Coolant Light/Electric Fan - Help!!!

[matt48]

Hi everyone,

I'm new to the site and have got a 2000 SLK 230 R170

I've got a problem with the coolant light coming on when i start the engine (hot and cold starts) where it stays on for approx 5 seconds and then goes out and doesn't come on again until I start her up the next time. This has only occured literally after I had a new battery fitted a couple of weeks ago, as soon as I started it up to drive away I noticed the light come on for 5 seconds and then go off. Does anyone have any ideas as to possible causes eg coolant/washer sensors, relays or fuses?

Coupled with that, I took it into a local specialist for some MOT work and got him to check it out. He couldn't find a cause even after replacing the thermostat and fan control module (which caused the coolant light to stay on permanently) and he also told me that the elctric fan wasn't cutting in. He shorted it to make sure it isn't the fan that's shot and it was spinning fine but he did say that he didn't get it too hot so maybe the fan wouldn't have cut in anyway as from reading various posts on this forum it seems pretty common for these engines to run at 100 degrees in traffic before the electric fan cuts in - is this usually the case? I had it at about 95-98 degrees sitting outside my house before I chickened out but the true test will be driving to work tomorrow.

Apart from that, now all the minor MOT work's been done it drives like a dream, it's just that I'm worried it's going to overheat and cook the engine and I'll be looking at a massive bill.

Any help or advice from you all would be greatly appreciated.

Cheers
Matt

 

[bundy]

hi matt take a look at the big fuses under the bonnet on the passenger side beneth a cover. Thhs is where the fuse for the fan is located. if the coolant level lamp stays on &coolant is,nt low this lamp comes on to let you know know the fan is disabled.
hope this helps
regards ted

 

[matt48]

Hi Ted,

Thanks for your reply.
I just went out armed with a torch to check the fuses but I don't appear to have a fuse box on the passenger side under the bonnet. I have a fuse box on the drivers side but these are all window, lights and heating switches - nothing saying that it's for the electric fan. I also checked the 2nd fuse box in the car on the drivers side of the dash and there are more fuses for the radio and other electricals but still no fan fuse.

The strange thing is that I would have thought that every car would need fuses for things like the fan, water pump, fuel pump etc but I can't find them anywhere. Any other suggestions?

Cheers
Matt

 

[television]

The electric fan does cut in at 100c. give it a run to get it up there, if it does not cut in by 105 turn your heater on max warm and fan and it will take the temperture down, Let us know what happens and I can guide you further.

Malcolm

 

[matt48]

Hi Malcolm,

Thanks for your advice. I probably should have let it get to 100 degrees but I couldn't face the thought of a head gasket going or a warped block, so basically I chickened out.

It's gone back the specialist this morning, I got my girlfriend to drop it off as it's close to her workplace and she said it didn't get above 85 degrees even though she sat in traffic for 5 minutes or so, but I'll call the garage shortly and tell him about the 100 degree thing, even though you'd expect him to already know that?

I'll let you know how I get on and thanks for your help.

Cheers
Matt

 

[matt48]

Update time.

The specialist has just called. He's found a "fuseable link" further back in the wiring for the electric fan which has blown, probably caused when the battery packed up as my stereo's fuse blew too. He's never seen this link on a R170 before and went back to the wiring diagrams etc to find it, but he now has one on order from Merc and once fitted the fan should work and the coolant light should stop coming on.

And he's doing it free of charge which is even better, so fingers crossed a good result by the end of today and I'll update again once it's all sorted.

Oh and anyone looking for a decent Merc specialist on the Aldershot area - try Martin at Mercury Mercedes Specialists on 01252 318318, he's an ex Merc technician and a very decent bloke.

Cheers
Matt

 

[matt48]

Problem solved!!!!

Martin called to say the new "fuseable link" from Mercedes has worked, the electric fan's cutting in when it should and the coolant light no longer comes on after the engine's been started, so that's a really good result.

As I said before, anyone in the Aldershot area looking for a decent specialist should give Martin a try, he's been spot on all the way and is a thoroughly decent bloke.

Cheers
Matt

 

[television]

So we can help others, any idea where the fusable link is located.


Malcolm

 

[matt48]

Ah now that's a good question and to be honest I don't know but I'll call him tomorrow and get him to tell me, and then I'll update the post.

Cheers
Matt

 

[bundy]

bet its where i said it was!!!!

 

[matt48]

I think you were right Ted, apparently there's a small covered box directly in front of the battery on the passenger side and it's located in there.

 

[xwingftr]

Hello Ted,

My 90 300se is having a similar problem, coolant light on-resevoir full-no leaks-etc...Temps range from 80 to 85 during daily use. Should there also be an additional fusebox, by battery, on mine? Thanks for the help!

Johnny
Dade City, Fl.

 

[panason1c]

Hi everyone,

I'm new to the site and have got a 2000 SLK 230 R170

I've got a problem with the coolant light coming on when i start the engine (hot and cold starts) where it stays on for approx 5 seconds and then goes out and doesn't come on again until I start her up the next time. This has only occured literally after I had a new battery fitted a couple of weeks ago, as soon as I started it up to drive away I noticed the light come on for 5 seconds and then go off. Does anyone have any ideas as to possible causes eg coolant/washer sensors, relays or fuses?

Coupled with that, I took it into a local specialist for some MOT work and got him to check it out. He couldn't find a cause even after replacing the thermostat and fan control module (which caused the coolant light to stay on permanently) and he also told me that the elctric fan wasn't cutting in. He shorted it to make sure it isn't the fan that's shot and it was spinning fine but he did say that he didn't get it too hot so maybe the fan wouldn't have cut in anyway as from reading various posts on this forum it seems pretty common for these engines to run at 100 degrees in traffic before the electric fan cuts in - is this usually the case? I had it at about 95-98 degrees sitting outside my house before I chickened out but the true test will be driving to work tomorrow.

Apart from that, now all the minor MOT work's been done it drives like a dream, it's just that I'm worried it's going to overheat and cook the engine and I'll be looking at a massive bill.

Any help or advice from you all would be greatly appreciated.

Cheers
Matt

My 2002 ML 270CDI has just developed a similar problem.....The coolant light randomly comes on and off during a journey , sometimes it will stay lit for a couple of minutes or sometimes longer or it might not come on at-all for a few days but today it lit up much more frequently and randomly came on and off many times times during a journey, the coolant is up to the full level and the engine is running at normal temp........the strange thing is that whilst the coolant lamp is lit the heated seats will not work, when the switch for the seats is activated the 'on' lights in the switch just flash for a few seconds and then they disable....but when the coolant light goes out the seat heaters will work normally!.
Any ideas?
Thanks in advance.