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MG MGB Technical - Rear engine oil seal

I have a serious oil leak from the rear engine oil seal of my 1972 MGB GT. I know that the engine has to come out. The flywheel and backing plate have to be removed. Can the seal be replaced with out need to remove sump, crankshaft etc?
Graham Smith

Graham, Yes, the seal is in the backing plate. Clifton
Clifton Gordon

Graham. Have you done this before? If not, Clifton is perfectly correct that all you need to remove is the clutch, flywheel and engine backing plate. However, you also need a new rear plate to engine gasket, a new rear main oil seal, the oil seal retainer and the tab-lock washer for the flywheel. As long as you are going this far, it is also a good idea to replace the clutch assembly, check the pilot bushing/spigot bushing and have the flywheel resurfaced. Having all the parts on hand before you begin makes for an easier job with less down time. Les
Les Bengtson

On a linked subject, is it also worth checking / replacing the front gearbox oil seal, it is difficult to determine which is leaking without disassembly. Also - does anyone know if you can remove the gearbox on a B without taking the engine out?? Can the engine be moved forward and supported for example, is there enough clearance then to drop the box?

Cheers,

Andrew
Andrew

Andrew,
This has been covered and is in the archives. Short answer full synchro non OD transmissions can be R/R'd with the engine in place. Is it worth it? In a flat rate shop, yes. For the DIY, I don't know, what other work would you like to do?
Leland Bradley

Graham / Les,

No you don't need to take off the backplate, the seal can be levered out and replaced with the plate in place.

Leyland,

Yes but not without undoing and lifting the engine and pulling it forward enough to get the angle on the box to drop it from below. Useful to have the car on a lift to do this, too.

Altogether less hassle to pull the engine and leave the gearbox in place.
Chris Betson

Chris,
You can leave the engine in place by rotating the transmission 180 degrees and removing the flywheel. The transmission will then clear the engine and come out. For a clutch R/R just slide the transmission back in the tunnel. Yes, a two post host is preferable for this job.
Leland Bradley

Graham, I have had problems with the new seals that moss & others are selling, the ONLY one that I will use on the motors I am rebuilding is a GACO seal that has been around a LONG time & thay sell them at Engles inports 800-253-4080. I had 3 moss seals leak oil on motors that were rebuilt last year.
Glenn Towery

In the past I always heard that if the rear oil seal was leaking it was a good idea to look at the main bearings as loose bearings throw more oil. A modern good quality rear oil seal should last a long time
-- no??
Barry.
Barry Parkinson

Thanks to all that have assisted me here. One other thing;can I remove the motor with gearbox (o/d version) still left in car. Would support of the gearbox with a box under it be the answer?
Graham Smith

Hi Folks:

When replacing the rear oil seal on a 5 main bearing engine, the crankshaft hub must be inspected for a groove worn into the hub. New seals will leak if there is a groove in the hub. A worn hub can be repaired with a speedi seal, a very thin shim that wraps around the hub. I told the price is around $50, and someone one this thread would have the part number. In addition, I have heard that there is a twin lip oil seal which will bridge the groove in the hub. If no one has these part numbers, I may have them around some place.

Note: if you do not use the parts above, the hub must welded and ground to the correct diameter.

Good Luck: Rich Boris 67 mgb roadster
Rich

Graham. I have never removed the engine without tranny by myself. I did do it one time "under supervision" when working with a couple of professional mechanics. So, yes it is possible. We used a floor jack to support the tranny because the engine was only out for a short period of time. (This was when I learned that the people who had recommended a "light smear of silicone sealer on the new freeze plugs" had probably never done a freeze plug replacement in their lives--if so, I wonder if they had three of them blow out, as I did, when the fired up their engines?) I would use a substantial support under the tranny bell portion so I could clean and inspect the inside of the bell, the front plate oil seal, the throwout bearing and the clutch fork bushing. Les
Les Bengtson

I have the motor out from my 72b & have had a go at undoing the bolts holding the flywheel on without success. I intend to try an impack wrench on the week-end for another go. I was wondering if the bolts maybe LH Thread or are they normal RH Thread? I guess they maybe loctited in
Thanks Jeff
jeff jorgensen

Jeff, They are not left hand thread. The bolt heads are short and you need to carefully select a socket to fit, usually six point. Some people have had to do some grinding on the end of the socket, but my Sears Craftsman has always worked ok. I do have an air compresser and impact wrench and never had any problems removing flywheel bolts. Good luck, Clifton
Clifton Gordon

