For info. . . .
 

I replaced my 185F (82C) tsat with a 176F (80C) version and made the VFC mod just before my car was due for smog check. My car runs a couple of 'notches' cooler than before but it certainly didn't make any difference in my smog results.

RPM --- HC(ppm) ---- CO(%) ---- CO2(%) ---- O2(%)
650 ------ 2 --------- 0.00 --------- 5 -------- 1.9
2450 ----- 3 --------- 0.00 --------- 8 -------- 1.8

So put in the coldest tsat you can find and don't worry about it!

Jim- can you post the part number for that 80-C thermostat?

Thanks,
:-) neil

Neil . . . .
 

PN: 116 200 03 15. Made by Wahler. Their PN: 4137.80D

Interesting that the CD-ROM calls for 185F (82C) tstat but all the current books call for 80C. After installing it and having a chance to evaluate it, it's perferred over an 82C especially in SoCal.

impressions on 83C thermostat
 

logged more miles using the 83C thermostat and for the most part, i'm pretty happy with it. it's too bad the ambient temps have been low - in the 60's, but i got to drive in stop and go NYC traffic and the engine temps were just fine. i even had to leave the AC on because it was 100% humidity and raining the whole time. normal temps are a hair above the 80C line so it's about 82-85C. cruising produces slightly cooler temps but not less than 80C. the first real test was stop and go after highway cruising and it rose to just under 90C, then subsided to 82-85C after a few minutes. and the final test was pulling into the garage and switching off after several minutes on the highway. i turned it on again after a few minutes and the temps had risen to about 97C, quickly subsided to 85C upon starting. with the 87C thermostat, it would have been around or even over 100C.

i'll see how it behaves in the really bad holiday traffic jams. last winter i got in some really nasty ones prompting me to install the cooling mod (in the dead of winter). at this point i'm leaving this new thermostat in there...

Manual fan switch
 

Bong,
You might be interested in this. The fan relay on a mini van I have went out, so I wired the fan directly to the ignition switch. It worked great and gave enough time to get an after market fan ($75 vs. $350 for an oe unit from the dealer). The problem was that when I turned off the engine it Dieseled for a few seconds. I never connected the two until I mentioned the 2 problems to a mechanic. He said that when you turn off the engine the fan winds down. Since the fan motor is DC, as it winds down it goes from being a motor to being a generator. The voltage it produces as a generator back feeds into the ignition system and causes it run on a bit. This is not much of a problem, but he said that the voltage backfeed will damage some of the car's computer circuits. I don't know if this is possible w/ your MB but you might ask your mechanic.

Sounds like this one is fixed.

Several folks have commented on the 80C tstat being preferrable ... occurs to me that the production tolerances in devices like this are likely +/- 3-5% = 2-4C.

Plus, is it really possible that engine operation will be affected pro or con by that 2C in a 82-110C operating range?