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MG MGB Technical - MGB oli leak

Shock!
An MG leaking oil.
Well durn it, mine leaked big time after the rebuild.
What ever could be wrong?
Well finally got 'round to puuling it out, and apart.
The only thing I can find is, the cork gaslet/seal, between the rear plate, the rear main cap and the oil pan is about a 1/8" gap.
That's has to be it!
Right!

So all you 'expurts' lemme know what you think.

Safety Fast
Dwight
Dwight McCullough

An 1/8" gap sounds like a good place for oil to leak out to me! So to clarify, the oil pan gasket sits firm on the rear main cap and doesn't leak, the rear main seal is in place, but the engine plate doesn't seat against the block, so you're getting leakage from the main? Is it possible that the crank is shimmed incorrectly so that it is shifted rearward? What is holding the engine plate out?
Jeff Schlemmer

Aren't there little rectangular cork pieces that fit in there? About 3 inches long and square section. Maybe one of them is missing? If you look on Chris Betsons site you can see the gap where they go:

http://www.octarine-services.co.uk/1.%20fitting%20the%20crankshaft.htm

Picture about halfway down where the end caps are being hammered into place.

Simon

Simon Jansen

The crank can't move. It's held in place by the thrust washers either side of the centre main bearing, so it's not that. The backplate must sit flush with the rear face of the block inorder to compress the gasket but the rear main bearing cap is free to float and must be set flush with the back face of the block before tightening it. Take off the backplate and slacken the rear main bearing cap, tap it rearwards and then forward until it is flust with the block. Check with aa straightedge and torque the cap. Fit a new rear gasket and a new rear main bearing oil seal of the uprated type fit a new cork section then refit the sump gasket and sump. Use blue Hylomar for all the gaskets and make sure that the sump face is not distorted. If all is well you should just and no more see the sealer oozing from all faces as you tighten the bolts.
Iain MacKintosh

Say, how about filling that with Hylomar?
Maybe?
Safety Fast
Dwight



Dwight McCullough

No, no, no. Sort the problem out properly and be confident. If you don't it's only botch that will rear its ugly head again.
Iain MacKintosh

Dwight, please fix it right. I don't want your oil on my windshield this summer! ;-)
Jeff Schlemmer

Jeff
What makes you think I'll be ahead of you?

It has to be that cork piece that's too short.
I just don't know how that happened.
Oh well............................
The head is at the machine shop to have the new SS valves ground in, and.
Now is the time to get the roller rockers, lightweight push rods, and a new clutch disc. Having a guy named the Clutch Dr. relining a pair of disc's.
$25 each!
Now what about the OD transmission I've had laying around since 1994?
should I use it without checking it out?
Safety Fast
Dwight

Dwight McCullough

At your peril. Maybe the cork pieces are too short on that as well !! I did than on one and the O/D didn't work properly plus there was no gasket between the O/D and gearbox. So, big oil leak.

No, our British cars don't leak oil by design its just the previous owners who have botched them for forty years.
Iain MacKintosh

I think I heard somewhere along the way there are only two ways to make a British car completely oil tight. 1. Don't use any oil or 2. Get yourself a very big shrink-wrap machine and start wrapping.

I find it easier to carry a spare can of degreaser in my boot for when I visit my old lady and leave those few drops of black on her lovely driveway.
D O'Brien

Oh yeah, I forgot.
What difference is there between early 5 main and later 5 main engine oil pans.
What I have 'discovered' is the rear of the pan on a late engine goes up at an angle. About an inch shorter at the rear of the pan than the early one.
So my question is, will my oil pump pickup still be OK?
It adds the capacity back to 5 quarts.
Moss's catalog shows two oil pans, one for 3 main, and one for 5 main engines. Same with oil pumps.
Safety Fast
Dwight


Dwight McCullough

Hi Folks:

The 5 main MGB motor can leak oil from the rear hub, even with a new oil seal. It is very important to inspect the crankshaft rear hub, prior to installing a new seal. The oil seal can wear a groove in this hub. This condition occurs with both the forged and casted crankshafts. The repair includes:
* weld groove and regrind hub to OEM dimensions,or
* use a speedi-sleeve and new oil seal (black)or
* a double lip seal is availabe to bridge the hub groove.