The flywheel bolt heads are thin. If your socket has a rounded lip, it will not go over the bolt far enough to get a good bite and instead will round off the bolt. I managed to get a reluctant bolt out by 1/ refacing a socket so the edge facing the flywheel was square and 2/ using a hand held impact tool. (The hand held tool you hit with a hammer to break the bolt loose.) By hitting down on the tool I got not only the torque to loosen the bolt but also an adequate grip on the shallow bolt head.
Barry
Barry Parkinson

I also have a rear main oil seal leak. Disgusting, especially when the engine has been genuinely rebuilt. [very carefully]

The gasket set and seals were from Moss. And I really like Moss!
So, it's gotta' come out again. I will try to get the 'better' rear seal.
And all is not lost, as now I'll install the overdrive transmission.
I previously had the OD in another car. [Austin Marina]
Yeah, yeah, it didn't come in that car.
Yeah, yeah, it was a Austin Marina.

But never mind, now I'll have to wire for the OD. Probably get the steering column switch.
Safety Fast
Dwight McCullough
Dwight McCullough

New seals don't leak if there is a groove in the crankshaft, as long as you fit the seal so that it runs in the groove.

I have never used speedi seal but I don't say it won't work just fine.

I have the crank surface ground down by about 5 - 10 thou to remove the groove - seals (the black LUF10002 version) work just fine on the slightly reduced diameter.

The engine comes out easily on its own -

Undo the bonnet stay and rope the bonnet upright out of the way - the boot handle makes agood place to tie the other end of the rope.

Pull the carbs & manifolds, alternator and starter motor, pull the rad & hoses, oil cooler hoses + rad mounting panel on early cars, leave the panel on the oil hoses and the hoses on the cooler, just dangle the lot over the front of the car.

Undo the engine mounts and the bolts on the top of the bellhousing, lift the engine till the gearbox hits the top of the tunnel - run a rope round the gearbox and tie off to the bonnet hinges.

undo the rest of the bellhousing bolts and pull the engine off the gearbox, adjusting the height of the engine to make sure the input shaft is centred in the clutch cover.

Reverse the procedure to refit the engine - just get the clutch properly centred so that the input shaft will slide in freely.

Whole procedure to pull engine, replace clutch & seal and refit, takes me 90 minutes, "drive in" to "drive out"
Chris Betson

Impressive - It would take me 90 minutes to just pull all the accessories from the engine.
Rick W

I am rebuilding my engine and got the gasket set in the blue and white cardboard package that says 'Rover Group' on it. Is this main seal OK or is it the one you all are saying leaks?

Thanks
Sam
Sam

Sam,

I would be suspicious of a gasket set that includes the rear seal - genuine Rover parts come in packaging stamped all over with "Land Rover" - Blue & white is the packaging that Payen use - so you might be OK here - is the seal black or orangey red?

The "improved" seal, LUF 10002 is black and made of Viton.
Chris Betson

Chris-

You are right - the seal came with the Brit-Tek ENGINE kit, not the Clough gasket set.
The seal is a red NAK seal. What do you think? Any good?

Thanks,
Sam
Sam

Sam,

I prefer to use the later black seal rather than the red one in my engines.

All I can say is that both will seal intially, but the black ones last better.
Chris Betson

You may wish to consider why the rear main seal is leaking oil. Perhaps you have excessive blow bye - i suggest that you perform a compression and leakdown test before pulling the engine.

the rings or block may have a problem that may not be dected until you're finished reinstalling the engine.

rn
RN Lipow

If the rear crankshaft hub has a grove in it where the rear main seal fits, it's more than likely still going to leak even with a new seal. Personal experience on two rebuilds with different seals from diferent suppliers.

Use a Speedi Sleeve which is available from Napa Autoparts for the MG to go over the rear crankshaft hub. This is a very thin steel sleeve that fits over the rear hub and makes a very smooth surface for the new rear seal to seal against. I have used one and they fit easily and work great. You can visit their website by searching for Speedi Seal, I think.

Andy 67 B, 74 GT
Andy Preston

I had the sleeve installed too. The grooves were pretty deep. About $50 but well worth it. Put one on the crank pulley too. Question for Chris- do you apply any oil/grease/sealant/sealer to the outside of the seal where it presses into the engine plate?

Thanks
Sam
Sam

Sam,

No - just oil the sealing lip on the inside and the crank very lightly and slide the seal gently over the crank so that you do not damage it in the process - you can get a plastic protective sleeve to do this with. Otherwise just be careful. Once on the crank, just tap it evenly all round until it is flush with the plate.
Chris Betson

Thanks Chris.
Sam

I checked with Engle imports and they carry the Payen seals and Red NAK seals. Where do you get the LUF 10002 seal in the states?

Thanks
Sam
Sam

This thread was discussed between 16/06/2003 and 20/06/2003

MG MGB Technical index

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