Puzzling Oil Leak

tonythetarga · 07-05-2021, 06:43 AM

I am baffled!! I have a 1973 1.7 L 914. I have fully rebuilt the motor and have had it running in the car. After my first test drive I found oil leaking between the engine and transmission.
Motor drop number one and replaced the rear main seal. It looked like there was a scratch on it from installation. Put in the new rear main seal put it back together and drove it for test drive 2. Same leak. A bit more research and the fly wheel o ring came up. Engine drop #2. I put in a much needed new fly wheel O ring as I missed that the first time. Also a new rear main seal, again. Took it for a test drive and still have a small(er) leak.
My question is… Will the rear main seal form to the fly wheel to create that seal a little tighter? Or should it be dry from the get go?
The leak is definitely behind the fly wheel. I’m not ready to drop the engine again, and I’m going to drive it a little to see if it will seat better. But I don’t even know if that’s a possibility.
Appreciate your feedback, as always.
Thank you.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

It should be dry from the get-go.

How thoroughly did you clean everything while you had it apart? Could there be oil on the back of the flywheel, for instance?

Double-check the oil gallery plugs that hide behind the flywheel. Over the years, they can start to get loose, and sometimes they even pop out! That one usually happens on cold-start.

Sniff the fluid that leaks out. Gear oil is sulfurous and smells stinky like rotten eggs. Motor oil doesn't smell like that. It's important to figure out which one is leaking, as that will tell you where to look for leaks.

--DD

tonythetarga · 07-06-2021, 05:21 AM

Thanks Dave. I've had the engine out twice since the original build. The oil is definitely engine oil. The galleys are not leaking at all. The flywheel was cleaned with brake clean before re-installing as was the area for the rear main seal. All I can think of is the the fit between the flywheel and the RMS which is why I wondered about the seal having to seat. I'll recheck end play as well. If the flywheel has too much end play, I presume oil can get by.
I will put in a dye and see what shows up for a source.

930cabman · 07-08-2021, 12:14 PM

Possible camshaft plug?

tonythetarga · 01:14 PM

Hi John,
I’m not ready to drop just yet. I have spoken to Larry at Ekstens and am going to run some dye first. Could be too much end play at the crank which would allow oil to escape and get past the RMS. In the middle of sorting some electrical issues and need to remove the gas tank to replace the front blower. Once again, the last 5% of the project is taking 25% of the time. Once the blower is sorted I’ll drive it again and then pull it next week. So much fun, isn’t it!

colingreene · 07-08-2021, 02:22 PM

The motor is so easy to pull I don't know why you wouldn't. Or even just pull the transmission.

tonythetarga · 07-08-2021, 02:41 PM

I’ve pulled it 3 times already. Didn’t say I wasn’t going to. I said I wasn’t ready yet as I have other stuff to do first and circulate some dye.

larrym · larrym's Garage

X2

Quote:

Originally Posted by 930cabman

possible camshaft plug?

tonythetarga · 11:30 AM

Thanks John and larrym for that plug check. It did look dry each time but I hope the dye will be definitive. For argument sake, if the plug is the issue, is there a way to seal it without splitting the case to put in a new one? Or, is it possible to replace and reseal without splitting the case?

930cabman · 07-09-2021, 01:56 PM

I am not far behind you with our build and I feel your pain as having been in this boat before. Hours and hours of work only to get kicked in the %#*&. I have never had the opportunity to attempt a reseal of a cam plug externally, but at minimum it is worth a try. Can you bench test prior to installing into the car? My thought would be an epoxy product or check with Larry.

jess p · 07-09-2021, 09:55 PM

That cam plug to my knowledge must go in when the cases are put together. Clean the area around the plug real well, then apply a two part epoxy or liquid weld.

tonythetarga · 07-10-2021, 03:11 AM

Thanks guys. I’ll keep you posted after the engine drop.

tonythetarga · 07-17-2021, 01:29 PM

Narrowed things down to end play! Now measuring more accurately to get correct shimming. What a trial.

930cabman · 07-17-2021, 03:07 PM

Today was a good day in the dog house? I might have a few shims depending on how much you need, let me know

tonythetarga · 07-19-2021, 04:14 AM

Quote:

Originally Posted by 930cabman

Today was a good day in the dog house? I might have a few shims depending on how much you need, let me know

Yes it was. Confirmed the total shimming I need with a dial gauge (.080"). That would leave me with .005" end play. The old shims are 11's and 12's (totalling .037") and allowed too much end play for this rebuild. I'll just order exactly what I need. Found a great source in CA. Thanks for the offer.
BTW, found the trans shaft seal was also leaking and replaced that. Probably original and was sitting there split in two! Had a new one and put that in too.

tonythetarga · 07-23-2021, 03:50 AM

Update...As it turns out, the shims and end play were not the issue. John, you nailed it with cam plug. Once heated up, there must have been enough wiggle room for oil to leak out under pressure. We sealed it up, put everything back together and test drove it yesterday. DRY!
So now, I can get to finishing off the other loose ends and get this on the road!
Thanks again!!!

930cabman · 07-24-2021, 03:20 PM

Quote:

Originally Posted by tonythetarga

Update...As it turns out, the shims and end play were not the issue. John, you nailed it with cam plug. Once heated up, there must have been enough wiggle room for oil to leak out under pressure. We sealed it up, put everything back together and test drove it yesterday. DRY!
So now, I can get to finishing off the other loose ends and get this on the road!
Thanks again!!!

Even a blind squirrel finds a nut every so often. I am glad you found it, the victories make these projects worth it, ...... sometimes. Did your original build include a silicone sealant at the cam plug? and what product did you use externally to seal it up? What sorts of odds and ends are you working on?

tonythetarga · 07-25-2021, 03:15 AM

I used Curil -T sealant during the build. Had to resort to some JB for the external sealing. Now it’s detail work… washer squirtters, radio, speakers, antenna, rain tray, side skirts and a final undercoat. I also have a dash cap to install. First things are what I need for NYS inspection. Checking to make sure everything works…all lights, wipers, horn, license plate lights etc. the other stuff will fit in along the line.

930cabman · 07-25-2021, 08:16 AM

Great news. get her rolling down the road and fiddle from there. Hate to admit but November is fast approaching so get some seat time when you can. Glad you found/repaired the oil leakage. That stuff will deflate many guys and often they throw in the towel.

tonythetarga · 07-25-2021, 08:29 AM

Exactly!! I was a hair away from unloading it prematurely. I was SO done. Now it feels good to fixing the problem.