Guys,
Finally been driving my D2 around town now that the rains have some back to the Seattle area.

2001 DII. about 99,200 miles on it.

Found that I can hear the AUX fan fire up at idle.

I am like - "oh great...."

So, I put my old OBDII scanner onto the OBDII port and took a look at live temperature data.

Seems my engine was right at 210 degrees F at Idle. And the AUX fan was running. The temp would not exceed 210 degrees F. Nor would the temp drop with the AUX fan on idling in the parking lot at Pizza Hut.

It was 53 degrees F outside.

So, I tried a few things..

o 210 degrees at idle - AUX fan on and running. No A/C on. Temp remains at 210 degrees F.

o A/C on coldest setting temp "LO" and engine will drop to 204 degrees F or so. IN parking lot not moving

o Heat on highest setting. Engine Temp from 210 degrees F and - can drop engine temp to 203 degrees F or so in parking lot not moving.

o No A/C on, no heat on. In fact - A/C heat OFF - engine at 210 degrees F. Rev engine to 1,500 RPM hold at 1,500 RPM for a minute and engine temp drops to 200 degrees F or so - not moving in the parking lot.

o 60 MPH on the highway for a few miles - temp drops to 197 degrees.

NO water fall sound.
99xxx miles.
Did head gaskets at 96,xxx or so.
Coolant level is OK.

I did clean out the outside of the radiator when I was in Boulder, CO.

New coolant at 96,xxx miles when head gaskets changed.

Belt looks to be routed OK.

Fan clutch????

I never hear my fan roar in the morning on this D2 - like our 1997 D1 does.

When our D1 first starts off in the morning, the large clutch driven fan always is heard for 5 seconds - the large fan driven clutch fan seems to be at high speed and then decouples.

The D2 never does this. I never ever hear the D2 clutch driven fan roar.

Ideas?
Can you guys ever hear your D2 clutch driven fan roar at acceleration?

How are your temps at Idle - sitting in a parking lot for 5 minutes or so?

AUX fans on?

Thanks guys. Appreciate it.

J

 

Let's go backwards -

197F on the highway at 5280 feet per minute - water pump and radiator seem to be doing their job. Radiator might have internal sludge, but hard to tell unless you check temp across fins top to bottom. A sludged radiator may be OK in cool weather at freeway speed, but would have problems at idle and also in hot weather.

Temp rises and won't drop back significantly at low power idle. This is a point in time when the fan is doing the cooling work, you can drive on the freeway without a fan (just don't linger in the drive thru). I'd say examine the clutch. When cold, spin and release, maybe goes part of a turn. Feels like peanut butter instead of penetrating oil inside. Repeat when warmed up. Should maybe go a little further, but should not "freewheel."

These viscous clutch units should roar at cold start (silicone inside has pooled to one side and unit would be fully coupled), then as spinning forces and warm up spread the silicone, the roar drops away. It would return ( perhaps slowly) as the temperature on the clutch face gets above 170F (radiator is much hotter). If radiator is sludged up, that center spot can be much cooler than the top, and air to the clutch face is not warm enough to bring it back on line. Of course an incorrect belt route only adds to the fun.

With a hand held IR thermometer you can check the rad fin temperature spread, and the clutch face temp, but I would do this with engine just switched off (more than 10F top to bottom is the start of some kind of sludge). The Mark I palm reader should be avoided for use in measuring hot radiator temps.

The Chevy Express van 2000 fan clutch for a 4.3 engine, non/AC, is the same size and rotation and thread as our clutch (six inch, reverse rotation, same WP thread on D1 or D2). May have to enlarge mounting holes in fan blade, or modify blade hub assembly. Or use a different fan.

 

Oops - also check to be sure that in all the previous work the electric fan is not wired backward. When fan is running, paper towel should be sucked toward grill, not blown away. Many times we try to focus on what could be wrong on a stock vehicle. I had a blown fan clutch, wrong belt route, clogged radiator, and PO replaced electric fans were wired backwards. When the electric fans came on, the reverse airflow almost brought the main rad fan on the blown clutch to a stand still. My PO had this truck on the "EZ Bake cycle" for a while.

 

fwiw that sounds about what my disco does temp wise....

 

At your mileage, it is safe to say your radiator is plugging up and it can not be cleaned out. Time for a new radiator, 180 degree soft spring t/stat, a new replacement viscus clutch if yours is original, a new coolant cap and green coolant.
Do these things and you should drop around 15 degrees in town.

 

Temps look spot on...?

 

That's what I thought. Not really above normal at all... unless you are running the 180 soft spring thermo, then it is definitely not running as cool as it should.

 

With the ambient air at 53 degrees, the engine is running warm at idle.

 

Thanks guys - as always for your detailed help.
Very detailed.
With all this I have a step by step plan.

I'll replace the fan clutch first - as Savannah has suggested.
(and it is easy)

And see what happens.

I have a thermal scanner in storage. If I can find it I'll test the radiator and see
what parts are at what temps.

If things are still bad - then get a new radiator..
as per Mike.

I may have another 1,200 mile drive to a new job in So Cal - if I get it.
So after that when I am getting paid again perhaps I can dig into
putting forth your wealth of knowledge and report on the progress.

As with the Boulder to Seattle trip - I'll keep at 65 MPH as per Savannah. As my drive shaft (even tho there are grease fittings) may have problems too.

Sincerely,
J

 

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