Transmission mystery '05 XC70

Faust · Post by **Faust** » 30 Aug 2022, 12:23

For a few months my tranny has been shifting somewhat erratically. Yesterday, while out for a ride, my engine and transmission lost their connection. Meaning stepping on the gas would cause the motor to speed up, while the car slowed down. After shutting it off for a few minutes, it moved normally for about 50 yards, then reverted to symptoms above. Had it towed home. getting home I noticed a "puddle" where the car had been parked. This appeared to be motor oil. Today, I dropped the splash pan and saw quite a lot of oil, but source was not obvious. Checking fluids, I noticed oil was very low, tranny fluid appeared to be overfull. My first thought was to get oil. Since the car seemed to be behaving normally, I headed for my nearby service station. Got about 400 yards and rolled to a stop. Gave it a few minutes and got the 50 yards to the service station, then had it towed home again. Is there any possibility that a low engine oil level can effect the transmission? Doesn't seem likely to me.

Post by **jonesg** » 30 Aug 2022, 16:20

Might want to try a glove test for crankcase pressure.
If it fails, it might be the rear main seal, not sure how it can affect the tranny but stranger things happen.

Post by **MoVolvos** » 30 Aug 2022, 19:33

Faust wrote: ↑30 Aug 2022, 12:23
Checking fluids, I noticed oil was very low, tranny fluid appeared to be overfull.

The question could be where in the system can motor oil get pushed into the tranny? The last time I thought I had either a powersteering or motor oil leak turned out to be the transmission pan gasket. I checked all 3 and for some reason didn't think it was the transmission and that lead to a damaged transmission.

viewtopic.php?p=607983#p607983

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Post by **vtl** » 30 Aug 2022, 20:44

Transmission fluid level check is performed with the engine running. Otherwise ATF will appear above the hot mark.

Your issue sounds like a classic clogged transmission filter. Look for a donor transmission, or do a rebuild.

Post by **kallekula** » 30 Aug 2022, 21:31

A clogged filter usually causes the oil pump to whine pretty loudly due to starvation.
Make sure level is correct. Take it to a shop if you don’t know how. Then take it from there.

Post by **br0dy519** » 30 Aug 2022, 22:50

kallekula wrote: ↑30 Aug 2022, 21:31 A clogged filter usually causes the oil pump to whine pretty loudly due to starvation.
Make sure level is correct. Take it to a shop if you don’t know how. Then take it from there.

Pardon my ignorance, which oil pump are you referring to? Is there a “transmission oil pump” on this car? One of the vibrations almost feels like a pump whine on my car…

Post by **kallekula** » 30 Aug 2022, 23:20

It’s not super loud but you definitely hear it when you’re behind the wheel.
That thing with suddenly loosing gears etc sounds familiar, and not good. But set the level first before doing anything else.

Post by **kallekula** » 30 Aug 2022, 23:23

Yes the automatic transmission has its own oil pump.

br0dy519 wrote: ↑30 Aug 2022, 22:50
kallekula wrote: ↑30 Aug 2022, 21:31 A clogged filter usually causes the oil pump to whine pretty loudly due to starvation.
Make sure level is correct. Take it to a shop if you don’t know how. Then take it from there.
Pardon my ignorance, which oil pump are you referring to? Is there a “transmission oil pump” on this car? One of the vibrations almost feels like a pump whine on my car…

Faust · Post by **Faust** » 31 Aug 2022, 19:56

kallekula wrote: ↑30 Aug 2022, 21:31 A clogged filter usually causes the oil pump to whine pretty loudly due to starvation.
Make sure level is correct. Take it to a shop if you don’t know how. Then take it from there.

Is a clogged filter just a matter of dropping the transmission pan? Is the filter right there?

Post by **vtl** » 31 Aug 2022, 20:07

Faust wrote: ↑31 Aug 2022, 19:56 Is a clogged filter just a matter of dropping the transmission pan? Is the filter right there?

No, it is hidden inside. Need to drop the transmission and remove the bell housing. At which point you can just go ahead and rebuild the whole transmission, since it is out and split in halves. And you know it is mechanically damaged by oil starvation.

Filter is the black plastic thing:

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