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2006 XC90 2.5T Timing Belt Flew Off

Help, Advice, Owners' Discussion and DIY Tutorials on Volvo XC90s. The XC90 proved to be very popular, and very good for Volvo's sales numbers, since its introduction in model year 2003 (North America).
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SoapyCoyote
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Joined: Sun Jul 09, 2017 6:55 pm
Year and Model: 2006 XC90
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2006 XC90 2.5T Timing Belt Flew Off

Post by SoapyCoyote »

Hi all,

As you can see I'm in a bit of a pickle. Timing belt flew off and everything is out of time now. Here's how it happened:

There was a high pitched squeal sound coming from the back side of the engine (I had no idea what it was) so I ignorantly revved the engine to see if I could better figure out what was making the sound. Little did I know that it was the water pump's impeller grinding itself into the engine block. When it had ground itself deep enough, it stopped very suddenly which in turn caused the timing belt to fly off (at about 3000 rpm's) So yeah, my valves are probably bent and I should probably remove the head and have it serviced at my local friendly machine shop. But maybe I got really lucky? Anyway....

I have replaced the water pump and the timing belt and the idler pulley and the tensioner pulley, but it has occurred to me that I may have done it terribly wrong. I didn't use a cam locking tool and I didn't find TDC (or close to it) on the #1 piston. Is that the correct reference piston? Is that the piston closest to the belt?

Also, where should my cams be when I get said piston close to TDC? As of right now, I think I'm supposed to just have the cams on their marks (using the cam tool this time) and also the crank on it's mark (while close to TDC) and also since these are VVT I'm supposed to have some play in the exhaust cam sprocket so I need to line up the mark of that sprocket while holding it wound clockwise against its spring all while using a cam locking tool on the opposite side of the engine.... I think this is right. Can you guys please help me?
SoapyCoyote
Posts: 64
Joined: Sun Jul 09, 2017 6:55 pm
Year and Model: 2006 XC90
Location: Salt Lake City, Utah

Re: 2006 XC90 2.5T Timing Belt Flew Off

Post by SoapyCoyote »

Also, will this tool work? https://www.amazon.com/ABN-Camshaft-Cra ... tool&psc=1

I'll be sure to click on the amazon link here so MVS gets paid
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SuperHerman
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Re: 2006 XC90 2.5T Timing Belt Flew Off

Post by SuperHerman »

See this discussion: viewtopic.php?f=10&t=26251

Read the discussion and it will answer all of your questions. Similar situation for the most part. Also, you can make your own tool if you wish at least for the original attempt to look for damage. If you find damage beefier tools are usually required as the VVT pulley removal torque is extremely high.

I will note that you most likely have bent valves. I will also say that I think your approach of testing it out with another belt is wise, even though you most likely have bent valves. I just had a Subaru engine swapped when the mechanic stated a pulley went and the engine was bad. As he towed it to his shop and his price was cheap for the swap I let him do it. Afterwards when I picked up the car and the bad engine, I broke it down only to learn everything was fine and a new belt and pulley would have solved the problem. I hope your case is the same.

Other things you can do is pull the spark plugs and look into the hole for damage. Valve collision marks on the piston tops is a pretty solid indication of damage. Also note how many valve marks and where as a reference if you have to pull the head. If you have a USB or other type of "snake" camera you can look into the cylinder for damage.

I did a head gasket about a year ago on the 2.5T and it was not too bad.
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mrbrian200
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Re: 2006 XC90 2.5T Timing Belt Flew Off

Post by mrbrian200 »

Bent valves really aren't that big a thing to deal with, though anyone would prefer not to if they can help it. I understand. For a little perspective here's something a little more "involved"
Toy.JPG
Toy.JPG (65.46 KiB) Viewed 2311 times
Off a Toyota 5MGE engine I worked on for my sister nearly 20 years ago. She didn't have $ for machine shop service I recall lightly honing/deglazing the bore with a hand drill tool, replacing the broken piston, and new valve stem seals and two new valves merely lapped in. It ran fine until the body rusted out terrible about 5 years later. It used a little bit more oil after that but not enough to smell/see in the exhaust or cause problems.
The interesting thing was the metal that broke off the piston wasn't in the cylinder. Which means it shattered into tiny bits and pushed out the exhaust. There were only a couple minor collision pits on the aluminum head so it didn't last long in there.
SoapyCoyote
Posts: 64
Joined: Sun Jul 09, 2017 6:55 pm
Year and Model: 2006 XC90
Location: Salt Lake City, Utah

Re: 2006 XC90 2.5T Timing Belt Flew Off

Post by SoapyCoyote »

Thanks for the quick replies guys! @mrbrian200 wow that is amazing! I feel more motivated than ever to tackle this project now. @SuperHerman, that's good to hear that the Head Gasket wasn't too bad as removing the Head and replacing valves may be in my very near future.

Now my two burning questions are:

#1 which piston do I use to find close to Top Dead Center?

#2 What is the cam position supposed to be at when the engine is at (or close to) TDC? I'm assuming that the cam marks will be what I use?
SoapyCoyote
Posts: 64
Joined: Sun Jul 09, 2017 6:55 pm
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Re: 2006 XC90 2.5T Timing Belt Flew Off

Post by SoapyCoyote »

SuperHerman,

I read and re-read viewtopic.php?f=10&t=26251 and alas on the 4th post from vegasjetskier none of his images are viewable any longer. :cry:

I did find this video https://www.youtube.com/watch?v=o4uLvH151-c and it looks like it applies to this situation... your thoughts?
SoapyCoyote
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Re: 2006 XC90 2.5T Timing Belt Flew Off

Post by SoapyCoyote »

Also, I read this viewtopic.php?t=72757 which says I don't need to find TDC on my engine. Is that correct? How can that be?
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Re: 2006 XC90 2.5T Timing Belt Flew Off

Post by mrbrian200 »

Timing mark on the crank is the best way - if you can see it clearly. I had trouble making it out on mine but how easy/difficult that is to see varies by year/engine.
If you haven't pulled the VVTs off the cams I don't believe resetting the VVTs is an issue - so long as all three timing marks on the pulleys line up with the marks on the cover/block once the belt is on its good.

