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Transmission slipping losing power until restarted?

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My electronic automatic transmission has an issue where it starts slipping and eventually loses all power in gear - feels like your in neutral; when you turn the engine off and let sit for five minutes or so and restart it will often have power and drive normal for a few more minutes before problem resumes; the longer you let it sit the better. I have replaced the valve body with new filter strainer TWO TIMES now and each time I can drive about forty miles with strong power to the wheels (no slipping) and good shifting until problem appears all over again - and once it appears you can no longer drive it more than a few minutes, even after sitting a day.

Found a few articles that suggest what may be happening is the transmission filter strainer is getting enough debris in it to stop flow and cause these issues; does this sound likely to anyone with knowledge in auto transmissions? I believe when you turn the engine off it stops suction and allows debris to settle in the pan, so that on the next restart it functions a few more minutes until debris is sucked up again. On the last valve body change I noticed the filter had a black film covering the metal strainer mesh - kind of a thin film of dense pulp-like material; this was not good, but did not look like a horrible clog either. The transmission fluid is all brand new, so was thinking maybe it just kicked up old debris.

Trying to decide whether this could still be old debris and if I should just change the filter again, or if the clutch discs are failing and a full rebuild is in order? Just sick of wasting time on it, so don't want to change the filter again if there is no hope. Any opinions are appreciated.
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I would think if there was enough trash in it to plug the filters it would be real obvious on the filter change and fluid colors.
I might poke a few holes in the filter as a temporary thing and see if the problem goes away but it really sounds like something is happening with the pump or seals. I would think if the clutches were worn out, they wouldn't hold at all, not just when hot.
Have a pressure gauge you can connect and run it down the road?
 

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Whose transmission that Chevy, Toyota or what?

A coating of a film like material on the strainer sounds like band or clutch debris. If enough of this is coming off that it’s on the filter rather a thin sludge in the corners of the pan then something serious is going on.

Bogie
 

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Also possible the o-ring seal on the filter neck is nicked and it's sucking air? It starts with good fluid but within minutes it's frothy and can't hold the clutches.

Whatever you do, quit driving it. Every slip might be the last slip before it's toast and needs a full rebuild.
 

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Discussion Starter · #5 ·
I would think if there was enough trash in it to plug the filters it would be real obvious on the filter change and fluid colors.
I might poke a few holes in the filter as a temporary thing and see if the problem goes away but it really sounds like something is happening with the pump or seals. I would think if the clutches were worn out, they wouldn't hold at all, not just when hot.
Have a pressure gauge you can connect and run it down the road?
Thanks, yes the original fluid before this latest work was fairly dark - but I have seen worse on transmission that run perfect, so hard to say. The first time I changed the valve body I replaced all fluid and then when that stopped working and I put the second rebuilt valve body in it - then that time I re-used some of the fluid and ran it through a 190-micron paint strainer, almost no debris - but the transmission filter that time had caught debris - that more of a black pulp I mentioned.

The thing I just cannot explain is why letting it sit for 2-5 minutes allows it to work for a brief period, I do not know much about auto transmissions - but if the oil pump was bad i would think that would act up more often? Its not an issue of it being hot, as 2-5 minutes is not nearly enough time to cool anything - the only thing that makes sense to me is the suction being stopped when the engine is turned off and it taking a few minutes for something to change, whatever that is.
 

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Discussion Starter · #6 ·
A coating of a film like material on the strainer sounds like band or clutch debris. If enough of this is coming off that it’s on the filter rather a thin sludge in the corners of the pan then something serious is going on.
Thank you Bogie, I just can't understand if the transmission is bad or a clutch disc is bad - how it can run nearly perfect during that first 40 miles and then within minutes act up? When I changed the valve body two different times - each time the rebuilt valve body I installed had a new oil filter strainer on it - so basically each of those times I was able to to drive 40 miles were under that situation; I cant buy a third valve body to test for obvious reasons, but I may just try replacing the filter again and see...
 

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Discussion Starter · #7 ·
Also possible the o-ring seal on the filter neck is nicked and it's sucking air? It starts with good fluid but within minutes it's frothy and can't hold the clutches.

