Hi All,

First time poster here. Tried searching for about a half hour, didn't find this issue, decided to post and see what happens.

My 2008 Volvo C70 is a beautiful machine! I had it running great! Just under 150k miles. Recent tires (140k), battery (110k), plugs (120k), both upper engine mounts, and starter. I knew I was overdue for timing belt replacement. Tires were chirping at the green lights by accident, I could pass with ease on the highway It was a warm summer evening with the top down when the radiator octopus hose gave way and allowed all my coolant to flow out, thankfully I was parked when a lot of the fluid came out. So, we finally got a rainy weekend here last weekend in Ohio so a friend of mine and I tore down the car and replaced a bunch of coolant related stuff (octopus hose, lower hose, thermostat, thermostat housing, coolant temperature sensor, coolant) as well as the timing belt. To get to all this stuff, we removed the air box, the computer/air filter contraption, the big turbo air hose thing on the front left of the engine compartment, the passenger side motor mount, the battery and battery box, the plug wire harness on the driver side including disconnecting the harness from all the connections on the top of the engine, and a few other smaller connections near the airbox and battery. We didn't touch the A/C system, and while we were there I wonder if I should have replaced the alternator as well but didn't touch that either. We also attempted to replace the lower motor mount, but the new part had a different thread size than the current bolt and so we pushed that fix to another rainy day.

Everything went reasonably well (the torque to remove the small screws on the phasers that the camshaft position sensors read a signal was super huge). We learned a couple of things, like I think I will remove that motor mount and jack the engine up every time I try to do any work on this engine.

But here is the problem. When we put the battery back in and connected the cables, there was a whirring noise from around the area of the computer and starter. It lasted about 10 to 15 seconds. The car started. It ran a little rough, it felt like it had an occasional miss on one of the cylinders at first but it evened out. We turned off the engine. We tried to restart it: it would crank but would not start. We removed the positive battery cable, waited a little bit, and reinstalled the positive battery cable. The car started, we kept it running, decided the gas might be old and so ran it to the gas station, kept it running, filled it up with premium gas, and drove it around some more; the performance was horrible at first, I used to be able to chirp my tires at the green lights, but now we have slow take off, slow acceleration, slow responsiveness for passing, etc. Drove it home. Parked it. It would not restart. Not even next morning. Cranks, but won't start/run. I believe if I remove and replace the positive battery cable again, it will start for me, but only once, not twice.

So now I am here sharing what I know hoping someone here has an answer? Did I fry the computer? Did we hurt something along the way with the timing belt replacement? Did we leave a connection undone?

Thanks in advance for your help here. Best, TommyG26

 

first step is to check the timing marks to make sure they line up. if all appears good, then think fuel, spark, compression. Not sure how changing the timing belt would fry an ECU, so I'd be more inclined to think you are not 100% timed correctly and may have possibly damaged a valve. I'd start with a visual inspection for any issues with wiring (were you near the coils?) /vacuum lines etc then consider doing a compression check For turbo engines look for a 150 PSI reading or so. If its low then that could indicate a cam timing issue or possible valve damage where you'd then do a leak down test.

 

We took off the timing belt cover and discovered we were off by a belt notch. We adjusted the belt and made sure we were dead on at all three places, put it all back together, and my car is back on the road successfully!

Thanks for the guidance!
Tom