Over Heating - Page 2 - PeachParts Mercedes-Benz Forum

drbrad · #16 07-05-2006, 02:39 PM

Hi guys:

Ok. I took it off the mountain and drove back up the mountain. The temperature guage maintained at way less than 80 degrees as I coasted down the hill.

When I drove back up the hill, at about half way up <1 km, the guage hovered just above 80 degrees. I assume this is when the thermostat opened up fully. As I approached my house at about 1.5 km, the guage jumped to over 100 degrees and then dropped down to just above 80 degrees. (It's a cool morning here in Vancouver.) So, I couldn't get it to over heat today.

When I got home, I pulled into the garage, popped the hood and turned off the engine. The fan IMMEDIATELY stopped spinning when I turned off the engine.

So...I guess this means that the fan clutch is ok.

My next step may be to flush and refill the cooling system?

Any other suggestions?

Thanks so much for your help.

This is kind of like medicine.....consult that is...

Brad.

Hatterasguy · #17 07-05-2006, 07:57 PM

As the radiators on these cars get older the temps tend to rise a bit. They should run at 80C give or take a bit.

You should remove and clean the radiator, the finns are probably clogged with junk. If that doesn't do it replace it.

The overheating under heavy load is a clue that the radiator is marginal.

drbrad · #18 07-05-2006, 11:06 PM

Ok...I'll check the front of the radiator and spray it down with some water to clean it.

Is there a proper way to clean the radiator on the outside?

Many thanks for everyone's help.

Hatterasguy · #19 07-05-2006, 11:31 PM

Yes, first you need to remove the radiator. Once it is out of the car you will be able to hold if up to a light and see what is clogging the fins. Hit it from behind with either an air compressor or gardon hose to dislodge that crap.

Check your AC condensor as well, those clog up too.

jlomon · #20 07-06-2006, 11:07 AM

I see that someone earlier in the thread mentioned the pressure cap on the coolant reservoir. Did you change the cap? If so, what was the result? I ask this because I just attended to a few simple things in the cooling system of my 94 C280 in May, and I have found an improvement in how the car handles high heat load. I have always changed the coolant according to Mercedes specs, and always use the Mercedes coolant. But this time I changed every hose in the system (I don't trust 13 year old rubber) and had a new pressure cap installed. I've had the car for over 6 years, and have never changed the pressure cap. I have no reason to believe the previous owner changed it, either.

Now I'm not naive enough to think that changing the hoses has done anything for cooling system performance. But as I said, the car handles high heat load better now. It doesn't heat up like it used to when stuck in traffic on the highway, or when moving into city traffic after being on the highway for a while. I suspect that the cap was no longer providing its full pressure, which lowered the boiling point of the coolant, which then resulted in decreased system performance.

This might not be your whole problem. But it might be a contributing factor. I'd suggest replacing it and seeing what happens before you go pulling the radiator. I was very surprised at the measurable difference from this simple thing.

drbrad · #21 07-06-2006, 10:32 PM

Hi J:

Many thanks for your suggestion. I know it gets a lot hotter in Toronto than in Vancouver.

I will swing by MB tomorrow and pick up a new cap and see how it affects my problem.

Things were pretty good today. It was about 20 degrees today and cloudy. The temp guage fluttered a bit. While driving for the first 10 minutes it hovered just less than 80 degrees, then spiked to above 100 degrees, then settled to just over 80 degrees. When I came to the hill, it stayed at just over 80 degrees, until I got three quarters the way up the hill (about 1.5 km) then it spiked to just over 100 degrees. It stayed there and didn't boil.

Any other suggestions before I consider pulling out the rad?

Many thanks again to everyone!

stephenson · #22 07-06-2006, 10:53 PM

Couple of comments -
1. Sounds like good advice on troubleshooting through the clutched fan and into the radiator itself
2. I hope some day to see some independent data on Waterwetter - so far, all I can tell is that is a self licking snake oil ice cream cone - reduce the ratio of coolant to water and add water wetter and it will run cooler. It will also run cooler if you reduce the ratio of coolant to water and don't add water wetter, right?
3. I would think your V8 should take that hill with limited stress - after all, it's not Texas in the summer .... it should normally run a bit about the 80C mark
4. Could there be a blown head gasket that is setting up heat bubbles in the coolant that sweep through and cause the spiking?

PILOT MAN · #23 07-07-2006, 01:54 AM

Have you checked the condition of your waterpump, it could be that the pump is not functioning to its full potensial and when heavy load is put on the engine e.g. when going up a hill, the reduced flow of water is not sufficient to cool the engine down.

