:shock:

sweet, doesnt look hard at all though. How did you know your thermostat is bad?

Thermostat Part number:
05142601AA

Price:
$111.00 - List
$83.25 - Shop

I think I just got a nosebleed - at least I hope it's my nose.

Is the viscous heater working overtime trying to get the engine warm?

Nope go to page 24-126 or 6001 of the service manual and read all about the viscous/engine coolant heater

K

The supplemental diesel engine coolant heater (viscous heater) uses an electro-mechanical clutch that receives a
signal from the diesel engine control module (ECM) via the A/C-heater control and the viscous heater controller, to
energize and engage the clutch. Once engaged, the clutch allows the viscous heater to increase the temperature of
the engine coolant flowing to the heater core to provide heat to the passenger compartment quicker than diesel
engines without the viscous heater.
The viscous heater uses friction to heat a special silicon oil within its housing. The generated heat is then trans-
ferred to the engine coolant when the coolant passes over the fins within the housing. When demand for passenger
compartment heat decreases the viscous heater receives an input from the heater controller to disengage the
clutch.
The supplemental diesel engine coolant heater cannot be repaired and, if faulty or damaged, the entire heater
assembly must be replaced.

Although that quote doesn't mention it, I thought it ran until a certain coolant temp was reached. Too warm here to check it out.

I suspected the viscious heater too, but 90$ is uber cheaper than the viscious heater components would be, I suspect. I've spent far greater that 90$ in attempt to fix far less.

I'd try the thermostat first too.

Well, the viscous heater only seems to be for the cabin heat according to the FSM, and you would figure if the viscous heater wasnt working but the thermostat was it would eventually warm up to normal operating temps, even in 70 degree weather, this one wont.

viscous does the coolant, if I am not mistaken .. no separation from the pass compartment and engine there ... also if the CRD is anything like a TDI .. it would never warm at idle in any temp without the viscous heater.

I'd still do the thermostat first unless I had a way to test either before purchase.

The 2.8L diesel engine uses a supplemental engine
coolant heater (1) to help heat the engine coolant prior
to it entering the heater core (4). This mechanical
device is commonly called a viscous heater. The sup-
plemental engine coolant heater is driven by the
engine accessory drive belt (3) and has an electro-
mechanical clutch (2) which is controlled by the
engine control module (ECM).

well let me put it this way, if your CRD never warmed up around you, would you suspect the viscious heater?

seriously this thing is not warming up in 70 degree temps, classic signs of thermostat failure.

its too bad its an expensive part and one that needs to be order to check it though.

Once again, the written word has failed me. I never doubted your diagnosis of a failed thermostat, I was just curious whether the viscous heater was trying to compensate. I have seen the viscous heater on mine run in the winter, but I have no idea where the cabin heater was set. It would be easy to test in cold weather, but I can wait. I've been cold before, it is overrated.