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Super Moderator CA 2012 SLK55 AMG w/P30
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14,202 Posts
I'll be happy to TRY to do a review, but I'm an old girl who can't even change a tire.... lol
That's ok. It'll describe how a non-mechanic can use the device (if and when you get one) (y) After all, there are more of us than the other kind 😉
 

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Registered 1998 SLK230
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56 Posts
Discussion Starter #43
OK update: So we came to the end of the road. Had no further ideas on what to check in regard to the overheating. We had put two different fans on it --- well, the one that came on the car when I bought it (the one that overheated), and one we pulled from a newer model in a scrap yard. My friend had connected both fans to a 12 V and both powered up, with the newer one having better speed. We wrote the fans off as NOT being the problem because they ran on the 12v. We replaced the original fan controller with the one we pulled from the same scrap car. Fan still didn't kick on, car still overheating. I opened up the original controller, no burned out or broken soldering or capacitors. Put the original back on the car. He tested the lines coming to and from the hidden fuse, to and from the controller, and to and from the fan. All lines OK. So today, it cost us over 200$ to have it diagnosed at a foreign car shop. He says it's the cooling fan. Is this possible???? He wants over 800$ to replace it.
 

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Super Moderator CA 2012 SLK55 AMG w/P30
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14,202 Posts
Did he give you a printout of the SCAN he did to arrive at this diagnosis? Keep in mind those P codes are fairly generic codes.

AFAIK, proper scan/codes are what, 5-6 digits with no P. Always willing to be corrected though 😉
 

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Registered 1998 SLK230
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56 Posts
Discussion Starter #45
Did he give you a printout of the SCAN he did to arrive at this diagnosis? Keep in mind those P codes are fairly generic codes.

AFAIK, proper scan/codes are what, 5-6 digits with no P. Always willing to be corrected though 😉
Hi Leonardo.... No, no scans, no codes. This is what the invoice says:

"Cooling system labor-vehicle is running hot. Checked fuse first. Fuse checked good but the voltage was low at the fuse. I unplugged the fan relay and the voltage went back up. Checked circuit at the blower motor. It had ground but no fire so I put voltage on it and it kicked my circuit breaker out on my tester. Need to replace blower motor/fan assembly first. $214.17
 

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Premium Member 2002 R170 SLK V8 5.0
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3,169 Posts
Hmmmm, I'd avoid that guy, the Circuit Breaker on those Power Probes is usually around 10 amps, that fan Motor is gonna Draw 40 + Amps, so yes it would kick his Circuit Breaker, I'm sorry to say it but I don't agree with his diagnosis, and I don't think he understands these Cars.

I've said it before and I have to say it again, get that Car on SDS, that is the only way to be certain and not just keep playing Parts Darts.
With the information I have from you right now my money is on Fan Controller, Temp Sensor or possibly a lack of PWM Signal to Fan Controller from Engine ECU, although I'm fairly certain that the Fan defaults to running at full speed if there is a Sensor or ECU or PWM Wiring issue, so back to Controller .......................

Almost every Mercedes Cooling Fan issue I've ever had has been Fan Controller, so the likelihood of you buying a faulty used unit is high !!

This rings Controller bells too :-

I unplugged the fan relay and the voltage went back up.
HTH :)
 

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Registered 1998 SLK230
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56 Posts
Discussion Starter #48
Hmmmm, I'd avoid that guy, the Circuit Breaker on those Power Probes is usually around 10 amps, that fan Motor is gonna Draw 40 + Amps, so yes it would kick his Circuit Breaker, I'm sorry to say it but I don't agree with his diagnosis, and I don't think he understands these Cars.

I've said it before and I have to say it again, get that Car on SDS, that is the only way to be certain and not just keep playing Parts Darts.
With the information I have from you right now my money is on Fan Controller, Temp Sensor or possibly a lack of PWM Signal to Fan Controller from Engine ECU, although I'm fairly certain that the Fan defaults to running at full speed if there is a Sensor or ECU or PWM Wiring issue, so back to Controller .......................

Almost every Mercedes Cooling Fan issue I've ever had has been Fan Controller, so the likelihood of you buying a faulty used unit is high !!

This rings Controller bells too :-



HTH :)
Thank you Dave. This guy was recommended by my regular Ford mechanic who won't touch Mercedes, and supposedly has 40 years of experience. What got me concerned, was saying to replace the fan 'first'. Like he was taking a guess, and wanting us to spend the money on that, only for it to be something else. I have a new fan coming in the mail by Friday. I'll order a new controller that same day if it turns out to NOT be the fan.

My friend put the other fan on, the one that we pulled from the parts car, and it came on when he was driving, but then in the driveway, it went off and didn't come back on. He drove it again, and it came on, and same thing when in the driveway.

Thanks!
 

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Registered 1998 SLK230
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56 Posts
Discussion Starter #49
Hmmmm, I'd avoid that guy, the Circuit Breaker on those Power Probes is usually around 10 amps, that fan Motor is gonna Draw 40 + Amps, so yes it would kick his Circuit Breaker, I'm sorry to say it but I don't agree with his diagnosis, and I don't think he understands these Cars.

