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Registered 1996 SLK230
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Discussion Starter #1
My new SLK 230 has a gearbox fault hence I bought it 'spares or repairs'.

When cold it smoothly engages reverse and first gear (possibly more gears I don't yet know*) and drives nicely but then before too long (seemingly when the engine/coolant/oil temperature has risen) there is no drive in any gear - it will rev but not go anywhere.

* no road tax or insurance so only driving it on my short stretch of private road.

In a couple of weeks I will receive my carsoft diagnostic kit from China so can read the fault codes but until then I ask if anyone has any ideas or suggestions?

I hope it's a positive sign it does actually drive and as well I don't think it's driving in limp mode as when drive or reverse are engaged there is no sudden 'jerk'.

On a negative point when there was no drive and I was giving the engine some revs there did seem to be a kind of screeching noise coming from the front of the car.

Any help appreciated . . .
 

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Administrator 2009 SLK 55 AMG/Founding Member 2006
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when was transmission service done last?
 

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It sounds like it's low on trans fluid. Driving or even starting the car will ruin the transmission. You might not have a dip stick. For some reason, MB didn't build the trans with one but you can buy one. Do that and check your fluid level. Repeat, don't even start this car until you figure it out.
 

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Registered 1996 SLK230
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120 Posts
Discussion Starter #5
Finally found my dipstick that I bought for my previous SLK.... Measured the level when cold and it seemed over-filled (around the level of where it should be when hot)... Obviously cold is not as accurate as hot but it does seem it cold be over-filled... My dipstick is not the best so I'm going to give it a day and take another reading (or buy a better dipstick) before looking to extract some fluid and see what difference that makes...
 

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Just make sure you check the auto trans fluid level when the engine is running. It will look overfilled if you check it with the engine off.
 

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Registered 1996 SLK230
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120 Posts
Discussion Starter #8
carsoft v7.4 fault codes before and after battery change

Update: my carsoft v7.4 arrived from China and thankfully worked fine connected via the rs-232 serial port on an old Dell Laptop running XP pro with the anti virus switched off.

No fault codes for anything transmission related but did have the following:

Instrument cluster:

B1041 CAN Communication Error with Traction Control Unit - verify the cable connection between the instrument cluster and traction control unit

Airbag:

2 SRS Malfunction Indicator Lamp (Ale15) - check cable, connections and operation of the lamp
27 Front passenger occupied childseat Recognistion Sensor (B48) - cable communication error - check voltage supply at connections + check continuity of cables
3 Voltage Supply Low Terminal 15R

VD (Vario Roof):

B1010 left front power window switch
B1121 Right front power window switch
B1010 Low Voltage Terminal 30E
B1267 Implausible RPM and VSS status signals
B1493 Gong
B12670 Trunk Lid open and trunk lid closed limit switch activated simultaneously
B1275 Trunk lid open limit switch
B1278 Hardtop (close) switch

PSE (Pneumatic System Equipment):

B1713, B1221, B1220, B1726 (each one repeated two times) no explanation notes

Knowing a poor battery could cause problems and at least one of the fault codes mentioned low voltage I did nothing until I could change the under-powered battery in the car (500a / 52ah) with a proper type 096 one (760a / 70ah).

Before connecting the new battery I checked the K40 module and was pleased to find it looked in really good shape. Connected the new battery, Started Car, Hard Lock Right, Hard Lock Left a few times (to reset any ABS/ESP/BAS lights) then switched off. Then cleared all the existing fault codes.

Then restarted the car and no more SRS light lit up. I cycled the gears a few times before taking a transmission fluid level with my new improved dipstick. The cold reading was off the scale indicating way too much fluid. I drove the car a short way on my driveway in reverse, drive, 2 and 3 (don't think I tried 4). All fine initially then I could detect a little slipping and then eventually no drive. Switched off, left it for a moment then restarted and it drove again back to where I could park up. Read the ATF level again and no change - off the scale. Fluid looks nice and clean (it should be).

During this time I found if I revved the car I would get an awful lot of grey smoke (perhaps not initially after starting the car up). Coolant Level is just above min and looks a nice red/pink colour.

Tried the roof out a few times up/down (with engine on) - worked fine but was slow - took 56 seconds to finish the closing sequence from being stowed in the boot.

Switched off and read the fault codes again . . . this time there were no fault codes except the following =

PSE (Pneumatic System Equipment):

B1713, B1221, B1220, B1726 (each one repeated two times) again no explanation notes.

So then, a few questions . . .

Are those PSE fault codes anything to worry about? anyone know what they are for?

To remove some ATF am I better off draining the pan - measure what comes out and put less back in - gradually taking a reading as I do so . . . or is it better to suck/syphon some out from above? If it has been over-filled should I do anything else? - bearing in mind the previous owner just replaced all the fluid and filter.

Would over-filled ATF cause grey smoke from the exhaust? I read about a vacuum modulator on the transmission (different car so not sure if the SLK 230 has one) that could suck transmission fluid into the engine and get burned up.

Sorry for the long post!
 

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Registered 1996 SLK230
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120 Posts
Discussion Starter #9
So yesterday I extracted ATF to get to the correct level...

I used a silverline 1.5ltr oil and fluid extractor pump costing £12 (model 104610). The supplied pipes were too short and too big to fit down the transmission dipstick tube so I had bought 2 metres of 6mm external diameter pvc pipe (4mm internal diameter) which was the perfect size for the dipstick tube hole.

To cut a long story short it took ages using the little hand powered pump to draw out the fluid but at least it worked.

How much was it over-filled?

2.5 litres !!!

I kept checking the level with my new dipstick as I went along (in park with the engine on after cycling through the gears).

Car would still drive for a little while forward and reverse then would loose drive.

