Serpentine Belt Tensioner Service Interval

BlueCRDKJ · **Posted:** Mon Aug 22, 2016 12:22 pm

Is there a specific (or recommended) service interval for the serpentine belt tensioner?

I replaced my alternator decoupler pulley over the weekend and from reading all of the posts about the ADP it got me thinking about the tensioner.

I have an 2005 CRD with 130k miles.

papaindigo · **Posted:** Mon Aug 22, 2016 1:30 pm

Not that I know of. The tensioner has essentially 2 moving parts a) a spring that causes it to pivot and hold tension and b) an idler pulley. Some have suggested that maybe the spring can lose strength over time but over what period of time is not mentioned. Frankly I am inclined to not worry about spring tension declining over time. More important is that idler pulley which I would be inclined to replace at the 100,000 mile TB change interval based on miles not age. The bearing is sealed but won't last forever. FYI the idler is the same as the serp belt idlers (NAPA 36101, just lose the big washer, or Precision Parts EP101).

Now if you have been driving for a while with a bad alternator pulley, which causes the tensioner to bounce around a lot, my opinion would be different as bouncing can stress the spring and the spring housing and cause premature failure.

The quick check for a bad alternator pulley is to crank up; at idle look at the tensioner (a flashlight shined down past the air filter box is helpful); if idler is essentially steady alternator pulley is ok but if idler is bouncing a lot (not barely twitching) then suspect a bad pulley.

WWDiesel · **Posted:** Mon Aug 22, 2016 1:49 pm

The idler pulley tensioner spring does get weak with age and mileage. When I installed a new tensioner pulley assembly a couple years back, there was a very noticeable spring pressure difference between the new and old tensioners... :wink:

The new tensioner made a big difference in the amount of bounce observed at idle!!! :-)r

papaindigo · **Posted:** Mon Aug 22, 2016 3:33 pm

How many miles on the one you replaced?

BlueCRDKJ · **Posted:** Mon Aug 22, 2016 4:11 pm

The serpentine belt tensioner and pulley's are original, so 130k miles. I just replaced the ADP this weekend because the belt was squealing when the AC was turned on.

TURBO-DIESEL-FREAK · **Joined:** Sat Apr 17, 2010 3:29 pm **Posts:** 1167

Your collective opinions regarding where to get serpentine belt parts would be greatly appreciated.

papaindigo · **Posted:** Mon Aug 22, 2016 4:54 pm

idParts probably has everything you need.

If one wants to shop around
1. Gates K061130 is the belt
2. idlers (3 if you do the one on the tensioner) are NAPA 36101 (just lose the big washer) or Precision Parts EP101
3. Litens 920834 for the AC pulley - it's slightly smaller than stock but not enough to matter and is grease filled.
4. viscous heater bearing can be replaced but not the clutch. If clutch goes out I'd just replace the bearing and leave the viscous neutered so to speak which is harmless
5. have no opinion on source of tensioner assembly other than idParts.

peteyz24 · **Posted:** Mon Aug 22, 2016 7:55 pm

Rock Auto for belt and Idlers

Gates Belt K061130 is $23.79
Mopar Idler 68211444AA is $30.79

They also carry the tensioner, but it is $200+ for some reason

WWDiesel · **Posted:** Mon Aug 22, 2016 9:24 pm

IDParts is your friend on this part! :wink:

http://www.idparts.com/serpentine-belt-tensioner-liberty-crd-oe-litens-p-2826.html

Ceearedeedriver · **Joined:** Fri May 06, 2016 8:44 pm **Posts:** 177

WWDiesel wrote:

The idler pulley tensioner spring does get weak with age and mileage. When I installed a new tensioner pulley assembly a couple years back, there was a very noticeable spring pressure difference between the new and old tensioners... :wink:

The new tensioner made a big difference in the amount of bounce observed at idle!!! :-)r

I've also seen them seize at the pivot on other vehicles. This can appear as though the spring isn't working. Add some oil and take them through their full travel a few times and they appear to work again. For a $40 part it's really not worth the risk and effort but of course on the CRD it's not a $40 part :roll:

papaindigo wrote:

2. idlers (3 if you do the one on the tensioner) are NAPA 36101 (just lose the big washer) or Precision Parts EP101

I noticed mine felt a bit slack and rough last time I did the TB so replaced the bearings on all three at the same time. Real easy to do and the bearings I used are most likely of better quality than what comes in the replacement OE idlers.

BlueCRDKJ · **Posted:** Sat Aug 27, 2016 1:50 am

I bought a new tensioner and pulleys. Before I took the old tensioner off I put my torque wrench on it and it took about 24 ft-# to move the tensioner. The new tensioner took about 35 ft-# to move.

WWDiesel · **Posted:** Sat Aug 27, 2016 11:22 am

BlueCRDKJ wrote:

I bought a new tensioner and pulleys. Before I took the old tensioner off I put my torque wrench on it and it took about 24 ft-# to move the tensioner. The new tensioner took about 35 ft-# to move.

