Transmission Flange Oil Leak From Split Pin

[jwrayth]

With the correct "O" ring you should not have to but if you do use silicone you must also use it on the roll pin. Lotus's have a special problem with that area. If you put the flange on 180 degrees from it's "proper" position the roll pin will not go in. Deloreans don't have that problem either.

Thanks David.

The plot thickens somewhat as when I took the drive axle off there was no sign of a leak from the splined shaft. I took the gearbox fill plug off to check how much may have leaked out, and fluid dribbled out which makes me think I haven't lost much if any fluid. The drive axle boot isn't split either, though the CV grease that escaped definitely came from the edge of the boot.

So my thinking is either;

• I still have a fluid leak but only when the oil warms up
• The rubber underneath the boot clamp has given way due to the previous gear-oil contamination
• The CV grease got contaminated via other means (I do have a rear main seal leak and have had for some time)

I'm going to replace the boot and clean the joint either way, and was intending to get the rear main seal done again this year anyway. After that I give up and will either do the Lotus silicone approach or I'll just pay for someone else to look at it as I'm sick of it

[kings1527]

Thanks David.

The plot thickens somewhat as when I took the drive axle off there was no sign of a leak from the splined shaft. I took the gearbox fill plug off to check how much may have leaked out, and fluid dribbled out which makes me think I haven't lost much if any fluid. The drive axle boot isn't split either, though the CV grease that escaped definitely came from the edge of the boot.

So my thinking is either;

• I still have a fluid leak but only when the oil warms up
• The rubber underneath the boot clamp has given way due to the previous gear-oil contamination
• The CV grease got contaminated via other means (I do have a rear main seal leak and have had for some time)

I'm going to replace the boot and clean the joint either way, and was intending to get the rear main seal done again this year anyway. After that I give up and will either do the Lotus silicone approach or I'll just pay for someone else to look at it as I'm sick of it

Were you able to solve this riddle? I'm dealing with a very similar situation right now (oil leak coming from the split pin hole). Thanks!

[Azar]

Same problem here

[DMCMW Dave]

If it's coming from the split pin you either damaged or didn't replace the rubber o-ring around the output shaft. Way down in there past the splines.

[Azar]

If it's coming from the split pin you either damaged or didn't replace the rubber o-ring around the output shaft. Way down in there past the splines.

Thanks Dave, we replaced the 2x O rings 103120. Will disassemble and check.
Can it be that the Diff Adj Nut (26) is not pushing all the way in so there is a gap inside, which the O ring can't seal?

[Azar]

Yes, it drops from the pin...

[DMCMW Dave]

If the roll pin is installed, the flange is in all the way. May have chipped or split the O-ring. Be sure to oil it when installing.

[Azar]

The DMC OE lip seal worked for me (sourced from DMC-EU), but the DMC OE o-ring did not (also from DMC-EU). With it all fitted Gearbox oil leaked along the splined shaft and out through the roll-pin. As can be seen in this thread though it appears my situation is not the normal, so the OE o-ring might suffice for yourself.

The 25mm/3.5mm cs O-ring is certainly a tighter fit and I can confirm that I've not seen the leaking re-appear after putting > 3000 miles on the car since my last updated in this thread.

And yes, I got the DMC-EU lip seals and O-Rings.... Just ordered 3,5 mm thick ones....

[Azar]

If the roll pin is installed, the flange is in all the way. May have chipped or split the O-ring. Be sure to oil it when installing.

Thanks Dave, will do. I hope it is an easy job, just need to unscrew the drive shaft bolts...

[DMCMW Dave]

Thanks Dave, will do. I hope it is an easy job, just need to unscrew the drive shaft bolts...

Biggest thing - be careful which direction the pin is going when you drive it back out. It's really annoying when you punch it out of the flange and into the side of the case, and then can't rotate the flange to keep it going or get it back in.

Then pull the flange off, and reach in with a pick tool to remove the o-ring. If the o-ring has split it may fall into the trans, so go slowly.