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Replace your Serpentine Belt (850/S70/V70/C70)

By Matt

Overview

serpentine belt for Volvo 850 There is only one belt besides the timing belt in 850/S70/V70/C70 models, and it's called the 'serpentine belt,' 'accessory belt' or 'auxiliary drive belt,' depending on who you ask. It transmits power from the crankshaft of the engine to the alternator, steering pump and air conditioning compressor.

Check your owners' manual for the change interval. My 1997 850's interval is at the 60k miles mark, which is where I'm at today. If you have your Volvo serviced regularly at a Volvo dealer or independent Volvo repair shop, it's probably on their radar, and you probably don't have to ask them to perform this. If they're good, you'll know if this belt has been changed recently or if it will be soon because they will have discussed this with you.

Parts

First off, the belt for my 850 T5 is Continental part # 6PK-1743. It was US$41.20 before tax. I spoke with Steve at Viking Auto Service about this belt, and he made a few points:

  • There's two lengths for the 850. Be aware of this when you order; the tech will need your model and year, and maybe even your serial/VIN number.
  • Volvo-branded belts are made by Continental. If the Continental is cheaper than the Volvo belt, buy it.
  • If you take long trips, keep your old one in the car... you know if this belt ever breaks, you'll be in Mexico or somewhere where a replacement will take 3 weeks to get to you by mule (not necessarily a bad thing).

Tools

I made my own tensioner tool There's two difficult things to this operation: operating the tensioner, and routing the belt. The tensioner is hard because you need a special tool, or you need to make one, to relax the tensioner to get the old belt off, and the new one on. The second difficulty is routing the new belt on the pulleys. IPD makes a serpentine accessory belt tool set that may be worth the US$30 to you. I built my own with a vise grip tool and three US quarters. For a belt guide I used a coat hanger.

Procedure

Make sure you have light. Sunlight, flashlight, overhead electric lights, whatever. It's dark and narrow in that belt area; work this out before you start. If you have a digital camera, take a photo (it won't be an Ansel Adams, trust me, but it can save you hours of headache if you forget the belt routing) of how the belt's routed first. View these when you're putting the new belt on.

Put the business end of the tool in the tensioner. Pull toward the front of the car. With your other hand (or if you're lucky, ask your helper) unloop the belt from the top-most pulley. Release pressure on the tensioner and remove your tool.

The belt should then come off the rest of the pulleys with ease. Then compare the old and new belts to make sure you bought the right one. To get the new one on, I started with the lower, rear-most pulley and worked up from there, all the time referring to my handy digital camera's LCD screen of the photos I had taken just minutes earlier.

To complete installation of the new belt, do the tensioner thing again and loop the belt around the top pulley. Mine was a bit difficult even with the tensioner at full-forward. It took me three tries. When it's on, double check and triple check that the routing is correct.

Reader Comments

Author: Brian P
While pulling the tensioner arm to it's maximum distance, insert an allen wrench into the round eye at the top of the tensioner. This will hold the tensioner in place, allowing two free hands. Once belt is on depress the tensioner again and remove the allen wrench.

Author: Ian T
After replacing my belt with a pattern part the car developed a wheeze, and squeal in damp weather. Upon advice from a reliable Volvo mechanic I was advised to use an OEM part which cured the problem, and was in fact cheaper from the dealer!

Author: Josh R
While I appreciated the ingenuity of the three quarter tensioner tool, I had a lot of trouble with it. The quarters kept bending before I could get the tensioner all the way open (and since I don't have a helper, I wanted to lock the tensioner in place with a nail or allen wrench). What I found worked really well is a 4 inch C-Clamp. Just place the clamp over the tensioner with the adjustable end up and pull towards the front.
Thanks for the great article.