Just as I stated earlier, they do get weak with age! :wink:

GordnadoCRD · **Posted:** Fri Sep 16, 2016 4:38 am

In going through everything I can think of to check on my 06 CRD, I came across a second magnetic clutch controlled pulley, top on the passenger side of the engine. It appears to be a water pump especially for the heater core. The bearing for this had quite a bit of axial play and dry bearing noise, so I pulled it out. It is not the same as the AC pulley bearing. I cannot find this bearing anywhere in IDParts, Mopar Online Parts, or even in any of my technical manuals "for this vehicle". The only diagram I can find that even shows the pulley is the one for replacing the serpentine belt.
Koyo DAC355222RR9D is the original bearing
VXB 35BD5222 is sold by Amazon for about 25 bucks, and double row round ball rollers, same as original
Santech MT2149 is sold by AutoZone for about half that, and is identical size. They swear it won't fit this vehicle though because they look it up under AC pulley bearing which is MT2024. Santech product info says they use single row tapered rollers though. I decided to try it anyway. It's listed as direct replacement for Audi, BMW, Land Rover, and Mercedes and was probably carried over to the Jeep from the Chrysler Crossfire.

flash7210 · **Posted:** Fri Sep 16, 2016 5:54 am

Quote:

I came across a second magnetic clutch controlled pulley, top on the passenger side of the engine. It appears to be a water pump especially for the heater core.

Its called a viscous heater and it helps warm up the coolant on cold days.
If you do a search for viscous heater pulley you will find more info about the bearing.

Its a somewhat unnecessary part that can be unplugged and bypassed or deleted completely without harm.

GordnadoCRD · **Posted:** Fri Sep 16, 2016 6:03 am

Thank you!

One thing I find disconcerting is having something so conspicuous staring me in the face, and knowing nothing about it.

I suppose if disconnecting the clutch causes no CEL condition, it will probably happen. It doesn't get very cold here very often.

WWDiesel · **Posted:** Fri Sep 16, 2016 10:31 am

GordnadoCRD wrote:

Thank you!

One thing I find disconcerting is having something so conspicuous staring me in the face, and knowing nothing about it.

I suppose if disconnecting the clutch causes no CEL condition, it will probably happen. It doesn't get very cold here very often.

Where do you live, you can add your location to your signature, it helps sometimes to know what part of the country you are located!
Simple way to disable the viscous heater clutch is to open the relay panel under the hood and find the relay for the viscous clutch and unplug the relay and save it for later use if it happens to get cold enough to need it. I keep mine unplugged most all the time and keep the relay in the glove box if temperatures get down below freezing which is very very rare in central GA...
Unplugging the relay will not hurt a thing and it does not set a check engine light!!! Will also improve your fuel mileage just a bit :wink:

GordnadoCRD · **Posted:** Fri Sep 16, 2016 2:30 pm

Done and Done

I still find it odd that all Mopar says about this, is that it's driven via AC type clutch. No mention that both the clutch and the bearing are completely different than the actual AC clutch and bearing for this vehicle.

I also wondered if this device couldn't be repurposed for those greaseburners out there, as a way to heat up their auxiliary fuel tanks. With the way these fuels seem to find their way to places they shouldn't be, it would likely require a bit of engineering. Not something I'm considering, just one of those random thoughts flying by.

papaindigo · **Posted:** Fri Sep 16, 2016 3:18 pm

Minor correction to WWDiesel's comment. Unplugging the viscous heater relay will not trigger the CEL light in the dash but it will set a code (B10B3-VISCOUS/CABIN HEATER RELAY CONTROL OPEN CIRCUIT) that can be "seen" if a code reader is plugged into the vehicle. This might??? matter if your state requires vehicle inspections and those inspections involve plugging in a code reader. Solution plug relay back in before inspection and either a) if you have access to a code reader then clear the code or b) about 5-10 drive cycles (crank up drive shut down - repeat) should clear the code.

Just a reminder to all if the viscous heater clutch bearing fails it is replaceable.

WWDiesel · **Posted:** Sat Sep 17, 2016 1:17 pm

papaindigo wrote:

Minor correction to WWDiesel's comment. Unplugging the viscous heater relay will not trigger the CEL light in the dash but it will set a code (B10B3-VISCOUS/CABIN HEATER RELAY CONTROL OPEN CIRCUIT) that can be "seen" if a code reader is plugged into the vehicle. This might??? matter if your state requires vehicle inspections and those inspections involve plugging in a code reader. Solution plug relay back in before inspection and either a) if you have access to a code reader then clear the code or b) about 5-10 drive cycles (crank up drive shut down - repeat) should clear the code.

Just a reminder to all if the viscous heater clutch bearing fails it is replaceable.

Thanks Pap for correction, you are right, I had completely forgotten about the soft code that it sets when unplugged. I edited the OP to clarify.... :roll:

GordnadoCRD · **Posted:** Sat Sep 17, 2016 5:50 pm

Thanks for the replies

The new bearing should arrive Monday.

The bearing is a direct replacement for the bearing in this clutch. http://www.ebay.com/itm/A-C-AC-Compress ... H7&vxp=mtr

Seems like a poor design that would require two completely different clutch units on the same vehicle.

Maybe it has something to do with making Japanese parts work on an Italian built engine installed in American(?) vehicles sold on multiple continents.

Again, I haven't checked if the clutch itself is actually the same, as all I needed was the bearing. Just figured it's worth checking for those that need.

Serpentine Belt Tensioner Service Interval

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