W202 has not much power when engine cooling fan comes on. Any ideas?

[theonewhosmokes]

Hello!

I have a 1999 C240 Sport Auto and when the engine cooling fan comes on, it has hardly any power and sometimes cuts out.

Also, on start up every morning or when the car has been standing for some time, it has hardly any power then too.

Anyone got any ideas as to what the problem could be???

Thanks, Paul

 

[lynall]

How often does the fan come on, and whats the normal temp and the temp when the fan comes on?
Do a search for maf.



Lynall

 

[wemorgan]

Would you describe the loss of power as miss-firing or just simply low on power by still with a smooth engine?

 

[theonewhosmokes]

The fan comes on when the temp is between 60 and 80. Sometimes it comes on as I start up if (I've driven to a shop and left it for about 5 mins and then re-start engine).

I don't think it's miss-firing, just seems to have no go.

Thanks for your help.

Paul

 

[stevesey]

Does yours have twin electric fans in front of the radiator and the engine driven fan behind? Or just the single electric behind?

 

[theonewhosmokes]

I have no idea. I'll just go and have a look..........

Thanks

 

[theonewhosmokes]

There is one big fan behind the radiator.

Hope it helps

 

[Adam230K]

Have you tried disconnecting the MAF and running the car without it?

 

[theonewhosmokes]

Have you tried disconnecting the MAF and running the car without it?

I have no idea where the MAF is and I have no idea how to disconect it. Is it an easy job to do?

 

[wemorgan]

I believe it's part 119 in this picture:

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[theonewhosmokes]

I believe it's part 119 in this picture:

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Do you think that's easy to reach under the bonnet?

 

[wemorgan]

Do you think that's easy to reach under the bonnet?

Yes, I believe it's next to the air filter.

 

[theonewhosmokes]

Yes, I believe it's next to the air filter.

Thanks wemorgan

Is it ok to run the car without the MAF?

 

[wemorgan]

I'm no car mechanic and have no experience of trying this myself, but I have read several posts in the past where people recommend this.

Try a search for 'air mass meter' or 'air mass sensor' for a more authoritative reply

 

[stevesey]

Thanks wemorgan

Is it ok to run the car without the MAF?

Yep - disconent and see if the problem goes away (ECU copes quite happily with no MAF - far better than with a MAF giving incorrect readings).

N.B Does the fan operate differently when the air-con is off? Might be a good way of checking if the problem really is fan related. In mine the front fars only really operate when the air con is on - so if you turn the air-con off you may find the fan operatres less.

 

[theonewhosmokes]

Yep - disconent and see if the problem goes away (ECU copes quite happily with no MAF - far better than with a MAF giving incorrect readings).

N.B Does the fan operate differently when the air-con is off? Might be a good way of checking if the problem really is fan related. In mine the front fars only really operate when the air con is on - so if you turn the air-con off you may find the fan operatres less.

I don't use the air conditioning at the moment. I have used it when I have been idle but not while driving.

It just seems to come on when I'm driving really slow and then it stalls the car. When I re-start, the fan comes on and I have hardly any power then it picks up with no problem.

Does that help or have I misunderstood you?

 

[stevesey]

I don't use the air conditioning at the moment. I have used it when I have been idle but not while driving.

It just seems to come on when I'm driving really slow and then it stalls the car. When I re-start, the fan comes on and I have hardly any power then it picks up with no problem.

Does that help or have I misunderstood you?

Ugh - just noticed my lousy typing in that last post.

An obvious thought just occurred to me - to see if really is fan related try unplugging the fan (keep an eye on the temp gauge of course - but unless you are in traffic it should be fine).

 

[theonewhosmokes]

Ugh - just noticed my lousy typing in that last post.

An obvious thought just occurred to me - to see if really is fan related try unplugging the fan (keep an eye on the temp gauge of course - but unless you are in traffic it should be fine).

So do you think it could be a problem with the fan then?

 

[lynall]

It it an electric fan if not sure post a pic of the engine bay.

Top drawing is a viscous fan ie bolted to the engine water pump and turns with the engine running.

Picture is wifes 320 112 engine same as yours but hers has an electric fan which you cant see as its tight up against the radiator and doesnt turn with the engine.

Unplugging the maf and running it wont cause any harm i did this not so long back and was driving to work and noticed engine check lamp on, pulled over lifted bonnet noticed plug off stuck it back on and carried on next day lamp was off so car must self clear any lamps that are no longer at fault.

Lynall

 

[theonewhosmokes]

It it an electric fan if not sure post a pic of the engine bay.

Top drawing is a viscous fan ie bolted to the engine water pump and turns with the engine running.

Picture is wifes 320 112 engine same as yours but hers has an electric fan which you cant see as its tight up against the radiator and doesnt turn with the engine.

Unplugging the maf and running it wont cause any harm i did this not so long back and was driving to work and noticed engine check lamp on, pulled over lifted bonnet noticed plug off stuck it back on and carried on next day lamp was off so car must self clear any lamps that are no longer at fault.

Lynall

Thanks for your post.

The fan in the the engine copmpartment is not like the drawing. It is not connected to the engine. I think it's like your wife's car. I shall take a photo and post on here so you can see - if it helps?

Paul