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Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 20364
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Merc clk 2004 cabriolet vibration on start up, disapears after

Resolved Question:

Merc clk 2004 cabriolet vibration on start up, disapears after 10 mins?
Submitted: 1 year ago.
Category: Mercedes
Expert:  Matt replied 1 year ago.


1st replace the spark plugs if any of them fail this checklist:

You can also try spraying some water on the coil packs with the engine running. It is possible the coil is faulty and causing the misfire. If you see sparks arcing with the water, then replace the coil.

I'd check the condition of the injector plugs / connections as this could be a lean misfire if an injector isn't firing properly - the best way to check this is with a 'noid' light

Then check all the connections to the engine sensors one at a time, remove each one and examine for signs of corrosion or damage and a squirt of contact cleaner ( not WD40) will also help.

This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and leans the engine out causing rough running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas around each joint in turn. If the engine rev's up you've found your leak.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine

Customer: replied 1 year ago.

The car is NOT running rough, it's 'vibrating' on start up and then disapears after 10 mins. I have been told it's a gearbox/Torque Converter issue.

As I've already said it has had a FULL service.

Also the engine mounts, crankshaft pully, alternator belt, front antiroll bar link, nearside front lower suspension arm. have all been replaced to eliminate these as possible issues.

Expert:  Matt replied 1 year ago.
Hello Paul

ok thanks for the extra information
in that case

I'd take a look at the colour of the transmission oil it should be a dark red colour if its black then its needs changing together with its oil filter. Also check its level with the gearbox warm and just after you've moved the selector through all the positions leaving it for a few seconds in each one and then back to park.

You can top up the box through the side fill plug if required and make sure you use the correct oil for your car as the fluids are not all the same. Some manufacturers recommended a change of the type of fluid - Speak to the local dealer and parts dept - they will advise you on the updated fluid to use..

If that’s all OK then check all the electrical connections of the gearbox, remove each connector in turn and spray with contact cleaner. Check that the wiring to the gearbox is in good condition with no chafing or frayed wire

Then - you should top up if low and re try it - or, if its level is ok - and condition is ok - then the next step is to drain it off - open it up and clean the filters inside -- refill and retry it..

Often - just doing the above cures many troubles with these - and you certainly can't condemn the unit without doing the above...

Customer: replied 1 year ago.

Hello Matt, if it is the Gearbox and Torque Converter as I've been told, as I won't be doing the work is this a big job and what should it cost?

Expert:  Matt replied 1 year ago.
Hello Paul

to replace the entire gearbox and torque convertor is about half a days labour providing they're not rebuilding your existing unit so can drop the replacement straight in

if you use a good used gearbox as a replacement then parts are about £1200 - brand new from Mercedes about £3400
Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 20364
Experience: BEng hons Mech engineering, in auto industry 22 years
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