The story is: The car started running hotter than I remember, climbing to 110 frequently. The aux. fans would kick in and bring it back down to just under 100. Thinking it was the thermostat, I changed it, but the car still ran the same. Next I ordered a new Behr radiator, and changed that. Still no change in the temp. Then the 'check engine' light came on so I went to see Enrique and he pulled the code: bad tranny vacuum modulator. He said I was ok to drive. At that time I asked him about the cooling issue and he said possibly the fan clutch. A couple weeks later, I was on the freeway and saw the temp near 120. I limped home and saw the aux. fans didn't/wouldn't come on. So now I've been changing the fan clutch, but the car still gets up to 100 degrees.


After reading Jim's site, It seems the fan clutch doesn't kick on until after 100 degrees, so I wouldn't know if it's working or not. On my Jeep Grand Wagoneer, when the fan clutch was engaged, the fan was hard to turn when the engine was warm, easy to turn when the engine was cool. The new fan clutch is pretty easy to turn all the time.

I never did think it was the waterpump, someone suggested it. The expansion tank does hold pressure, but I could use a new one.

I was having the car towed to Enrique this morning but AAA didn't send a flatbed and they are really busy today. I'll shoot for tomorrow.

Thx,
Dcraig

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1994 E420, Pearl Black/Black. 2.82 rear diff., AMG front spoiler, painted lower half. SOLD

1972 & 1974 BMW 2002tii's.

There you go again. "I limped home and saw the aux. fans didn't / wouldn't come on...."

There's your problem. If the aux fans didn't / wouldn't come one, why did you then suspect the fan clutch? The aux fans weren't on, and they should have been on.

Are we using different word for the same item? The fan clutch is for the viscous coupled fan connected to the front of the motor.

The aux fans are the electric-driven fans at the front of the radiator.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

It doesn't seem normal that in 65 degree weather, driving around town, that the temp should reach 110 degrees and the aux fans come on. Am I wrong?

It is going to Enrique because the fans won't come on, but, it doesn't seem that the car should get hot enough to kick on those fans unless something is not working properly.

In the summer the car would stay between 100 and 110, day and night. The only thing that saved the engine from meltdown were the aux. fans.

We are talking about the same things.

Dcraig

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1994 E420, Pearl Black/Black. 2.82 rear diff., AMG front spoiler, painted lower half. SOLD

1972 & 1974 BMW 2002tii's.

Just guessing here, but the aux. fans should be on at low speed nearly all the time, even at idle, and is what normally keeps your car in normal operating range.

If they are not on, then your car quickly goes up to higher temps, and then the high speed engages, which saves your engine from overheating.

I'm not saying your viscous fan is bad. Could be.

When I owned my 1993 W124 300E (3.2) "E320", I had the same overheating problem, took it to Enrique, and he showed me that the fans weren't engaging at low speed.

I thought it was my viscous fan, but he showed me that it was working, and explained that they rarely go bad.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

It is normal for E420 as long as the temp is not in the RED. It may get close but the fans will not allow it to exceed into the RED.

But there's still something wrong with your car. It's November, even in SoCal you should not be running at 110, unless you're sitting idle in traffic. If the car is moving it's not going to normally get that hot. I've found that removing the belly pan helps but I still think you've got something else going on. I'm in Arizona, we're 10 degrees above normal (which is normal) and I'm running at 80 to 90 this time of year with no fans kicking on ever.

Exactly.

I don't understand why everyone is ignoring the fact that his aux. fans are not running.

His aux. fans should be running nearly all the time, and they're not.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

i am having the same problem. it could be the temp sensor going bad. my gauge moves up and down. it even goes above 120C. i though the engine is toast, but it keeps running. then eventually goes down to middle. i am changing the sensor this weekend and see if that is the trouble... could be air in the system.

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93 Toyota Corolla 177K
95 S 500 coupe 82K
92 400E 180K (SOLD)
94 E 420 150, blown gaskets (SOLD)
http://www.kanio.net/mercedes_signature.jpg

I don't think you have a fan problem. It's either a bad thermostat or a bad radiator/expansion tank cap.

but how do you explain the fact that his low speed aux fan is not on? They are on at low speed whenever the a/c is used, which is basically all the time. The HVAC system always has the a/c engaged, except when using the EC button.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

I have the EC on all the time, but rarely have the AC on. It needs to be re-charged, so I just keep it off. One of the things I need to get around to.

Now the AC fan has stopped working. There isn't a relay that works the AC fan and the aux. fans is there? The AC fan has been dying a slow death I think so I don't think they're related.

Dcraig

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1994 E420, Pearl Black/Black. 2.82 rear diff., AMG front spoiler, painted lower half. SOLD

1972 & 1974 BMW 2002tii's.

I'm not an expert, but low a/c pressure could be your problem. When the refrigerant is too low, a switch prevents the compressor from running to prevent it from burning itself up. A/C pressure is also what tells the low speed fan to come on.

I think they're related.

But then again, I'm just an armchair mechanic.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

Dcraig, If you are concern about running a 100 and 110 you should purchase the resister from Jim. There is not a problem with your fans. It is normal for the e420 m119 V-8 engine to run at that temp. My e420 temp varies all the time. When I first purchase my e420 I had big concern about my temp running up to 110 I later learn that the MB design the vehicle to run at that temp. Jim has a solution to your high temp issue. If you want to run your fans and keep the temp lower then purchase the resister from him.

You can change your fluid, thermostat, hoses, fans' motors, relays and fan clutch it won't matter because the resister is what kick the fans on/off through the computer modules. Jim has your solution.

Sorry, Paul, but that's not true. Low speed aux fans only come on when refrigerant pressure is above the set point. On my M119, aux fans generally do not come on when ambient temps are below 80 degrees F even with AC on.

I'm with buckwheat - I would wonder about how "good" the water pump is. They are known to have impeller problems, so they can still pump coolant but not as efficiently as they should. As I recall, this is a particular problem with aftermarket pumps, but even OE ones can eventually wear.

The fact that coolant temps are getting to the point that they are really seems to point to inadequate coolant circulation.

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Steve
'93 400E

I disagree. With the a/c on, the aux fan should be on nearly all the time.

I think we'll have to leave it to Enrique at Mr. MB Motors. He's had more than enough time to figure this one out.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".