Serpentine belt tensioner question

DGM635csi · **Posted:** Tue May 05, 2009 3:30 pm

Hello, I have been trying to find a good description of how to compress the belt tensioner on my CRD, and so far I have discovered that you need a 15mm spanner wrench, or something similar with enough leverage to twist the sprung part of the tensioner clockwise in order to lower the pulley and release the tension from the belt. I was wondering if there is a better location to place the wrench other than on the bolt that holds the pulley on the tensioner, or is this the only location. Also, the tensioner seems rather stiff compared to other vehicles I have worked on with auto tensioners (mostly BMW's), and I was wondering if there is a risk of damaging the bearings on the pulley by overtightening the bolt when you twist the tensioner. I was also wondering if the anyone has tried to replace the bearings on these tensioner or idler pulleys? If so, what size bearing did you need.

JeepinJarhead03 · **Posted:** Tue May 05, 2009 6:08 pm

stick a socket on your torque wrench or pull bar and have at it, pully bolts are really on there, theres really no chance in hell that you'll manage to overtighten or loosen the bolt used for operating the tensioner mechanism without an impact gun

the tension you're putting on the bearing is pretty much nothing compared to the shocks it gets under normal operating conditions

some of the IH models I'd skip using the bolt and a socket or wrench and stick a prybar or long screwdriver down between the mount bolt and the pully bolt and use that for leverage, that or it would have a square slot for a pull bar

wolcott · **Joined:** Thu Nov 10, 2005 4:16 pm **Posts:** 108

DeLisle sells a serpentine belt tensioner wrench that is available at most auto parts stores. These have a long handle, and are very thin to get between the tensioner pulley and the radiator. I have one and used to release the belt on my CRD, and the belt appeared to have normal tension. The direction you pull to release the belt would also tighten the bolt holding the tensioner pulley in place (I assume it is a right hand thread), so you don't have to worry about loosening this.

These wrenches aren't too badly priced. I believe that mine was $18 or so.

kccrd · **Joined:** Thu Mar 08, 2007 10:35 pm **Posts:** 267

I just put my ratchet wrench on it turned it to the right a few inches and remove the belt. Then I took the pulley off, cleaned it and put some high temp grease in the center and replaced. I did put some tension on the belt and held it up at the top of the engine so the belt would not fall off the crank shaft pulley it is a bear to put it back on that pulley since it is so low if you do that is will save your knuckles some good scape's.

wolcott · **Joined:** Thu Nov 10, 2005 4:16 pm **Posts:** 108

One other thing that I've found helps with serpentine belts, besides a belt wrench, is to use some high powered magnets to temporarily clamp the belt to the pulleys while you are getting it correctly positioned on all the pulleys. These help a lot, and save a lot of cursing and sweating.

ChesterCRD · **Posted:** Wed May 06, 2009 9:37 pm

I used a 15mm open end wrench on the tensioner pulley. It's not as bad as it first seems...it seems really tight. I had mine on and off about four times while playing with my alternator (chasing an elusive rattle). Mine got easier to move after the first time I moved it I think...or maybe I was just startled by how stiff it was the first time I moved it and then got used to it. Anyway, take your time...if you get frustrated take a break...have some water...hit it again in a few minutes. I found it easiest to get the belt around all the working pulleys, then move the tensioner and slide it onto the idler pulley. It's tight, but very doable.

Serpentine belt tensioner question

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