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root cause(s) of auto tranny slip
so, i have a few threads going about a power loss problem i'm having, and while it hasn't happened badly recently, it happened slightly today - i think.
if so, i think it may be my tranny slipping that's the issue. my RPMs were definitely climbing today, but acceleration was slow. boost was low too (like only 2-4 psi at ~3000rpm), but i imagine that would happen if the engine has less load on it than it should, right? if i would keep the pedal steady at relatively high RPM, the truck would accelerate, but only very slowly, then sometimes take off like i'd expect it to at that RPM/pedal position. sometimes it wouldn't, though... i'm no auto trans expert, so my question is - is a slipping auto trans necessarily internal to the trans or could it be from an improper install in the first place? i just bought the truck recently and i know the PO changed the tranny himself. however, its still under warranty from Jasper, but for only another month or so. if its definitely a trans problem and not a potential install problem, i'll start the warranty claim now. if its a potential install problem, i should probably pull it, check it over re-install and run it some more to see if that was the issue... thanks! |
Not really anyway it could be an install problem, since it is driveable. If it is slipping, you're right, your boost would be down from no load on the motor.
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Your driving it so the installation is fune. I'd be curious about the TC being the issue and or other internal issues. My verdict is to smell the fluid and then I'd pry pull it and send it in.
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fluid
How does the fluid level look? Any leaks? Did the PO put a new TC in or use the one off the old tranny? Dumb questions I know. Is it slipping in left turns?
Scott |
If the trans is slipping it is easy to tell. Pull the dipstick and smell the fluid. If it smells burnt and the fluid is brown or black it's slipping and needs to be rebuilt. If the fluid is red and doesn't smell burnt it is NOT slipping. It only takes a mile or two for a slipping clutch to be totally destroyed.
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Jasper pays labor to remove and replace.just take it to any authorized jasper dealer.its real easy that way.
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Originally Posted by bvmbandit
(Post 13433727)
How does the fluid level look? Any leaks? Did the PO put a new TC in or use the one off the old tranny? Dumb questions I know. Is it slipping in left turns?
Scott
Originally Posted by Mark Kovalsky
(Post 13433986)
If the trans is slipping it is easy to tell. Pull the dipstick and smell the fluid. If it smells burnt and the fluid is brown or black it's slipping and needs to be rebuilt. If the fluid is red and doesn't smell burnt it is NOT slipping. It only takes a mile or two for a slipping clutch to be totally destroyed.
Originally Posted by fordman67
(Post 13434151)
Jasper pays labor to remove and replace.just take it to any authorized jasper dealer.its real easy that way.
let me ask a few more general questions, though, to get my thought process out there: - if i'm on the pedal, and up around 3000 rpms, but not accelerating quickly (or at all), can it be anything else other than a tranny problem? i would think that any engine-side issues would simply lead to low RPM's being the cause of low power. - i've had my scanguage set on 'trans gear' when this problem is occuring, and it appears to be in the correct gear for the speed - though would that reading just be telling me what the PCM is calling for, but maybe not what the tranny is actually doing. i.e., can it tell me its in 3rd, but really still be down in 1st or 2nd. like i said - a few times when its doing this, it will all-of-a-sudden take off like it just got into the right gear or something. - if the vss were the problem, the PCM would still show the trans gear as being low, causing it to not shift, right? plus, the speedo would be dropping out pretty visibly, i'd think. with a VSS being digital, i'd think it would either read correctly, or read nothing. is that not right? |
Most of the symptoms you are describing is exactly what happens to my truck when the trans. fluid is low...not saying this is the case but would make very sure fluid is correct type and at correct level and on a level surface when checking it. When fluid gets low 1 quart can make the difference in slipping and no slipping at all. Slipping in left turns indicates the beginnings of fluid starvation in an E4OD. These are some things and ideas to look for as I am no expert by a long shot....they are based on my own experiences with the E4OD.
