Quote:
Originally Posted by sarg
I still believe, however, that the fluid flush dislodged some gunk which was holding a seal together somewhere, once that seal went it was curtains.
In other words, tread very carefully, only an expert will do for this job.
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I don't subscribe to the dislodged gunk theory. Having seen the inside of a few of these in my time, they are always spotless as ATF has some pretty powerful detergent properties and so washes any dirt in to the sump or the torque converter where either the filter or centrifugal force prevent it doing any harm. ATF is often used as an engine flush for this reason too.
The only 'dirt' which could really be in there is clutch material, and if thats floating around in the oil then there are much bigger problems! Everything else is metallic so should be stuck to the magnets. Old oil does break down slightly and go dark grey instead of yellow.
I do totally agree with the second statement though, since if you get this wrong it can easily do some fairly terminal damage to things. Mine was hacked about by the PO's indy garage and had the sump stuck on with bathroom sealant so oil leaking everywhere! By the time I got it home it was 4-litres low and killed the torque converter.
The key weakness in these gearboxes is the bearing and oil seal on the first clutch pack. If that is at all tenuous then running it low on oil could tip it over the edge. Thats where the Mackies change comes in to its own, as at no point does the oil level drop below normal as their machine replaces it as it comes out (although this method doesn't change the filter). A sump-off change by nature will drain everything and then re-fill and, as it needs to be running to get the full amount in, will temporarily cause the level to be lower than normal. I think it is this event which pushes almost-failing gearboxes over the edge, and the oil change gets the blame.
It makes me wonder if there could be a better method of re-filling which would get more oil in before start-up and then drain off the excess, which may then avoid this problem. Maybe a modified fill-plug...