W140 Diesel Radiator Fan Question - PeachParts Mercedes-Benz Forum

R100RSCA · #1 09-05-2015, 01:47 PM

I feel really dumb to ask this question... I bought a 1994 W140 diesel about a year ago. Only this summer I found out when going up hills, say about a mile, the temperature will go up to 110 degrees. I flushed and replaced the coolant, and new radiator cap, nothing helps. I though something wrong with the fun clutch and then I realized that the two fans I was checking were not the radiator fan I was thinking. At some point the radiator was removed and never put back. My car has been running without the radiator fan for almost a year. Surprisingly, even in the stop and go condition, 100F with A/C on, I don't see temperature goes over 90. Now I need to get a new fan, new clutch. My question is, will the fan/clutch from a gas version fit on my diesel? I checked epc website, they have different part number, and gas version seems to have a plastic cover that covers the clutch, but diesel version only have fan blade and clutch, use a bolt attach it to water pump?

Any input is greatly appropriated.

Thanks for reading and have a nice weekend.

mannys9130 · #2 09-05-2015, 03:11 PM

If they have a different part number, they're probably different.

I'd use the cash to buy an electric rad fan and do the conversion. The engine driven clutch fan saps performance.

R100RSCA · #3 09-05-2015, 03:28 PM

Quote:

Originally Posted by mannys9130

If they have a different part number, they're probably different.

I'd use the cash to buy an electric rad fan and do the conversion. The engine driven clutch fan saps performance.

Those two fans will engage when water temperature reach around 105. I ordered some metal film resistors to modify the coolant temperature sensor so that fan will engage at 92(Got the idea from K6JRF#17). You meant to have a electric fan behind the rad plus the two original electric fans in front for rad?

Thanks

mannys9130 · #4 09-05-2015, 04:07 PM

The engine driven fan is for the radiator. Its job is to keep the engine cool during normal operation.

The fan(s) in front of the condenser are there to cool the condenser and if need be, provide additional air to cool the radiator if the engine gets really hot.

So, you've been driving around with no engine fan (meaning the only air moving through the radiator was ram air from driving) leaving only your aux fans to come on in extreme circumstances.

By adding an electric radiator fan behind the radiator where the engine driven fan should go, you'll have that fan pulling air through the radiator at a stop to keep the engine cool, and the front aux fans to come on only if the AC is on or if the engine gets really hot. The rad fan should kick in at around 90-100 or so, and the aux fans should kick in at 105-110. The thermostat starts to open at about 85C abdcis fully open at 100, so you'll never get below 85.

R100RSCA · #5 09-06-2015, 12:18 AM

Thank you for the explanation, I will look into that route too!

Mxfrank · #6 09-06-2015, 05:59 PM

The engeine fan usually engages at around 95C, but this is AIR temperature, not water temperature. The gasser fan might work, but you'd have to be sure both of the engagement temperature and the fan diameter. Manny's suggestion of an electric fan at the back of the radiator may be the more expedient solution. Cheaper too, you should be able to find a 16 or 17" Permacool fan for $100 or so. You can trigger it with a thermo switch that inserts between the radiator fins, or use one of the spare 22mm bungs on the left side of the head to install a VW fan switch. You'll also need to tuck an extra relay in somewhere. What I would use is a later Mercedes fan relay with the fuse in the top, and wire it directly to the battery.

compu_85 · #7 09-08-2015, 09:28 AM

The gas engine fans spin the opposite direction IIRC. You want to get the diesel fan and fan clutch (both of which have 606 part numbers now).

-J