I was reading on the allison website that the transmission filter in the tranny pan should only be changed when the tranny is being overhauled. Did I read that wrong, or is the only one that needs to be changed the spin on???
The filter in the pan is just a metal screen on the oil pickup. The only time it needs to be changed is at an overhaul and if changing to an Allison or aftermarket "deep" pan, when a deep pickup will be required. The only filter that should be changed out normally is the spin-on.
But where in the GM literature is it written that the in-pan (sump) filter is changed only at overhaul? I find it on page 56 of the Allison Owner's Manual but not in my GM Owner's Manual.
I ask because I had my transmission serviced today at 31000 miles and I paid a bunch extra because they replaced the sump filter. I asked about it and they said it was their common practice per GM policy.
The internal filter screen is only a "chunks" filter and unless there's been a serious internal damage incident that would produce "chunks" or you have changed pan depth which would mandate a different pickup it could be simply visually checked and left alone.
GM Service manual - 7-856 Automatic Transmission - Allison
Oil pan replacement, steps 5 to 8:
5. Remove oil pan (5) and gasket (3)
6. Inspect magnet (4). Excessive metallic particles or large metallic particles may indicate a need for overhaul or replacement of the transmission.
Important: DO NOT remove the suction filter or seal if only replacing the oil pan or oil pan gasket
7. Remove the suction filter (2) by pulling straight down where the suction tube is seated in the main housing.
8. Remove suction seal (1) from the filler or from the seal bore in the main housing. Discard the old seal. Discard the filter, if it is being replaced.
Therefore- "GM recommendation" as quoted clearly with an important warning in the service manual is DO NOT mess with the suction filter unless you have evidence and are rebuilding the transmission for large metallic residue!
And it costs $45 at the GM stealer and this shop probably charged him a total of $75 p&l to do an unnecessary and non-recommended replacement (IF they did it at all). So your point is? Edited by: Idle_Chatter
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