• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

Transmission slips (doesn't move) when hot.

500dollar744ti

500dollar744ti

still rides with MrDoug
300+ Club
Joined
Feb 2, 2007
Location
Falls Church, VA
It's been a while since I've had a sincerely technical question but I need to pick your brains.

Current car in question is a 2000 v70 n/a (aw55-50sn). Transmission makes a whining noise like the pump is sucking air, similar to low power steering fluid noise. For about 10 minutes the trans will operate normally but begins to slip once the engine is warmed, then goes completely neutral in all forward gears and reverse, it just revs.

If I let the car cool down, trans is working again. I know the answer to this problem, the car needs a transmission. It has been the answer to this problem every other time I've seen it which is not often but more than five times.

In the last year I put a trans in two 960s, one 850 and now this v70 is doing it.

The reason I'm getting curious is that a co-worker had a 960 doing this as well. He put a junkyard trans in it but didn't swap the torque converter. The junkyard trans did the exact same thing, worked and then slipped completely into neutral after a few minutes of driving. He put another junkyard trans in that car and swapped the torque converter with it, problem solved.

This 2000 v70 is a friend's car, the original trans lasted 326k miles, it finally started banging in and out of gears. We got what we thought was a good used trans for it and I installed it Saturday. All was working after installation, shifted silky smooth but after about 20 minutes the trans began to slip and went neutral in all gears.

SOOOOO, my question is, what causes this? Has anybody confirmed the issue to be a bad torque converter? Has anybody confirmed the issue to be anything that they have successfully fixed?

I want to take the good torque converter from the old trans and put it in this one that slips, but only if I can confirm that the torque converter is indeed the problem.
 
I haven't experienced this on a Volvo, but converter problems were common on the diesel trucks we serviced. I have seen bad converters, but normally they are failed or not, no cold operation at all. The problem I found with the symptoms you describe we're due to excessive wear and loose tolerances due to the wear.
 
*PUMP CLEARANCE ISSUE* inside the torque convertor...the "noise you hear"
is CAVITATION (nasty foamy AIR BUBBLE filled fluid)
our practice on EVERY trans o'haul is a NEW torque convertor (the guy we
used to have do torque convertor rebuilds died last year...sad...the fellow
bought his bidness" is a nice enough guy but doesn't have the same skill-set)
 
TM - Sad state of affairs. Old school skills (gawd - manual labor) are truly dieing off. Why repair when you can R-n-R the damn thing. $15 part + 2 hours of labor or $300 part + 15 minutes of labor ...
 
Sort of sounds like a screen that sucks up a bunch of crud and then drips it off once you "let it cool" and such.

Maybe in the case of the one with the converter, a bunch of that sh1t from the converter wound up in the pan, but the trans still worked so all that old cruddy fluid crudded up the screen, it would drip off again if left to cool and then would clog itself up again.

That simple screen has a profound affect on all things shifting if it stops up and one would think it would make the pump whine. Simple enough to drop the pan, wash it in gas/acetone or some such and blow it out no?

At this point it may have delined a clutch and various solenoids maybe clogged so it definitely could well be a paperweight.

The 960 with the converter sounds like a screen might have solved it...probably not wise to mix the converter like that, but I would guess if one cleaned the screen and magnet it might have fought another day.
 
TrickMick said:
*PUMP CLEARANCE ISSUE* inside the torque convertor...the "noise you hear"
is CAVITATION (nasty foamy AIR BUBBLE filled fluid)
our practice on EVERY trans o'haul is a NEW torque convertor (the guy we
used to have do torque convertor rebuilds died last year...sad...the fellow
bought his bidness" is a nice enough guy but doesn't have the same skill-set)
Click to expand...

so the clearance issue is in the torque converter or in the front pump? i have an extra torque converter and it would be a pretty quick swap to just change the converter.

i appreciate your help as you have been the most informative here, i will refrain from knocking any of your posts in the future and if i do disagree i'll make sure it's constructive criticism. :)
 
One easy way to see if a pump has failed is to slightly loosen a transmission line with the car running. You should get fluid forcing out. If you can remove the line fully and it just drips then your pump has failed. There also is a pressure port on the side of the transmission case where a gauge can be added in and the pressure accurately checked but the easy quick check is to just crack a line. If you have pressure but still no go in any gear it is probably a failed converter. If it pulls normally in any gear but not all gears then the converter is probably ok and the problem is most likely something internal. Internal problems could be any number of little things to something major. A single failed o ring can cause all sorts of issues but finding it normally requires a full teardown. Failed clutches are easier to diagnose but will require a complete overhaul. Some problems are valvebody related and could be a failed shift solenoid, faulty harness or once again a simple o ring. It's easy to say a trans has faile but determining the cause for failure can sometimes be very difficult or impossible to diagnose without a teardown.

