Hello everybody, new user here. My name is Mike, and I work at a shop here in NJ. I'm actually posting for a guy I work with. He has a 1998 Volvo XC70 that he bought with a broken timing belt. It had a few bent valves and he rebuilt the head and put a new timing belt and tensioner on it, and now it won't start. It has spark, fuel, and compression (though the compression is a little low), but won't start. Also when you crank it over it makes a popping sound like it is backfiring back into the intake. We were looking at it today, and it looked to me like the way the cams were times, it has the intake valves opening before the exhaust valves on the exhaust stroke, so I'm wondering if maybe something is messed up with the cam timing. He lined it up with the dots pointing to the corners of the timing cover so I don't know. Has anyone ever had a problem with a car not starting after a head rebuild? Is there maybe something stupid that we are all missing over here? Thanks in advance for any help.

Mike

 

One key thing is to make sure the Cam sensor wheel and the Dist. rotor holder are fitted properly to the back of the cams.
They will usually only go on one way. But sometimes people feel the tooth on the back of the parts seat and tighten the screw. But it might be 180 out. Which would make it sounds like you described above.

 

Well we got it running today. The cam timing was definitely wrong. The guy went to a junkyard and looked at another car to see where the lobes of the cam were at TDC, and the exhaust cam was off. He marked the cam gears before he took them apart, but now with the cam timing just approximated, he was able to get it to start. It runs real rough though, so it's probably off a tooth or 2, so he's just going to move it around a tooth at a time until it runs right. I don't know how this could have happened and have the car still run enough to break the timing belt though.

 

He might have bent another valve if it was off to much.