W208 CLK 320 - Some engine issues

[mbenz1]

It does know when the oil is replenished and topped up. It saves this info in the instrument cluster.

So I was kind of wright about the engine having the ability to detect new oil etc... You have mentioned that this info is saved. Does this mean that the service schedule / remaining miles for next service will be interrupted if I were to change the oil now?

Would it be better to wait and change the oil when the ASSYST notifies?

 

[rorf]

If you are not happy about the previous oil then just change it - if the assyst is working it will then just extend the mileage to the next change (if it does, as sometimes only works on engine hours). My Assyst seems to to come up at 15000 kms or 18 months regular as clockwork

 

[mbenz1]

If you are not happy about the previous oil then just change it - if the assyst is working it will then just extend the mileage to the next change (if it does, as sometimes only works on engine hours). My Assyst seems to to come up at 15000 kms or 18 months regular as clockwork

I'm double-minded now about changing the oil. Just for the sake of the service schedule complexity of the Assyst system, I will leave the oil change and stick to it's original service plan... Remembering off the top of my head, 10W-30 semi synthetic oil was put in! That's.nowhere near the recommended oil (0W-40)

 

[mbenz1]

Update:
I have got the car through the STAR diagnostic check at my local MB specialist.

There were some stored 'small faults' represented as 'f' in the results log. The chap said those were due to the car being jump started (which causes 'f' logs).

The STAR check is clear and the mechanic is suggesting the following can be the cause for the shaking issue:
MAF Sensor
Spark Plugs

I will inspect the MAF soon and if its dirty then I will get it changed. If still no avail then my next idea will be to get OE/genuine spark plugs (if not already installed).

The mechanic said that the shaking is very unlikely to be due to engine.mounts, especially since the car has only done ~79,000 miles.

 

[mbenz1]

Update 2:
I opened up the MAF sensor housing today and inspected the film. The film has a thin transparent layer of dirt (grease/dust) on it.

I disconnected the MAF sensor and started the car and also went through P,.N, R and D but the same shaking issue at idle was still present.

So from this diagnosis do I conclude that the MAF sensor is faulty/dirty which is causing or partly causing the shaking and rpm fluctuation at idle?

Also, maybe I forgot to mention, the engine noise and exhaust note is not smooth and constant like a V6 should be...the note is a bit 'bouncy or fluctuating' if you can.understand what I.mean.

So from here, what would you guys suggest. Thanks

 

[rorf]

If the MAF has a thin film of oil on then it is definitely history. What air filter is on the car - this should be checked and changed if necessary back to the original type before installing a new Bosch MAF.

 

[mbenz1]

If the MAF has a thin film of oil on then it is definitely history. What air filter is on the car - this should be checked and changed if necessary back to the original type before installing a new Bosch MAF.

I'm not sure if its oil tbh. Its a semi-transparent layer of dirt - the colour of the dirt layer is not brown/black etc...

The MAF in the car is a Bosch, so I'm not sure if its the original one or has been changed before aswell.

I will check the air filter - if I change the MAF then will definitely makesure a genuine MB air filter is used.

I am taking a gamble this time since I'm not sure if the MAF actually needs changing (£140 at ECP). My local MB specialist is too busy atm so I'm in search for another reputable MB specialist in Leicester who can diagnose the issue since it could also be caused by faulty coil packs, plugs, plug leads and boost leaks etc. I don't think the gearbox may be the issue since the car has only done 78,000 miles.

 

[mbenz1]

Update 3:
Eventually the mechanic at my local MB specialist had some time to look at the car.

He took.out 2 spark plugs from one cylinder and they were NGK plugs and also had some black crud around the thread. He said as far as he.knows, NGK plugs are not specifically for this.model.

Now I have the car booked to get the spark.plugs changed for new genuine MB plugs and also I will get a genuine oil/filter, air filter service done since the car has had semi-synthetic 10-W40 oil, which is far off the recommended oil. Hopefully the problem will go away. I will keep this thread updated.

 

[rorf]

Correct plugs are Bosch FR8DPP33+ (7422) platinum tip.

Another way to check MAF is to disconnect it when engine is idling and if idle improves then MAF is a problem. I would also change the crankshaft position sensor whilst at it.

 

[gbjeppm]

3. The steering does seem a little hard - This car has 225 tyres at the front and 205 tyres at the rear (I know this sounds wrong and I will investigate this further) but could this wheel set-up be causing the hard/heavy steering.

It is perfectly normal to have staggered wheels on a CLK320, mine does.

I would expect 205/55 16 on the front
and 225/50 16 on the rear.

The handbook will tell you all the possible tyre and rim sizes.

If staggered the wider rims should always be on the back, although you say they are on the front.

I wonder if the previous owner rotated them, not realising that they are staggered.

 

[mbenz1]

Correct plugs are Bosch FR8DPP33+ (7422) platinum tip.

Another way to check MAF is to disconnect it when engine is idling and if idle improves then MAF is a problem. I would also change the crankshaft position sensor whilst at it.

Yes, I did do this diagnosis. After disconnecting the MAF, I started the engine and the shaking and fluctuations in the idle still existed. I got the MAF checked by the mechanic at my local MB specialist and he said its just a little dirty but not that dirty that it would need changing. So I guess the MAF seems okay here.

