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MG TD TF 1500 - Engine removal part 3

A few notes on my desire to remove the engine.

First I must say that Mobius is running great. It's got power, pep, responsiveness and reliability. It handles great and is a pleasure to drive.

I've got Len's roller lifters and cam. The head has been reworked and is fine. All bearings are good. I've recently cleaned the cylinders and put in new pistons (+0.060")and rings(Did not bore the cylinders. Just clean and hone). Timing gears, chain and tensioner all good. I am using a modern seal in the front and in over a year there is not a drop of oil leaking anywhere from the front end. I have no problems with water flowing through the engine and it never runs excessively hot. Oil pressure good.

The rear of the engine is a sad story. Lots of oil coming out. The real seal is not doing its job. Oil gets into the bell housing area and can't drip into my drip pan fast enough. The flywheel is spinning it out the starter motor hole. I've got leakage from the bell housing seal. A little from the sump to engine seal at the rear. My under carriage from the rear of the engine back, is always a mess.

My thinking is to take the engine out. With so many good parts to it, I would like to do minimally invasive surgery.

Can I just take apart enough to examine and fix the rear seal?

As always,
TIA,
Mort
Mort 50 TD

Mort,
Unless you put one of those kits in the rear, there really isn't a seal.

It could be something simple, like that 1/2 shaped top piece got loose or crocked or something clogged the down pipe on the rear main cap, but could be worse.

Best case you get out of it with an oil pan gasket. Worse case, the archimedes scroll is too small or missing.



Blair
Blair Weiss

Mort,
You may want to do a leak down test before you pull the engine. If,as we suspect, there is compression leaking past the rings and in to the crankcase, this would be confirmed with a leak down test. You could confirm this, and maybe have the effected cylinders identified. Keep us posted.
-David.
D. Sander

Mort
Are you running a supercharger?
That could assist in pushing more pressure past the pistons?
I remember some fancy plumbing, if I remember correctly, on the tappet vent pipe.
Have you tried letting it go to atmosphere instead of the carbs to see if that helps with the oil coming out the back seal?
Just a thought.
Rod
R D Jones

Blair,
There is an existing kit in the rear but it came with the car. Judging by some of the other problems I inherited from the PO, I question it's effectiveness. It also could be one of the older ones. I believe they change their design at some point in time. I will know more when I take it apart. I've also been told that if you line bore the seats for the bearings and allow only .001 inches of clearance for the rear main, that will eliminate the leak.
Mort
Mort 50 TD

David,
The last leak test I did was before I put in the new pistons and rings. I will do it again before I tear down the engine.
I tried to measure crankcase pressure by attaching a gauge to the dipstick hole. I could not get a reading on the pressure gauge at all. I believe it was Declan who suggest a manometer but I've been too lazy to construct one. I think the pressure gauge might not have been sensitive enough.
Mort
Mort 50 TD

If it's an old Moss-type seal, then the rubber seal itself is probably toast. These have been upgraded in recent years to a better design. The seal kit itself works great, but they have to be installed very precisely. You can't simply follow the instructions and bolt it on, you have to measure everything along the way. Often the parts will need to be machined to fit your particular block, for optimum positioning over the crank.

As for what's involved, you will need a new front seal, oil pan gaskets, timing cover gasket, rear main cap cork seal, replacement rear rubber seal, gasket sealer, the usual tools and a lot of patience. Possibly a speedi-sleeve also. The crank may need to come out, so have safety wire on hand as well.

While it's apart, check the rear oil galley plugs. Rear seals are often blamed for leaks when the threaded plug and/or core plug are actually the culprit. Get them in tight. Seal the threads well. Epoxy the core plug if necessary. I use cylinder sleeve retainer and double up on the plugs.

Good luck!
Steve Simmons

Rod,
As I mentioned earlier I don't think the rear seal is the only culprit. That is one of the reasons I vented the side cover to the air cleaner just before my carburetor on the supercharger. My thinking is that the vacuum caused by the carburetor pulling in air would help relieve the pressure in the crankcase.
Perhaps the leak down test will lead me to consider Resleaving the cylinders to get a better fit.
Mort
Mort 50 TD

This thread was discussed on 03/10/2015

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