Spin on Filter drip

Paulbreitag · 2025-09-18T19:48:06-0400

On my 2005 Silverado, the Alison spin- on filter is dripping. I replaced the old filter because it started to drip. Thinking a new one would remedy the problem I changed it to an OEM Alison filter. It is still dripping. Has anyone had that same issue, and if so, how did you fix it?

davester3500 · 2025-09-18T22:28:33-0400

Did you do anything besides remove the old filter and install the new one, like check if the center fitting was still tight and undamaged, that the mating surface was nice and clean and didn't have an old gasket stuck to it, or even that the trans fluid wasn't coming from someplace nearby?

Paulbreitag · 2025-09-19T18:31:05-0400

Turns out I've got a gasket leak between the bell housing and tranny.

Paulbreitag · 2025-09-19T00:18:36-0400

I didn't check the center fitting or the mating surface. The old gasket came off clean and the drip was coming down from the side of the filter. I'm going to take it back off tomorrow and check the fitting and make sure the mating surfaces are clean. Thanks

jango_bmx11 · 2025-09-19T03:45:50-0400

I thought I had the same problem, but it was actually the gasket of the external oil cooler block off plate that was leaking and running down the side of the filter. Look almost directly above your filter on the side of the block

Paulbreitag · 2025-09-19T12:10:36-0400

Thanks, I'll check that out.

19trax95 · 2025-09-19T11:19:21-0400

Check to make sure there are no gouges or starches on the mating surface. That will cause it to leak. Also, in my experience, the Allison filters like to be out on a little tighter than say a oil filter. I usually get them fairly tight by hand. Beyond what is marked on the filter. Obviously don’t crank it down and fully compress the seal, but try going a little more with it and the standard.

Paulbreitag · 2025-09-19T12:15:41-0400

Thanks. I'm going to pull it off again today and check the mating surfaces. I cranked the filter on pretty tight to see if the drip would stop, but it continues. I'll make sure I didn't damage anything.

Paulbreitag · 2025-09-19T18:28:29-0400

😆 Ya, it makes it stiff. No, unfortunately I've got a gasket leaking between the trannt and bell housing.

Garykk · 2025-09-20T12:40:37-0400

You’re sure it’s not a rear main seal leaking?

Paulbreitag · 2025-09-20T13:00:12-0400

No. Turns out it's the bell housing gasket.

Spin on Filter drip

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