Tech Topics

The New England M.G. ‘T’ Register has a long history of providing its members with advice and technical expertise on the restoration and maintenance of our special cars. We present some of our favorite technical articles and tips here for members and visitors alike.

 

THOSE LEAKY ENGINE OIL SEALS
Hal Kramer #3094
Would you like to stop the messy oil leaks (or at least most of it) from your XPAG or XPEG engine? I had to have my engine rebuilt in the fall of 2004 after number three connecting rod bearing spun on the crankshaft journal and made a terrible noise.

While the engine was at the re-builder, I spent many hours researching and calling knowledgeable people concerning oil seals for both the front and rear of the engine. Considering the state of modern technology, I felt that this was the time to correct as much of the leak problem as possible.

I came across a tech note (not in TSO) which described an oil seal for a Mercedes-Benz that was rubber coated around the outer shell and would fit perfectly into the front seal cavity of the engine. However, I found that this oil seal had been discontinued But the tech note did contain the dimensions for this seal. Armed with this vital information, I visited the friendly local foreign auto parts store. Giving them all the info I had concerning the Mercedes-Benz seal, they went on the computer and came up with an identical seal (aren't computers wonderful?).
It was a camshaft oil seal, #6482273 for a Volvo. It met the criteria for the MG engine: it was dimensionally correct; it was rubber coated on the outer edge so it would conform nicely to the cavity shape; and it had a double knife-lip along the inner edge to form a better seal around the crankshaft pulley.

When the re-builder installed the seal into my engine, he told me that it fit so well additional sealant would probably not be required. But to be on the safe side, he used a small amount of RTV around the inside of the cavity before installing the seal. This is a "must do". The rear oil seal, however, is another matter. There were only two choices to
prevent oil from leaking (or, in some cases, running out) from the rear of the engine. I could either have the engine re-builder install the new style seal sold by Moss Motors or retain the original type oil thrower by using new parts. I had previously purchased one of these seal kits when they first were advertised thinking I would use it if the engine needed to be rebuilt. After reading several articles and talking to many MG "T" series friends, I changed my mind several times on this issue.

The Moss seal is a modern type which uses seal ring that rides on the surface of the crankshaft rear flange. When properly installed and fitted to the crankshaft flange, it works well and does not leak nor drop oil as the original type does when the engine is turned off I investigated and received many reports from people about the Moss seal. I found that some worked better than others. So rather than take the chance that mine might be a leaker, I decided to retain the original type oil thrower and to expect a small spot of oil to appear under the car whenever I turned the engine off. In defense of the Moss seal, however, I theorize that the problem (with those that leak) is not the seal but is the crankshaft.

The instructions to install the seal are very thorough and the components are well machined. It appeared to be a winner. However, I began hearing stories about a leak problem with several installations. Later I found that Al Moss had developed a new longer life seal. This, I was told, solved the leak problem. But I still heard stories that some recent installations still leaked. After discussing this with several installers (professional engine re-builders and do-it-yourself types), it became apparent to me that the problem was not the seal but might be caused by the surface of the crankshaft. The surface must be absolutely concentric with the main journals and be perfectly smooth for the oil seal to work properly. The latter item can be easily solved by using a "Speedi Sleeve", (Moss Motors part number 433425), slipped over the flange of the crankshaft. But if the flange is not concentric with the main journals, a leak problem may still occur. I have no analytical data to support this theory but there has to be a specific reason why this problem sometimes occurs.

The results of my decision on both the front seal and the rear oil thrower turned out to be very good. After about 1000 miles on the re-built engine, there is no (or at least negligible) leakage from either end of the engine. Of course, I still get that little one inch spot forming on the driveway under the rear of the engine whenever the ignition is turned off but I can live with that. A small drip cup attached the bottom bolt of the bell housing catches that small amount to eliminate the oil spot on the driveway. I still use kitty litter in a tray in the garage just in case!!

Correction of front oil seal part number, re: Hal Kramer article on Engine Oil Seals.
I have had several calls and e-mails from members having difficulty obtaining the Volvo oil seal mentioned in Hal's excellent article on engine oil seals. When inquiring about part number 6842273 at the dealer just add -2 to the end of the number and the parts person will be able to find it for you. The correct number is 6842273-2. Hal also adds "By the way, the cost of the oil seal at an auto supply store is about $6.50 and at the dealer it is about $16.50 for an identical part. Does that surprise us?? Happy hunting! Tech-Ed.

 

 

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