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2004 xc90 with a busted timing belt - head removal?

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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SuperHerman
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Re: 2004 xc90 with a busted timing belt - head removal?

Post by SuperHerman » Mon Oct 29, 2018 7:34 pm

One last items, if you do decide to buy the car. Pull the spark plugs and look down the hole to see if you have piston contact marks. If you have a scope even better. If it passes this test or you feel it is inconclusive, before removing anything more than required to replace the timing belt, put on a new timing belt and time the engine correctly. Then rotate the engine by hand to see if you have any bent valves. If it passes this test do a leak down and/or compression test (leak down better as you will be turning engine by hand and will lessen the chance of additional damage. Leak down test doesn't need to be precise, just rotate engine and see if each piston will hold pressure during an entire rotation. It will be obvious if a valve is bent as you will never build more than 20psi max during a full rotation - you will hear it leaking like crazy the entire rotation. Be careful you don't get clubbed or torqued during the process - a helper wouldn't hurt. You are spinning blind here because you cannot see the valve train - basically relying on the fact that at some point during the revolution the valves will all be closed for each cylinder. Repeat the process for each cylinder and take notes on which pass/and or fail and if you want from which side intake or exhaust or both so you know where to look when the head is off. Or as the head is coming off, stop once you get a hard fail - your choice.

Reality, if you can turn it by hand a compression test would be faster and easier. Pick your flavor.

You just want to make sure you didn't get lucky and get a car with a broken timing belt and no bent valves. Rare but it happens. I say this because I had a Subaru where my mechanic told me the valves were bent because a pulley went bad. After sourcing a new used engine and having it installed I got the car back with the old engine in the trunk. For giggles and lack of something to do I tore the engine down only to find out everything was fine except the bad pulley. No bent valves even though in 99% of all similar instances one gets bent valves. So I am just saying, sometimes one gets lucky and it is worth a shot if you are buying the timing belt part anyway.

precopster
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Re: 2004 xc90 with a busted timing belt - head removal?

Post by precopster » Tue Oct 30, 2018 12:41 am

Certainly worth a try....stranger things have happened
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