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TR2/3/3A Differential Gasket & Oil Leak

SteveBones

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Hello,

For my 1958 Triumph TR3A, I recently replaced the differential pinion gear seal & the differential cover gasket. The good news - zero oil leakage from the pinion oil seal. The bad news - there is quite of bit of oil leaking from the differential cover. When I removed the differential cover, both surfaces where cleaned and a new new gasket from Moss along with gasket sealer where used. Looking for help and feedback on the following regarding the diff cover oil leakage:

1). The Moss differential gasket is really thin. I was thinking of replacing with a thicker gasket that I will cut out myself. Has anyone used the Moss diff cover gasket successfully - w/o oil leakage? Should I plan on using thicker gasket material?
2). What gasket sealer would you recommend. I used what I purchased and use for the valve cover gasket vs using a silicon gasket sealer. For the replacement, I will go with a silicon gasket sealer unless someone else recommends some other gasket sealer type or particular brand.
3). Any suggestions for determining if there are high or low spots on the differential cover itself? I was planning to use a straight edge to check for uneven surface. I did not check the diff cover surface the first time.

Thanks in advance for any recommendations you might have on this.
 

groupdeville

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Not sure if the cover bolt holes are blind holes or not, but if the holes go through to the differential oil, then oil may be working its way out along the cover bolt threads. Check the cover for warpage also.
For gasket sealer, products containing Hylomar are my go-to these days, mostly because it's oil and gasoline proof. It's also thick enough to fill irregularities in housings. Expensive, though.
Others may suggest great sealers as well.
 
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SteveBones

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Thanks for the recommendations.

Not sure if the cover bolt holes are blind holes or not, but if the holes go through to the differential oil, then oil may be working its way out along the cover bolt threads. Check the cover for warpage also.
For gasket sealer, products containing Hylomar are my go-to these days, mostly because it's oil and gasoline proof. It's also thick enough to fill irregularities in housings. Expensive, though.
Others may suggest great sealers as well.
 

Bruce100

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+1 on hylomar. Permatex Fuel Resistant is equivalent to hylomar, and references hylomar on the label. I just used it to stop all the leaks in my gearbox and am totally sold. Follow the directions carefully. I tried cheating a little and didnt get a perfect seal. Redid it exactly as instructed and zero leaks. Not even a drip as proven with UV dye.

I also use it as a.sealer for threads, fixed leaky drain and filler plugs. Dont overtorque, which distorts the sealing surface, and where possible resurface parts like covers. I use wet dry sandpaper, wet, on a very flat surface. 400 down to 600 grit.
 

CJD

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Be sure to beat the holes in the cover back out with a ball peen hammer. When bolted the holes deform inward. It will not seal unless the holes are knocked back outward slightly, allowing the cover to fully seat on the gasket. Lay the edge on your bench and carefully hammer the holes. If you use silicone, use the black tube, which is made for direct oil contact.
 

martx-5

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...
1). The Moss differential gasket is really thin. I was thinking of replacing with a thicker gasket that I will cut out myself. Has anyone used the Moss diff cover gasket successfully - w/o oil leakage? Should I plan on using thicker gasket material?

I don't remember whether I got my gasket from Moss, but it was thin and leaked. I cut my own from 1/32" generic gray fiber type material that I got at the FLAPS. End of leak.
 

Graham H

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I took my diff cover off three times trying to stop the leaks until i finaly got smart and put some plumers tape on the thread of the filler plug, the oil was wicking up the thread. A litle bit of oil goes a long way?

graham
 
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SteveBones

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I wanted to provide an update to my regarding the leaking differential cover. Thanks for all the recommendations. One big issue it turns out was that the bolt holes were deformed inward. I straighten them out. Never would have thought to even look for this. Thanks for the recommendation. This saved me from further headaches and aggravation.

Also, thank you all for the recommendations on what gasket sealer to use. Took me some time to find the time to get this all finished and wanted to provide an update.

Be sure to beat the holes in the cover back out with a ball peen hammer. When bolted the holes deform inward. It will not seal unless the holes are knocked back outward slightly, allowing the cover to fully seat on the gasket. Lay the edge on your bench and carefully hammer the holes. If you use silicone, use the black tube, which is made for direct oil contact.
 

mrv8q

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Good on you, and +2 on Hylomar. My diff is the one area on my car that does not leak!

Think I used Hylomar on the cork valve cover gasket, and no leaks there either.

The great thing is that the cover can be removed and straightened up, as you found out.
 
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SteveBones

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Thanks! It is so funny to me that having a diff that does not leak can be such a wonderful and enjoyable thing! I guess it is one of the many pleasures of Triumph ownership.


Good on you, and +2 on Hylomar. My diff is the one area on my car that does not leak!

Think I used Hylomar on the cork valve cover gasket, and no leaks there either.

The great thing is that the cover can be removed and straightened up, as you found out.
 
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