Fan Clutch Operation Details

Sword_of_the_Spirit

Active member
This may sound odd, but I never recall my original fan spinning at idle and within 2-3min of idle warmup. Does that mean it was already on its last leg when I took off?
 

Sword_of_the_Spirit

Active member
The electric services when the a/c is on. I’m referring to the viscous. My above few posts are because I’ve been “spoiled” with actually PCM controlled fans and old school belt drive fans. Viscous type vehicles have only been a recent addition.

edit:are instead of is
 
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Sword_of_the_Spirit

Active member
Indeed that fan does. Begs to wonder why as it doesn’t do too much to help when above 221. Unless the few posters that have high temp issue still see little overcoming a slight incline with an inoperative main fan and presumably a good electric. Which brought me to my solution.
 

220629

Well-known member
Indeed that fan does. Begs to wonder why as it doesn’t do too much to help when above 221. Unless the few posters that have high temp issue still see little overcoming a slight incline with an inoperative main fan and presumably a good electric. Which brought me to my solution.
:idunno:

Back when my 2004 engine driven viscous fan was marginal, while towing the boat the engine temperature would sometimes climb to above the 215F hash mark. The times that the electric fan kicked on (the noise was noticeable) the temperature always stabilized and most times slowly came down. I would never recommend depending upon the electric fan as SOP, but in my experience when it is enabled it does help.

A OEM design properly operating cooling system has kept me happy. It also seems to work for most T1N owners worldwide.

vic
 

Midwestdrifter

Engineer In Residence
I would say some ~80% of cooling system issues reported here are due to failed fan clutches. The remainder (not counting leaks) are stuck thermostats, and clogged radiators (internal and external).
 

az7000'

2007 Navion on a 2006 3500 chassis
How do you tell the difference between the noise of the electric fan and the oft-reported "roar" of the viscous fan?
You know by the sound…. Another is to get out and look to learn the difference is my experience
 

Axiom

Mike from Florida Van Man
Yep, I was always confused when people said the clutch should engage at 220 F, that just seems too hot. My EuroParts-SD clutch is engaging around 190 F with AC on full blast and it audibly sounds like a dump truck.

The last clutch we bought (from MMS) arrived flat and was permanently engaged. Had serious lack of power and sucked our fuel economy dry. When I bought the EuroParts clutch, I bought it with a water pump and the two were packaged together in a way so that the clutch never goes flat.
 
I would say some ~80% of cooling system issues reported here are due to failed fan clutches. The remainder (not counting leaks) are stuck thermostats, and clogged radiators (internal and external).
So at 80%, fan clutch sounds like it could be a "Root Cause" here?

My sprinter appears to have a normal operating cooling system. It will normally fluctuate on a warm day between 190F - 206F. But, I really don't like to see it fluctuate that much and I am constantly watching in fear of temps quickly rising above 206 and overheating like so many others have experienced here.

I know temp range of 16F is not much. My reference is an 06 E320 with the OM648 (Six cylinder version of the OM647) and in this car the temps are rock solid and don't rise at every small incline like the T1N. I know that I am comparing apples and oranges here, but if there were a larger cooling margin designed into the OM647 system there wouldn't be such a large "Normal" operating temperature being posted on this forum.

From reading here I am becoming more interested in modifying a fan clutch to operate full time to reduce the temp fluctuations and add a little more cooling margin. and maybe reliability....

A 3% loss in mileage would be a happy trade for me. Getting away from the temp fluctuations and give me piece of mind, and eliminate that 80% root cause of when is that fan clutch going to fail while I am not looking and overheat my engine...
 

Midwestdrifter

Engineer In Residence
Many MB cars don't have a true temperature gauge, you may be surprised if you hook up a scanner and monitor temperature. My 1.9L turbodiesel Jetta never exceeds 190F. However it has nearly twice the radiator it needs (the radiator is designed for the 6 cylinder gasoline engine). The same engine in industrial applications does see temps higher than that.


It also takes more than twice the power to move a big van down the road vs a tiny car. Comparing the two is not reasonable in any way. There is a reason the OM647 was derated for the sprinter application vs the car. A sprinter can easily peg the engine at 100% load for 25 minutes climbing a grade. While a 3,500lb car would be at 50% load climbing any interstate mountain pass in the country.

A fried of mine has a late 80s MB 1000 series overland truck (weighs about 20klbs). The inline 6 will oscillate between 190 and 215F all the time. These trucks were designed to run at full load without any "ram air" effect, so the fan clutch is always cycling, similar to the sprinter. My van doesn't normally start deviating from 190-195F unless I am over 80% load, or ambient temps are 105F+.

As discussed in other threads, it can be unnerving for those used to unchanging temperature gauges, but there really isn't anything wrong with a mild swing, as the fan ramps to full speed.

215 is no where near overheating. The thermostat isn't even fully open until 190-195F. Another 20F isn't melting anything down, or even impacting wear.


Assuming your fan clutch is working properly, and you want to to be locked all the time. Just bend the spring outwards about 1/8" with a pair of pliers. Just tweaking both sides basically. That will have the fan spinning at 70-80% all the time.
 
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Yea, I get that it's not reasonable to compare the two. The e320 is a wedge shape @3,200lbs and gets 40MPG whereas the van is a brick shape @5,500lbs and gets 20MPG.

I would like to see temps in my T1n more in line with your 1.9L Turbodiesel Jetta. i.e. twice the radiator it needs...

Maybe a larger radiator or locked fan clutch will proved that extra margin. I don't know.
 

Midwestdrifter

Engineer In Residence
A larger radiator would require a front end shaped like a pickup truck. There is a reason all the 400HP mega pickups ($$$$) have those enormous grills, they need them for the radiator.

If watching the temp gauge rise above 190F gives you anxiety, you can just tape over the gauge below 225F.
 

Midwestdrifter

Engineer In Residence
Almost every industrial engine spec I have seen specifies a normal operating temperature between 190 and 220F. 190F being the minimum, not the maximum. I have not seen any evidence indicating accelerated wear above the magic 190F number. In fact many newer high efficiency engines have thermostats that open at 200-205F.
 

3Play

Well-known member
I'm watching this thread because my 2004 routinely is at 215 while in traffic in Tucson in 100deg. weather.
It also gets to about 220 on long climbs in hot weather at highway speeds. It is never heavy, the conversion and solar system only weigh about 400lbs. max..
I can definitely say the clutch has been layed flat multiple times, for days....The system has been flushed, radiator and water pump and thermostat have been replaced...
It has always run at those temps since I bought it. I will replace the clutch because it is probably overdue, but is 220F in 100deg. ambient normal?
 

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