| Author |
Message |
    
Ron Lewis
New User
Username: great48
Post Number: 17
Registered: 01-2009
| | Posted on Sunday, 03 May, 2026 - 23:09: |    |
Hi, everybody.
I need to repair a persistent oil leak from the rear main area (i.e. at the back of the sump) so will be removing and resealing the sump and doing something about the wooden dowels in the rear main bearing cap, as well.
Having combed through the topics in the Early Post War forum, I can’t find any reference to the use of RTV sealant for sealing the sump (and omitting the paper gasket) and possibly – possibly, that is – also omitting the wooden dowels and sealing inside those channels with RTV. With really thorough preparation and cleaning, I have had good success with RTV on other car sump leaks.
The Bentley sump appears to have nice wide sealing faces, making me think it would be an ideal situation to use RTV as the sealing medium, but I would like to hear back from the forum before going down that road, so would appreciate any comments, thoughts or feedback, please.
Cheers, Ron Lewis |
Jeff Martin
Frequent User
Username: jeff_r_1
Post Number: 754
Registered: 07-2018
| | Posted on Monday, 04 May, 2026 - 02:33: | |
Before doing anything, keep the sump half full of oil, and see if that doesn't solve your problem.
Adding too much oil will overwhelm the reverse spiral, even more so going up hill.
The other leak that develops is the cam shaft cover plate at the back of the engine, oil runs down the block and mimics an oil sump leak.
Big job dealing with that...
I can tell you it's not the dowels, it never is.
Oil can seep out between the main rear bearing cap and the block, and a thin layer of ATV can be added there, being careful not to put so much in that it squeezes into the main bearing. |
Jeff Martin
Frequent User
Username: jeff_r_1
Post Number: 755
Registered: 07-2018
| | Posted on Monday, 04 May, 2026 - 08:37: | |
I modified the drain pipe from the spiral so it's in the middle of the sump to keep the spiral from being overwhelmed.
The engine was in the car when this taken and the photo was then "flipped".
A section of the sump had to be removed to accommodate the new pipe.
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Ron Lewis
New User
Username: great48
Post Number: 18
Registered: 01-2009
| | Posted on Tuesday, 19 May, 2026 - 20:43: | |
Thank you, Jeff, for your comprehensive information and the explanatory photo. I have been running the car with the oil level well down from the full mark, but the leak is still persisting from the rear main bearing area.
I have also checked that the clutch oil lubrication line isn't causing a problem, but that line has been plugged by the previous owner, so that isn't contributing to the leak, either.
Which now brings us back to my original enquiry of using RTV sealer to seal the sump. Any thoughts anybody?
Cheers for now, Ron Lewis |
Jeff Martin
Frequent User
Username: jeff_r_1
Post Number: 756
Registered: 07-2018
| | Posted on Wednesday, 20 May, 2026 - 02:51: | |
Put the car up on blocks, wipe all the oil off, including the back of the engine. (get in there as best you can)
Start the engine, and use a bright LED thin flash light to watch for leaks on the cam shaft cover end.
Unless there is a big gouge in the mating surfaces of the pan and block, that is not your problem.
Another source of a leak is the speedo cable, it can make its way to the back of the sump and drip there.
Maybe your pan is warped, but unlikely....
I've had my car for 30 years, and I know this engine very well.
I would be surprised if using RTV would solve your problem. |
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