'05 Serpentine belt tensioner replacement

[poolmike]

This repair is not too terrible. It can be done by anyone who is handy with the tools.

Tool list:
E10 inverted Torx socket
E12 inverted Torx socket
12 point 17mm socket
a small sacrificial allen key/nail/ anything that will hold the tensioner under load(see pics)
3/8" drive ratchet
1/4" drive ratchet
Various length extensions for above mentioned ratchets
7mm x 1.00 tap
7mm x 1.00 die
10 fingertip eyeballs
PoolMike's Guide to Proper Swears and Vulgar Language During Sprinter Repair(in stores soon)


Here is the first pic from the top of the engine. It is difficult to snap a good shot to demonstrate what a failed tensioner looks like in place.





A pic from the bottom side.




You can almost see how the tensioner pulley is almost 1/2" forward of the power steering pulley. The ratchet and 17mm 12 point socket are on the tensioner release head. Pull the ratchet to release belt tension and install small sacrificial allen key/nail/ whatever into the little holes to hold the tensioner sprung...this is done so you can access the bolts.

Take your E10 inverted Torx socket and try to remove the two bolts that hold your precious tensioner in place. Fight with them for 1.5 hours using only your fingertip eyeballs for vision. Right about now you will need to consult PoolMike's Swear Guide. Take a deep breath and realize...this would be so much easier if that #$%%$%^^$##$ air conditioning compressor wasn't in the #$%%^ way. Obtain your E12 inverted Torx socket and remove the three bolts that hold your compressor in place(EASY and WORTH IT!!!)

Remove the two bolts from your tensioner, then remove your tensioner.


Here is the damage. The busticated tensioner is on the left.




Here is the part number on my new tensioner




Reassembly.

Take your 7mm x 1.00 tap and run it through the two bolt holes for the tensioner. Take your 7mm x 1.00 die and clean the threads of your two bolts. I tried installing the bolts without tapping the holes and for whatever reason they fought me. You are only dealing with aluminum and small bolts in a very awkward location, so BE CAREFUL!!! Breaking a bolt off here WILL BE A PROBLEM!!

After cleaning the threads, the bolts went in with no problems. Slide your air conditioning compressor back into place and bolt it up. Route your new serpentine belt. Take your 17mm 12 point socket and ratchet and move the tensioner to remove the factory installed hold pin. Release your tensioner and you should be done. Check to make sure your belt is seated properly and fire it up!!

[sikwan]

Thanks Mike for the write-up.

How many miles are on the tensioner?

[poolmike]

85,000ish

[kkanuck]

Hi Mike,


Did you put a factory Serpentine back, or install a Gatorback?

[poolmike]

Factory, right from the dealer. Tensioner and belt set me back $230ish. I don't have the receipt in front of me for the exact number.

[mawsea]

would you recommend an anti-seize or locktite?

[abittenbinder]

Originally Posted by poolmike

Reassembly.

Take your 7mm x 1.00 tap and run it through the two bolt holes for the tensioner. Take your 7mm x 1.00 die and clean the threads of your two bolts. I tried installing the bolts without tapping the holes and for whatever reason they fought me. You are only dealing with aluminum and small bolts in a very awkward location, so BE CAREFUL!!! Breaking a bolt off here WILL BE A PROBLEM!!

After cleaning the threads, the bolts went in with no problems.

DO NOT chase the timing cover's belt tensioner mounting threads with a tap. Also, DO NOT chase the bolt threads with a die.

I will post a tech alert on this subject- but for now let me stress that it is important to use the original (new or used), unmolested, 10.9 grade, THREAD FORMING bolts for this highly stressed component. These will NOT install with finger pressure-that's normal. Doktor A

[hkpierce]

Pool Mike's pictures seem to have disappeared.

These are the two idlers - both grooved for the 612:


P8010137.JPG

This is the tensioner:

P8010136.JPG

All the pulleys are made of plastic. I found that the flanges tend to randomly chip away for unknown reasons, but the pulleys seem to be OK notwithstanding the chipped flanges.

[kartmad]

The tensioner on my Sprinter has developed a squeak. Pretty sure this happened after I gave the enginer bay a good degreasing. The squeak is very annoying and most noticable at idle, when the tensioner tends to move around a bit. As engine revs increase and the engine smooths out, the squeek disappears. With the belt removed, I have tried spraying some light oil on the join in the tensioner, but it has no effect. If the tensioner is rocked back-and-forth using 17mm spanner, I can get it to produce the same squeek I hear at idle.

Anyone fixed this sort of problem, without complete tensioner replacement?

[Jsloane]

That same idle-speed squeak had been annoying me for months, and several Continental belt replacements and one tensioner replacement didn't change it. Last week, at 99K miles, I fitted two new
upper idler pulleys and a Gates #K060888 belt. Now the squeak is gone at idle speed and only a tiny chirp remains when the transmission downshifts from 2nd to 1st with the a/c on. The pulleys changed were both the p/n 68020888AA type, both with grooves to match the belt. One of these is slightly larger than the smooth surface idler it replaced, and the larger diameter may cause the belt to run tighter against the tensioner.

Bottom line, after 500 miles, no problems and a significantly quieter idle.