Timing Belt Issue... Any idea how much damage?

firstvolvoS70 · Post by **firstvolvoS70** » 17 Feb 2010, 08:45

I purchased an '98 S70 from the original owner about 18 months ago. It had about 160K miles but tons of service records. Mostly routine stuff and nothing major. This lady was a fanatic about her car to include monthly detailing, religious oil changes, etc. Needless to say we felt great about purchasing the car for our teen daughter's first vehicle. And then yesterday I got the dreaded call... "dad, my car won't start!"
After I poked around the hood for a few moments and had her turn over the engine I realized something wasn't right. After looking at the timing belt cover I noticed there was a groove cut into the cover right along the path the belt travels. I removed the cover and realized the tensioner had failed and the belt was slipping off the gears. The belt had a lot of slop and was not tight at all. The obvious is the tensioner has failed. I reviewed the service records and realized the belt was replaced about 40K miles ago but no mention of the tensioner.
The car was running fine the night before when it was parked and has not started and ran with the belt loose and sloppy. Is there a chance the damage to valves and other internal parts of the engine is minimal since it wasn't running and hasn't run with the belt off or loose. I'm inclined to replace the tensioner and belt, set timing and see what happens? Any advice? Any testing or checking anyone can recommend?

Post by **vegasjetskier** » 17 Feb 2010, 09:29

firstvolvoS70 wrote:I purchased an '98 S70 from the original owner about 18 months ago. It had about 160K miles but tons of service records. Mostly routine stuff and nothing major. This lady was a fanatic about her car to include monthly detailing, religious oil changes, etc. Needless to say we felt great about purchasing the car for our teen daughter's first vehicle. And then yesterday I got the dreaded call... "dad, my car won't start!"
After I poked around the hood for a few moments and had her turn over the engine I realized something wasn't right. After looking at the timing belt cover I noticed there was a groove cut into the cover right along the path the belt travels. I removed the cover and realized the tensioner had failed and the belt was slipping off the gears. The belt had a lot of slop and was not tight at all. The obvious is the tensioner has failed. I reviewed the service records and realized the belt was replaced about 40K miles ago but no mention of the tensioner.
The car was running fine the night before when it was parked and has not started and ran with the belt loose and sloppy. Is there a chance the damage to valves and other internal parts of the engine is minimal since it wasn't running and hasn't run with the belt off or loose. I'm inclined to replace the tensioner and belt, set timing and see what happens? Any advice? Any testing or checking anyone can recommend?

Yes, there's a chance your engine is OK internally. The way to tell is as you've suggested: put on a new belt and tensioner to get the cams timed up right. However, before trying to start it, I'd see if you can crank it through by hand. If there's minimal resistance the valves are probably free. You can then try to start it. If you have a lot of resistance when cranking through by hand, stop (to prevent more damage) and then remove the head to fix it.

Post by **wheelsup** » 17 Feb 2010, 09:35

If it was cranked with the belt loose/out of time valves are bent. Good news is it doesn't mean the death of the engine, you can fix that fairly readily. A little expensive but if the car was cared for well worth it IMO.

Post by **polskamafia mjl** » 17 Feb 2010, 12:05

I agree, this isn't a death sentence for the car. The head can be salvaged.

Post by **Ozark Lee** » 17 Feb 2010, 14:32

Assuming that the plastic spacer is still in place on the top of the tensioner and since it didn't fail at speed I think your odds are very good that the motor is OK.

I would go Vegasjetskier's route. You can use a bungee cord to hold up the tensioner roller and rotate the engine by hand to check the cam timing. If it is off by more than a couple of teeth then chances are there is damage to the valves.

Assuming that the valves are OK then replace everything in the timing system - tensioner, belt, tensioner roller, and idler roller. In my case I always replace the water pump as well when I do the major maintenance which is at every other timing belt change.

...Lee

firstvolvoS70 · Post by **firstvolvoS70** » 22 Feb 2010, 19:08

Well... I got the parts today and reassembled, set the timing and tried to fire it up. NO GO! It sounds pretty rough. I would compare it to the noise of a dragging starter. I pulled the plugs one at a time and did the old fashion compression test of stuffing a rag in the hole and turned the engine over. No compression on at least 2 or 3 cylinders. One cylinder send the rag flying into the air. Not scientific I know but I didn't have a compression tester handy. Those new parts sure are nice and shiny but she still won't run. What's next?

Post by **Ozark Lee** » 22 Feb 2010, 20:20

Not scientific I know but I didn't have a compression tester handy. Those new parts sure are nice and shiny but she still won't run. What's next?

Yank the head. Everything will then be revealed.

A friend of mine that was a mechanic at the marina at the end of my cove once likened taking a head off to like opening a Christmas present - you never know what you will find.

Even if you decide to buy a used motor at the end of the day you are halfway there by removing the intake and exhaust manifolds to get the head off.

When removing the head use steady but firm pressure on the head bolts, they have been stretch torqued and they tend to break if you yank on them with the breakover bar.

...Lee

firstvolvoS70 · Post by **firstvolvoS70** » 23 Feb 2010, 15:25

Spent the morning(well most of the day actually) tearing down the engine. And there it was two nice little dimples in the top of each piston on the intake side. Bent valves on all 5 cylinders. Now to find a used head or have this one reworked. Any more suggestions?

Post by **Ozark Lee** » 23 Feb 2010, 17:37

The dimples on the top of the pistons are by design. What you need to look for is sharp gouges since they will create hot spots. If you have them you can use an Emory cloth to smooth them out.

You might be best of just getting a rebuilt head. Clearwater Cylinder Heads has a great reputation for quality and price. www.cylinder-heads.com Hopefully you have your lifters soaking in oil and in their original order.

Pictures will help us help you.

...Lee

firstvolvoS70 · Post by **firstvolvoS70** » 24 Feb 2010, 08:19

Pictures are attached... You got me on the lifters in oil and in original order. What are those consequences? I've already called and priced the head from the source you suggested. What else do you recommend replacing while I am in this deep? As I hope you can tell i am somewhat mechanically inclined just a little(or a lot) short on the technical knowledge side. Any and all information is greatly appreciated.