Always replace the converter when replacing the transmission. If you get a known good used tranny get the converter with it(personally I'd go with a good quality reman). If you get a reman or new tranny get a reman or new converter. A good quality reman converter does not normally cost that much. The converter is just a fluid filled centrifugal clutch and just like a normal clutch it does wear and can slip just the same.
 
Last edited:
okay, so do a pressure test at the test port on the trans, if it has good pressure when it's slipping then it's the converter. if the pressure drops significantly when it's slipping then it's a pump problem?

i hate being the guy who just replaces the entire trans because i don't care to figure out what's actually wrong, i really would like to fix this using parts from the old trans. i feel like there's enough good parts to make one good trans but then it comes down to my time, like how many times do i really want to take it apart again.
 
here's a screed (AW50-42L) on diagnostics....when I get to the shop I'll see what
Mitchell has to say about the PRESSURES...for now read this and XFer what
you can to your trans...:
www.volvoclub.org.uk/tech/service/850/AutoTransDiagnosis.pdf
here's a short but GOOD on from the "valve body re-build boys" AW55-50sn:
www.sonnax.com/system/pdfs/86/original/TASC-TIP-01-09.pdf?...
low pressure due to BUSHING failure (again, AW55-50sn):
http://www.gearsmagazine.com/view.ashx?article=e25ea84f-b16e-4f32-b88c-db4fe8ada707

the main thing to consider at this point is :
What was the FAILURE MODE of the ORIGINAL transmission??
it it exhibited similar temp / operating scenario the only thing common
is the TORQUE CONVERTOR that wasn't exchanged....I *know* it
sounds silly but I've been caught out by this due to MARGINAL
PRESSURES and severe lack of funds that forced me to "at least
TRY to original torque convertor"....
back atcha in a bit....FWIW, I've seen several of these transmissions "pack up
w/crud" from the clutches being burned due to abuse...and they didn't die as a result
of "hammering the snot out of the trans"...just HEAT FAILURE cooking them off...
the valve bodies and solenoid literally "packed up w/the black goo death".....
did the fluid you drained out on the exchange have dark colour / burnt smell /
BLACK PARTICULATES?? if so...you may be facing a full teardown to get the valve body / solenoids and clutch pack sorted....
sorry for not being "DEAD NUTS ON" but that IS the nature of these failure modes....:-(

*UPDATE*
Mitchell on demand is useless as tits on a boar...."wiring diganosis" ONLY...I'll keep looking....
for the PRESSURE specs...sheesh...
 
Last edited:
TrickMick said:
here's a screed (AW50-42L) on diagnostics....when I get to the shop I'll see what
Mitchell has to say about the PRESSURES...for now read this and XFer what
you can to your trans...:
www.volvoclub.org.uk/tech/service/850/AutoTransDiagnosis.pdf
here's a short but GOOD on from the "valve body re-build boys" AW55-50sn:
www.sonnax.com/system/pdfs/86/original/TASC-TIP-01-09.pdf?...
low pressure due to BUSHING failure (again, AW55-50sn):
www.gearsmagazine.com/view.ashx?article=e25ea84f-b16e-4f32...

the main thing to consider at this point is :
What was the FAILURE MODE of the ORIGINAL transmission??
it it exhibited similar temp / operating scenario the only thing common
is the TORQUE CONVERTOR that wasn't exchanged....I *know* it
sounds silly but I've been caught out by this due to MARGINAL
PRESSURES and severe lack of funds that forced me to "at least
TRY to original torque convertor"....
back atcha in a bit....FWIW, I've seen several of these transmissions "pack up
w/crud" from the clutches being burned due to abuse...and they didn't die as a result
of "hammering the snot out of the trans"...just HEAT FAILURE cooking them off...
the valve bodies and solenoid literally "packed up w/the black goo death".....
did the fluid you drained out on the exchange have dark colour / burnt smell /
BLACK PARTICULATES?? if so...you may be facing a full teardown to get the valve body / solenoids and clutch pack sorted....
sorry for not being "DEAD NUTS ON" but that IS the nature of these failure modes....:-(
Click to expand...

well, i attribute the failure of the old trans to being strait up worn out. it started slipping/banging into gears around 315,000 miles, it finally went out with a big bang at 326,000. it still drove but very poorly.

this new trans, from the junkyard, swapped with the torque converter from the junkyard, shifts flawlessly until it warms up with about 15 mins of driving and then it just goes to nothing. no forward, no reverse, no winter mode in 3rd gear, no low gear, no second gear, nothing.

if this might be an indicator of a torque converter, the engine does rev to about 1000 rpm when put into drive and the issue is occurring. i know the torque converter puts a load on the engine when in drive so the ECM compensates for this added load by increasing idle speed.

when the car does not move and freely revs in any gear position, the idle is high like there's absolutely no load on the engine in gear.

does that indicate a torque converter or could that still be a pump issue?

i'll look more into the documents you linked to on my lunch break.
 
