British-Cars.org

Welcome to the DMR Site for British Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Monumental Stuff Up

Lack of diligence has cost me dearly installing the Moss rear seal kit. A repeat of the motor removal task and motor bench running with the fly wheel removed revealed I still had an oil leak.

Inspection mirrors and black magic didnt divulge its source. Removal of the sump and the rear main cap with the seal retainer intact revealed all.

When I originally ground back the rear face of the rear main cap I believed I had removed sufficient material to facilitate the bottom half of the seal retainer to fit up square to the top section. I was of the opinion the two seal retainer assembly cap head bolts had been tightened sufficiently when I tested for clearance between the seal retainer and the rear main bearing cap, obviously NOT. The fact that the two sections of the seal retainer were not fitting squarely was the source of my leak.

Today I learnt a valuable lesson, fit the top section of the seal retainer, install the crank with Speedi Sleeve installed omitting the rear main cap,fit the seal onto the speedi sleeve ensuring it is fully inserted into the top section of the seal retainer, fit the bottom section of the seal retainer ensuring the meeting faces are square and there is no gap when the assembly cap head bolts are tightened.

Then and only then check for the required clearance between the rear face of the rear bearing cap and the bottom section of the seal retainer. Temporary fitting the seal prior to this process assists in ensuring the two faces of the seal retainer halves are fitted correctly.

Removal of the bearing cap and the bottom section of the seal retainer to apply "Permatex" to bond the components was carried out as per the Moss instructions once again ensuring that the two faces of the seal retainer halves were fitting correctly pior to tightening the bearing cap nuts.

Once curing time has elapsed, the cap and bottom half of the retainer will be removed to bond the seal into the retainer and refit the components ensuring the seal retainer halves are fitted correctly.

Complete motor reassembly and another motor bench run should hopefully provide a positive outcome.
G Evans

Thank you for sharing your experience with us. This is the type of information which is of great value to this site. I also had a problem installing my rear main seal kit. I am sure that this is something that you may have also checked for, but I found that after doing a trial fit of the retainer only, without the seal that the retainer was not concentric with crank flange after taking careful measurements between the the inner diameter of the retainer's seal seat and the crank flange, using a small telescoping guage. I had to eventually modify the three mounting holes by counterboring them to accept setscrews to provide some movement for centralizing. Fortunately I discovered this problem before reassembling the engine. Cheers Phil
Phil Atrill

Current update on this saga that may give further insight into making this conversion a worth while task.

I now have an oil leak free engine, however the motor has only been bench run at this stage.

After completely disassembling the bottom section of the seal retainer from the rear main bearing cap and removing another 0.020 from the cap rear face I carefully cleaned all mating surfaces. Applied the recommended "Permetex Black" sealant to the mating surfaces and reassembled the cap and seal retainer into the motor tightening all fastenings.

The motor was left untouched for 24 hours prior to removing the cap with the retainer attached to clean the drilled oilway as recommended by Moss. Reassembled the components torqueing the bearing cap nuts to spec and applying sealant to the retainer mating faces.

The motor was know inverted so the rear main cap pipe drain was vertical, the drain was charged with engine oil and left standing for a few minutes. What was observed was oil seeping from the face where the main cap and the bottom half of the seal retainer sits against the top half of the seal retainer. The amount of surface area where these faces meet is very minimal.

Blue air was the order of the day. Removed the bearing cap with the bottom half of the retainer intact and stripped the two components apart. Oil tracking thru the "Permetex" was observed and despite the 24 hour wait time the sealant was still tacky in the areas unexposed to air.

Time to bite the bullet and try a different approach. I had available a "JB weld" kit. All mating surfaces of the cap and retainer were cleaned and degreased, "JB weld" applied liberally to the bottom seal retainer to bearing cap face and the components assembled tightening all fastenings. At the same time "Permetex" was applied to the seal retainer mating faces.

An interesting phenomena now occurred the "JB weld" formed a gusset where the previous leak was observed increasing the contact surface area. The "JB Weld" had commenced to form a rigid bond between the components.

Another 24 hours lapsed prior to repeating the oil charged drain tube test, no more oil leakage was the result.

Motor completely assembled amd bench run still no oil leaks.

Concerns I have "JB Weld" is rigid, "Permetex" is flexible, will it fail with time owing to expansion and contraction of the components and/or the longitudinal thrust forces that the crank shaft is exposed to. Is the drilled oil way blocked by "JB Weld"?

Other concerns I express are, Moss machines the seal retainer out of aluminium (a material with a high coefficient of expansion) which is being fixed to materials with lower coefficients. Can the methodology for sealing mating surfaces be improved by having the two halves of the seal retainer mechanically interlock?

Pricing and the limitted market may proclude any future development of this solution.

G Evans

I have to admit that I have always worried about the integrity of the "Permatex" seal between the bottom half of the retainer and the bearing cap face. I have heard of a mechanic that actually creates a mechanical bolt on connection, as well as the permatex between these two parts, by drilling through the bottom retainer and tapping into the the face of the bearing cap. The other concern with these kits is that the lip of the seal just barely sits on the leading edge of the crank flange even with an overhanging speedy sleeve. Some folks fabricate a thin spacer ring to place behind the seal to bring it forward slightly, in an attempt to allow for more seating surface. All in all, I feel that these kits could do with a redesign to address some of these issues. Cheers Phil
Phil Atrill

Your experience is exactly why I decided to "take the hit", and return my seal kit to Moss, substituting the oil drip pan , that I made...(see my thread about this).
Anyway, I "chickened" out at the end, as I didn't have enough confidence in my ability, especially after reading other threads about the seal being difficult to install, and make oil-tight.
Thanks for confirming my decision....
I would have been devastated to learn, after the car was back together, that I had a rear seal leak. (I had no way to bench test the motor).
Good luck with your project.
Happy New Year.
Edward
E.B. Wesson

I think a lot of the problem with the kits is variation in the casting at the back of the block casting,main cap, position of the crank in the block, and crank flange thickness. I would guess the foundry used multiple casting boxes, which may well vary quite a bit. Not to mention who knows what has happened to the block over the years with line boring, wear, etc. I suspect that the kit may fit pretty much perfectly on some blocks, but not so well on others. I do think using just Permatex to seal (unless you have two perfectly fitting machined faces) is pretty sketchy at best. George
George Butz

This thread was discussed between 30/12/2011 and 01/01/2012

MG TD TF 1500 index

This thread is from the archives. Join this live forum now