Overdrive oil leak

[PhilJane]

Good morning all,

Have been investigating an oil leak from the gearbox and overdrive on my TR3A and it was perhaps wishful thinking that I thought it was a drain plug leak. Having changed the oil recently with probably lower viscosity oil, the leak seems to have got worse. Cleaning down , it appears to be coming from the gearbox to overdrive adaptor plate. I have nipped up the clamping nuts but the leak persists. Is this a common leak path and is there any in situ fix or is it gearbox and overdrive out?

Thanks in advance, for any advice.

Phil.

[Don Elliott]

There is a distinct possibility that some previous owner tightened up the overdrive onto the rear of the gearbox without first pulling back the oil pressure pump which is driven by an eccentric cam inside the rear of the overdrive. This would have put such a force onto the adapter plate that it may now have a crack in it and this crack can cause quite a leak.

 

If you pull the gearbox and overdrive (as one piece) out through the tunnel opening with the overdrive still attached, you will be able to remove the overdrive from the rear of the gearbox. Then remove and replace the adapter plate if you find a crack.

 

If, at this point, you find no crack and the adapter plate looks flat, then use new gasgets and some approved sealant on the gaskets and joining faces and put it back together as per the instruction manual. Be sure to pull down of the cam pump drive inside the overdrive and tighten it all back together again.

 

Let me know what sealant is best because I have had a weep of oil around this area for quite a few years.

 

Or do nothing and check your oil level frequently and top it up often.

[PhilJane]

Don,

Good to hear from you and thanks for your response. I support your suggestion of a cracked plate, as the leak can be measured by the size of the pool of oil under the transmission rather than the frequency of the drips. Not sure what has caused the oil leak to deteriorate though, whether I had lost all the oil prior to the oil change, using a slightly lower viscosity synthetic oil and then fully topping up the transmission or the two seconds in reverse gear with the overdrive engaged?

Interesting one about the use of sealant on soft joints. I know some believe that if the parts are clean, dry and flat then additional liquid sealants are unnecessary, whereas the practical world says the liquid sealant takes up all imperfections and fills the gaps. Is there a well documented guide to gearbox/overdrive removal? Looked at the Haynes manual and that seems OK.Better get the ramps out.....

Any joy in the Concours recently?

Phil.

[Norman D]

Listen Phill, dont tell anyone about this but I had exactly the same leak from the same place and deduced the paper gasket had failed, not wanting to remove gearbox etc at this time I cleaned the area thoroughly and degreased and scuffed it and applied a smear of plastic metal product around the joint,to my amazement it worked! Just a bodge I know but it will be easilly removed if(when ) the gearbox is out for more serious work. Remember,keep it to yourself. Norman

[Don Elliott]

pHIL - mORMAN HAS AX EXCELLENT IDEA. iN FACT MAYBE THE po DID THE SAME AND SINCE YOU BOUGHT THE tr, MAYBE THE "CAULKING" HE USED SEVERAL YERS AGO HAS DETERIORATED SUSENLY. iF YOU REPEAT THIS, YOU'LL ENJOY YOU tr3a THIS SUMMER AND MAYBE WE MIGHT BE ABLE TO MEET UP IN hARROWGATE.

 

Phil - Norman has a great idea. I suggest that this is what a PO might have done and since you have owned it, the "caulking" has failed. If you do this(maybe with JB WELD, you'll enjoy your TR this summer and we might meet up at harrowgate.

 

Yes, the TR is running fine. Like a Swiss watch. I drove it 860 mles last weekend where I was awarded "Best Engine Compartment".

[pfenlon]

Good morning all,

Have been investigating an oil leak from the gearbox and overdrive on my TR3A and it was perhaps wishful thinking that I thought it was a drain plug leak. Having changed the oil recently with probably lower viscosity oil, the leak seems to have got worse. Cleaning down , it appears to be coming from the gearbox to overdrive adaptor plate. I have nipped up the clamping nuts but the leak persists. Is this a common leak path and is there any in situ fix or is it gearbox and overdrive out?

Thanks in advance, for any advice.

Phil.

 

 

Phil this plate can be "bent" and not look it. I had the same problem on my 3A after fitting a new O/Drive unit, it peed oil from the plate area, another plate fixed it and it doesnt take long when its removed from the car!

 

not a lot of help but its an OUT job to do it properly.

[PhilJane]

Norman, Don and Pete,

Good to hear from you. It seems this is not an uncommon oil leak. I might be tempted to try a temporary repair to get me running over the next two or three months, but recognise it really is a gearbox and o/d out job to rectify the problem properly. Good to know to check for flatness and cracking and not just replace the joint.

Congratulations Don, are we going to see some engine photos? Looking forward to catching up with you shortly!