MG Car Repair: 1973 MGB Clutch Spin Problem, rear main oil seal, diaphragm type

Question
Hi Howard,
The car was partially overhauled 2 years ago and included a new clutch. The clutch at that time did not release properly so I thought the problem was incorrect bleeding of the slave cylinder. The car was left as-is due to other time commitments.
Recently I found that the slave cylinder has adequate travel but the clutch will not release.
I have pulled the engine because of the clutch issue and a substantial rear main seal oil leak.
What should I look for to verify the clutch disc operation?
How difficult is it to change the rear main oil seal?
Should a engine restraint rod assembly be present on a 73 MGB?
Thanks for your help!

Answer
Hi Rick,
If you are sure you have all of the air out of the clutch hydraulic system and you still have a dragging clutch, look at the pilot bearing in the back of the crank and remove the disk and check that it slides freely on the input shaft spline then spin the input shaft with the disk on it to see if the disk has any wobble in it. (It is easy to warp a disk when assembling the engine to the transmission). A warped pressure plate spring is possible but less likely as the diaphragm type spring are not prone to warp. Some aftermarket disks are know to have the plates between the linings too springy and the result is a thick soft disk that is difficult to disengage.

As for a rear main seal leak in only two years, you need to note the oil pressure because too much oil clearance in the main bearings will knock out a rear main seal. If the oil pressure is ok (60 to 80 PSI on hot oil) that is not the problem and you can just pull the rear main seal and drive a new one in. Be careful not to scratch the seal surface on the crank.

I recommend using a engine restraint rod on all engines.

Howard