FCP has a decent video which includes showing how to line up the marks.


Since you will be manipulating the cams/crank that are all way off when turning anything and encounter hard resistance you will need to fiddle with changing the positions any or all three so that that pistons clear valves while you reposition it all back into correct time.
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Re: 2006 XC90 2.5T Timing Belt Flew Off

Post by SuperHerman »

I don't recall the exacts on the 2.5T, but on the 2.9, which I remember, when the Crank is set to the timing marks the engine IS NOT at TDC.

So the advice above to use the crank marks is how I would proceed. Near the end of the post I cited above Precopster, a man from down under, and I discuss the basics of engine timing. Even though I was talking about the wrong engine, the 2.9 rather than the 2.5T, the principles are the same. TDC is not required if Volvo provides you marks, which they have. The issue is whether your camshafts are 180 degrees off your crank shaft when they are at the marks. The bottom end of the engine only has 360 degrees, the top end (because it rotates twice for every one crank turn on the bottom end) can be off 180 degrees. (In a sense they have 720 degrees when the timing belt is attached.)

Without a timing belt on you just need to put everything into position at their respective marks and put the rear camshaft holders on as an additional measure. Right now your main concern is ascertaining whether you have bent valves. With the Crank at the mark, and if you want, the special tool in the starter hole to lock the crank - your timing will be correct up to the point of setting your VVT. (You can use a 3/8" extension as the tool to lock the crank via the starter hole)

The issue you may encounter, discussed near the end of the above cited post, is that some of the valves may hit the pistons as you rotate the cam into the correct position. Here you will have to play with the crank, back and forth movement until you can get the cam to rotate without hitting the pistons as you work it around to the timing marks. You want to keep the crank pretty close to the correct mark and after each manipulation and cam partial rotation move the crank back to its mark. You are turning both the crank and cams by hand, never forcing anything. The point which was never flushed out with Precopster, the man from down under, was whether the valves would hit the pistons when the cam was rotated and the crank was set at its timing mark on the 2.5T. (On the 2.9 it would not b/c at the crank timing mark all the pistons are down far enough where crank to piston contact is not possible. Precopster, the man from down under, advised that if this happens just manipulate the crank until the valves don't contact the pistons and you can rotate the cam as you work towards the correct cam marks. You will have to do this for both camshafts. Now if the 2.5T does not have one or more of its piston all the way up when the crank timing mark is set, like the 2.9 design, you should be able to freely rotate the cams only encountering the cam valve springs as resistance. I believe this to be the case as Volvo designs its engines all in a similar way, and if you end up having to pull your heads you can visually verify this, and then you can update us.

One caveat - you may have bent valves. Did you look down the spark plug holes to see if you can find any hit marks? Did you try sticking a camera scope down there to see if you have bent valves? If you have bent valves you may still be able to manipulate the entire engine to correct timing, but when you put the timing belt on and rotate the engine by hand you may have contact. It really depends on how bad the valves bent, if at all. The only true answer will be a compression test.

Setting the VVT can be difficult. The videos and numerous write ups discuss this and are a good resource. Many have read the VIDA instructions and had no issues, others cannot understand them. Some have gotten the timing right on the first try, others have failed. Several years ago, in the dead of winter, I brought my Volvo to have the water pump changed. The shop that did it, after three failed attempts at setting the timing was shocked when I brought it to a Volvo specialist to get it timed correctly and gave him the bill. After being accused of sabotage, I laughed at the owner and told him that was the craziest thing I had ever heard. I asked him why would I open up the timing three times and mistime it and then bring it to his shop three times and finally to a second shop? After thinking about it - he agreed and paid for the repair. Story is that setting the VVT is tricky. I got it right on the 2.9 and my 2.4T, but they had single VVT.

One thing of note - I don't believe you can cause any engine damage by having your VVT mistimed. You will have codes and poor performance.

Some one confirm????

So if you get stuck on the VVT timing, and someone does confirm, you can still do a compression test to see if you have bent valves even if the VVT is not set correctly. When one changes the front cam seals one has to remove the VVT assembly. If you take off the head to change the valves, you can replace the seals and leave the VVT on by sliding the seal off the other end - some use as a work around. Also, if you make your own tools, which usually bend when you try to take off the VVT torx bolt, you can work around this by sliding the seal off the other end and leaving the VVT assembly undisturbed. The VVT assembly has two parts, front adjustment are the 10mm bolts, and then the actual hub. Leaving it undisturbed makes things easier to time.

I hope that provides some guidance. Hopefully Precopster, the man from down under, will chime in as he really knows this engine.
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Re: 2006 XC90 2.5T Timing Belt Flew Off

Post by mrbrian200 »

I don't think he has to worry about setting the VVTs at this moment: He hasn't pulled the pulleys off the cams, in which case he need only worry about lining up the marks. If he ends up pulling the head to replace bent valves he has to remove the VVT pulleys from the cams. At that point he has to know how to set the VVTs because they aren't keyed to the cams and can be rotated freely on the end of the cam until you torque down the bolt, you have to make sure they are in 'reset/rest' position when lining up the timing marks before torqueing the center bolt down to the end of the cam.
The potential misalignment is between the hub and the camshaft. If you haven't removed the hub, so long as the timing marks line up after the belt is installed ECU will properly control the VVTs when you start it.
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