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Oil leaks

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David_Doan

Jedi Warrior
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I can't believe that I've not posted for almost 2 years. I finished the car (almost) in the summer of 2018. It runs and drives pretty much flawlessly. Now with some extended time at home, I've decided to address some minor issues. The main thing is excessive oil leaks. It absolutely leaves a few black spots every time I park it. I know the rear main seal leaks (like all 948's) but it is also leaking around the valve cover and and engine side covers.

IMG_0473.jpg IMG_0435.jpg IMG_0450.jpg IMG_0454.jpg IMG_0457.jpg IMG_0458.jpg

Any hints and tips for the best way to seal these? The valve cover has a cork gasket and was sealed with Hylomar blue. I'm surprised it leaked, and it only seems to be in one place. Hopefully cleaning and re-sealing will address that.

The side covers leaked a lot. On these I used rubber gaskets with no sealant, clearly that didn't work. They also leaked around the bolt hole where there was no gasket, just a metal washer.

Hopefully addressing both of those will help a lot. I'm then thinking about a catch-can of some sort for the oil that leaks from the rear main. Anyone have experience in making one of these? I remember seeing something a while ago, may it was posted here on BCF.
 
Can't resist... that's quite the panel of relays you have there. Can you shoot a photo of just that?
 
Thanks David. THAT is quite the wiring job (dash, panel in the engine-bay, etc.)!
 
I made an oil catch tray a while back. I used a bread pan and added a drain so I wouldn't have to take it off to dispose of the drippings. I tried to attach photos but don't see them in the preview. I'll try again if they didn't attach. I see they are too big. I will reduce them and try again.
 
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The tappet covers should have a cupped washer and a rubber seal for the bolt.

For the rocker cover I use contact cement for the gasket to the cover, this keeps it in place and makes it re-usable. On the head side of the gasket I smear grease for the seal.
 
I have posted the following information before so I'll try and be succinct as possible.

Assume the valve cover and tappet covers are somewhat warped. Look for the twists and warps and flatten them to the extent possible then proceed with the steps below.


  1. Remove the covers and scrape off the old gasket and sealant from the covers, the block, and the head.
  2. Clean those surfaces with a paper towel wet with brake cleaner or similar.
  3. Apply a thin film of grease to the flat surface of the openings to the block and the top of the cylinder head.
  4. Press the gasket firmly into the thin layer of grease so it is stuck to the machined surface.
  5. Now apply a thin bead of RTV to the cover in the gland where the gasket will sit.
  6. Fit the cover to the block or head making sure the gasket remains in contact with the machined surface.
  7. Fit the fasteners to the cover and tighten them finger tight (no wrenches).
  8. Leave the covers like that over night and in the morning tighten the fasteners to the specified torque.
  9. I forget the order of the fasteners and washers for the tappet covers but make sure those are installed in the right order and apply a bit of your Hylomar (or similar) to the side cover washers.

If you take these steps the gasket will make intimate contact with the flat machined surfaces on the engine. The RTV both bonds the gasket to the cover and fills any gaps present due to the covers not being flat.

Once you do this you will be able to remove and reinstall the covers a few times without introducing leaks or needing to replace the gasket.
 
Aircraft Spruce sells a nice drip pan that you can use for leaks. If it can catch the oil from a radial engine, it sure can catch the oil from an A-Series motor. It's plastic, so if you accidentally run over it, it will snap back into shape unlike a metal pan.
 
dklawson said:
I have posted the following information before so I'll try and be succinct as possible.

Assume the valve cover and tappet covers are somewhat warped. Look for the twists and warps and flatten them to the extent possible then proceed with the steps below.