Clearly the over-filled transmission fluid has caused some significant damage - I understand the fluid is likely to have 'foamed' causing starvation like symptoms and as well excessive pressure may have blown some seals.

Looks like I will be selling the car on for spares and repairs - might be worth me dropping the pan and changing the filter first as one last 'cheap' thing to try.

Poor SLK... I was hoping to save it as there are not many 1996 cars...
 

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Why don't you buy a used transmission and replace it? It's not that hard to do. You need some solid stands and a good floor jack and that's about it.
 

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Registered 1996 SLK230
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120 Posts
Discussion Starter #11
Yes used transmissions and torque converters can be had for £100-150 so once new fluid, filter and gasket are taken into account it could be fixed for £200-250 if I'm lucky... It is tempting but a lack of time and experience is putting me off....

Perhaps some fellow forum members can convince me it's fairly straightforward??

I imagine I would need to get the correct 'age' of gearbox from another pre-facelift car?
 

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Yes used transmissions and torque converters can be had for £100-150 so once new fluid, filter and gasket are taken into account it could be fixed for £200-250 if I'm lucky... It is tempting but a lack of time and experience is putting me off....

Perhaps some fellow forum members can convince me it's fairly straightforward??

I imagine I would need to get the correct 'age' of gearbox from another pre-facelift car?
Sorry bro, but if previous owner neglected car that bad your better off getting rid of it. Ya you could go through the trouble of replacing tranny, then you find something else neglected. It becomes a huge money pit IMHO and its best to start out with one that at least was properly maintained and serviced. Any over filling of lubricants is just as bad as no fluid (windage-air in lubricating system). Your burning oil too so its a good indication the engine oil might have been over filled at some time or it could be the tranny oil, either way big problems.
 

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Registered 1996 SLK230
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120 Posts
Discussion Starter #13
Sorry bro, but if previous owner neglected car that bad your better off getting rid of it. Ya you could go through the trouble of replacing tranny, then you find something else neglected. It becomes a huge money pit IMHO and its best to start out with one that at least was properly maintained and serviced. Any over filling of lubricants is just as bad as no fluid (windage-air in lubricating system). Your burning oil too so its a good indication the engine oil might have been over filled at some time or it could be the tranny oil, either way big problems.
I hear what you say - always a risk there are other issues.
To be fair the previous owner may have only made the one mistake during his brief ownership (he only managed 750 miles over 6 months).
Previous owner to him bought the car as a 12 year old 'approved used' Mercedes for £5k in 2008 so the car was certainly in good shape then and the bodywork still is now - one of the things that appealed to me.
Reckon I can get £650+ for it as it stands - the front bumper, wings, bonnet and wheels must be worth £500+ alone?
 

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Premium Member 2005 SLK55 AMG; 2005 SLK350
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5,147 Posts
Question: Did the noises subside after you corrected the fluid level?

These transmissions have a float valve for over-fill conditions. Unfortunately I don't know exactly what happens when the valve closes. Perhaps someone with the service manual can comment. See http://www.all-trans.by/assets/site/files/mercedes/722.6.1.pdf

Also, the "pilot bushing" (where the wires exit the transmission) is known to leak, and if unchecked can wick ATF all the way back up through the harness and into the transmission computer, ruining it. This can cause "reverse and first-gear-only" symptoms. This type of leak is easy to detect by inspection - feel the wires for oily substance. The computers can be found on fleabay for ~$100 USD. Usually, though, a failed computer doesn't manifest only after warm-up.

The R170 conductor plate (flexible circuit board inside the transmission) is only rarely known to fail here; replacing it is relatively inexpensive and straightforward, with no electronic coding required. This might be worth a $100 gamble if there are no further noises.

I have heard of the torque converters failing in these cars causing all manner of drivability issues - but lack of shifting is not one of the typical symptoms.

The smoke out the tailpipe is a completely different matter.
 

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I hear what you say - always a risk there are other issues.
To be fair the previous owner may have only made the one mistake during his brief ownership (he only managed 750 miles over 6 months).
Previous owner to him bought the car as a 12 year old 'approved used' Mercedes for £5k in 2008 so the car was certainly in good shape then and the bodywork still is now - one of the things that appealed to me.
Reckon I can get £650+ for it as it stands - the front bumper, wings, bonnet and wheels must be worth £500+ alone?
If I were you and I really liked that body style and were not considering upgrading to a newer style, I would just keep it. You could part it out and have extra parts for another one unless you just don't have room for it. Probably get more in long run selling parts off it.
 

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Registered 1996 SLK230
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120 Posts
Discussion Starter #16
Thanks for the input guys.

It's a warmer day today so I'm going to fire her up and take another look at the tailpipe to see if the smoke is now reduced / gone. To be honest after getting the ATF to the correct level I didn't take much notice. I will also listen to see what noises the car is making.

Having said that . . . .

The car only owes me £662 which I can easily get back in 'easy to remove' parts so I have pretty much decided to strip the car for parts and scrap what is left over. I wanted a bit of a project but dismantling the car wasn't what I had in mind lol.

If I can find another pre-facelift silver SLK needing non-engine or gearbox repairs I could be on to a winner - I have one on my radar already lol.
 

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Registered 1996 SLK230
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Discussion Starter #17
To finish the story there was still a lot of smoke coming out the exhaust when I tried the car again on a slightly warmer day.

Not to worry - I'm going to take the worthwhile parts off the car and scrap the rest - the parts will come in handy for the replacement car I collected today (couldn't resist) . . .

1998 Linarite Blue SLK 230, 80k miles, AMG Front Bumper, Rear Bumper, Side Skirts, Alloys, AMG Private Plate, Aircon, Heated Seats.
Car has some chrome roll-over hoops and clear Lens chrome angel eye style headlights I'm not sure I want to keep so they might be the first things I swap over.
 
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