I will try to get the CPS done also if possible. Do you know roughly at what milleage they fail?

It is perfectly normal to have staggered wheels on a CLK320, mine does.

I would expect 205/55 16 on the front
and 225/50 16 on the rear.

The handbook will tell you all the possible tyre and rim sizes.

If staggered the wider rims should always be on the back, although you say they are on the front.

I wonder if the previous owner rotated them, not realising that they are staggered.

I have finally got the rear 205 50 17 tyres changed now. The fronts are 225/45/R17 and my local tyre shop had the same tyres (225/45/R17 - part worn) in stock coincidentally and he suggested to put those at the back. So I now have 225/45 all around. The ride is significantly more smoother now and the bumps in roads are handled with more ease and less noticeable.

 

[mbenz1]

Update 4: (with pictures)

I got the NGK plugs (see attachments) removed to new genuine MB plugs and also got the bad 10W-40 oil and cheap oil filter replaced with MB spec oil and filter.

As you can see in the pictures, the tip/head of the plugs have some accumulation of black crud. That's why the mechanic at MB specialist said to change them asap since they were not the correct plugs for the engine and not in good conditions.

Outcome: engine is a lot more quieter, smoother and faster and the fluctuation in the rpm needle at idle has decreased significantly.

But the shaking issue at idle is still present... Straight after the service, the shaking at idle had reduced but two days after service, the shaking increased back to normal again.

The mechanic has suggested to observe the shaking for atleast 100 miles due to new plugs and oil etc...

Since the STAR check is clear, a faulty MAF, coil pack or plug leads is unlikely to be the problem, as suggested by the mechanic.

I'm now thinking that the below maybe the causes?

Fuel filter? It has been changed in the previous service but I have a feeling that a non-genuine filter has been used, since a non-genuine oil filter was used.

Battery? The car starts always on first click but I think it cranks for a little longer than a usual car...could a low battery effect spark plug/coil pack performance?

Crankshaft pulley and alternator belt? These two items were replaced in previous service (not the service just done.now) and I fear that either non genuine parts have been used or they have not been installed properly, because there is a chain rattle type noise from the.engine which is loud on cold startup and quieter when warm and always occurs when accelerating. But could this cause the shaking.issue by any chance.

Thanks

 

[mbenz1]

Advice will be very helpful guys...

 

[mbenz1]

Bump...

 

[mbenz1]

There hasn't been much recent response on this thread but I will update it anyway.

I left the car today at my local MB specialist and demonstrated the shaking/shudder at idle to the mechanic. The chap said they will check/diagnose all the possible causes.

Later, I had a call and the mechanic said everything seems to be faultless. Furthermore, the STAR check is also clear.

Now, the mechanic has suggested that a clean of the air intake pipes/components may solve this problem. The car is booked for the clean of the air intake and this is most likely the last thing mechanic can suggest.

Can anyone suggest what could solve this problem, besides cleaning the air intake? Could a blocked throttle valve cause this problem?

 

[BlackC55]

The plug leads are very common to fail in this engine and it will cause a misfire. It's easy to do a resistance test on them.

Are your engine mounts worn too?

 

[mbenz1]

The plug leads are very common to fail in this engine and it will cause a misfire. It's easy to do a resistance test on them.

Are your engine mounts worn too?

I told the mechanic about whether engine.mounts would be the cause, he said its very unlikely for the mounts to be faulty in this engine and at the current mileage (79,000).

I told the mechanic about checking the coil packs and plug leads with a multimeter - I can't comment if he has carried this check or not but he did mention that any fault in the coil packs or leads will show up in STAR.

BlackC55, I have a multimeter at home...could you explain the procedure of how to check the resistance of the leads please?

It's definitely not a misfire...I think a 'semi-misfire' would explain the shaking better.since its only a slight shake...

 

[BlackC55]

Mounts can be worn at 79k. Especially if they are original.

The lead has a resistance amount actually stamped on the lead. Measure the resistance of the lead measuring Ohms.

A Star will not pick up if the leads are faulty. It will pick up if there is a slight misfire in "smooth Engine running"

 

[mbenz1]

Mounts can be worn at 79k. Especially if they are original.

The lead has a resistance amount actually stamped on the lead. Measure the resistance of the lead measuring Ohms.

A Star will not pick up if the leads are faulty. It will pick up if there is a slight misfire in "smooth Engine running"

The mounts are definitely original, I will tell the mechanic to check for play in the mounts while I'm there.

To remove a plug lead, is it done by:
- Removing lead connector from the plug
-removing lead connector from coil pack (or opening the coil pack and then removing lead?)
Am I correct to assume that removing the leads is simply plug and play procedure and no involvement of STAR or re-coding etc?

I must admit, the mechanics at my local MB specialist tend to be very dependant on the STAR check and not very keen on the traditional diagnostic methods, unless there is a 'problem'. I spoke to the mechanic yesterday and he said they can clean the air intake free of charge. If that is of no avail then I will have to check the lead resistances my self - I know this will be a challenge for me since there are 12 leads and some are difficult to access...

 

[BlackC55]

Play can't be checked. It's a visual check.

Just pull the lead off the plug and coil to check it. They are plug and play. No coding required.