  1. Remove the covers and scrape off the old gasket and sealant from the covers, the block, and the head.
  2. Clean those surfaces with a paper towel wet with brake cleaner or similar.
  3. Apply a thin film of grease to the flat surface of the openings to the block and the top of the cylinder head.
  4. Press the gasket firmly into the thin layer of grease so it is stuck to the machined surface.
  5. Now apply a thin bead of RTV to the cover in the gland where the gasket will sit.
  6. Fit the cover to the block or head making sure the gasket remains in contact with the machined surface.
  7. Fit the fasteners to the cover and tighten them finger tight (no wrenches).
  8. Leave the covers like that over night and in the morning tighten the fasteners to the specified torque.
  9. I forget the order of the fasteners and washers for the tappet covers but make sure those are installed in the right order and apply a bit of your Hylomar (or similar) to the side cover washers.

If you take these steps the gasket will make intimate contact with the flat machined surfaces on the engine. The RTV both bonds the gasket to the cover and fills any gaps present due to the covers not being flat.

Once you do this you will be able to remove and reinstall the covers a few times without introducing leaks or needing to replace the gasket.
Click to expand...

Two of you guys recommending grease on the engine side, I will give that a shot tomorrow. New gaskets came today
 
In the method I wrote about, the grease is used like a thin film glue and release agent. If I used some other assembly method I would not use the grease.
 
dklawson said:
In the method I wrote about, the grease is used like a thin film glue and release agent. If I used some other assembly method I would not use the grease.
Click to expand...

That's what I meant. I have found multiple recommendations to use sealant on the valve-cover and grease on the head with cork gaskets. The same for oil pans.
 
dklawson said:
I have posted the following information before so I'll try and be succinct as possible.

Assume the valve cover and tappet covers are somewhat warped. Look for the twists and warps and flatten them to the extent possible then proceed with the steps below.


  1. Remove the covers and scrape off the old gasket and sealant from the covers, the block, and the head.
  2. Clean those surfaces with a paper towel wet with brake cleaner or similar.
  3. Apply a thin film of grease to the flat surface of the openings to the block and the top of the cylinder head.
  4. Press the gasket firmly into the thin layer of grease so it is stuck to the machined surface.
  5. Now apply a thin bead of RTV to the cover in the gland where the gasket will sit.
  6. Fit the cover to the block or head making sure the gasket remains in contact with the machined surface.
  7. Fit the fasteners to the cover and tighten them finger tight (no wrenches).
  8. Leave the covers like that over night and in the morning tighten the fasteners to the specified torque.
  9. I forget the order of the fasteners and washers for the tappet covers but make sure those are installed in the right order and apply a bit of your Hylomar (or similar) to the side cover washers.

If you take these steps the gasket will make intimate contact with the flat machined surfaces on the engine. The RTV both bonds the gasket to the cover and fills any gaps present due to the covers not being flat.

Once you do this you will be able to remove and reinstall the covers a few times without introducing leaks or needing to replace the gasket.
Click to expand...

This seems to have worked, thank you.
 
The one sure way to stop valve cover leaks is to replace the tin cover with a cast aluminum one.
nice flat surface seals nicely With finger tight hold down screws.
 
Amen to that. My TR6 has a solid aluminum cover that has never leaked - not even a drop. Be careful that the corner of the gasket doesn't get caught inside when you tighten the cover.TR6-engine left side 6.7.19.jpg
 
Mk3Sprite said:
The tappet covers should have a cupped washer and a rubber seal for the bolt.

For the rocker cover I use contact cement for the gasket to the cover, this keeps it in place and makes it re-usable. On the head side of the gasket I smear grease for the seal.
Click to expand...

I do the same on the valve cover gasket and use "Three Bond" on other problem spots. Permatex form-a-gasket on machined faces with gasket. On those side covers I would definitely use the Three Bond and the correct seals around the bolts.
 
Oil leaks are a pain I was able to stop the oil leak around the bolts of the side covers wit’h some Teflon tape wrapped around the washer and a bit around the bolt head.
you have a tube directly to atmosphere so I don’t think crank case pressure is an issue.
guess I would try some aero gasket sealer on a freash set of gaskets and make sure that the covers are totally flat.
any dish in them will leak. As to the rear crankshaft leak.. that is a problem that is expensive but you would have a full synchro trans.. �� my fix was a 210 trans and a rivergate kit
 
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