Auto transmission suddenly stopped working . . .

Ingolf

Ingolf

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Fellow Frogger
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Oct 23, 2014
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102
Location
QLD
My car is a Peugeot 505 GTI (1988).

Just recently gear changes have occasionally been a touch clunky. I was advised to change the transmission fluid by draining the sump, topping it up with new fluid, driving for at least a hundred kilometres and then repeating the exercise 2-3 times until the fluid was once again bright red.

The first time just under 2 L drained out, the second about 1.6 L whereas I'd been advised to expect that 3 L + would drain out each time. In any case, even after the first time the gearshifts did seem to be a little smoother.

Having completed the second change today I went for a little drive to see how it felt. Everything seemed good but it suddenly dropped out of gear less than 1 km from home. I can move the gear selector (and the arm on the side of the transmission still moves accordingly) but none of the positions engage any of the gears. In reverse, there's a bit of a hum as if it's trying to do something but no engagement and in all of the other positions, nothing.

We towed it back home and I checked the fluid level which had dropped to the end of the dipstick. I topped it up (took about half a litre to bring it back up) but that didn't make any difference so I just left it.

Many years ago I put two separate problems to this esteemed forum :) and got terrific feedback so before making any other moves I figured I might get lucky for a third time.

Ingolf
 
Are you sure that there is enough fluid in the box , the amounts drained out seem very low , check oil level at idle in park , over filled is better then under filled when looking for faults
You may have stirred up any debris in the sump and they are now in valve body .
The sump and valve body is not hard to remove , dismantle and clean .
 
Pavel Moore said:
Since you mention " Many years ago ..." i wondered if your auto box is a ZF3hp22 or a ZF4HP22. If the latter then the following PDF, pages 7/1-7/8 may be helpful.
https://drive.google.com/file/d/1hunf8Rpgm5poN8p3X3rvMRXRC3qNBcrE/view
Also, did you use Dex 3?
Pavel
Click to expand...
Thanks, Pavel. Yes, mine is the ZF4HP22 and I did use the Penrite Dex-III.

Complicated piece of machinery, isn't it! In the section on diagnosing faults it was interesting to see how often the solution was "replace gearbox". 👀
 
Rally said:
Are you sure that there is enough fluid in the box , the amounts drained out seem very low , check oil level at idle in park , over filled is better then under filled when looking for faults
You may have stirred up any debris in the sump and they are now in valve body .
The sump and valve body is not hard to remove , dismantle and clean .
Click to expand...
You're right, Rally, the drained amounts seemed very low to me too. So, I'll follow your suggestion and check the level at idle in park.

I am as dumb as a stump when it comes to auto transmissions . . . is the valve body easily accessible when the sump is removed?

The puzzling thing to me (well, one of them) was the suddenness with which the auto transmission stopped transmitting. It almost seems like that radical sudden change might be due to something like the pump ceasing to work or something else systemic of that kind. Does that make any sense?
 
Hi Ingolf,
I just want to verify something absolutely....have you been checking the transmission fluid level wile the engine is running ? Or with the engine off ?

I have known people who were not aware you need to check it while the engine is running. And the fact that you had less fluid come out than you should indicates that you have been under-filling it, which is what happens when you check the fluid level with the engine switched off.....even though the level looks fine on the dipstick at that time..
 
Hi Beano,

Guilty . . . I've always checked it with the engine off.

This afternoon I took Rally's advice and checked it with the engine running and nothing showed on the dipstick. I put in about another half a litre but haven't yet properly checked what that did to the level . . . I'll do that tomorrow.

I don't know if you read my reply to Rally but would really appreciate any thoughts you have on the question I posed in the last paragraph. It just seems kind of weird that an issue with the fluid level (critical though it obviously is) could produce an instantaneous change from running smoothly to simply not working at all.
 
I would urge you to read the PDF download I offered you -- especially page 8 -- which is what Beano stated about having the engine running; but also having the engine/transmission at operating temperature.
Also; if draining the oil allow it to do so over night as quite an amount will filter down from the hydraulic workings.
Your statement "Everything seemed good but it suddenly dropped out of gear less than 1 km from home." would appear to me to indicate a blocked filter. With fresh oil any particles would, initially, likely be flushed off -- only to be sucked up thus covering the filter surface again.
The pages of the PDF will inform you how best to do this.
Pavel
 
Thanks, Pavel.

Your suggestion about a blocked filter perhaps being the cause makes a lot of sense. Certainly, it seems to me it could explain how the failure could happen so suddenly.

I searched the PDF for "filter" and came up empty; would you mind pointing me to the pages that would help me with clearing the filter?

Ingolf

P.S. Point taken about page 8 and measuring the fluid properly. I was way off on this so thanks to everyone for clearing that up.
 
Firstly obtain the filter kit which should also have a good sized rubber[?] O ring. Plus, of course, a sump gasket.
CAUTION ! Do not under any circumstances use excessive silicon gasket goo on the gasket. When bolted up any excess is squashed out and will end up coating the filter mesh. Just a very light smear is enough.
Refer to PDF page 10 and, for refitting, pages 86 & 89.
Pavel
 
Hi Ingolf,
Don't feel bad...I didn't know either when I bought my first auto 505. However just by chance it came up in the conversation with my local Pug repairer, who told me that if the fluid got really low because of not checking it correctly, the gearbox clutch packs (similar to those in a motorbike) would burn out just like THAT (and he clicked his fingers). Which explains how yours stopped working so suddenly.

