Rear main leaking

[frenchblatter]

My friends TC has a converted rear main oil seal.
There is oil leaking from the area. He took the engine out a few months ago and I fitted a new seal even though it looked ok. I did motice the half round cork seal on the sump was wet so dug it out and found two seals had been fitted. I replaced them with a new seal. He refitted the engine but it is still losing oil, a lot of oil.

I'm not sure if the rear main seal has been done correctly. Is it possible that the chap who fitted it didn't drill the drain hole and if so would this cause a leak.

Thanks

[Bob Schapel]

Hi Lyn and Norman,
If it is a Moss seal, yes the drain hole MUST be drilled. In fact when I made similar seals from 1988 to about 2000 I said the drain hole should be about 10 mm, which is much bigger than the small hole Moss suggests. I am new to this site so don't know how to post a photo. On the MG Enthusiasts site I posted a photo a couple of weeks ago which pointed out another area which must be sealed to stop leaks whether it is original, my seal or a Moss seal.
Bob Schapel, South Australia

[Marv]

Bob, I tried to find your Mg Enthusiasts post but only came across the camshaft discussion. Can you give us a better lead to the right spot.

Marv

[Bob Schapel]

Hi Marv,

It can be found in the 2016 archives under "rear seal oil drip". I will try to email you the image. I am assuming I can not post an image on this forum like I can on the enthusiasts forum?

Bob

[Steve Simmons]

Click "full editor" just below the quick reply box. There you will find the attachment section. Just click browse to find your photo, optionally add a comment to it, and click "add the file". Then submit your post.

[Bob Schapel]

Thanks Steve.
Bob

[Marv]

Got your direct email Bob , Thanks,

Marv

[frenchblatter]

Bob, that's what I'm going to check when I have the engine out in JUne. It was suggested it may be the camshaft core (freeze) plug but he says it's been checked and is OK.

My problem is trying to see the Moss picture of where the drain hole should be drilled. The B&W picture is so dark I can't see it.

Thanks for the help.

[Steve Simmons]

There is a color version on the Moss web site for download.

[ian theobald]

Like all T series ,mine leaks like any other British car of that era.
The rest of the motor is bone dry.
My solution was to fita catch tray underneath as motor does not consume any oil and sounds healthy,even after 30 yrs.
I must admit does iratate me but thought of disturbing an otherwise healthy motor makes a catch tray an easy decision.
I purchased from UK Site Totally T Type 2 and seems to do the job but my sump has ribs up to bell housing so some oil still escapes as well as out of back of starter motor
As my car is on full rego and used often will stay that way.Have no clue as to what type of seal even fitted.
I,m not sure how bad your leak is but try to enjoy just using.
By all means investigate if motor has a reason to be removed but dont make it the sole reason.
Just recently went to an historic air show and looked in engine cover some pkane with several 18 cyl radial engines and was suprised at the oil that was sprayed out .reminded me of my TC with it,s oil stains from louvers on drivers side like some old war bird so its not justTC,s that are incontinent
My back wheels are another source of oil but just enough for dust to stick Gives the car a certain patina to it
Has a benefit that spokes never get surface rust. Good luck

[stephen stierman]

When I bought TC2911 some years ago, it leaked a pie plate of motor oil from the rear seal at shutdown. When I rebuilt the engine I installed the Moss seal, very carefully. Not carefully enough, I believe the ends of the bolts that secure the flywheel to the flange may have contacted the seal and pushed it off the contact surface, it leaked profusely. I went back to the original slinger arrangement carefully installing it with minimal clearance as instructed by several sources. It will leak two or three drops at shutdown after a long run as they normally may do when the engine stops turning, it does not seem to leak when running. I am reasonably happy with this as most TC's I have seen are a great deal worse than this.

[frenchblatter]

Ian & Stephen, tisi isn't a drip, it runs out. Used about 3 pints of oil in 60 miles. I didn't fit the seal so I'm going to check if the bolts have been shortened and if the drain hole has been drilled. The owner took the engine out and I went to him and fitted a new seal and a new half round cork to the sump. It was OK for a day then started pouring it out again which makes me think the bolts are touching the seal. However there was no sign of this on the old seal. I'll be much better at it in my, well lit garage.

[Gene Gillam]

Some of the best information about resolving rear main oil leaks can be found here: http://www.mg-tabc.org/library/ChevyRearSeal.pdf

If you're pulling the engine, turn it on its end as shown at the end of the article and pour oil into the rear main drain tube...you'll quickly find where your leaks are.

[stephen stierman]

Norman,
If the Moss seal has moved away from the crankshaft flange, oil will exit pretty quickly. Oil pressure will blow by the reverse threads since the top half of the slinger arrangement has not been installed. This is assuming a core plug or gallery plug has not been dislodged. I never felt comfortable installing the Chevy seal as once you make that decision there is no going back.

[dirk w dondorp]

agree with you Stephen, I have very good experiences with a Moss Seal and Speedy Sleeve!

[Gene Gillam]

I don't use the Chevy seal either but David's comments on troubleshooting leakage at the rear main are applicable to the Moss seal also. It's how I troubleshot and found my leakage points.

[frenchblatter]

The seal was in place when I replaced it a few months ago, which is why I didn't think it was the seal. I'll have the engine out in a well lit workshop and can then inspect it properly. Finding the half cork soaked in oil (on the face) and two seals in there comressed to 25% of the original I assumed I'd found the problem.

We'll see next month.