This pulley here is moving and stopping on its own with a clicking noise and serpentine belt slides over it for a while till it starts to move again. So my question is how to fix it ie replacement parts the serpentine belt was recently replaced and any possible damage if I let it go for a while thanks.

That is your Viscuous heater.

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Silver 2006 KJ 2.8L CRD Limited:
GDE ECO Tune / Fumoto Valve / E-Tecno GX3123 7v Glow Plugs / 2nd Gen Fuel Head / Mishimoto RED Hoses / Rockers/Lifters @ 114k / Hayden FC + 11 Blade Nylon / Sears P1 Battery / Transgo 45RFE-HD2 Reprogramming Kit / Timken Front Bearings

So it is normal operation and it won't harm or cause any more issues.

Normal or maybe not totally normal. In normal operation the very outer portion of the viscous pulley rotates at all times. You cannot easily see the rotation but if you carefully touch the metal edge adjacent to the serp belt you can feel it rotating hence the serp belt is not "sliding" across the pulley. What you hear clicking and see rotating is the clutched inner portion. When the clutch engages the serp belt drives the "guts" of the viscous heater to, at least in theory, supply a bit of extra cabin heat until the engine coolant reaches a set temperature at which point the clutch disengages and the outer portion free wheels sort of like an idler pulley. See Roostre's post at viewtopic.php?f=5&t=60567 for some chat and pictures of the assembly.

What may not be totally normal is for it to click on/off as you describe. The 3 CRDs that I have access to have the viscous heater relay pulled so the clutch never engages, saves a bit on mpg and we don't need the theoretical early heat boost, hence I cannot check but I would have thought it would simply click on and run until it's no longer needed at which point it would click off. The FSM is no particular help as all it says is the clutch is electronically controlled. Perhaps the clutch cycling on/off during the warm up cycle, similar to the AC clutch cycling on/off, is normal I just don't know.

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

bump

What they (above) said.

I would add that, once the stock thermostat goes (seems to with some regularity - sticks open), you're then putting the burden of getting the coolant up to temp on the viscous heater... an expensive item which then is forced to work overtime trying to heat what the radiator cools.

If you live in cold climates, it's nice if you want the defroster to work anytime soon. Otherwise, you'll probably never miss it once you get your thermostat working; signs of an open t'stat: temp gauge at the first mark rather than closer to 12 o'clock.

If your t'stat is working, the viscous heater should run less frequently once the engine is at temp. It's primary mission is cabin heat prior to reaching operating temperatures, and perhaps fuel efficiency from reaching that goal sooner.

Mark

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2005 Liberty CRD
2004.5 Cummins 5.9L TD, F1s, NV5600 6-speed in a '93 GMC Suburban

msilbernagel makes a good point. If your tstat is marginal (e.g. does not reach just a 1/2 needle width or so left of vertical) then your engine coolant is running cold. If the coolant temp is right on the borderline of where the viscous engages then I could see the viscous clutch cycling on/off as viscous raises coolant temp enough to shut the viscous off and then the radiator lowers coolant temp enough to cut viscous back in.

Try this - open the power distribution center (black rectangular box just forward of the battery) and pull the R36 viscous heater relay. This will shut off the viscous heater clutch. Take a drive that's long enough, depends on ambient temp, to get the engine fully up to operating temp. If your temp gauge is not nearly vertical, as noted above, you need to replace your tstat (you can try the inline tstat option if you want but I'm not a big fan of that route). If your temp gauge is near vertical then my notion may be wrong.

FYI http://www.greendieselengineering.com/f ... st/19.page has a good image of the proper temp gauge readings (just above 176F and not quite to 216F is where it should run)

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

So i did have a bad Tstat at one time now it is fixed (got new OEM installed ) and it does get to operating temp within the couple of miles and cabin does get warm nicely so i was thinking has any damage been done already or it is a simple case of heater heating and rad cooling down so it keeps clicking will check the idling at cold start.