Where is this oil leak coming from?

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Mark Roth
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Where is this oil leak coming from?

#1 Post by Mark Roth »

I just got back from a spirited 200 mile drive and noticed some oil drops on my garage floor. Hasn't happened since a rebuild about 6,400 miles ago. The bottom of the engine has been dry. It looks like the leak is coming from the forward side of the engine and coating the sump. I've attached some photos. Main seal? Oil cooler unlikely? If it is the main seal, can I take it on the Texas Hill Country Rallye on March 9 which is a spirited 1,000 mile round trip or should I try to get it repaired before?
Oil Drip 1.jpg
Oil Drip 2.jpg
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David Jones
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Re: Where is this oil leak coming from?

#2 Post by David Jones »

From what I can see I'd guess that the main seal has a small leak. Unless the oil level has dropped by a noticeable amount I'd drive it and monitor oil level but carry a couple of quarts of oil.
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Dave Erickson
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Re: Where is this oil leak coming from?

#3 Post by Dave Erickson »

Mark, are you sure its motor oil? Smell it, feel it and make sure its not transmission oil leaking from the mainshaft seal. I've seen VW engines go for many thousands of miles with a leaking main seal, so you should be good waiting until a more convenient time comes along.

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Re: Where is this oil leak coming from?

#4 Post by Hugo Karasawa »

It can be from the crankshaft main seal or from the metal gasket for the flywheel. The oil leaks to the back of the flywheel and drops to the gearbox housing. That square hole is there so that the oil that leaked does not puddle and you notice that there is a leak.
oilleak.jpg

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Mark Roth
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Re: Where is this oil leak coming from?

#5 Post by Mark Roth »

It’s definitely oil. Transmission is filled with blue Swepco. I just checked the dipstick after it cooled off. I check the oil cold. Went down about a quarter inch in just under 200 miles. I don’t know when it started. The sump is oily but not dripping. I’ll see if someone can replace the main crankcase seal in the next two weeks. What brand is the best? I’m tired of fixing this engine. It was finally working perfectly and now this. 👹
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Re: Where is this oil leak coming from?

#6 Post by Dave Erickson »

Mark, since the oil seal worked fine for a while, the cause might not be a bad seal; i.e. it could be from a groove worn into the flywheel hub. They make a speedi sleeve that can be installed on the flywheel if that is the problem.

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Mark Roth
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Re: Where is this oil leak coming from?

#7 Post by Mark Roth »

Thanks,
I’ll see if the guy who built the engine in 2020 can check it out.
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Re: Where is this oil leak coming from?

#8 Post by Harlan Halsey »

Mark,
Just monitor the oil level for a few thousand miles. A little oil leak is pretty normal. They used to call these cars NAZI road oilers back in the day. A little oil keeps the underside from rusting. You can waste a lot of effort trying to make there 356s something they aren't. Remember, Porsche thought 600 miles per quart oil consumption was no cause for warranty fix.

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Mark Roth
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Re: Where is this oil leak coming from?

#9 Post by Mark Roth »

Thanks for the reassurance guys. In the almost 30 years I’ve had the car I’ve never had a seal leak. The valve cover leaks in the beginning were cured by Vic’s gaskets. Had drips from the sump plate studs. Replaced those, no leaks. I was just concerned that the leak would become massive and catastrophic.
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Al Zim
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Re: Where is this oil leak coming from?

#10 Post by Al Zim »

Mark; Check your crankshaft end play. You can do this in the car without removing anything. I would also check the specifications of the clearance of the crank to #1 main bearing and the clearance to the case. This should be with the with the work order. Zim
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Re: Where is this oil leak coming from?

#11 Post by Bruce Smith »

Hi Mark. I've got four 356s, two 912s, and a 911T. I put drip pans under all of them.
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Mark Roth
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Re: Where is this oil leak coming from?

#12 Post by Mark Roth »

The drip doesn't bother me. I've had cardboard under my car since I've had it. It's the seal issue and the danger of a catastrophic failure that I am concerned about. We will be driving flat out for two days and getting there and back is freeway at 80mph at times. Could go through a lot of oil quickly. Also don't want to be a "smoker." I've been behind those cars and it's not pleasant.
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Re: Where is this oil leak coming from?

#13 Post by Ken Tuvman »

Mark Roth wrote: Sun Feb 19, 2023 1:10 pm The drip doesn't bother me. I've had cardboard under my car since I've had it. It's the seal issue and the danger of a catastrophic failure that I am concerned about. We will be driving flat out for two days and getting there and back is freeway at 80mph at times. Could go through a lot of oil quickly. Also don't want to be a "smoker." I've been behind those cars and it's not pleasant.
Hi Mark - theoretically your green oil light would come on before a catastrophic engine failure - I do t line oil leak’s myself but theses engines are older technology- I volunteer at Palm Springs Air Museum and 95% of the engines on the WW2 planes drip oil / I have a oil pressure gauge on my 356 that adds a visual of how my engine is running- I say take your trip and 3 quarts oil (I doubt you’ll use much).
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Re: Where is this oil leak coming from?

#14 Post by Wes Bender »

You have until March 9th. For peace of mind I would pull the engine and replace the seal if it is leaking. If it's something else, you can make decisions as you go. You're probably OK as others have said, but I also understand your concern.
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Re: Where is this oil leak coming from?

#15 Post by Al Zim »

Mark, you have a leaker not a smoker. Have you checked the crankshaft end play yet? al zim
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