AL4 auto transmission thunk from 1st to 2nd

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gwest
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AL4 auto transmission thunk from 1st to 2nd

Post by gwest »

I have a 2007 Peugeot 207CC Vti 1.6 automatic with 131,000 km that thumps when changing from 1st to 2nd.

I bought this car as a non-runner so I don't know how the transmission operated before I bought it. I ended up putting a replacement engine in it. I have changed the transmission oil 3 times over 2600 km. I used Mobil ATF LT7114 and followed the recommended procedures. Initially it whined badly in all gears, particularly on overrun, but this has improved with time. Not so the thump from 1st to 2nd. But, I should add, it only does it when it is half-warmed up (~40-50C transmission oil temperature), not when cold or fully warmed up. There are no fault codes or warning lights. Very occasionally I get two thumps. A friend recently reset the oil wear counter for me, and it appeared that it had been previously reset in 2013, so it may have had a previous oil drain. After three changes the oil is still quite opaque when tested in the standard 150g Vegemite jar, but better than it was.

I have carried out some transmission monitoring with a generic scan tool and the oil pressure generally seems to follow the guide pressure with some exceptions when the gears are changing. The display is very limited and it is not possible to download the results so that I can examine them closely. And I think it is recording at 1 sec intervals, so there will be limited data during gearshifts.
I am contemplating changing the pressure regulation solenoid and while I am at it, the one for the torque converter. Can anyone tell me if these solenoids are identical as appears to be the case with many advertised on eBay?
My VIN is VF3**************[VIN obfuscated, can be read by forum staff], manufactured May 2007. The code on the transmission housing is 20TS28 / 1239769.
RichardW
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Re: AL4 auto transmission thunk from 1st to 2nd

Post by RichardW »

There are 4 valves, 2 different part nos (2 of each). Don't know what's what. They are both priced at £129.58 in the UK.
AL4electro valves.jpg
gwest
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Re: AL4 auto transmission thunk from 1st to 2nd

Post by gwest »

Thank you Richard, that is very useful. The fact that the no. 2 electrovalves have the same part number (2574.16) indicates that they are identical, even though they serve different purposes. Elsewhere on the forum Marc has a diagram that shows the inboard solenoid controls main pressure regulation, and the outboard one controls the converter lockup.

There are instances on the forum where changing the solenoids did not fix the problem, which probably meant that the cause was something else. But you also hear of problems with the temptingly cheap solenoid valves available, so you may not be able to be completely certain that the new part works properly. I am wondering if I could simply swap the two solenoids (part 2574.16) and see it the problem disappears or at least changes, on the basis that it would be unusual for both solenoids to be problematic?
ozvtr
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Re: AL4 auto transmission thunk from 1st to 2nd

Post by ozvtr »

There are 2 types of valves and 8 electro valves in total.

The 5 valves on the side and 1 on the bottom are on/off type valves and allow or stop the hydraulic fluid from moving the slider valves inside the valve body (yes, valves controlling valves).

The 2 on the top are modulator valves. They are switched on and off quickly to control fluid pressures. Because they are modulated at high frequency they tend to fail more often than the other type of valve.

There are a lot of things that can go wrong in the auto box. Changing the modulator valves is the cheapest and easiest thing to do. Unfortunately, as you said, it's no guarantee that will fix your problem.

Yes, you can swap the 2 valves over. However, if one of the valves proves to be your problem you will need to pull the valve body off...again...to replace the valve. Remember you need to drain the fluid, remove the valve body cover, disconnect the connectors...blah,blah...refill the gearbox to the correct level. I had to remove the battery box just to fill the gearbox. Get the idea? You are better off just biting the bullet and change both valves. But...that's just my opinion. :-D

I had bad shifts, limp mode and the flashing snowflake of death in one of my Citroen C3's. I changed the valves and presto, the gearbox came good.

From what I can see I think the Peugeot's valve body is a bit easier to get to. The engine and gearbox coolant lines are in front of the valve body cover on the C3 making it a little more difficult to remove the valve body.

It's not a hard job and there are dozens of videos on youtube. However lining up the leaf spring and the manual valve/selector quadrant is a bit tricky. The leaf spring position needs to be adjusted while the spring is under compression! Then you may need to adjust the selector switch on the top of the gearbox.

They are not on that parts diagram but it's recommended that the 2 valve body hydraulic o-ring seals be replaced if you remove the valve body from the gearbox. I didn't replace the ones on mine and it seemed to be OK.
gwest
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Re: AL4 auto transmission thunk from 1st to 2nd

Post by gwest »

You have convinced me ozvtr- I have just ordered two valves and a cover gasket. Thank you. Ostensibly, the valves are made in France. Given your comments on the tricky reassembly of the valve selector I will opt for maximum accessibility- I have become quiet proficient at removing the front bumper on the 207CC although moving the condenser and radiator is a bit more work! I also note your comment on the 2 O-rings - if they are like the elastomer seals on the oil filter housing they don't last forever. Or 8 years for that matter! I have been forced to take a closer interest in O-rings over the course of my ownership of French cars so I will have a look at them and see if there is an obvious metric equivalent. I will also see if I can work out why I can't transfer screenshots from my scan tool (Launch 123E) so that I can show some of the transmission oil pressure data to see if it aids diagnosis.
ozvtr
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Re: AL4 auto transmission thunk from 1st to 2nd

Post by ozvtr »

gwest wrote:
05 Jan 2022, 12:11
Thank you.
Don't thank me yet. You may come to curse me if it doesn't work! :-D
gwest wrote:
05 Jan 2022, 12:11
I also note your comment on the 2 O-rings - if they are like the elastomer seals on the oil filter housing they don't last forever. Or 8 years for that matter! I have been forced to take a closer interest in O-rings over the course of my ownership of French cars so I will have a look at them and see if there is an obvious metric equivalent.
They are actually a special shape, almost tubular. You will need to get a set from PSA if you decide to change them, but I advise getting them before you proceed (if you decide to change them, catch 22). There is nothing worse than having to down tools and wander all over town looking for bits in the middle of a job. Again, mine sat proud of the mating surface indicating to me that they had not lost their elasticity.
gwest
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Re: AL4 auto transmission thunk from 1st to 2nd

Post by gwest »

I could have saved myself a fair bit of time if I had taken your advice and approached my Peugeot dealer about spare rubber seals. Instead I sought comfort from the Internet but was disturbed to find that a seller on eBay UK wanted over $100 for one! I then tried several Australian transmission supply places- one had them listed but had no stock. I did find them in Poland for a very reasonable price except that the freight was US$55. So I recanted and phoned the dealer. They could not find them on their system! By this time however I had accumulated a few part numbers, 2219.16 and DP0.SQR03, and this did enable them to track them down. $4.50 each.
I also had some vindication of the decision to replace the regulator solenoids when the car went into limp mode and flashed its snow and sport lights. It displayed an error code, P0006 indicative of a pressure regulation problem. It disappeared half an hour later but I was still feeling quite pleased with myself.
ozvtr
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Re: AL4 auto transmission thunk from 1st to 2nd

Post by ozvtr »

gwest wrote:
15 Jan 2022, 10:46
They could not find them on their system! By this time however I had accumulated a few part numbers, 2219.16 and DP0.SQR03, and this did enable them to track them down.
LOL! You had to do their job for them?
gwest wrote:
15 Jan 2022, 10:46
It displayed an error code, P0006 indicative of a pressure regulation problem. It disappeared half an hour later
You will probably find it will come and go now until you fix it. The next phase is "limp mode". The gearbox locks into 3rd gear. Stopping the car, turning off the ignition and restarting the engine usually fixes it temporarily.