W202 C240 Refuses To Start....

[Seans Dad]

Unfortunately, my 1st post here is the subject of a problem with my car.

The car is a 1999 W202 C240 Sport Auto Estate.

Yesterday, I drove 5 miles to our local filling station in it, parked the car, was gone for 5 mins or so, and when I returned, it refused to start, or even turn over.

I had ignition lights for around 1/2 a second, then they extinguished altogether, but the cooling fan was running constantly while the ignition was switched on.

I called my breakdown service, who duly arrived, and we found that the earth cable that connects to the a/c compressor was broken. He repaired this, and I had full ignition lights, and the cooling fan had stopped whizzing away. But still the engine refused to crank over. All it would do is try to turn over, but go only a fraction, as we could see the aux belts turning slightly. The mechanic said it may be a starter/earthing issue, so I agreed to have the car recovered back to my home so I could investigate further.

Got the car home, and up onto my ramps, removed the plastic undertray, and found the engine earth strap had snapped. Bingo!!! I thought. I removed it, repaired it, clean it all up with a wire brush, refitted it, but still had the same symptoms, ie, engine struggling to turn over.

My thoughts then turned to the battery, so I removed it, charged it up for 24hrs, and put it back on tonight after work. Still nothing though. I then nipped to Halfords and purchased a brand new Bosch battery (800 amp, more than enough to turn the engine) but again, it refuses to turn over, just a slight groan, and the belts turn slightly again.

I'm now at a loss. Headlights are nice and bright, c/locking works fine, all other electrics work fine, but the engine refuses to turn over.

Have I missed something?? Is there another earth strap somewhere?Any fuses I should check?

My thoughts now are towards the starter motor, or CPS, but I'm not sure.

The starter looks like an absolute pig to get to.

Any thoughts or advice please, gratefully received.

Thanks.

Dan. (sorry it's long winded!!)

 

[BlackC55]

Have you tried to turn it over by hand?

I suspect a starter motor issue or the main feed cable that goes through the passenger footwell is heavily corroded, loose or not connected.

 

[misfire84]

I had a similar fault and it turned out it was the terminal on the starter motor was lose and not making a good contact under load ( while attempting to crank )

 

[Seans Dad]

Have you tried to turn it over by hand?

I suspect a starter motor issue or the main feed cable that goes through the passenger footwell is heavily corroded.

When you say "turn it over by hand", I assume you mean with a socket & bar on the crank pulley?? If so, no I haven't tried that.

The main feed cable is I assume the one that runs from the battery? How would I access this to inspect it?

Thanks for your reply, and sorry for my ignorance!!! I'm new to MB's, give me an old Jag or a Rover, and I'll go right through it, no problem!!

Dan.

 

[Seans Dad]

I had a similar fault and it turned out it was the terminal on the starter motor was lose and not making a good contact under load ( while attempting to crank )

The one thing I haven't checked is the starter motor connections, mainly due to the fact that it's a PITA to get to!!

The car is still up on my ramps though, and will stay there until I can get it running again, but it may have to wait til the weekend, due to work constraints.

Thanks for replying.

Dan.

 

[Seans Dad]

I've been scouring the 'net, and have read that the ECM (engine control module) manages among other things, starting of the engine, and regulates when to turn the cooling fan on & off.

As my initial problem was no ignition lights, and the cooling fan was constantly operating, I also read that this happens because the ECM cannot determine the correct coolant temp, so therefore goes into "safety mode", and switches the fan on constant.

Would I be correct on any of the above?
Where is the ECM located? Apparently bad earthing issues can cause it to malfunction, is there any way to "reset" it?

Just trying to shed more light on this headache/migraine of a problem.

Thanks.

Dan.

 

[Seans Dad]

Well, I have tried a new battery, with no joy, and today I fitted a new starter motor, but still no joy. The engine wants to turn on the key, but it's as though it's "jamming up" when I try it.

My neighbour, who helped me today, has said that it may now be "hydraulic lock-up".

We took off the air filter housing, and the filter was sopping wet, and there was moisture in the housing, leading us to beleive that the engine has sucked in water, meaning the engine cannot turn over due to too much compression.
Tomorrow I will remove all six spark plugs and turn the engine over to see if I can release the pressure in the chambers. BTW, the engine does turn by hand, I had a socket & bar on the crank pulley, and it turned ok, so the engine is not seized.

This is why some 4x4's have big snorkels fitted to them, so they can drive thru deep water without sucking in water.

Just before the car died last week, I did go thru a puddle which caused the car to aquaplane, so I'm wondering if the engine sucked up some of this water.

Will post results here later.

Dan.

