DIY: 2005 Volvo XC90 2.5T 110K miles: Timing Belt, Water Pump, Serpentine Belt

[chitownV]

I would also question the recommendation NOT to do the camshaft seals until 190k miles. From experience, these can go as early as 100k miles and cause an oil leak. If these get changed, you should change other seals and o-rings at the same time. To wait until the VVT hubs go, well, that can be a discussion if NOT changing the VVT seal, plug seal, and camshaft seals, may shorten the VVT life. VVT hubs are costly. Another thing is, doing the timing belt is meaningless if the belt gets oil on it from leaking camshaft seals. I wouldn't say they are needed when doing the 100k mile timing belt change, but I would not wait until 190k miles.

Here is some discussion on which parts are needed when doing camshaft seals: https://www.matthewsvolvosite.com/forum ... haft+seals

[KingFatty]

I'm thinking of trying this procedure to replace water pump, timing belt, pulleys/tensioner, and serpentine belt on a 2006 XC90 2.5T.

My question is, to better understand why the camshafts and crankshaft need to be rotated into the singular positions indicated by the timing marks.

I'm guessing it has to do with the valve springs, and when the camshafts are in that position the valves won't push the camshafts around at all?

Because wouldn't it be easier to just make a line on each camshaft cogwheel and the camshaft, but extend that line onto the belt, so you have three marks that are exactly perfectly indicated on the belt.

You take off the old belt, and line up the new belt to copy the marks exactly to the precise tooth location, for each of the three marks.

then you put the new belt on and just line up the marks. I haven't done this before but mentally I keep thinking that would be equivalent to this procedure, except it wouldn't care whether the timing marks are lined up, like you could do it regardless of where the timing marks are?

Bottom line I feel like the new belt doesn't care where the engine rotation is, just as long as the new belt maintains the exact same tooth engagement between the camshaft and crankshaft cogwheels?

[chitownV]

There are numerous very good reasons why you should time or align the timing marks.

One, you have baseline to reference in case things get out of alignment. Being off by a tooth has happened to people because the VVT allows for some movement. If you are too off, then you can bend valves.

Two, belts stretch over time so marking teeth with the old belt vs the new could be off.

Good practice is just that, good practice. They develop for many reasons and lining up the timing is done for every single vehicle when ever a belt or chain is removed.

[abscate]

[Bottom line I feel like the new belt doesn't care where the engine rotation is, just as long as the new belt maintains the exact same tooth engagement between the camshaft and crankshaft cogwheels

Exactly.

The problem is the relationship between cogwheel and camshaft, in a VVT CAR like Volvos from 1999-, changes. The pulley moves on the cam about 3-5 teeth, very close to the threshold where the valves hit the pistons.

Set up the timing marks, going past them and back on a VVT CAR, whenever the belt comes off.

Speaking from personal experience, Once you have to walk the cams back from interference even once, you will never want to do it again

[KingFatty]

Any addendums to this DIY guide?

I read on another message board there is a tip to unfasten the engine mount on passenger side, to jack up the engine at an angle to make it easier to access the timing belt area.

Another tip on a video was to put paint marks on the old belt that go onto the cog wheels so you have exact per-tooth reference marks. Then transfer the marks to the new belt exactly on the same teeth counts, so you can visually confirm exactly the same arrangement when you put on the new belt.

Anything else to add?

[chitownV]

Always align the marks and the paint on the belt/cogs can be used as a backup in case things get out of alignment. I like to put paint pen marks on the actual timing marks so it is easier to see. Then as you check the rear cog/sprocket alignment (closes to firewall), use your phone to take a pic. The viewing angle is difficult to get a straight eyeshot and taking a pic will give you a straighter view as well as allow you to zoom in. Later, when you install the new belt, take pics again so you can feel assured things are aligned before starting up.

You can try to access the tensioners without raising the engine first. I took my bit to a belt sander to shorten it so it fits without raising the engine.

I would also suggest using Scotchbrite 7448 or 7447 pads instead of steel wool. The Scotchbrite pads are used as an automotive standard of practice and use either aluminum oxide or silicon carbide.
https://www.3m.com/3M/en_US/p/d/b40071748/
https://www.3m.com/3M/en_US/p/d/b40071750/

For safety, if you don't already have a 2.5 or 3 ton jack that has the lift for the XC90, it is safer to use a larger jack than to put a smaller one on two stacked planks of wood. The larger jacks also have a wider footprint making them safer and having a jack on the ground reduces the risk of wood planks sliding.

[cn90]

UPDATE:

- I wrote this DIY back in Nov 2017 at 110K miles.
- Around Nov 2021 (a few months ago), the front cam seals start to leak, a drop here and there on the
garage floor.

- I already bought the cam seals (Corteco) but don't have the time at this moment to replace the cam seals.
- So for those of you who do TB etc. at 115K-120K, you may as well replace the cam seals while there...

[chitownV]

Yup, done that. Need to get the cam locking tool online and watch how to mark & clock the VVT hubs on Youtube. Also get new camshaft seals at both ends of the camshafts, hub seals, and the end plug seals (the VVT torx covers). No need for the rear (driver's/left side) plastic covers because that's for non-VVT cams and is replaced by camshaft position sensors for the VVT. You will see in Youtube videos for S60s that there could be one VVT (not dual like XC90) and the non-VVT camshaft has the rear plastic cover.

Mentioned here for parts: https://www.swedespeed.com/threads/exha ... st-7602111

[abscate]

If you bought the cheap cam holding tool,throw the m6 bolts in bottom of the nearest lake. Get some real ones from Belmetric. This saves us hearing you whine about snapping them off in the back of your cam and having to take your engine head cover off

Yes, the more expensive one is less than the cheaper one plus the bolts. Funny how that works

[cn90]

Another UPDATE, this time it is a TB job on the 2007 S60 2.5T with 115K miles...

Talking about belt routing, coming from P80 (1998 S70 etc.), I always route the TB as shown
in VIDA and youtube video by FCPEuro:
- Crank ---> Idler Pulley ---> Intake Cam ---> Exhaust Cam ---> WP ---> Tensioner Pulley.

Well, the VVT makes it harder to do it this way (Counter-Clockwise approach) bc I don't have a helper to
help rotate the VVT all the way CW. Every time I route the TB this way, it pushes the VVT CCW, it
was very annoying.

After 30 minutes fighting with this CCW approach, I did it the CW way, it was much much easier!
Simple bc when the TB is routed this way, the CW approach helps tension the VVT Hub in place.
Try it this way and you guys will see it is a piece of cake...

- Crank ---> Tensioner Pulley ---> WP ---> Exhaust Pulley ---> Intake Pulley ---> Idler Pulley....
1-2-3-4-5-6 as shown.

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