I had this problem with a 66B,fixed the leak with a snakeoil compound that you can't buy today. The compound worked until I torn the motor down for a rebuild (maybe 150K miles later)

Good luck: Rich Boris 67B
Rich Boris

Just re-fitted a backplate. It hadn't been giving problems but I had a look to see what might be happening to Dwight.

Gaskets aside, leaves the question of whether the plate is being clamped tightly. The 14 bolts are critical in length as the holes are blind. Spec may vary depending on the plate and block so the best way is to clean all the block holes and run a tap down them. Then clean the bolts and check they will all screw in far enough to clamp the backplate. There is not much room for error. On the common 5 bearing with recessed holes the 8 lower ones are an unusual 7/8". If someone has used 1" bolts or there is crud down them, some won't be clamping. It's that tight a margin - they even need the thickness of the spring washers to clamp. A clue may be that the originals in that location may have thin heads. The top 2 aren't recessed and use ordinary head 1" so it's possible to mix in these by mistake.

Yes I built an engine with a speedi sleeve (like a thin bean can, slides over the crank end with loctite) nearly 30 years ago when they first came out and it worked great. I was telling my friend, a Rover mechanic, about them and he'd never heard of them. I didn't know if they were still available.

Rich
Rich

I can't remember the setscrew mix up on the backplate Rich but it is a very important point. Look at the face between the plate and block and you should jusy be able to see the blue hylomar at the joint if it is tight. That back main bearing cap is also vital and it is essential that it is tightened up flush with the block rear face BEFORE the backplate is fitted. Rear seal is very important as well as is the cork that goes into the bearing cap. These are the correct length DONT cut them. They will compress into the groove when the sump pan is fitted
Iain MacKintosh

Yes, the cork should be about 1/8" longer and need compressing so the ends fit tight and square but I've opened packets to find them shrunk too short and others so long I had to cut them to get them in. Payen were good but there are lots of old stock and cheapo pattern types out there. Some are dense cork/rubber compound and some just seem to be more natural cork which will shrink, so you have to think about how it should fit. Rich.
Rich

Iain, I'm out of touch - what's the new uprated type oil seal you mention? Is it this black one instead of the orange they used to be? Rich.
Rich

No Rich its the orange one but as fitted to Sherpa vans!! Can't remember the part no right now but it is recommended in Peter Burrges's book How to power tune an MGB. I've fitted them to both my cars and they don't leak. Local Rover stockist can supply but just give him the part number because if you mention MGB or Sherpa he'll just shake his head.
Iain MacKintosh

Use LUF10002 black viton seal - this is the improved Sherpa seal.

I would be surprised if the source of the leak is the cork seal - it provides very little sealing at its ends, oil round that part of the cap is not under pressure and the cap shuld be a pretty tight fit - so any oil leak past the ends of the seal will be a mere spotting - more than that has to be coming from the rear seal, sump gasket or somewhere else entirely.
Chris at Octarine Services

LUF10002 black is the one I've just fitted. Seemed tighter on the shaft than I remember.
Rich

Yes Rich that's the part number. It does fit well and of course comes with the plastic guide. It WONT leak.
Iain MacKintosh

Thanks for all the advice folk's.
I have another new 'orange' seal, new gaskets coming, and will double check those end plate bolt length. Plus I will tap/clean the bolt holes.
Then I need to address the crankcase pressure problem.
I found the valves and top of the piston very carboned up.
I did clean 'er all off, but am fairly convinced that the pressure problem caused this.
I checked one rod bearing but not the mains. It runs so well, and has very good oil pressure.
Say, maybe this would be a good time to 'baffle the oil pan?
You know, the older 18G that holds the full 5 quarts of oil?

Safety Fast
dwight


Dwight McCullough

Dwight, if you've got crankcase pressure problems it's got nothing to do with the top end of the engine. Check the bores, pistons and rings which is straightforward seeing as you are in pieces anyway. That contributed greatly to the carbon build up.
Iain MacKintosh

If you look at the MGA board you will see that Ford are using speedi-sleeve on their new mega buck car!!
David Witham

Dwight, I use a K&N filter that just clamps onto the lifter valley cover tube, as well as a vented oil cap. I don't have pressure problems - and best of all, no oil leaks (I know, its only a matter of time...) Maybe now you can try out that crank scraper and let us know if it works!??
Jeff Schlemmer

yes, and it would add to my oil capacity. But lack of $$$$$$$$$$

Safety Fast
Dwight
Dwight McCullough

This thread was discussed between 26/02/2005 and 07/03/2005

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