cases, the engine will take advantage of the dire situation and actually consume the oil. Sucking it in and buring it alive. The oil, confused and frightened, mistakenly allows this to happen thinking that it is a means of escaping the case. Not realizing until it's far too late, that escape is impossible by this means.

And thus the cycle of four-cycle life continues on . . .

TC; that's pure poetry!!!

TC, I want some of whatever you were drinking when you wrote this!

All,

Thanks for the replies. I have torn the heads and cylinders off the driver's side 3 times now with no change in the oil drip. The last time I even added Permatex No 3 to the head bolt washers.

I am running bigger bore jugs (90.5mm) and stroked to 82mm. That is a good thought about the boring of the case not being deep enough. I have a depth gauge that I will check. In addition, I will use the bluing method just to verify (although I call it the sharpie method since I don't have any bluing).

As for the oil cooler, I am positive that it is not the source of the leak. I have an external oil cooler and a 911 shroud. I checked for leaks by running the engine without the shroud and it is definitely around the cylinders.

Also, I am now sure that it is not oil running down the head bolts to the base of the cylinder, especially after I used sealer on the head bolt washers.

This weekend, I will tear this down one more time (hopefully only one more time), measure the depth to ensure no interference, and then reassemble using the gold Permatex RTV this time instead of the Permatex #3.

I appreciate all the suggestions. Any more before I go through this hassle again? Thanks.

Paul
I

TC, great story but....the case is vented to atmospheric pressure at least. Some oem supply
a vacuum to lower that psi even further. Note the trend of having a vacuum pumps on drag racers. If inadequate yes psi will build forcing oil, fumes, vapor towards any area with less pressure=granted. Oil scraper rings are for "slung" or "splashed" oil, they don't control pressurized oil. I just find it very funny that you would have such a constant rate of drip
from "slung" or "splashed" oil. It's either a good sized defect or a combo of weak sealing and case pressure. But since I pictured our friend here checking the leak in his driveway on his back I didn't take in to account the violent engine movements above. We'll see. Good Luck!!!

Paul,
Since you're going back in to find the leak, here's something you should check if you haven't already.
Case Savers (again). If the case is case savered for 10MM studs, with the heads removed (barrels too if you're going that far) check that the case savers are tight in the case, and that the studs are not loose in the case savers. Oil can leak around the threads of the studs and/or case savers. If studs are loose or come out easily, clean and reseal them. Case Savers are usually not a problem. They shouldn't come loose.

If your case has 8mm studs, and the case savers (inserts) are the stock ones, they shouldn't be a problem, because the threaded bore for the studs doesn't go all the way through . I've never seen a case that has the stock inserts for 8mm studs leak around the inserts.

Greg B

Also I've read this tip which might help; use Loctite on those studs too.

" I just find it very funny that you would have such a constant rate of drip from "slung" or "splashed" oil."

Agreed.

Are the oil galleys and internal routing close enough to the outside surface of the case for the head tin to have vibrated and worn a small cut through the case near the oil cooler. Maybe just a nick that would let enough oil escape but not effect pressure readings?

Since all of this is happening around the number four cylinder, if it isn't slung oil, it must be pressurized and thats an area of "activity" considering the cooler and galleys feeding in and out and such. There may even be a hair line crack under and forward of the cooler mount (a REAL trouble spot on the early 356's) that's causing continual seeping.

Maybe . . .

Or . . . the oil . . . thinned, weakend, and overheated from it's endless journey through the darkened galleys and internal routing . . . may be seeking any passage way or exit possible that will bring it to the light of day and eventual escape. Freedom! A primitive and primal urge found throughout . . . the cycle of four-cycle life.

either way. different stories same outcome=trouble.

