C70 I fear the worst.....

[JonG]

I was driving my Wife's 2003 C70 yesterday. On the way home at a light the engine started making a terrible screech like a belt was shredding or something and then the engine stopped running. The engine will turn over but not start. I plan on taking the timing belt cover off later today to start tracking down the problem. is there anything else I should check? I'm wondering if an idler did fail and it threw a belt or of the belt shred. either way the sound was pretty horrid and I fear the worst.

[JDS60R]

Please take a few pics to post. I'm hoping for the best for you. If the idler did lock up I hope the belt stayed on ,or maybe jumped just a few teeth.

Either way, You will know once you pull off the belt cover and align the marks. If you jumped time over 3 teeth you can reset the timing and do a quick compression test to see if its time to pull the head.

If all the intake valves are shot the motor makes a different sound when trying to start. If the compression is gone it no longer sounds like pulses when turning over. Just sounds like an electric motor running. I do not suggest turning the motor over again until you have inspected and corrected the cam to crank timing relationship.

[abscate]

Heres hoping it was the serpentine belt and not the timing belt

How many miles and how overdue were you??

[JonG]

Thanks. Yeah it does have what sounds like compression when I last turned it over. I'll be on it later.

[JonG]

It's definitely the timing belt. I was able to see enough with a flashlight by removing the top belt cover. Based on the racket that when down when it broke I'm sure the valves are toast. Is there a way to check that doesn't involve removing the head or buying a new belt? The car was given to us with 130k miles. It's pretty rough. I was told the timing belt had been changed. It's now got 140k miles. If the valves are bent it's probably not worth fixing I'm guessing.

[JDS60R]

Always re seat the belt with the marks correctly and check for compression. If the belt broke it is most likely bent valves. You can
1. Buy the cheapest local belt and check compression.
2. Pull the cam cover and remove cams - then check for compression (remember the sealant is expensive and you want the car where it can stay,protected from weather for 2 weeks while you finish this job)
3. remove spark plugs and bring a cylinder to TDC ( not the mark on the crank - actual TDC) and do a leak down test
4. Use boroscope to inspect bent valves though intake or spark plug holes.
5.Remove intake and check for bent valves with flashlight.
6. Remove injectors from rail and try and see in little hole for bent valve.

There are more ways but they start to get silly er and more dangerous.

[bmdubya1198]

The belt couldn't have been changed too recently if it just snapped. Does it look like it just broke, or the idler pulley failed? Or can you even tell? And if it was just the belt that failed, what brand is it?
If the valves are bent or burned, it might be worth fixing, depending on how much you can get a good cylinder head for. Or you can tear it apart and replace each individual valve. It really depends on the condition of the car at that point. 140,000 is low mileage for a P80.

[JonG]

so I was slightly mistaken. I was able to really dive into it today. The belt didnt break but it looks like the tension pulley lost tension and the the belt came off. im not sure that better or worse but I can use the belt to see if I still have a good valvetrain. My question is what is the best way to turn the valve pulleys to their alignment marks without the belt attached? The rear pulley turns but the front wont. Thanks for all your help.

fwiw, the water pump feels way gone. its hard to turn and crunchy.

[jcdillin]

Still about the same, the front cam isn't turning because you probably have a few of the intake valves bent that are jamming everything up. At minimum you are looking at a head job and a few replaced valves.

[JonG]

does anyone have an estimate of what a head job and valves cost?