The Triumph Dolomite Club - Discussion Forum

Guys, I'm hoping for some intel/advice/experience with dealing with a sump gasket fluid leak from my Dolly's BW65 automatic gearbox. An attempt had been made some time in the past to stop the leak by smearing sealant on the outside of the gasket.

The leak is more of an annoyance than a serious issue, but I'm doing a number of jobs on the car and would like to sort this. I have removed the sump and given it a through clean, removing all traces of the old gasket.

I wonder whether anyone on here has had this problem and how they went about dealing with it. Relying on just the gasket to keep the fluid in? Using the gasket with sealant - on one side of the gasket/both sides - which brand of sealant etc?

I always pay attention to torque wrench settings, which may be relevant to this fluid leak problem as I suspect the sump bolts were overtightened in a bid to try and stop the leak.

Any advice gratefully received.

Best

Andy H

You shouldn't need any sealant if using a good quality gasket, have you checked the lip of the sump isn't damaged?

First thing to do is put a straight edge over the sump and see just how out of true it is! Overtightening was and still is endemic with BW boxes and the sump suffers. It's probably better to make a gasket from some suitable thick gasket material than use an off the shelf one (i've even seen cork ones which are worse than useless) And i'd probably be using some kind of silicone sealer too. Though this IS risky, get too much in the sump and you'll block the filter.

In America, you can buy "improved" or custom cast alloy trans sumps for almost any domestic autobox, to get over the very real problem of flange warping, whether such a part is around for a BW 65, I couldn't say, but if there is, I'D buy one! I suspect not, as an autobox is not something associated with a "hot" car in the UK!

Steve

Carledo wrote: ↑Mon Jan 11, 2021 11:42 pm First thing to do is put a straight edge over the sump and see just how out of true it is! Overtightening was and still is endemic with BW boxes and the sump suffers. It's probably better to make a gasket from some suitable thick gasket material than use an off the shelf one (i've even seen cork ones which are worse than useless) And i'd probably be using some kind of silicone sealer too. Though this IS risky, get too much in the sump and you'll block the filter.

In America, you can buy "improved" or custom cast alloy trans sumps for almost any domestic autobox, to get over the very real problem of flange warping, whether such a part is around for a BW 65, I couldn't say, but if there is, I'D buy one! I suspect not, as an autobox is not something associated with a "hot" car in the UK!

Steve

I suppose machining it flat is out of the question?

Ok. First question, is it definitely the sump leaking? Quite common on a 65 box to get leaks from the breather pipe tube or the kick down cable entry point, both of which will run down and gather around the sump flange making it appear the sump is leaking. Suspect this if it only leaks after its been stood for a week or so, what happens is the torque converter drains back into the box and over fills it, causing leaks from areas that are not meant to see fluid.... Only cure is to run the car every week to keep the torque converter full.
If it is the sump - it's usually because it's been distorted in the past from over tightening. A little attention with a hammer and straight edge will sort that.
Gasket - never ever use sealant. Not on an Autobox. They seal fine with the standard cork gasket if everything else is ok. There is a updated rubber gasket that's supposed to better available from a Rover Specialist - I tried it, it swelled up within a year and leaked.... Gone back to cork.

Just as a suggestion, would it be possible to use " Plastigauge " or similar on the cleaned surface, torque up the fixings and then check how evenly the Plastigauge is compressed ?
Tony.