Volvo Rear End Accessory Drive / R.E.A.D. / READ Rebuild

Added 04/30/2020

If you have a READ question, you can give me a call at 301.881.9429. I am busy running the shop, and about 70% of the calls I get from people thinking they have a bad READ unit, do not. So I just ask that you do the following before calling.

  1. Read through this entire page.

  2. Remove the dipstick to see if the noise goes away. If it does, then it is a clogged PCV system, and not a bad READ unit.

  3. If you think you have a bad READ unit, remove the main drive belt, start the car, and see if the noise goes away. If the noise goes away, you most likely do not have a bad READ unit. Look at the one-way clutch, idler, tensioner, and water pump. If the noise does not go away, and it is coming from the READ, then it is most likely the READ. Sometimes you can even feel the play in the bearing.

In January 2014 we did our first Volvo Rear End Accessory Drive / R.E.A.D. unit rebuild. I’ve also heard it referred to as the Volvo Rear Engine Auxilary Drive and the Volvo READ.  I was not able to find much information on the web about the R.E.A.D. unit, so I thought I’d share our experience for those who are looking to learn more about the Volvo READ. unit and the rebuilding process.

In January 2014, we were contacted by another local shop that had a 2008 Volvo XC90 with a noise coming from the back of the engine near the alternator. They found the service bulletin number 21–9 that described a noise near the back of the engine. It said the cause was a failure of the gear drive. The gear drive is what drives the R.E.A.D. unit by the crankshaft. They asked if we were familiar with the issue and if we do the job. We had not done the job before, but two of our technicians had recently attended a training session on SI6 or short in-line six cylinder engine. They were very interested in putting the new knowledge to work. We discussed the job. We talked about how it would take an investment of about $2000 in special tools and we would certainly lose money on the job, but we decided the experience is worth it. The vehicle was brought to our shop and we ordered the tools.  Once the tools arrived we began the disassembly procedure to remove the Rear End Accessory Drive / R.E.A.D. unit. At that time we believe we would just be replacing the gear drive as the bulletin stated.

If you watch the video above you will see that the noise turned out to be the bearing inside the READ unit, and not from the gear drive addressed in the bulletin. Below is a picture of the Volvo SI6. I found this picture online and I’ve included it here because with the engine out of the vehicle it’s much easier to see the R.E.A.D. unit. The READ unit is the box near the back of the engine with a small gear that looks like a timing belt pulley.


The name Rear End Accessory Drive describes only half of what the Volvo R.E.A.D. unit does. While it does drives the alternator and the Accessory Drive Belt, it also connects the crankshaft with the camshafts. In the next image you can see how the read unit attaches to the timing chain.


This was our starting point.Most of what you see here on top of this engine needs to be removed to get to the rear and accessory drive unit.


The first step is to remove the right front wheel and move the inner fender out of the way to access the front of the engine. Once that’s done there’s a plug in the front of the engine that covers the crankshaft. This has to be removed so special tools that locks the crankshaft in place can be installed see that here in this image.


The next step is to remove the intake manifold and everything on that side of the engine above the read unit.


Next the front timing chain cover needs to be removed.


Then the timing chain in gears needs to be removed.


Then the rear timing chain cover.


Once all of this is out-of-the-way we can now see the read unit.


The next step is to remove the R.E.A.D. unit and gear drive. There’s a special tool to remove the gear drive from the block, however, if you are careful, you can usually get it out without the special tool. It’s very critical at this point to inspect the journal where the gear drive sets as well as the roll pin that locks the gear drive shaft to the block. If any of this is damaged, Volvo recommends replacing the engine. The Volvo literature states that the READ unit is mated to the block, and cannot be replaced separately. This makes no sense to me though. If the main drive gear is parallel to the crankshaft, then the rest of the shafts should be parallel.

Once we had the gear drive out we found that was not the cause of the noise. What we found is a failed bearing in the Rear End Accessory Drive. In this picture the bearing is shown on the left.


There are quite a few special tools required to disassemble the R.E.A.D. unit and reassemble it. This is a picture of the R.E.A.D. unit is disassembled and ready for reassemble. Also in this picture you see the new gear and bearing for the read unit. Volvo sells the bearing here as one assembly it cannot be purchased separately. Unfortunately this is the last picture we took, I wasn’t expecting to make a video or this page.


Reassembling the car went pretty smooth.  I’m happy to report that the vehicle has been on the road trouble free for several years now.  We did our second on on 03/2016 and that one is doing well also.

Update April 30, 2020.  

It seems we have become the READ experts over the last few years, and have developed a number of solutions. We have sourced all the bearing, so we can now rebuild units without using the $600 Volvo kit. We have rebuilt units in stock, or can rebuild yours. We have tool recommendations, and we manufacturer some. We also sell the bearing kits, if you want to do the job yourself.

Whatever route you go, you are going to need these tools to remove the timing chain, to get the READ off. I recommend searching on ebay for the kit pictured here. They normally sell for $150 – $200 as of this writing. I just searched, and saw them as low as $91 and as high as $565. Just search “volvo 3.2 timing tool”.


You can purchase one of our rebuild units here:

They are $500 including the bearing for the main drive gear, with a $200 core. So you pay $700, and when we get a reusable (the case is not damaged) core back, you will receive a $200 core refund.

Rebuilt Volvo R.E.A.D / READ Unit

This rebuild includes replacing all the bearings and seals. The case, gears and shafts are inspected, and reused, reducing the cost significantly from the Volvo kit. It comes with a one year warranty from the date of purchase. Should the unit fail, we will provide a replacement unit, and cover shipping both directions.

It also includes the bearing for the main drive gear. You will need to install that yourself.

If you would prefer to do the whole job yourself

The next thing you are going to need is the tools to remove the sprocket from the READ unit. I have yet to see anyone remove the sprocket without these tools. One guy claimed to, but when it got to me, teeth were broken off the sprocket. Even if you manage to get it off, it needs to be torqued to 300 ft lbs. when you put it back on. And we found out the hard way that if it is not properly torqued, the engine will tighten it for you, bending valves in the process. You can get these tools from Volvo, however, the last time I checked they were over $1000, and it would take a month to get them.

We manufacture a set of tools to remove the sprocket. You can find those here. They are not as pretty as Volvo’s, but they work as good, if not better.

Volvo READ / R.E.A.D. Tools 997329 & 9997317

You can purchase the complete bearing kit here.

Volvo READ / R.E.A.D. Bearing Kit

We also have a complete kit, with the bearing kit, and sprocket tools here.

Volvo R.E.A.D / READ Unit Bearing and Tool Kit

Note, we highly recommend replacing the one-way clutch on the READ unit, as we
believe the failure of these one-way clutches is what causes the READ unit
bearing failure. Also check the one-way clutch on the alternator, and replace if


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