I've said it before and I have to say it again, get that Car on SDS, that is the only way to be certain and not just keep playing Parts Darts.
With the information I have from you right now my money is on Fan Controller, Temp Sensor or possibly a lack of PWM Signal to Fan Controller from Engine ECU, although I'm fairly certain that the Fan defaults to running at full speed if there is a Sensor or ECU or PWM Wiring issue, so back to Controller .......................

Almost every Mercedes Cooling Fan issue I've ever had has been Fan Controller, so the likelihood of you buying a faulty used unit is high !!

This rings Controller bells too :-



HTH :)
Also - sorry if I am dumb on this stuff - but where is the temp sensor and what do you mean by Controller bells - or do you mean belts? If so, which belts would be the ones to check (photos if you can)? Thanks!
 

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Premium Member 2002 SLK320
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729 Posts
Hi Ms Goody,
You said previously "I unplugged the fan relay and the voltage went back up. ". Dave said "This rings Controller bells too ", which means what you said rings some bells in the back of his mind that reminded him of faulty fan controllers. :)

And the coolant sensor
 

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Registered 1998 SLK230
Joined
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56 Posts
Discussion Starter #51
Hi Ms Goody,
You said previously "I unplugged the fan relay and the voltage went back up. ". Dave said "This rings Controller bells too ", which means what you said rings some bells in the back of his mind that reminded him of faulty fan controllers. :)

And the coolant sensor
Ohhhhhhhhhhhh. I guess I look to be confused when it comes to things automotive... lol
 

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Registered 1998 SLK230
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56 Posts
Discussion Starter #52
I was reading through some threads on this site related to temperature sensors and the controllers.... Someone had mentioned that he resolved his problem by replacing the MAF sensor. The person who had done this asked the group if the MAF could somehow be related to this problem, but nobody answered, and then the thread grew old and isn't open for comments now I believe.

When we had our hands in the 'parts car', we pulled the MAF sensor, just so I'd have one on hand. It looks brand new.

So asking again - if other things fail, COULD the MAF sensor be somehow related?
 

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Super Moderator CA 2012 SLK55 AMG w/P30
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14,202 Posts
Be aware of world-wide time differences so replies may be delayed 😉
 

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Premium Member 2002 R170 SLK V8 5.0
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3,169 Posts
So asking again - if other things fail, COULD the MAF sensor be somehow related?
No, but I'll never say never on any MB, so as you have one and it takes mere minutes to try it could be worth a shot, but usually only Cooling related items would stop it from working.

Thing is this, these Cars usually default the Fan to run flat out if there is a problem, but it won't run if the Controller is faulty ;)

HTH :)
 

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Premium Member 2001 SLK200K/2001 SLK320
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2,088 Posts
My friend put the other fan on, the one that we pulled from the parts car, and it came on when he was driving, but then in the driveway, it went off and didn't come back on. He drove it again, and it came on, and same thing when in the driveway.

What temperatures are on the temp gauge when this happens?
 

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Registered 1998 SLK230
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56 Posts
Discussion Starter #56
Be aware of world-wide time differences so replies may be delayed 😉
Thanks. I worked for an airline for 10 years, so trust me, those time zones are a thing in my head. ;)
What temperatures are on the temp gauge when this happens?
Since I got it, even before it actually overheated, it was running hot at about 80. It will usually go up to 100 or so, but since the overheat episode, I don't drive it to let it get hot like that. It freaked me out a bit, I've never had a car that doesn't drive at the mid-range of the temp gauge. This one being so high on the upper end of the gauge worried me from the start.
 

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Super Moderator CA 2012 SLK55 AMG w/P30
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14,202 Posts
Your temps are in normal range per other members
 

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Premium Member 2001 SLK200K/2001 SLK320
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2,088 Posts
^^ THAT ^^

It isn't running hot @80c

My 200 runs at around 82c and my 320 runs around 85c-86c, which is normal for both of them.

Most MB thermostats open in the range of 85c-88c with running temps anything up to 105c - 110c being perfectly acceptable and as long as the fan is running at that and doing it's job then it should be fine. I really wouldn't worry unless it starts getting IRO 120c.

As an aside, there are 'stats available (Mahle, Hella, Trucktech) that open @71c for concerned guys in the HOT climates ..

@Australian ~ what you got down there?
 

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Premium Member 2002 SLK320
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729 Posts
We get days of 46C here sometimes. My 320 runs around 80C when driving, going to 100C in stationary traffic. I had my SLK for years before I heard the engine cooling fan running. It hardly ever runs. I don't think I've ever heard it run on full. As far as I know it's still the factory thermostat in it.

I wish it was 46C right now, it's 6am and about 5C at the moment!!! Brrr.
 

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Premium Member 2002 R170 SLK V8 5.0
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3,169 Posts
Hi,

So when you say "Overheated" did it actually lose any coolant ?

If it didn't then it didn't overheat ;) As the others said, idling in traffic at 100 on a warm day is not really an issue, but it should drop down when Fan cuts in, then Fan should switch off, then it will rise again, rinse and repeat.

When it is at 100c does the Fan cut in on slow speed ? ...............
Note that you can barely hear it as it runs very slowly to start with, and only steps up if needs be, which here in UK is not often, I'd advise going for a drive to get it fully warmed up, then returning home, leave it idling and when it gets to 100c open the Bonnet and OBSERVE whether the Fan cuts in slowly, then off then repeat etc......................

Or as I'm always saying, easier way is to get it on SDS and do the test routine ;)

HTH ;)
 
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