Scott
Originally Posted by OldWoodsDiesel
(Post 13434922)
the fluid level looks fine, new or old TC is not a dumb question as i didn't think to ask when buying the truck! so, i'm not sure. there would be about 30k on this trans by now, so i'm not sure the TC would still look new if i yanked it. would a bad TC lead to these sort of intermittent problems? and can i bench test it once its out in any way to confirm that was the issue? and yes, it does slip in left turns, but it also happens during straight driving and right turns. what would slipping in left turns indicate?
well, i'll have to pull the dipstick again. its possible the PO put brand new fluid in it just before selling it. but it sounds like from what you're saying, once it starts slipping, it wouldn't just go back to not-slipping and driving normal, right? on the way in to work today, it was driving fine with plenty of power. any chance it could be torque-converter related, as mentioned above? well, that's good to know - i'm just trying to avoid pulling it, sending it back and having them tell me there's nothing wrong with it. i at least want to convince myself its the tranny before going that route, so i can better argue with them to fix it :-) let me ask a few more general questions, though, to get my thought process out there: - if i'm on the pedal, and up around 3000 rpms, but not accelerating quickly (or at all), can it be anything else other than a tranny problem? i would think that any engine-side issues would simply lead to low RPM's being the cause of low power. - i've had my scanguage set on 'trans gear' when this problem is occuring, and it appears to be in the correct gear for the speed - though would that reading just be telling me what the PCM is calling for, but maybe not what the tranny is actually doing. i.e., can it tell me its in 3rd, but really still be down in 1st or 2nd. like i said - a few times when its doing this, it will all-of-a-sudden take off like it just got into the right gear or something. - if the vss were the problem, the PCM would still show the trans gear as being low, causing it to not shift, right? plus, the speedo would be dropping out pretty visibly, i'd think. with a VSS being digital, i'd think it would either read correctly, or read nothing. is that not right? |
well, thanks for the info Scott - i will definitely check the fluid level today at lunch. it is also very possible that the PO used the wrong fluid in the tranny. he was a nice guy and a recently-graduated automotive technician, but if he was doing the tranny job at his work, i bet he just used whatever tranny fluid they had on hand there.
without access to a viscosity tester, maybe i'll just drain a small amount out, go buy a quart of the known right stuff and compare the 'feel' of the two. low level or low viscocity fluid fits with the fact that this issue seems to primarily crop up when the truck is warm. particularly when its driven, shut off, then driven again about 1-4 hours later. |
swap a zf5 and if the problem goes away it was the 4eod.
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Originally Posted by 21411
(Post 13435704)
swap a zf5 and if the problem goes away it was the 4eod.
that is my exact plan - but i am trying to make sure the problem is with the tranny and not the engine first :-) i have a zf5 and most components sitting on the shelf in the barn right now. just trying to the reigns on any existing issues on the new truck before the swap! :-) |
OK - hopefully this is it! maybe? fingers crossed...
i checked the trans fluid at lunch today and it was not burnt - didnt smell bad and was a nice clear/pink color. it was overfilled by about 2-3" above the cold fill mark (i checked it when cold), though. Mark, could that cause the sorts of problems? i hope so! again, i'm no expert on the internals of an automatic transmission, but it makes sense that too much fluid could prevent proper TC and/or valve operation... i'm not sure what that equates to in excess volume, but its probably a few quarts overfilled, i figure. i'll drain it down to the proper level this weekend and hope that's the culprit. |
Originally Posted by OldWoodsDiesel
(Post 13435801)
OK - hopefully this is it! maybe? fingers crossed...
i checked the trans fluid at lunch today and it was not burnt - didnt smell bad and was a nice clear/pink color. it was overfilled by about 2-3" above the cold fill mark (i checked it when cold), though. Mark, could that cause the sorts of problems? i hope so! again, i'm no expert on the internals of an automatic transmission, but it makes sense that too much fluid could prevent proper TC and/or valve operation... i'm not sure what that equates to in excess volume, but its probably a few quarts overfilled, i figure. i'll drain it down to the proper level this weekend and hope that's the culprit. |
hmmm ok - i'll give that a try as well - but the dipstick has a 'cold' area and 'hot' area with the cold being small and down near the bottom of the plastic end of the dipstick and the hot being longer and up near the top of the plastic end.
my fluid was up onto the cable portion of the dipstick by about an inch... i should read the manual to determine proper checking procedure, though :-) |
Just throwing out ideas, but since you say it mainly happens at higher rpm's and when you get on it, has anyone else suggested a weak fuel pump or hpop? Those would both cause power loss if they were going bad. What injectors are you running?
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