Auto tranny problems on 3.8 V6 '92 Commodore Station Wagon Executive

[albertross74]

Hey guys, am new on this forum, just looking for a bit of advice on my Commodore as am starting to run out of ideas what to do next!

The car has been leaking tranny fluid from the gasket seal around the pan since December, but only very slowly. Drove all the way from Sydney to Canberra for Summernats, and then Sydney to Cairns and back with no difference in the performance of the car shifting gears and without the leak increasing.

From where it was leaking all signs pointed to the gasket seal of where the pan mates to the box under the car, so bought a new one and fitted it. Stupidly put the tranny pan back on really tight and put the nuts in no specific order, so was still leaking slowly (only found out afterwards that the nuts needed to be not much more than hand tight, and the nuts have to go in a certain order as not the twist the crappy sheet metal pan!).

When cold it wouldn't change until you hit 2500 - 3000rpm, but then once warm it would go back to changing at around 1500rpm. Drove it like this from Sydney to Melbourne no probs, then en route to Adelaide she wouldn't shift at the same rpm for each gear so it would change from 1st to 2nd at about 2500rpm then the rest of the gears would be the usual 1500rpm. Carried on driving like this making sure oil was topped up all the time to Adelaide then back towards Sydney, and on the way back going up some pretty big hills near Wollongong she dumped her load from around the seal of the tranny pan and loads of oil poured out! Let her cool down and nursed her back to Sydney.

Done two gasket changes after got back to Sydney, first one wasn't in properly so popped out making oil go everywhere. Then second one made sure to be super precise, even let the gasket goo dry for the full 24hrs, then took her out for a test drive, was driving really well, almost how she drove when bought her, then when she got a bit warmer and dumped her load again, grrr!

I'm all out of ideas what to do next? Thinking about just taking her down to the local garage and getting a quote, but thought I may aswell try asking you guys on here first. Many thanks for your help.

 

[vamplestat]

are you useing a cork seal or a rubber seal on the pan?

 

[albertross74]

cork ones, the Transgold ones you get in a box with a filter too from SupercheapAuto

 

[vamplestat]

half the problem there, with the cork seals if you tighten them up just that little bit to much they will leak like a sieve. i think it was AutoPro that stocks the trans service kits that have the rubber seals. i was having the same issue with cork seals, could never get it to seal correctly. changed it to a rubber seal and haven't had a single leak since. give them a call and see what they have in stock.
also check the rear transmission seal where the tail shaft Yoke sits.... they tend to leak as well given their poor design.

 

[hi_ryder]

you have to also make sure you scrape off any old cork residue and gunk from where the seal sits on the pan and the tranny. i clean mine with a razor blade, make sure the metal is like new before putting the new one on. dont want any places for the new oil to creep by... i always go around and make sure all the bolts have the same firmness, even if ive gone and done 3 rounds of tightening.

if you wanna change when the tranny shifts you just need to loosen or tighten the kick down cable, its the other cable thats attached to your throttle body (not the accelerator cable)

also might sound like a stupid question but your using new trans fluid every time you change the gasket right?

 

[albertross74]

cheers for your responses guys.

It's just weird the way it goes from not leaking at all to then suddenly dropping loads of oil, to then just dripping slowly!

Cleaned up the tranny pan so much that I could have eaten off it haha, and same with the mating surface on the tranny.

Will give the kickdown cable a bash when I get this leak sorted.

Just re-used the same fluid as it hadn't discoloured, due to not being in the system for long at all, me and my mate must have been through around ten of the 5 ltr fluid cans since the problem started, so the old fluid has long been flushed out!

 

[Customcreations]

I will assume that you know how to read the fluild level correctly. But just incase. With car in Park, on level ground, engine running at idle and most important at correct operating temp after engine has warmed up. If you fill it too much cause the car isn't running and you get an incorrect read it will "spit" the dummy (punn intended). Also does fluid come out the dip stick, is the seal at the base of the dipstick pipe leaking?. Did you make sure you got the old O ring out when you changed the fluid filter. The funniest thing with cork gaskets is the seal best if you smear them with grease instead of trying to get it all oil free. Probably not many people that would do that with grease or even know it maybe???. You already mensioned that you found out not to tighten the bolts too much. Finger tight then half or 3/4 turn should do it. I use a drop of thread locker just to be sure they dont come loose either but the rubber seal would make it easier. If you do have fluid come out the top it may have starte getting water in to the trans through the radiator to trans pipes but I'd say you would have noticed that by now. This possibly covers most of it. Good luck nutting it out. PS: I would add a tube of Nulon gearbox and trans lube with PTFE to it once you get it leak free. It will improve the performance of the transmision and help it live longer.

 

[hi_ryder]

also its never a good idea to put used trans fluid back into the tranny. regardless if its not that old, its still unfiltered and any debris in it can wreak havoc on your clutch bands and other parts....

 

[vamplestat]

all good points ^^

when it starts jumping from overdrive to 4th and then back to overdrive again while at cruising speeds of 100kms like mine does atm, you know there are problems.....

 

[Customcreations]

all good points ^^

when it starts jumping from overdrive to 4th and then back to overdrive again while at cruising speeds of 100kms like mine does atm, you know there are problems.....

When you say overdrive to 4th I assume you ment to say overdrive to third?

If that is happening in your trans it may just be you need to check the fluid level and make sure it isn't just running a bit low.

I had that with my trans and after topping it up to correct level it fixed it.

If the level is correct, try adding 125ml tube of Nulon PTFE additive for geaboxes, diffs and transmisions. It works a treat. REALLY!!!

It only costs aroung $16 for the 125ml tube.
Even better is get a 250ml tube and add some to the diff too. Even if the diff gives you no grief it will improve it due to its anti friction properties.
It's compatible with LSD too.