It could be both.

A failed pump will not supply the torque converter with any fluid and thus will not do anything.

A completely failed converter can just spin and not engage.

The next thing I would do is unhook a trans line at the radiator and place a pan under it and start the car very breifly while someone is watching. Takes 5 min and doesn't even require a jack. You should get a solid stream. If nothing then it's not your converter.

Sorry that it's not much help but that's the nature of the beast. I can look up line pressure specs tomorrow at work for you if noone else gets them before then.
 
that's ok, i'll do that with the trans line. i'm gonna try and make a trip to scoop another trans at the junkyard unless i can definitely confirm a bad converter. thanks for your help.
 
i haven't got a chance. the car is still sitting in front of my friend's townhouse where it was towed.

when i get a chance to get over there, i'll look. since this deal needs to be done, i can't really fuss with taking it apart two more times, i'm going to try and find a healthy trans at the junkyard this weekend. i do intend to test for flow at the cooler when i get a chance.

my friend's wife needs the car back in working condition as soon as possible.
 
500dollar744ti said:
i haven't got a chance. the car is still sitting in front of my friend's townhouse where it was towed.

when i get a chance to get over there, i'll look. since this deal needs to be done, i can't really fuss with taking it apart two more times, i'm going to try and find a healthy trans at the junkyard this weekend. i do intend to test for flow at the cooler when i get a chance.

my friend's wife needs the car back in working condition as soon as possible.
Click to expand...

check LOCAL for a rebuilt torque convertor....there *should be* a "go to guy" that local
shops use.....
 
well, that's the thing, i have a good torque converter sitting on my bench. i'm hesitant to install it though. it would have to be that (free + time) or pulling a junkyard trans w/ converter ($90 + time). i can't see any other repair method in the $90 or less price range. :)

either way i'm pulling the trans again, i have the most confidence in a junkyard trans of known origin (i pulled it) rather than junkyard trans that someone else pulled and sold to my friend as a replacement.

i've never had a problem with a trans that i've personally pulled from the junkyard myself, i get 'em from good 'n wrecked cars that obviously had to be moving and working to hit whatever they hit. my luck with transmissions bought from others who have pulled them or just pulled and purchased by other people has be very spotty. half of 'em work and half don't.

the friend who owns this car needed a transmission for his other car, '98 s70 with a manual, he got a trans online and the 3rd gear syncro is shot. it grinds badly going into 3rd and he just usually skips 3rd. he's been doing that for a year, i still have to find another trans for that car as well. :lol:
 
Take a look at how a torque converter works and you will realize it isn't going to be temperature dependent. It either works, or doesn't. You have internal leakage in the transmission that gets worse as it warms up. I've replaced a couple of transmissions due to this. If you want a tid bit of information that confirms that conclusion, I sold the converter from one of those transmissions to a friend of mine because the owner of the car he was working on dropped his converter on the concrete and bent the snout where it drives the pump. The converter out of the trans that was doing exactly what you describe is in another car and is working fine. It's not the converter. The transmissions I'm referring to were both AW-71L.
 
sounds good to me. i've also heard that moisture from sitting outside can dissolve the glue that bonds the clutch material. once that happens, the clutch material gets clogged up in the pump pickup after running a while and all pump pressure is lost.

that's the theory i'm going to go with.
 
500dollar744ti said:
sounds good to me. i've also heard that moisture from sitting outside can dissolve the glue that bonds the clutch material. once that happens, the clutch material gets clogged up in the pump pickup after running a while and all pump pressure is lost.

that's the theory i'm going to go with.
Click to expand...

That can happen as well, however, the trans I'm referring to had almost new looking fluid in it. I went so far as to drop the pan, change the filter and then, flush the trans. Same problem. As soon as it warmed up, no go. And I mean, no go. It wouldn't even pull itself across a level surface. That was $50 worth of filter, gasket and trans fluid and 2-3 hours of my time for nothing. If you drop the pan and it is relatively clean in there, stop.
 
You must log in or register to reply here.
Back
Top