Where is this oil leaking from? 1981 rabbit diesel

[ReubenG]

I replaced my oil pan, thinking that that was the cause of this slow drip oil leak, but that didn't fix it (even though my old beat up oil pan had NO gasket!)  The drips accumulate on the transmission before falling to the ground.

[Dakotakid]

Due to budgetary cutbacks, we are no longer able to issue medals for this particular circumstance!

Oil can and will leak from these engines in multiple places. Multiple places. Multiple places. You just have to spend some time playing detective and investigate. The drip from the plate divider between the trans and the block is a common place (low point) for oil to jump ship.

Valve cover gasket. Vacuum pump o-ring. Oil filter housing. Possibly rear crank seal. Merry Christmas....dude! You're there...we're here.

[ORCoaster]

My son had a particularly odd leak in his oil system so he finally decided to throw in some of the dye they make for this purpose and hit it with an ultraviolet light.  The stuff my son had turned bright green like anti freeze color under the light. 

You might try some of that.

[ReubenG]

Oil filter housing looks clean. VCG also looks clean. I'll look into the vacuum pump and the rear crank seal...

[air-cooled or diesel]

another thing, it could be the pan bolts under trans tunnel, use a 1/4"drive 10mm and a 1/4" wobble to get in there.snug good, sometimes you have to re-snug a time or two.

[ReubenG]

I was able snug all the oil pan bolts (yes, I used a 10mm wobble socket)...

[Dakotakid]

Was this engine block recently "refurbished" and sent to a machine shop? There is a reason I ask. There is a small soft plug on the back of the block which is removed to flush out the oil galleys, etc. You can not see it with the trans on.

Additionally, this is engine oil right? No smelling like gear oil? It will be hard to tell if rear crank seal is leaking while assembled.

Oil from the belt end of the block will actually "migrate" from (leaking int. shaft seals, crank seal, even cam seal) the front, along the seam between the bottom of block and oil pan, all the way to the trans end and then drip off the tin piece.

Anyway, was this engine recently disassembled?

[damac]

I have the dye in my rabbit right now but haven't had a chance to try the find a leak kit.

I suck so bad though, I have 3 engines that I completely resealed in the past couple years and every damn one of them leaves drips when turned off

[ReubenG]

70k original miles, runs perfectly, never rebuilt/disassembled, etc... (no turbo, no a/c, no p/s)

[southernman]

Guys, there seems to be a common thread when I start discussing oil leaks in these engines. I completely rebuilt my 82 1.6 about a year ago, and was not happy to see the recurring puddles under mine. However, the tendency for these engines to leak around the valve cover seals is routine - but it shouldn't be considered "normal". Here's why:

I build mostly hotrod and race engines (American Iron and a few diesels), so I decided to put an oil pressure gauge on my engine to check oil pressure. It was in the stratosphere at 80 to 100 lbs while cruising at freeway speed. My truck has the .75 5th gear and the rpm's are under 4K @ 70 mph. The oil pressure requirement on a full-fledged race engine is 10 pounds per 1000 rpm - stock engines is ~6 psi/1K rpm; meaning our engines should never exceed 40-50 pounds oil pressure. My Cummins dually rarely exceeds 45 pounds and leaks are not a problem - even after 250K miles...

I built a blown hemi years ago for a pro-street car, and installed a customers Keith Black "top fuel" pump as he had requested. In less than 5 minutes it would suck the oil pan completely dry and register zero oil pressure !!! Extreme oil pressure can destroy an engine.  Obviously, the VW diesel is at the other end of the extreme, but high oil pressure WILL cause leaks in ANY engine. Exceed more than 10 lbs/1K rpms and you're running higher pressure than most RACE engines. .Think about it

I decided to dig in a little deeper, and I've got some photos I can post if anyone wants to see why our engines run excessive oil pressure - excess pressure that pushes too much oil to the upper end, flooding the cylinder head, resulting in leaks. Maybe it's a pure coincidence that the valve cover gaskets and seals are the most poorly designed gaskets on these engines.

I've commented on excessively high oil pressures in the past, and I'm pretty sure someone else has posted about this, so I took a used oil pump apart I had lying around; drilled out the spring retainer plate; and removed the spring and bypass piston, cover and gears.

Turns out the clearance between the bypass piston and bore in the oil pump is so tight, that even the smallest of debris causes the bypass piston to lock up. I had to force its removal, and both piston and bore were significantly scored.

I'm planning to pull the pan and pump on my trick in the next few weeks and I'm going to ream the piston bore to give another .002 clearance. I'm also going to check spring rate, and order a lighter spring to get this thing down to ~40 psi max at cruise speed.

I'll keep you guys posted, but I'd be willing to bet most of our oil leaks would be eliminated, or at least significantly reduced, if we can just get the oil pressures down to reasonable levels (10 psi @ idle and <50 lbs cruising - hot).

Southernman

[theman53]

When there is stuff in that piston it will skyrocket. I clean mine and use a cotter pin to make sure the freeze plug looking thing doesn't let the spring out by accident. This is a trick I learned from CRSMP5. When they used to race the 1.8's in the 80s he said they would use a SBC spring for the oil bypass instead as it let off so much of the pressure. I see around 90-100 cold, but warm I only get up to 50 or so at high rpm. I guess what I am saying is I agree with you on the pressure. Adding .002" maybe excessive, maybe not. Post results. Mine doesn't leak unless you over fill it BTW

[southernman]

That's interesting, but the clearance value is based on un-filtered oil being routed through the bypass any time it's being acted upon and I suspect as detergents in our oil do their job, some of the debris that's returned to the pan could exceed  a couple thousands - easily... Plus, the .002 "controlled bleed" would help reduce cold oil pressure as well. As a builder, I've seen the damage high oil pressure can do to our engines.

This reminds me of the age-old debate on which oil to use once an engine is seasoned, and starts using oil (out the tail pipe). Most say dump higher viscosity oil to help "seal it up", but the opposite is true. As oil rings lose tension, higher viscosity increases oil consumption due to lack of tension. Drop the viscosity under such conditions and the rings can scrape the cylinder walls adequately and control oil consumption. If you want to accelerate wear on your older engines, pour high viscosity oil in it, and you'll be pulling and rebuilding much sooner...

The Chevy sb spring also might be viable, but I plan to measure the spring that's in it and order a couple springs I've spec'd to drop the oil pressure. Thanks for the reply !

[theman53]

I honestly think that 99% of the problems with our leaking is the junk stamped steel valve cover.

I 100% agree if you have IM, cam, or similar leaking then the high oil pressure is the factor. But if all you ever have leak is the valve cover buy a new one. I got a G60 cover and all of the sudden I no longer had leaks. After years of driving mk1's and had the stock stamped steel cover I got the aluminum one and rarely ever see a dribble even when reusing the gasket. Now, is high oil pressure to blame originally? Might be. The previous owner may just continue to tighten to stop a leak warping the 1/16" stamped steel cover. I just think it is crazy how junk the valve cover is on these.

BTW The way CRSMP5 said was that the SBC spring dropped right in

[ReubenG]

Solved MY issue... turns out the new oil pan (that I replaced) had not been tightened enough, so I went around it again and again and again, and now NO OIL LEAKS ANYWHERE!