Hey guys.

I have begun the process of removing the mechanical shaft fan from my C36 entirely. Steps:

• [done] Fit a 79C behr thermostat (down from factory's 87C unit)
• [tried + failed]Soldering in a 860~1K Ohm resistor into the AUX fan switch in parallel to alter engagement point and bring it down 9-12 degrees from 105C
• [ ]Flush, refill and bleed coolant mixture
• [ ] Get rid of the viscous clutch mechanical fan

A few notes: this car loves the 80C t-stat. Why did Mercedes use an 87C unit? Emissions? Federal MPG ratings? I tossed that crap, and put a 79C Behr unit and my car loves me for it. Any of you experience sluggish pickup when fully warm? Anyone else's car rips when its cold? Consider running a cold air intake system with something like the 79C thermostat.

7C Celsius difference will not affect oil temps enough to make a longevity difference on something like 0W-40 full synthetic, which is what I run. Mercedes ARE NOT engineered to be super sensitive to expanding metal tolerances, not nearly tight enough for 7C to have any lasting longterm effect, at least. They are engines like any other engine, higher quality at that.

Encountered Issue #1:
Removing the viscous clutch looks like a huge pain in the ***. There is no room in there. Not room between radiator and engine. No room between the belt, pulley and the inside of the clutch mounting. Very annoying procedure. I have yet to tackle this.

Is the clutch being held to the pulley with an allan bolt? Is it an 8mm like people say it is? Might have to remove the radiator to do this right...

Encountered Issue #2:
Soldering in a resistor to the coolant temperature sensor is easy and all that, but http://k6jrf.com/MB_S500.html is misleading, at least on my M104. According to the page, I should run the resistor parallel to contact leads #2 and #3, which is the BLUE and YELLOW\BROWN on my harness.



However, this screws with the ECM's temperature readout, showing about 50C when the car is cold. Meaning I got the wrong leads, since theres is 2 pairs. One for ECM and mixture control, and another strictly for the AUX fan engagement.

Any insight guys?

 

subscribed.

 

I have to note I also own a 1993 BMW 325i and have performed the equivalent on that car with GREAT SUCCESS. It is a very popular mod for the E36 (BMW, not MB) community.

Considering that unless you have serviced your viscous clutch, it is probably shot anyways like mine is, leaving the fan in 1:1 stuck mode all the time. That creates a ****ton of unnecessary noise at high RPMs and definitely does not help with throttle response as well as hanging RPMs.

Anyways, I guess I'll just ring the engine harness from the ECU to find the right AUX fan switch contacts.

 

Funny- just yesterday I was thinking how hot temps just kill this car. I have a 96 as well. In seattle we've been hittin mid 90's- my car turns into an absolute dog in this weather and when the engine temp approaches 100c. Try flooring it at 40 and see what happens when it's this hot.

Let me know if that cooler tstat makes the car throw a code- I'm thinking about trying that and the 92c cool harness.

thanks

 

There is simply no way running at 80C will make this car throw a code.

I beat the living crap out of the car last night, dead spot on 80C.

Just go ahead and do it. It certainly won't hurt the receding headgasket problem on the M104 also as an added bonus!

 

Think i will- not like it's hard to change who knows, maybe it'll save the HG too.

Got a P/N for the tstat?

 

Got it at home. Once everything is done and is proven to work as it should I will release all details.

P.S. - Replacing t-stat alone is a 10 minute job. Be prepared to have a little coolant mixture ready though.

 

TIP: To remove the mechanical fan, a classical 90 degree bend allen key is a must. Forget about sockets. The trick is to remove the clips securing the radiator to the radiator support. Then you can lean the radiator even further away from the fan. it is indeed an 8mm size one.

I have a few videos I am uploading to youtube. Basically with 73F ambient temperature and without cool harness mod, with 80C t-stat, the temps went as high 95C.

Definitely not good enough for me. I want it to run at no higher than 85C. Looks like I either need an intense cool harness mod or to invest into a new clutch, as mine is locked up. The car definitely loves the FDM though, I will keep trying to make this work.

For the average C36 owner, I highly recommend a 79/80C t-stat swap.

 

Anybody done this mod in a C43?? Have to check the thermostat at the next service because when driving hard, the temperature gauge runs just under the unmarked line between the 80° and 120° marks. Could this be the 100° mark?

 

the 79s, are not a perfect fit, sometimes they can cause issues due to not allowing enough coolant flow.

with aftermarket performance radiator you will have zero issues.

 

The thermostat on the C43 is integrated into the housing. I found this out last winter. I don't think there is a huge variety of thermostats available, unfortunately.

A search of the forums revealed posts from years ago where a fellow modified the housing to fit a cooler thermostat though.

 

that line indicates 90°C.

 

Are you sure?

 

I have no idea how you are making the claim.

Did you read and notice I am talking about the Behr unit and are referring to Behr specifically? Do you have experience first hand?

Next step for me is full coolant flush and rinsing my radiator, seeing whats up with all that. Cooling performance should be better than it is now.

Today we had it go slightly over 90F. I live in Connecticut. Pretty high humidity also as I live in a valley with a river and all that.

****ed around for an hour or so today. Town: ran it in 2, 3 or all 4 gears as experiments. Picked parking lots and just chilled in them with the engine idling.

Went on highway, tried 3 and 4 gear modes. WOT tests and all that. Temperatures have never breached midway between 80C and 100C marks, meaning about 90C or so. Still too high for me (this is WITH the clutch fan now).

I will be doing a full coolant drain, flushing the radiator and refilling it with a PEAK acid green 50/50 mixture with distilled water. Maybe ill get water wetter.

 

yes i am for i have tested it witha laser temp reader pointed at the water temp housing and with the star tester showing what the temp ie ecu is reading.

 

why Green antifreeze? Big no- no on these cars?

 

Why is that? Why on 'these' cars?

 

Just pay more and get the merc certified antifreeze. some of the products on the mrk are not compatible with the alloy used in the head, so the product will not safe guard you from corrosion.

 

book calls for g5 antifreeze- aluminum parts that's why.

Frankly, there isn't any use for green anymore. Anything works better these days for a similar cost. I for one don't use the stuff in anything- even my Pontiac even gets the equivalent of dex-cool (it's got a huge aluminum radiator in it tho)

rjp

 

red or blue (benz) works much better ... the green stuff is old school

 

100+ at a drag strip will leave quarter mile times in the 15s...

 

Dennis whats part number for this behr t-stat? CT represent, I know what its like to watch the temp reading creep up on I-95 when your in stop and go bs. Keep us posted, rated 5 stars......as usual

 

Yes please let us know the part number for the 79 degree therm awesome thread btw!

 

One I got: Behr 1002000715

http://www.autohausaz.com/search/pro...ber=1002000715

Also, I guess with so many people throwing their arms up in the air, I should do the Zerex coolant afterall.

Another note: In this setup, the difference between viscous fan and no fan at all isnt large at all. I will experiment further over the weekend.

 

It sux. I thought something was wrong with the car it was lagging so hard.

rjp