Is my Torque convertor giving up?

AMck

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Hi. Well I have been trying to sort out harsh gear changes on my 2000 SL320 for a little while now - so any help would be appreciated.

Sorry if this is a little long, but just want to try to get everything relevant down.

The symptoms

The harsh changes are not constant - it can also give some lovely smooth changes. The worst changes are usually on light throttle or on overrun when changing up.
eg when crawling in traffic or after accelerating up to say 30 or 40 mph and then lifting off the throttle.
Also occassional hard changes down when slowing for junction etc.

On heavier accelleration it will sometimes seem to change gear, the revs will rise a little and then drop back to where they were before about a second later actually change gear.

kick down was very poor with quite a bit of hesitation

Work to date

Replaced ATF (4 liters) and filter - no real change

codes read and code present -

116 Component Y3/6b1 (transmission oil temperature sensor) or
component Y3/6s1 (starter lockout contact) is sporadically
faulty or both

Also the data was read for the adaption values (sorry don't have these). the values were in 2 columns and the left figures were around 140 and the right column around -40. Informed these should be much closer.

The 116 code when cleared comes back.
code cleared and adaptive values reset - no change

Following advice I pulled the hydraulic block and electroplate and sent them to Technical Automatic Services who bench tested them and found no faults.
They re-calibrated the unit and returned it. Refitted with another 5 liters of ATF, new filter and pilot bush (no signs of atf in old one). Codes cleared and adaptive values reset.

This did produce some changes - kick down quicker and smoother, some gear changes a little smoother, but the harsh changes are the same.

Code 116 also returned.

I did notice just before sending electro-hydraulic unit off some very slight droning, but thought this might just be resonance from the exhaust.
Not so sure now - it is like the noise you get when driving over the non skid surfaces near crossings. Only happens on light throttle at about 1300rpm. So noticable in 4th at around 30mph and 5th at 40mph. By just, either very slightly depressing or releasing the throttle the noise will go.

Did a stall test and the engine will rev to 2500 rpm, from what I have read this should be closer to 1800.

I have bought a new electroplate to fit, but now wondering if this could be a TC fault?

Any thoughts would be welcome

Thanks
 

Alex Crow

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the way you describe the droning is absolutely bang on for a TC lockup clutch fault - ie specific engine speed and throttle position. you probably find it is more likely to happen going uphill too.
 
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AMck

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Thanks for reply Alex.

At the moment I don't notice anything when going up hills, but will watch for this.

Are there any other tests that can be done to confirm this before I plunge for replacement?
 

Xtractorfan

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Have you checked the gearbox ecu for oil contamination, worth a check if only to rule it out.... also suggest that you find a good autobox specialist and get a second opinion...
 

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Re what Alex said on the ECU.

One of the longest post we ever had was on a 129 320 owned by Raj back in 2006. Mine would do the same thing at times.

It is a known thing that the 2 CAN bus wires on the end of the plug give a poor connections. the cure was to clean and use non drying switch cleaner on the multi plug,, most of the fault codes thrown up are meaningless MB know of this fault and it is recorded
 
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AMck

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Have you checked the gearbox ecu for oil contamination, worth a check if only to rule it out.... also suggest that you find a good autobox specialist and get a second opinion...

When I removed the old pilot bush there was no signs of any oil contamination and all the contacts looked clean. New one fitted when electro-hydraulic unit refitted.

I have spoken to a local auto specialist who want to have a look at it before giving opinion (but did mention one way clutch) - which is fair. Hopefully will get car into them sometime next week fo an opinion.

Does anyone have recommendations for an auto trans specialist in S Wales/ S West area - might be better to start new thread to ask this?
 
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AMck

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Thanks Malcolm.

Had a read of the problems Raj had - quite a story!

Having now read that post maybe another problem I have could be relevant.

I also have codes for the central locking, although it works perfectly, including the infra red to shut/open the windows.

B1102-002 lines to component A26/1 (front left IR receiver unit)
B1103-002 lines to component A26/2 (front right IR receiver unit)
B1706-002 Check control line to component N10/2 (Combination relay (turn signals with trailer hitch, rear window defroster, wiper motor, ATA) for short to ground.

I don't have a trailer hitch and wipers and rear window defroster works ok. I have cleared these faults and they always return

CDC - CD changer

N1118 Faulty initializing by D2B master

Again radio/cd works fine and again fault code returns after clearing

I don't think these are CAN or am I incorrect?

The final problem is, I think, relavent to the CAN theory is my ignition light (CEL, MIL) on far right of cluster does not come on when the ignition is turned on. I have checked the bulb - this is fine.

There are no fault codes for the instrument cluster.

I still have the feeling this is a mechanical problem, but I will have a check of the connections as soon as I get chance.

Doing some reading my symptoms do seem like a problem with the one way clutch or the lock up clutch. Although I do remember reading sometime ago on the forum that these cars don't have a lock up clutch on the torque converter. Can anyone confirm this?

Thanks

ps - Do you have a copy of the CAN wiring information you mentioned in the post about Raj's car - would it be relevant to my early 2000 car?
 

television

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What a list,, I know that the ignition switches can give problems, the feed to the N10 comes via the switch rather than from the fuse box as on the earlier cars, and the switch can loose contact with the N10.

The gearbox does have lock up, but it never locks up completely. the mechanical sprag clutch does not come into this I think

The radio is an odd one,, there is little info on this as the car was discontinued in 2001, its not CAN controlled as you say

My big problem is that I cannot print off the wiring diagrams, but I will take a look for any useful stuff that I can send
 
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AMck

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What a list,,

Thanks Malcom.
and I didn't add the soft top errors, although I think they are old stored codes as when last used soft top it worked fine.

Again, with the other errors I don't have any problems with the car except the transmission and the lack of an ignition warning light.

At the moment I am wondering whether to fit the electro plate I already have, or to wait until I can get to an auto trans specialist for an opinion. At the moment pretty much all my spare time is being spent on SWMBO's car as we need it for our family hols in a few weeks.
 
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AMck

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Well I have been to an auto transmission specialist.

After driving it he confirmed there was a problem with the lock up on the torque converter. This could be caused by a faulty converter or it could be from the electro-hydraulic unit controlling the lock up.

Now to decide whether I just live with it till it gets to bad or invest in some repairs.:confused:
 

television

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It will still only cost you £3.75 to get a can of non drying switch cleaner and do the connector on the ECU, the CAN bus connections only use micro amps, and the fault is a known recorded one by MB, wrong or no information is all it needs for most of your faults
 
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AMck

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Hi Malcolm.

Sorry I should have also said in my previous post that I bought some contact cleaner from Maplins on Monday and treated the contacts. This was the Servisol Super 10. Unfortunately there was no change even after resetting the adaptive values again.

So my plan is replace the elecro-plate as I have it already and keep my fingers crossed. I suspect this won't solve it but who knows - at least it should sort the 116 fault code.

Probably won't get chance to do this for about a month as I have rather a lot of jobs to sort on my wife's car before we head off to France in 2 weeks.( replace differential, replace transmission cooler, full service, rebuild air suspension valve unit and compressor to name just a few things :lol:)

I will update the post though when I do.

After that I suppose I will either just live with it until things finally give up or take a chance on replacing just the torque converter with a recon unit.

Thanks for your help to date

Alan
 


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