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MG MGB Technical - Rear oil seal - alternatives?

Hi guys,

I suspect my rear oil seal has stopped sealing as there's a lot of black car blood coming out of the rear of the engine.

I know replacing the seal is a bit if a pig, what with the gearbox removal, etc., so I was wondering if there is a "best" type of replacement seal, as I don't want to be doing this again fir a long time.

Alternatively, is there anyone thing out there that people have used that is better than the standard seal?

Thanks in advance,

Grant
G Hudson

Grant,

Does your car have a seal? It is an option that can be added. I don't know if newer 18V engines had them, and I don't know what car you have, but the older ones had a scroll instead of a seal.

If you have a scroll, it is likely that your crankcase ventilation system is not working properly, and thus allowing pressure to blow the oil out. Alternatively you could be developing more crankcase pressure than the PCV system can cope with.

Charley
C R Huff

All 5 bearing motors have a seal.
It is a PITA to replace, so do it properly. MOSS has an upgraded seal available. Another must is to fit a SPEEDI SLEEVE onto the crank. This fixes ant grooving the crank may have. Because of the orientation of the sleeve the is the probability of damaging the seal when fitting, so wrap a bit of tape over the edge of the seal whilst fitting the seal.
It can all be done without removing the back plate.

Might be worthwhile doing the clutch while you're in there.

Herb


H J Adler

Hi guys,

Thanks. I'd rather not do the clutch as its only done about 500 miles. I'll check out moss for a seal and see if they do the speedi sleeve too.

Thanks,

Grant :-)
G Hudson

Sorry to try to lead you astray, Grant. As Herb has corrected me, I realize I was thinking of the Sprite/midget.

Charley
C R Huff

Hi guys,

Being I don't have the gear to pull the engine, and cash is a little short at the moment, I decided to just cross my fingers.

In doing so, I put some kitchen towel under the sump, taped onto the front cross member and the tubing under the gearbox. Low and behold, the oil is NOT coming from the gearbox area at all. It's coming from the right hand side under the dipstick.

Now it looks like the sump gasket isn't doing its job, so I've got a new one.

However, my question is (because I'm acutely paranoid) "can you get an oil leak from the base of the dipstick, ie, can that tube break and leak where it goes into the engine?". The oil us definitely not blowing out of the top of the tube.

Huge thanks in advance,

Grant :-)
G Hudson

Grant,

I believe you can get a leak where the dipstick tube enters the block, but as evidenced above, I sometimes confuse the A and B series engines since I have both.

However, what you really need to do is find the leak. To do that I expect you will need to clean it up and watch it when the leak first appears on the clean engine. Some throw some talc on the engine at suspect areas to make the oil show up better.

Charley
C R Huff

Grant, check your oil cooler line where it meets the adapter at the rear of the block. If it's just a bit loose, it can leak oil all over the place and make you think that the leak is coming from somewhere else. Moss carries an uprated rear main seal that was designed for the Sherpa van. It has multiple sealing lips and comes with a handy plastic installation tool. I just installed one on a customer's '72 GT while I was replacing the worn out clutch. Installation was very easy. I hope your leak is a simple matter of tightening a line. RAY
rjm RAY

Also check the flexible hose for the oil gauge feed where it attaches to the block, a common source of leaks.
Paul Walbran

The dipstick tube screws into the block. If you look carefully at the flare at the top of the tube you will see a slot each side for a screwdriver.

If the tube is loose, it will leak. It could also be cracked, but that's unlikely because the tubes are quite thick walled, so if you haven't been trying to bend it, it should be fine.
dominic clancy

"The dipstick tube screws into the block"

Some, later ones are pressed. It seems to have changed while 18GG and GK engines were being supplied.
Paul Hunt

This thread was discussed between 02/06/2015 and 10/06/2015

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