 

[BlackC55]

A compression check is what is needed.

 

[Ultymate]

When you say you repaired the main earth lead that had broken are you sure you made a good repair as that cable carries a massive amperage when you're trying to turn the engine over. Try putting a jump lead between your battery negative terminal and any clean metal part of the engine and try starting again.

 

[Seans Dad]

When you say you repaired the main earth lead that had broken are you sure you made a good repair as that cable carries a massive amperage when you're trying to turn the engine over. Try putting a jump lead between your battery negative terminal and any clean metal part of the engine and try starting again.

It was the ENGINE earth strap that has broken, and not the main earth cable that runs of the battery neg terminal. I repaired the strap thoroughly, and cleaned all contact areas to ensure a good earth.

I have also tried running a jump lead from the engine block to the chassis as a secondary earth point, but still nothing.

Battery earth terminal, cable & earth point are all good (battery is brand new)

Thankyou.

Dan.

 

[Seans Dad]

The saga continues..................

I removed the twelve (twelve!!!!) spark plugs, but still no joy, so I think hydra lock can be ruled out.

I have purchased a new engine earth strap, but have yet to fit it, but when I do, I shall double-double check all electrical connections, ie, starter, battery, earth points, etc.

After an in-depth discussion with a MB dealer, who'll remain nameless, they have said it could be one of three things, other than the above.

1. Crankshaft Position Sensor.

I'm assuming that even if this has failed, the engine would still turn over on the starter freely, but not fire up?? Or is there a "failsafe" system that prevents the engine from turning over to save further damage?

Where is the location of the CPS on the 2.4 V6?

2. The ring gear requires lubrication.

This is a special mineral based grease apparently, and as there are, I quote the MB dealer, "over 130 types" of grease, they'd need the chassis number of my car to supply the correct type of grease. Really???


3. The ignition switch has failed.

The ignition switch on my car is the later electronic type, and the fact that the starter will turn the engine for a fraction of a second tells me that the ignition switch is OK, but as I'm no expert, I could be wrong. I get full ignition lights at position 2, and the motor cranks, albeit briefly, at position 3.


Any ideas anyone?

Just off to take some more headache pills!!

Thanks,

Dan.

 

[BlackC55]

Does it behave any differently after the new starter was fitted?

 

[Seans Dad]

Does it behave any differently after the new starter was fitted?

No, the new starter was fitted, but it was doing exactly the same as with the old unit.

It just turns for a fraction of a second, then nothing.

Dan.

 

[BlackC55]

Remove the starter and leave it wired up and try it off the engine.

Look at the ring gear too when you take the starter out. Look at the condition of the teeth

 

[Stratman]

If you have a voltmeter try this.

Measure the cranking voltage on the starter motor terminal itself. Many years ago I had a Ford Fiesta which was a poor starter. It turned out the connector on the end of the starter cable was corroded and wasn't making good contact with the terminal. A good clean and all was well.

 

[Seans Dad]

Update:-

Been out to the car this morning, fitted the new engine earth strap, but no change.

So I then thought I'd try something else.

I left the ignition on, and touched both starter solenoid terminals with a long screwdriver, and blow me down, the engine turns over!! But it won't fire up, just turns & turns. The cooling fan comes on straightaway too.

So what could it be? The engine will turn over, but not on the key.

It won't fire up, but I assume that's because I'm bypassing the immobiliser??

Would it be a starter relay issue, ignition key issue, or a bad connection at the starter motor??

Help please, as I think I'm nearly there.

Thanks,

Dan.

 

[Seans Dad]

I've just changed the crankshaft sensor for a new one, but still no change.

Dan.

 

[BlackC55]

When you bride the starter to crank it turn the ignition on to the crank position. It may start.

On the left side (sitting in the car) under the bonnet unsrew the cover with 4 philips screws and loo inside there for any blown fuses. The cover normally has air conditioning written on it.

 

[Seans Dad]

When you bride the starter to crank it turn the ignition on to the crank position. It may start.

OK, I will try this in the morning.

On the left side (sitting in the car) under the bonnet unsrew the cover with 4 philips screws and loo inside there for any blown fuses. The cover normally has air conditioning written on it.

I've already checked here, and all the fuses were OK. I pulled each one out in turn to check them.

Dan.

 

[BlackC55]

To power the starter send 12V down the purple wire on that relay unit. make sure you unplug it. It is a fairly large wire compared to the rest. if you are not sure, don't do it.

It sounds like either the K40 relay is kaput, the ignition switch or an issue with the engine control unit.

You need to get it plugged into a star and read some vaulus within the Drive Authorisation System to make sure the stater is getting the OK signal from the engine control unit.