Engine surge/hunting when cold

[corned]

Hi all.

Here's another winter issue with the 211. I have had similar less pronounced symptoms earlier in the year, but now the cold weather has arrived the symptoms appear to be getting worse.

From cold, the engine revs wander around, particularly on a very light throttle setting and at the lower end of the rev range. Occasionally, it gives the appearance of a clutch which is slipping and the drive is hesitant and jerky too. The throttle input is steady, but the revs hunt up and down by a couple of hundred rpm. As the engine warms up, the symptoms gradually disappear. When fully warmed up, it behaves exactly as it should - smooth as you like.

I6 E320CDI, last of the I6s, 5-G 'box. ATF+filter change less than 20k ago.

Do you diagnose this as:

a.) They all do that, Sir!;
b.) MAS on its way out/needs a clean;
c.) Sounds like there's not enough ATF in your torque converter;
d.) Gearbox is sha**ed;
e.) None of the above.

Advice and opinions, as always, very much appreciated.

 

[AMG19]

Check for any external oil leaks - the GB electrical plug is the usual suspect and check the GB oil level and condition of the oil - sounds like the gearbox oil level could be low to me.

 

[corned]

Thanks. I'm hoping it's something simple like that. I have no reason to suspect anything more sinister, unless anyone on here can throw any further light on the subject. There are no apparent leaks anywhere under the car.

I think I might be as well investing in one of those Ebay dipstick kits. How do you get the filler tube cap off without breaking it?

 

[AMG19]

Buying a dipstick is a good idea - although my indie wouldn't charge me to check my GB oil level and nor should any decent indie.
Unfornately you need to break the tag on the top of the cap. Simply snap the top of the tag off and push what remains through, the cap will then come off. New tags are cheap as chips.

 

[corned]

My problem is that there are no decent indies within easy reach of me! And I'm not averse to getting my hands dirty if necessary.

To press you on the cap/tag thing; I note that the black cap has a red tag in it. When you say snap it and push it through, I take it the bits can't drop down the filler tube? Or can they, and I need a deft hand to prevent potential disaster?!

 

[NW_Merc]

My W202 did this, obviously its not the same model as your car so I really cannot compare like for like, but my gearbox failed soon after this surging.

 

[corned]

Um - thanks for that!

Let's hope not.

 

[mobeyone]

Low oil? mine has started to do this and I have just had the oil changed but I only bought the car in May of this year so I am going to go back and have the oil checked to make sure.

Just to add, I always let the car warm up or until I see a black bar appear in the temp gauge before I drive off.

 

[NW_Merc]

Would it be worth having the fault codes read?

 

[corned]

To press you on the cap/tag thing; I note that the black cap has a red tag in it. When you say snap it and push it through, I take it the bits can't drop down the filler tube? Or can they, and I need a deft hand to prevent potential disaster?!

Can someone please advise on this little matter? Thanks in advance.

 

[AdamG]

Can someone please advise on this little matter? Thanks in advance.

The broken part of the tamper pin drops down on the outside of the pipe. The cap over hangs the edge of the filler pipe. You should be able to catch it in your hand.

Adam

 

[corned]

Ah - I see. Thanks!

 

[corned]

Dipstick tool arrived this morning. Went for a run and then checked the level. Slightly low perhaps, but nothing which caused me any alarm. Topped up so the level is right at the top of the top hot marker, so we'll see what happens if anything next cold start.

I doubt this will change anything though, as I only added 100ml at the most.

The car will need a service before Christmas anyway, so I'll ask them to check out everything gearbox related while they're at it.

 

[Alex Argent]

I have had exactly the same issue ever since I got the (MB) stealer to change the ATF on its last 'A' service back in May. At the time, the car had around 85,000 miles on it. I'm uncertain if the fluid was ever changed previously. I have owned it since 2008 with 65,000 on it (it's used as a second car, hence the relatively low annual mileage).

Up until the ATF change, the changes were silky smooth and I really never had any problems at all. However since the change, when cold the rev counter fluctuates +/- 200-300 revs at a steady throttle setting, and it tends to hunt for the gear change. It certainly seems to be changing up (i.e. 1>2, 2>3 etc) much sooner than it used to......unless I keep my foot on the floor

It went back to the dealer three times

First time they said no problems found or fault codes recorded. However next morning when cold, it done exactly the same. On questioning the service receptionist over the telephone (whom I hasten to add didn't have a clue what the difference was between a torque converter and Star Diagnostics ) it then transpired they had only changed the gearbox fluid and not the TC. When I reviewed the invoice, sure enough they had only billed me for 3 litres of ATF. I tried to explain that it all ended up mixing together with the remaining 5 litres in the TC, so what was the point

So it ended up going back a second time to have the TC fluid changed plus a new filter/gasket. At least they only charged me for the materials and no labour. On collection, and the 15 mile drive back home all seemed well.............until the next morning when it was cold again

So it went back a third time....and it was after I left the car with them overnight so they could investigate when cold that they stated the TC was knackered and quoted me £2600 to replace

Up until now I have learned to live with the issue as it still seems fine once warmed up, however clearly I need to get something resolved soon. It has now done about 6,000 miles since this last service.

