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Discussion Starter #1
I just bought a 2008 407 HDi wagon unseen with an auto tranny issue [BVA AM6 box]. I thought it would likely be the flaring issue associated with the valve block [like my other 407 had, but which an oil change/gearbox counter reset cured], but it is a serious problem with the auto's 'clutch' mechanism.

It starts and runs fine, but when selecting either reverse or drive, the 'clutch' part of the system barely releases [virtually no 'slip' whatsoever] so the engine bogs down and mostly stalls. When I manage to get it moving, it drives well and up/down shifting is fine.

Anyone have any ideas as to what the fault might be? Would it be a faulty torque converter or is it the valve block. Or maybe even the ECU?

I scanned it with Diagbox and there were no errors whatsoever reported for the AM6 box.

I am going to do an oil level and condition check and see if there are any obvious signs there like low/overfilled oil or burned oil etc.

If worst case is that it needs a new torque converter and tranny, can the auto box be removed without dropping the whole engine/box assembly? The car is in overall very good nick apart from this issue, would be a shame to wreck it, but that may still happen
 

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Discussion Starter #2
Bit of an update, finally got it up on my hoist and drained some of the fluid out. It was smelly black burned oil so I decided to go further in and do some inspection/cleaning of the hydraulic control block. Not very difficult to remove it after removing the cover. Now have it opened on my bench and slowly going through it to see if there is any obvious fault. Checking all solenoids for operation/resistance etc.

While I was under the car, I noticed there as quite a severe oil leak down the rear of the motor. I traced this to a leaking rocker cover, plenty of oil pooling in the injector recesses and a lot of burned/baked solid oil. Removing the rocker cover/inlet manifold combo is quite a job! When I finally got it off, I discovered that the EGR system is really a piece of ****. The intake system was really clogged up with a hardish thick oily residue. The most difficult of this to remove is actually down in the cylinder head itself. The intake manifold is 'relatively' easy... Still busy with that. Standard degreaser battles to shift it.

So, like in my other 406's/407, the EGR will be trashed... The way I look at it, the mess it creates in the intake system cannot possibly contribute to more efficient cleaner burning, but have the very opposite effect as the intake system slowly blocks up with crud.

Some pics.. valve body out and then disassembled.





manky intake system..



 

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Brilliant post; impressive work.

The EGR is supposed to reduce oxides of nitrogen which are the new enemy. But yes, it is an Fing stupid system.

With the slushmatic: I remember that the AL4 box was known for problems with the two pressure regulator solenoids (the two at the top of the valve block). I think there was a redesigned solenoid, or it might be an improved aftermarket part. These look very similar; might be worth reading up on.
 

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The AL4 modification was to double the frequency of the valve excitation (software) plus fitting new Borg-Warner valves designed for the higher frequency.
 

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Discussion Starter #5
I have successfully repaired 4 AL4 boxes which all had the 2 valve problem, that is what gave me the brave pill to tackle the AM6 box. But there is a mountain of detailed info out there on the AL4 box issues, unlike the AM6 box.

There is not much out there on this box despite it being used in a wide range of manufacturers in a diverse range of models. There are also variations to the valve block depending on what make of car it goes into. There are kits out there for Volvo, but these internals differ somewhat to what is in the peugeot, so of no help here.

The common approach is to replace the whole valve block, but I have found some details on diagnosing/testing for faults within the block itself. If I do not get it right, I will just replace the whole box with a second hand unit as I can get a complete unit with 90 day guarantee for quite a lot less than the cost of a new valve block. Time will tell.. Will update post with whatever I end up doing.

As for the intake system, I am still scrubbing away at it, that crud sticks like sh** to an army blanket and even petrol/thinners is struggling with dissolving it [currently soaking it.... again!].
 

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Discussion Starter #6
Just an update and some further questions..

I worked out the issues with the gearbox valve bank but, on pricing the replacement bits, discovered that it would cost more than getting a second hand gearbox. I had already located a gearbox from a mechanic who was wrecking an accident damaged 407 with low mileage which he had looked after for several years so knew the gearbox was good and was prepared to give a warranty on its condition. So, purchased and installed.

I followed the directions outlined in servicebox for the removal, but there were a few smallish steps needed which were not anywhere in servicebox or the Haynes manual. Anyway, took a few hours to do the removal and replacement and car is now driving really well. I will now do an oil change of the box to give it a fresh start.

However, now that it is going, I did a Diagbox check and it came up with the 'usual' glowplug error. I als did a check on the DPF state and found it was 83%. Also found it had not done a regen for over 800kms, whereas it had previously averaged about 340kms between regens. I have checked the resistances off the glowplugs and found one to be reading very high, so the fault is real. Obviously one of the reasons it is not regenning. So now need to figure out exactly which plug is faulty and replace it. Easier said than done though...... anyone done this job before and can give me any hints to make the job easier?? I have determined that the egr heat exchanger unit has to come off to get to the glowplugs, or can they be got to from under the engine? Also, where to buy glowplugs from? I dont have any ready source for them here in NZ except from the agent, and their pricing is scary...

The other issue the engine has is that the thermostat is not working much, seems stuck open as the engine temp stays very low, essentially at the bottom of the scale <70C. This would also not help regeneration. I priced a new one from peugeot here and ... WOW! WTF.... does that come with a new car attached??? Again, only supplier over here is peugeot, so will do the usual and source from UK/ebay.

Just as a matter of interest, does anyone have the cost of the thermostat from peugeot in the UK?? Part number 1336.Y9

Have found this on on ebay, are parts from this supplier any good? Citreon C4/C5/C8/Dispatch & Fiat Scudo and Ulysse 2.0 Thermostat 1336.Y9 New | eBay

Anyone to try for glowplugs in the UK? I am a bit sceptical about ebay suppliers for glowplugs as there is a lot of cheap sh*t out there.. Any recommendations for suppliers/ebay sellers?
 

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Discussion Starter #8
Good selection and prices but shipping to NZ kills it unfortunately. Listed as 151.02 pounds.

Price from Peugeot here for thermostat is just over NZD600.00 or the equivalent of 349 of your British pounds...!!!! [my keyboard won't output the pound symbol]
 

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Discussion Starter #11
If ever anyone wants to do a real mongrel job, try replacing glow plugs on the 2.0L 407 HDi in situ.... :(
 

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Discussion Starter #12
Question...

I purchased one of those centre display units off fleabay to replace mine which has the expected peugeot built in failure to display anything problem. However it will not respond to any button inputs from either the RD4 or stalk and remains flashing in french.

I know it must work somehow as my brother's identical 2008 407hdi sw has one fitted [prior to him purchasing it] and it works perfectly.

Any suggestions?
 

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Discussion Starter #14
Yes, it does.

I finally found the process buried DEEP within Diagbox [PP2000 does not work on my 407, too late a model being a 2008].

The process to set up the centre display is in the REPAIR section, but really buried there, and when I first came across it, it did not seem to have any ability to be configured, just displayed a whole lot of options that were all disabled. Could not find any way at that try to make any changes. That is when I came on here to see if anyone knew how.

Went back and tried again, several attempts and then finally found how to make the deactivated options 'activated'. The process needed was not intuitive to me, I really stumbled onto it by frustration more than anything else. Requires a sort of double/triple confirmation.... anyway, got it set up finally and it is working now, although a full fault scan now brings up the centre display ecu as 'not recognised'. But it works so happy days, I can now see what is going on with my radio, trip counter etc.... :D

If anyone wants the process, I will go in and document the long windy road to success... ;)
 
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