I will wage my 5c ont the waterpump, there is only a limited number of things that can llead to a over heating engine:
1. blocked inner radiator core
2. blocked outer core of radiator, air not getting by the fins.
3. none functioning thermostat
4. blown head gasket
5. water pump

In your case i wouls suggest cleaning the radiator, get a new cap, if this does not solve your problem, change the waterpump

drbrad · #24 07-07-2006, 11:10 AM

What sorts of symptoms would I expect with a faulty water pump? The car appears to be just fine, and only recently started overheating with the hotter summer weather and only when climbing the hill.

In otherwords, would I see a heating problem with regular driving?

Thanks for your suggestion. I will be getting a new cap this morning on the way to the clinic.

Brad.

sokoloff · #25 07-07-2006, 12:09 PM

Usually with a bad water pump, you ought to see a little bit of coolant weeping from the water pump area.

Len

lee polowczuk · #26 07-07-2006, 01:09 PM

I have been on the sidelines watching this one.....

This seems like a classic case of a partially clogged radiator.....

it does not take much to pull a radiator and clean it good....

it might be just as easy to buy a new radiator...pretty cheap item..

86560SEL · #27 07-07-2006, 11:18 PM

I have a potential problem with my 380SE. While it does not overheat, it comes close (in my opinion). The gauge goes 3/4 of the way up (near or slightly over 100*C) in SLOW stop and go city driving. It may not be classified as overheating, but it goes higher than I would like for it to be. On the highway (at speeds over 55), it runs normal. I NEVER have seen or heard that auxiliary fan on. The ONLY time I ever hear the clutch fan is when I first leave of the morning (when the car is cool) and I can hear it ROAR until the car gets to about 40 MPH, then it quietens down. I never hear the fan again, no matter in engine temperature.

I guess I need to check.... 1. clutch fan, 2. aux. fan, 3. change coolant, 4. flush radiator. Oh, BTW, yes, it has the "no-no" green coolant.

drbrad · #28 07-08-2006, 09:38 AM

Well, went to MB yesterday to buy the new rad cap. Here's the scoop.

the MB thermostat opens at 84 degrees celcius.
I bought a new rad cap and put it on yesterday.
the car is a 1982 380 SEL.
I bought it from a friend's dad who had it serviced at MB for 25 years! (Incl. all oil changes)
MB printed out the service history (39 pages.)
aside for some other major MB service (tranny, timing chain, etc.) a new MB rad was put in at 190, 000 Km (present milage is 224 K)
the parts guy I spoke with suggested all of the same things that have been mentioned in this thread. (Fan clutch, thermostat, he was doubtful about the cap, but it only costed me $12 CAD)

So, yesterday was pretty much the same as the day before. No heating problems while driving around the city. I didn't drive up the hill until late at night, (and it was quite cool last night) and although the temp did reach above 100 degrees, she didn't boil.

To recap...I've changed the thermostat, and now changed the rad cap...and still no noticable change. My main problem continues to be overheating when driving up a long steep hill.

I've checked the fan clutch, and the fluid mixture and it's very clean. The rad looks clean but I may try to leave it in and just spray it down today followed by air from a compressor.

Thanks to everyone for following this thread and assisting me with the problem. Where should I go from here? I love this car, but never had problems like this with my Toyotas!

Brad.

drbrad · #29 07-08-2006, 06:48 PM

I was out today trying to clean the outside of the radiator and noticed that there is a fan INFRONT of the radiator.

I've now looked at my manual and figured out this is called an Auxillary Fan.

When I checked the fan, as previously suggested, I checked the fan behind the radiator.

Anyways, the car was still warm...not hot...but warm...and I turned on the engine. The fan behind the radiator was spinning, but the one in front wasn't. Can someone tell me more about this Auxillary Fan? Is it clutched? I took a look in a Performance Products Catalog, and it shows an exploded diagram of the engine and cooling system. It looks like this is an electronic fan? Maybe its broken?

Any suggestions would be apprciated.

I think I'm getting closer to the problem.....

Thanks again to everyone....

Brad.

drbrad · #30 07-08-2006, 07:23 PM

I've done a search and read another thread regarding Auxillary Fans.

They were talking about a different car, but I assume the principles are the same.

Can someone explain more about the fan systems to me and how I can determine if the front auxillary fan is broken. If so, it doesn't sound like its that difficult to replace.

Any help is greatly appreciated.