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Re: 1992 V6sei auto gearbox repair

Posted: Sun Mar 17, 2019 9:42 am
by White Exec
Pressure-gauge check possible?

Re: 1992 V6sei auto gearbox repair

Posted: Sun Mar 17, 2019 10:41 am
by Dieselman
MTXM wrote:
Sun Mar 17, 2019 9:12 am
I also wondered whether an obstruction in the oil cooling circuit would prevent circulation as a whole and the operation of the box - probably not? With regards, Matthew T.
Any obstruction to flow of ATF will stop the box from working, but lack of cooling wouldn't stop it immediately.

You appear to have no flow, even without any pressure requirement. That would indicate either a significant blockage, pump failure or lack of drive to the pump.

Re: 1992 V6sei auto gearbox repair

Posted: Sun Mar 17, 2019 1:28 pm
by Dean
MTXM wrote:
Sat Mar 16, 2019 10:07 pm
My mechanic suggested that I could check operation of the pump by partially detaching a gearbox-air cooler hose and turn over the engine, which I have now done with rather interesting results. After detaching one and then both hoses and placing suitable receptacles there was no flow of oil through either hose! I have also tried blowing through the hoses with the result of only minimal discharge of oil and very little flow of air. My guess is there must be a blockage somewhere in the system, that would explain the on/off and then off for good operation of the box and perhaps the addition of the cleaner and recent oil change made matters worse? I wonder where the blockage might be and the possible cause, perhaps another piece of oil seal from the governor! Regards, Matthew T.
The oil is picked up from the sump, sent to the pump, then when the torque converter is full through the oil cooler to the valve block and then to the rest of the components before being returned to the sump.
You should not be able to blow back through the pump and I would expect blowing through the valve block would be difficult or impossible unless you can reach governed line pressure.

If the torque converter as been previously miss aligned it could have fretted the locating pegs off of the pump or the torque converter hub

D

Re: 1992 V6sei auto gearbox repair

Posted: Sun Mar 17, 2019 4:25 pm
by MTXM
Thanks chaps and in particular Dean for confirming the route taken by the oil, which means assuming l have a blockage there is no supply to the valve block. I think myself that a pump failure is unlikely since there is no debris in the oil and the initial failure followed by recovery surely also points to either a pressure leak or blockage. A leak would be more probably worsen rather than temporarily heal but a blockage could clear and then return. The pressure test suggested would confirm operation of the pump that after checking the pipes should certainly be my next move. Regards, Matthew T.

Re: 1992 V6sei auto gearbox repair

Posted: Sun Mar 17, 2019 4:37 pm
by White Exec
Matt,

"My mechanic suggested that I could check operation of the pump by partially detaching a gearbox-air cooler hose and..."

Sorry I don't know this 'box as well as you, but what is this?
If the ATF-water heat exchanger (oil-cooler) arrowed on the bottom of the box in your photo, then the hose connections will be carrying coolant, and should have no connection to the gearbox hydraulics - so no transmission fluid should be coming out there anyway. (These items are pretty much identical to the engine oil coolers under the filter.)
I've likely got this quite wrong, but am confused.

Re: 1992 V6sei auto gearbox repair

Posted: Sun Mar 17, 2019 5:05 pm
by Dieselman
There is an ATF to air cooler mounted behind the radiator.
If no fluid is travelling to that, the box won't run.

Re: 1992 V6sei auto gearbox repair

Posted: Sun Mar 17, 2019 5:29 pm
by White Exec
OK, with you now. All makes sense.

Re: 1992 V6sei auto gearbox repair

Posted: Sun Mar 17, 2019 5:34 pm
by MTXM
Thanks Chris and I can understand your confusion as the oil feed to the air cooler passes through the water cooler! With regards, Matthew T.

Re: 1992 V6sei auto gearbox repair

Posted: Sun Mar 17, 2019 6:55 pm
by xantia_v6
Dean wrote:
Sun Mar 17, 2019 1:28 pm

The oil is picked up from the sump, sent to the pump, then when the torque converter is full through the oil cooler to the valve block and then to the rest of the components before being returned to the sump.
I am not convinced that that description is completely accurate. The torque converter (I believe) runs at a lower pressure than some of the other hydraulic components, so I don't think that it can be in series.

It appears to me (from the diagrams in the Saab manual) that the pressure regulator contains a separate valve for the torque converter (and cooler) feed, but I don't understand the purpose.