| Transmission Filters - partially GMC related [message #271594] |
Tue, 10 February 2015 08:41  |
bobby5832708
Messages: 237
Registered: November 2006
Location: Winter Springs FL
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Last year Tom in Virginia had issues with the way various trans filters worked and fit in his GMC's TH425. I just ran into essentially the same issue with my daily driver, a 2005 Ford Crown Vic. It seems that all trans filters are not created equal.
Story:
Last August I bought the trans filter and fluid from a major auto parts store (I don't remember which one, it's either Autozone or Advance) and did a trans service. Several days later the trans started randomly shifting strangely -- for example it would shudder halfway through first gear or delay the 2-3 shift. It happened when accelerating from a light or, more frequently, when making a right turn. Also a WOT 4-2 the engine would rev to the limiter and in a couple of seconds bang into gear. Sometimes I could drive 10 miles and it would work fine and sometimes the trans would act up every half mile.
Figuring the trans probably was sucking some air due to a leaky filter and also being lazy and not wanting to drop the pan again so soon I added another quart of fluid so it was now about 2 inches above the full mark. The trans worked fine after that.
On the Ford filter the pipe that goes into the trans is very short compared to the GMC filter. Also, instead of a typical o-ring, it uses a relatively wide seal about 3/8" high, about the equivilent of stacking 2 o-rings on a GMC filter. Because of the short pipe it doesn't take much more fluid to completely submerge the filter/valve body connection. On the GMC it would take probably a few quarts of fluid to submerge the filter/case connection and by then the fluid level would be so high that the rotating parts would be whipping the fluid. That's why on the Ford the extra quart was not really an excessive amount.
Yesterday I dropped the pan on the Ford and the filter fell out while the seal stayed in the valve body. I put the filter back up into the valve body but the seal was so loose it would not hold the filter, the seal was tight in the valve body though. I removed the seal from the valve body and put it on the filter. It was really loose. I put the filter back in and it took some effort to insert the filter/seal in the valve body but there was still very little friction between the filter and seal and the filter fell back out. I think I found my filter leak! Since I was doing some modifications to the valve body we tested the filter fit yet again with the valve body laying on the workbench. Tony S also agreed that there was something definitely wrong with the way the filter and it's seal were working (or not working). The seal was waaaaaay too loose on the filter pipe.
This time I used a genuine Ford (Motorcraft brand) filter. This filter has the seal glued to the filter pipe, it won't come off. I wanted to measure the diameters of both filters pipes but couldn't because of the glued on seal of the Motorcraft filter. With the new Motorcraft filter the transmission works fine with the fluid at the proper level. Amazing what happens when the trans pump is not getting air in it.
The only identifiers on the filters are a "CW 309" on the bad filter (aftermarket brand) and a "Filtran" on the good one (Motorcraft brand).
Questions/Observations:
1. Not all transmission filters are made the same.
2. Sometimes it's worth it to buy the more expensive part from the OEM.
3. How many trans rebuild jobs have been done when it was the filter causing the problem?
4. How many transmissions have been ruined by people who keep driving with it shuddering and banging because of a leaky filter?
5. Did Tom's GMC have a "CW" filter in it when it was acting up? Does it have a "Filtran" in it now?
Bob Heller
2017 Winnebago 29VE
Winter Springs FL
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