Furthermore, there were another 3-4 minor issues that I requested they also rectified during the service (not relevant in this post, however nothing to do with the gearbox/engine). I was charged for carrying out investigatory work and was told when I collected the car the first time around that all had been resolved. In fact only one of the 4 issues was ever resolved....the remaining 3 still persist to this day.

I should have been much harder on the dealer however by this time I had completely lost what little faith I had and made a promise to myself never, ever to take the car into this dealer again.

And that is pretty much where I am at the moment. Still living with the problem(s) despite a hefty service and repair bill.

I'm trying to run the remaining miles to its next service (which is showing as a 'B' at present) a bit lower and will then book the car into Ollie down at Horndean. He has done a couple of ATF changes on previous models I have owned over the past 4 years or so, with excellent results (and much more competitive rates). Plus it may be up for a discs and pads change by then and I'd much sooner give PCS my well earned cash than franchised MB dealers whose expertise seems to be diminishing by the month.

The fact that it's an overnight stay in Portsmouth (I live in Suffolk) is completely irrelevant to me. I'd sooner get these jobs done properly rather than by so called "technicians" that appear to have just come out of high school (and blonde (clue?) service receptionists that know jack sh1t about anything).

I'm just hoping the issue is one of incorrect ATF levels. I'm aware that correct level is critical to operation. Or hopefully something else.......but I'm certainly very far from convinced that it needs a new gearbox or TC.

Hey-Ho.

Further update to follow once Ollie has had his greasy paws on the case

 

[AdamG]

What atf did they use?

Did they use the later 7 speed fluid?

I know everyone says it is fine for the 5 speed gearbox but I found that the 7 speed fluid caused a vibration on gearchange and a general vibration at low revs.

This all started when I switched to the newer fluid. To try and cure it I then changed the fluid several times (7 speed fluid), changed the lockup solenoid, the torque converter, and finally had the valve body refurbished.

None of the above made any difference. So on a recommendation from someone on the U.S forums I put the old 5 speed shell 3403 m115 fluid in and it made a vast difference.

The 7 speed box has torsional damping springs in the lockup clutch so I assume it can operate with a fluid that offers less slip. That's my theory anyway

Adam

 

[Alex Argent]

What atf did they use?

Did they use the later 7 speed fluid?

I know everyone says it is fine for the 5 speed gearbox but I found that the 7 speed fluid caused a vibration on gearchange and a general vibration at low revs.

This all started when I switched to the newer fluid. To try and cure it I then changed the fluid several times (7 speed fluid), changed the lockup solenoid, the torque converter, and finally had the valve body refurbished.

None of the above made any difference. So on a recommendation from someone on the U.S forums I put the old 5 speed shell 3403 m115 fluid in and it made a vast difference.

The 7 speed box has torsional damping springs in the lockup clutch so I assume it can operate with a fluid that offers less slip. That's my theory anyway

Adam

Adam

Thanks.

Interesting. I'll see if I can establish what fluid they used.

As it happens, there does seem to be a slight vibration.....but again only when cold. Everything appears fine once it gets up to full working temp (85degC).

Watch this space

 

[Johnny-P]

I have a 2004 w211 320cdi est AG and had all the symptoms you have described.
Took it to my local indy and after describing the problem he said without hesitation it was the TC slipping!!!
Any how he said to prove the fact he would get it plugged up to STAR and lock the TC and prove if it was the case.
We went for a drive with it locked and low and behold it was like driving a new car.
I had an exchanged unit fitted and haven't looked back, it drives like new and have covered 3000mls since with no problems.
Obviously having this done also included new filters and a complete drain/refill of all fluids so should be good for another 40,000+mls.
Hope this helps!!

 

[mobeyone]

It depresses me reading about the potential problems with the transmission on the w211 7g.

Is it acceptable for a manufacturer to produce a car which can have such a catastrophic failure of one if it's main components on what was an improvement on a already problematic car?

Wish I never bought mine now.

 

[corned]

Well, I have just returned home from a little trip out. The cluster temp gauge showed nothing when I went out, but I am not going to count that as a proper cold start.

However - it has to be said that it ran as smooth as silk. The rev counter never wavered in the slightest, and the changes were perfect.

I'm not counting my chickens just yet though. We'll see what it goes like in the morning, when it can do a proper cold start.

 

[Alex Argent]

I have a 2004 w211 320cdi est AG and had all the symptoms you have described.
Took it to my local indy and after describing the problem he said without hesitation it was the TC slipping!!!
Any how he said to prove the fact he would get it plugged up to STAR and lock the TC and prove if it was the case.
We went for a drive with it locked and low and behold it was like driving a new car.
I had an exchanged unit fitted and haven't looked back, it drives like new and have covered 3000mls since with no problems.
Obviously having this done also included new filters and a complete drain/refill of all fluids so should be good for another 40,000+mls.
Hope this helps!!

Johnny

As a matter of interest, who was the indy (anywhere near East Anglia?) and how much did they charge to fit the exchange unit?

Thanks.