Whatever you do, quit driving it. Every slip might be the last slip before it's toast and needs a full rebuild.
Thanks, I have installed two times now rebuilt valve bodies, so two different valve bodies - each had a new oil filter strainer on the valve body, plus the original valve body that basically had the same exact symptoms; so can probably rule out the O-ring as three different oil filter strainers have been in play now unfortunately. I probably will just pull the pan again so I can actually inspect this latest filter strainer and see if it has debris in it, just not a fun job!
 

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Thanks, I have installed two times now rebuilt valve bodies, so two different valve bodies - each had a new oil filter strainer on the valve body, plus the original valve body that basically had the same exact symptoms; so can probably rule out the O-ring as three different oil filter strainers have been in play now unfortunately. I probably will just pull the pan again so I can actually inspect this latest filter strainer and see if it has debris in it, just not a fun job!
This debris you describe is an issue, obviously. It is either coming from your transmission frictions or you converter clutches. Sadly, if it was mi e, I would pull it and overhaul it. You have seen the same result 3 times, the original time and now 2 times more with valve bodies. So, it needs a teardown and a deeper investigation for the source of the issue. We always want it to be something easy, but I am guessing this is a fairly high mileage unit and has a lot of parts worn out.
 

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Discussion Starter · #10 · (Edited)
This debris you describe is an issue, obviously. It is either coming from your transmission frictions or you converter clutches. Sadly, if it was mi e, I would pull it and overhaul it. You have seen the same result 3 times, the original time and now 2 times more with valve bodies. So, it needs a teardown and a deeper investigation for the source of the issue. We always want it to be something easy, but I am guessing this is a fairly high mileage unit and has a lot of parts worn out.
It only has a little over 100K, that is why I am so hesitant to replace the transmission, the rest of the vehicle is very good condition and its hard to believe the transmission itself is worn out, but you're probably right. I have been away all week, but plan to pull the pan and inspect the filter - so will try to post on that soon.
 

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The fact that it has issues with junk on the strainer/filter after just 40 minutes should be a big warning sign that its not just a valvebody replacement issue.....those particles are being shed from somewhere.
A new strainer in a good used 100K miles transmission should take at least another 50k miles to come close to covering the strainer with junk again...not only 40 miles.
 

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Discussion Starter · #12 · (Edited)
The fact that it has issues with junk on the strainer/filter after just 40 minutes should be a big warning sign that its not just a valvebody replacement issue.....those particles are being shed from somewhere.
A new strainer in a good used 100K miles transmission should take at least another 50k miles to come close to covering the strainer with junk again...not only 40 miles.
Yes, not looking good, pulled the filter again today and clogged again with gunk.
 

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Discussion Starter · #13 · (Edited)
Finally pulled the transmission filter again today; this filter only had about 40-miles on it since new.

Is there any possibility that this debris is still just gunk dislodged from the new transmission fluid, or does this look like clutch disc material or actual disc breakdown? Just don't want to replace the transmission if not needed.



 

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Discussion Starter · #14 ·
Finally able to test drive 10-miles today with the New Filter Strainer installed - runs perfect again, shifts great, holds power - zero issues... But, clutch friction discs (or whatever is causing the debris) could still be slowly disintegrating for all I know. Guess we'll see what happens at the 40 mile mark again.

I just keep thinking this debris may clear up at some point, its really hard to spend thousands replacing a transmission that works so well otherwise!
 

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Finally able to test drive 10-miles today with the New Filter Strainer installed - runs perfect again, shifts great, holds power - zero issues... But, clutch friction discs (or whatever is causing the debris) could still be slowly disintegrating for all I know. Guess we'll see what happens at the 40 mile mark again.

I just keep thinking this debris may clear up at some point, its really hard to spend thousands replacing a transmission that works so well otherwise!
Eventually, it just might. Not sure how many filters that might require. The lines too and from the transmission cooler and the torque converter also contain this debris so it may well take a while to flush it all out. Sorry to shares this news, but just being realistic.
 
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