I sold a good auto box a few years ago for $ 80 or $ 100. You may be able to pick one up for a similar low price. The fitting is a bit of a pain, but I did one myself once....out on the street. Lucky it was a dead end street....
 
Thanks Beano (I think!).

From your comment I'm guessing you don't think there's much chance the problem is the filter suddenly blocking up? Or indeed anything else that might be relatively easily fixable?😋
 
Auto fluid has two jobs to do: lubrication and hydraulics. If the fluid is way too low (or the filter's completely blocked), you'll get no drive and no damage (as long as it isn't run this way for very long). The problems come when the fluid is somewhat low (or the filter partly blocked) and the pump is drawing some fluid, but not enough.

Are you sure you now have enough fluid? I haven't any experience with the ZF trans, but with most boxes, when checking the fluid level after a change, you run the engine AND (foot on brake) run the selector slowly through all ranges 123DR, feeling the transmission engage each. This fills all the hydraulic passages and the torque converter and could easily suck a couple of litres out of the pan. Then back to P and check the level. If it's low, add fluid and repeat the whole process until you're sure there aren't any air pockets left. All with the engine running.

You're doing the same sort of thing as bleeding brakes or power steering.

If you have enough fluid, I'd still check the filter before writing off the box. If there is a lot of debris in the filter it probably means a clutch pack has let go and that might be uneconomic to repair, but if there's no obvious debris, maybe it's just a leaking O ring in the pickup, or sticking valves in the valve body, which can be fixed cheaply (and yes, the valve body -- a hydraulic computer -- is accessible once the pan's off).
 
Last edited:
Unfortunately, unless you are in Europe you will find it almost impossible to get the required parts to do a substantial repair/rebuild.
I have this year tried to get parts in Au, to no avail inc ZF who say not interested and not making the parts anymore.
In Europe, they make aftermarket parts but not ones for the 505 specific. Jag, RRover ok.
I ended up converting to manual BA7 5 speed because I was lucky enough to find a magic box that is silent and smooth I'm over the moon
If you contact me I will steer you straight on the conversion which is really not difficult.
Cheers Peter.
 
robs said:
Auto fluid has two jobs to do: lubrication and hydraulics. If the fluid is way too low (or the filter's completely blocked), you'll get no drive and no damage (as long as it isn't run this way for very long). The problems come when the fluid is somewhat low (or the filter partly blocked) and the pump is drawing some fluid, but not enough.

Are you sure you now have enough fluid? I haven't any experience with the ZF trans, but with most boxes, when checking the fluid level after a change, you run the engine AND (foot on brake) run the selector slowly through all ranges 123DR, feeling the transmission engage each. This fills all the hydraulic passages and the torque converter and could easily suck a couple of litres out of the pan. Then back to P and check the level. If it's low, add fluid and repeat the whole process until you're sure there aren't any air pockets left. All with the engine running.

You're doing the same sort of thing as bleeding brakes or power steering.

If you have enough fluid, I'd still check the filter before writing off the box. If there is a lot of debris in the filter it probably means a clutch pack has let go and that might be uneconomic to repair, but if there's no obvious debris, maybe it's just a leaking O ring in the pickup, or sticking valves in the valve body, which can be fixed cheaply (and yes, the valve body -- a hydraulic computer -- is accessible once the pan's off).
Click to expand...
Yes, you're right, checking the filter does seem a no-brainer. Thanks also for the in-depth explanation about ensuring the fluid is properly distributed and adequate.
 
peuter said:
Unfortunately, unless you are in Europe you will find it almost impossible to get the required parts to do a substantial repair/rebuild.
I have this year tried to get parts in Au, to no avail inc ZF who say not interested and not making the parts anymore.
In Europe, they make aftermarket parts but not ones for the 505 specific. Jag, RRover ok.
I ended up converting to manual BA7 5 speed because I was lucky enough to find a magic box that is silent and smooth I'm over the moon
If you contact me I will steer you straight on the conversion which is really not difficult.
Cheers Peter.
Click to expand...
Thanks Peter. I'll see how things unfold and may well contact you when everything is a little clearer.
 
Ingolf said:
Thanks Beano (I think!).

From your comment I'm guessing you don't think there's much chance the problem is the filter suddenly blocking up? Or indeed anything else that might be relatively easily fixable?😋
Click to expand...
Bring out yer dead ! (rings bell) :)
 
peuter said:
Unfortunately, unless you are in Europe you will find it almost impossible to get the required parts to do a substantial repair/rebuild.
I have this year tried to get parts in Au, to no avail inc ZF who say not interested and not making the parts anymore.
In Europe, they make aftermarket parts but not ones for the 505 specific. Jag, RRover ok.
I ended up converting to manual BA7 5 speed because I was lucky enough to find a magic box that is silent and smooth I'm over the moon
If you contact me I will steer you straight on the conversion which is really not difficult.
Cheers Peter.
Click to expand...
absolutely NOT true. I had mine completely rebuilt by a Auto Transmission specialist in Sydeney. Parts are readily available as this box was used in many Land Rovers etc. But of course, some of the internals are different.
 
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The most common cause of 4HP22s just suddenly stopping all drive is the shearing of the splines in the torque converter where they mate to the input shaft. They are a known weak point in early 4HP22s (pre 1992ish).

Torque converters can be rebuilt (expect $400-$500 if you remove and replace), and the wearing components that you would replace during a transmission rebuild are the same in a 505 as they are in a Jag or Land Rover, and as such are readily available. The parts that are unique to the 505 aren't parts that need replacing during rebuild, such as the output shaft.
 
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