TC,
Everything inside the VW motor churns oil like a taffey machine.
Next time you have the oil sump plate off of a 4 cyl 356 or 912 motor, Start it up (for a few seconds) with the plate off and take a look. It's scarey.
The most significant gains in horse power (in the dark ages when SCCA FV's were popular) I ever made while researching VW (40 hp) based Engines for Formula Vees was through "oil control". We did some extreme stuff to manage the oil inside a running VW.
Think about what the cam gear does as it run submerged in the sump; And why there is a baffle under the Generator/Alternator tower. And... about what happens when oil pressure is too high and the oil pressure releaf valve shoots oil back into the sump.
If a oil port was compromised, even a "nick" would send a gusher everywhere and oil pressure would be history.
The VW aircooled motor is ALWAYS expanding and shrinking with temperature. Different materials used shrink and expand at different rates. A VW motor that doesn't "mark it's spot" by leaking a little oil is pretty rare.

Greg B

Greg,

You're preaching to the converted. I've owned Harleys, Nortons, Porsches and VW's. They all curn oil like butter and they all leak like mad.

Bruce is pushing the "pressure" theory, I'm hanging onto the Chaos theory for now. Although the "cycle of life" approach IS a bit more . . . fanciful . . . and still holds some appeal.

I'm not saying it's a pressure leak. I'm saying that "if your case is pressurized" as was stated above you have other issues. I'm also "guessing" that to have such a consistant leak from
splashed,thrown or other in the same area/spot, above the oil level, will eventually turn out to be an obvious issue. A seep,weep, stain I can see from any sealing surface. But a leak as
described has to be from a defect. Something warped, out of round,cracked, improper torque
etc...Like I said before "I've been wrong before" but I enjoy the "who dunit" detective factor.
As for old stuff that leaks. Yes I've had almost one of all of the English sports cars made
a Norton, Vw's etc...They all thought I was crazy (and said it couldn't be done) when I used
the twin stromberg carb'd cars as my everyday cars. "They" said you have to keep on adjusting etc, etc....What a load of crap, rebuilt them the first time correctly and they never let me down. I did used to get quite a few looks when I bought and drove my mg as my
winter car because I didn't want salt on my TVR. "Almost" anything can be renewed correctly
without leaks. Notice I said "almost".

Hey everyone!

I just finished yet another teardown. This will make the fourth time. I was hoping that TC's suggestion that the case was not bored deep enough and that the jugs were bottoming out/not sealing on the barrel shims was right. No joy. I removed the barrel shims and the jugs fit all the way down.

As I am now sick of tearing this thing down, I looked again at the case savers. I am running 8mm studs. I did check and only the bottom rear insert actually opens into the case, so that is the only one that could possibly be leaking. I decided to go for the overkill method and took my handy drill to countersink the case savers down to case level and definitely below the spot on the case where the jugs seal.

In addition, I decided to go with Permatex Ultra Copper this time. I now have the Ultra Copper curing and am waiting until tomorrow to torque the heads down. I know that the direction on the Ultra Copper stated that retorquing was not necessary, but it seems like an easy way to ensure that the sealer is under compression.

Everyone keep your fingers crossed for me. Hopefully tomorrow when I finish reassembly and initial engine warm up, I will not see a puddle under my car anymore. Thanks for all the advice so far. Keep it coming.

Paul

Hey,

How about one of these . . . keep the oil inside the case under control. . .

http://cgi.ebay.com/ebaymotors/VW-BUR-BUS-GHIA-OVAL-EMPI-STYLE-WINDAGE-TRAY_W0QQcmdZViewItemQQcategoryZ46098QQitemZ8041941804QQrdZ1

Paul -- How did this story end up?

Mark

I'd like to know too!

I'm bored with it . . .

Hey all,

Sorry for no updates till now. I have been busy at work.

I think I finally got the leaking stopped, at least with getting the car up to operating temperature on stands. I am hoping to get the car out this weekend if it gets a little warmer here in SoCal. BTW, are there any clubs or people that get together in L.A. for a Sunday afternoon drive up/down the coast?

Paul

Yeah! I had my money on the Ultra Copper. It fixed the same thing for me.
Mark