Electric radiator fan swap on a CRD?

dgeist · **Posted:** Thu Nov 20, 2008 7:55 am

So, as the colder weather starts to hit, the 2.8 is taking longer and longer to get up to temp in the mornings (and consequently, economy has suffered). I'm reminded of the ads for electric replacements for the viscous coupling mechanical fan and was wondering if anyone had done this mod on a CRD or another small diesel and would like to share their experience. I've only had one other vehicle with a mechanical fan and it's only used to haul drywall and lumber back and forth from the home improvement store, so I honestly don't know if the switch is worth it or just hype.

Dan

gmctd · **Posted:** Thu Nov 20, 2008 10:32 am

The engine-driven viscous engine coolant heater should be a fairly broad hint that the radiator fan(s) have little to do with the underheating properties of a small under-worked Diesel engine - you could remove both fans and the engine would not warm up any faster - a Diesel engine makes only enuff BTU to get the job done - no use expecting any more than that out of it - you might look into an ESTY(?) Diesel fuel-fired heater to get the ECT's up where things are toasty and operationally copasetic - hint: put a piece of cardboard in front the radiator, note any difference in warm-up B4\after

retmil46 · **Posted:** Thu Nov 20, 2008 12:32 pm

Fuel fired aux engine coolant heaters are made by Espar and Webasto if I remenber correctly. Seen plenty of them installed on Class 8's over the years.

But they're also pretty pricey. I checked a few years back on a full-up kit for a friend with a '98 Cummins 12 valve - well over a grand. And that was for one of their standard kits - a one-off special app might run even higher.

Just an aside - you guys DO remember we have an electric block heater on these beasts, right?

dgeist · **Posted:** Thu Nov 20, 2008 12:44 pm

gmctd wrote:

The engine-driven viscous engine coolant heater should be a fairly broad hint that the radiator fan(s) have little to do with the underheating properties of a small under-worked Diesel engine - you could remove both fans and the engine would not warm up any faster - a Diesel engine makes only enuff BTU to get the job done - no use expecting any more than that out of it - you might look into an ESTY(?) Diesel fuel-fired heater to get the ECT's up where things are toasty and operationally copasetic - hint: put a piece of cardboard in front the radiator, note any difference in warm-up B4\after

Fair enough. With that said, how does the swap relate to other factors, i.e. does reducing the constant mechanical drag actually buy you much in the way of efficiency, or is it a load that's analgous to something like running the AC all the time?

vtdog · **Joined:** Fri Sep 30, 2005 11:27 am **Posts:** 640

I hate to be the contrarian here, but I think that you are way over thinking this issue. Yes, in colder weather it does take longer to get the engine to "normal" temp. It is a simple matter of physics that it takes longer to get to a set temp from a colder starting point. It will take longer from 30F than from 80F to get up to operating conditions. In addition, since the diesel is less effecient at lower temps I suspect (and here I am just guessing) that the heat output per unit of fuel being used is also less and means the engine is less effecient, etc so that might be another reason the engine increases temp more slowly.

However, having said all the above, don't worry about this issue. I realize it does get chilly in GA, but not like here i northern New England. The little engine starts and runs at very low temps (below zero) and gives off enough excess heat to run the cabin heater. In very cold weather my temp gauge holds at "11:50" instead of "11:58", but the cabin heater still warms up the inside.

Yes the mpg is lower in winter (partly because of winter blend fuel and partly because of diesel engine response to cold) but the reduction in mpg is NOT worth the expense or effort being discussed. My general mpg drops to around 22-23 from 25-26 in the cold weather. In addition, in real cold weather it takes 5-10 miles of driving at non-hiway speeds to get the tranny to shift to overdrive. This programmed function gets the engine to temp faster, but also cuts down on the mpg. I suspect my experience is no different from any else.

gmctd · **Posted:** Thu Nov 20, 2008 7:32 pm

Correct - the seasonal switch to #1 often upsets folks keeping track of fuel economy, as it has less btu-content than #2 - plus, all things lubricated with Dino-offal tend to require more power to overcome cold-increased resistance to movement - cabin-heater comfort is not a good indication of what is occuring in the engine bay, as that unusual device attached to the upper-turbo-side front corner of the engine is an auxilliary heat-generator, strategically installed to lull the driver into thinking all is well - that's why you're warm'n'cozy even while yer engine is still enduring coldblains - as afore-mentioned, the belt-driven viscous heat-generator is good indicator that engineering was aware of the exceedingly slow warmup due to low btu thruput of the unloaded 2.8L Diesel engine

The viscous-coupled clutch fan will start off fully engaged due to gravity: all the silicone fluid is gravitated down into the lower channels, giving full lockup at startup - however, after the engine is started, centrifugal force will sling the fluid into the proper reservoirs, the clutch will disengage, and the fan will freewheel - I would leave things as they are, engine-driven fan in-place, adding a piece of cardboard to see if it improves warmup

fastRob · **Posted:** Thu Nov 20, 2008 8:37 pm

Zipped up the Alaska Tent a little more today, it was cooling down at idle, coasting.
Plug it in to get started in the AM.
Watch out for water in the fuel, or move to the south.

dgeist · **Posted:** Fri Nov 21, 2008 1:44 am

Thanks for all the comments. I should have never mentioned the cold, as it's really not the biggest factor in my mind (the temp MPG drop is a given based on what is above and I'm okay with that). Mostly I was wondering it there was much to be gained in putting in an electric fan and the explanation of the viscous clutch leads me to think "maybe, but not enough to justify messing with it".

I'll try some cardboard for the warmup benefits once it actually starts freezing overnight (it's only done that once so far this season).

Dan

Pablo · **Joined:** Thu Feb 02, 2006 10:06 pm **Posts:** 1201

Earlier this year there was a great big long discussion about electric fans... Let me find the link:

http://www.lostjeeps.com/forum/phpBB3/vie ... sc&start=0

Electric radiator fan swap on a CRD?

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