Psy2cho has a wagon which punches a much bigger hole through the air than the sedan. The cooling system is clearly undersized for his car in his climate.

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CENSORED due to not family friendly words

Hell, I knew the 603s did...never crossed my mind to check the M103.

'A1042050210' is the PN from the EPC! Going to find myself one ASAP. More coolant flow and more airflow over that puny radiator is always welcome.

BMW did this with their M30 I6s. Went from a 144mm pulley to a 130mm pulley, about 0.5" smaller. It was optional for the Afrika Korps destined vehicles but became standard around 1989.



Like you, I still agree the radiators are too small in these climates. I remember another shop owner here telling me something similar about my W116 280S. The radiator was too small, even with the oil cooler. He preferred to remove the oil cooler and go with the larger radiator.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

I think 1042050210 is just the updated part number, I don't think the size is any different than stock. I've ordered two as replacements, I don't remember them being smaller.

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Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.

I just went through this. M104 wagon black on black in Tucson. Replaced the entire cooling/hvac system; Nissens radiator/condenser, Graf water pump, hoses, 82c thermostat, mb water switches, Denso compressor and drier+switches, evap, new spal aux fans, zerex 50/50. Everything. @110F my temps still went to 105f. What worked for me was replacing the new Behr fan clutch with the upated Sachs one.

Now even with super high ambients my temperatures never go above 95f even with the a/c running at idle. Incidentally I’m running r154a as well and getting 44f at idle and 36f freeway which I think is also helping as far as condenser heat dissipation.

Might want to check into the updating fan clutch or go the Spal electric puller way.

Hoping my parts car has a MB thermostat, if so, will change this evening and report back.

ps2cho, if you want, I still have my Spal electric puller you can try out and see if it works for you still pretty new, only had it for a year. If it works for you then you can buy it from me. Although, I did remove it because I didn't think it was keeping my temps low enough. I am using the viscous fan, which has done better.

Also, why is the Sachs clutch better or updated? There are only 2 things that I can think of what would make the Sachs better or updated, and that is either sooner flexing of the bimetallic strip....which would not mean anything unless the thermostat had opened up allowing the coolant into the radiator, or the viscosity of the silicone fluid has a higher weight. The latter would seem more likely as I have drained out a clutch and filled it with 30k silicone and when the clutch was locked, it was spinning at 100% of speed vs 80% with no slippage.

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1990 190E 3.0L

Not sure entirely but several people on the “other” forums have said the cut in temp is lower for the Sachs unit. I have also read the Behr clutches are quite flakey. For my situation and high ambient temps the lower therm and Sachs clutch is what ultimately worked.

Ok, so then the bimetallic strip flexes sooner allowing the clutch to lock up sooner. I wonder what the cut in temp is because if it is still before thermostat releases coolant to the radiator, I don't see how it would make much of a difference. On the other hand, running a 79C thermostat would most likely yield great results with the Sachs clutch.

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1990 190E 3.0L

Typo above, the bypass plunger only moves .175", not 1.175".

If the problem was drag related, ot would tend to get hot at high speed. That's not generally the issue. Drag increases as the square of speed, so slowing down would cool it off. That's not happening.

As for a cooler thermostat, it's not going to change the max temp, just the lower limit. I'll know later this afternoon if the thermostat change has made a significant difference. If not, I'm going to start playing with one of these thermostats to see if I can change this.

The OP is driving in 110f. Slowing down isn't going to help with the m103s inadequite cooling system.

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CENSORED due to not family friendly words

Well, so much for that theory... left work and got stopped in construction on the way home (lane rural highway, 60mph to a dead stop for 3 mins). Never moved the needle. Headed to town (70mph rural 4 lane), no problem, even at stop lights. Got into town traffic and there it goes again. Never got much over 110C, but still don't like it.

Two things... it takes at least a 30 minute drive to get it to this point in 95F ambient temps. Also, it seems if it ever gets over the 100C mark, it just never can get caught back up.

Busy this weekend, but when I get some time I'm going to drill some holes in the cap of one of these thermostats and see if it makes a difference. I could live with having a summer and winter thermostat, if needed.

As for full opening temp, all the other vehicles I have ever owned never varied more than a few degrees no matter the ambient. Tells me start to full open temp is probably a range of 5-7C.

Thinking like this? 2/3rds way down
Thermostat Replacement and modification

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Ok, just glancing at some boiling point info... 50/50 coolant mix is good for 106C at no pressure. 15psi cap bumps that up to 125C. I guess technically we are safe at 110C, but I still don't like it. Too many folks saying their car used to hold 85C all the time and doesn't anymore.

Interesting that you say most folks report their cars always held at 85. That's exactly the same for my '81 300SD until recently. For the last couple of weeks it has been settling at about 100 or just a bit over. So I knew something was not normal.

Just replaced my viscous fan and everything seems to be back to normal. The old one was original 37 years old.