Hi everyone -- relatively new user here.

I have a 97 850 non-turbo sedan with about 232k miles on it (meticulously maintained ). Unfortunately when I started it yesterday in my garage, it didn't really start and just rumbled for .50 seconds, then shut off with a puff of bad smelling smoke from the tailpipe. The next crank/attempt to start the car sounded more like when a cylinder dies (long cranks mixed with short ones, but no bad mech noises), so with that awful feeling in my stomach I dove in to learn more.

-Compression is very low and ranges from 15psi to 60psi across all cylinders. In order it's something like:
1: 10 psi
2: 25 psi
3: 15 psi
4: 60 psi
5: 60 psi

-Using the cam pulley tdc mark as a reference (along with the whiteout from the last timing belt change), cylinder 1 is NOT at tdc (maybe an inch below) and the harmonic balancer mark is at about 90 degrees (3 o'clock) instead of noon. No damage to the belt, rollers or tensioner that I can see -- everything spins nicely while cranking with the spark plugs out. The timing belt, the belt tensioner, the tensioner idler and the idler pulley were all replaced with volvo factory parts at 225k in 2014.

So, how the heck did this happen? Has this happened to anyone else (belt slip a few teeth of out time, etc)? It has a B5254 interference motor, so I am planning for the worst (valves and cylinders collided, ie new car time) but hoping for the best (belt somehow slipped without valve damage, slip back into correct time and re-check compression).

Also, does anyone have any tricks for slipping the belt back into time the easiest way possible?

Thanks for reading.

 

I would not scrap the car before trying to fix it. First thing I would do is what you suggested, get it back in proper time and then do a compression test. You might be surprised to find it is back to normal. I think the reason you have low compression is because valves are staying open when they are not supposed to because the timing is AFU. Once it is properly timed again, spin it by hand a few times to be sure nothing is hitting. If that is ok, try doing another compression test. If after all that it is still low, pull the head and either get it re-worked or get a new head. Getting the head worked on should be no more that about $500. A decent junkyeard head will run about $300 or so. Hardly worth scrapping the car over $500 in work. Just my .02 though.

 

Thanks for your reply, Psaboic. I really don't want to junk it either (it's super clean) but I'll have to do some soul searching offline after I see if the valves are bent or not.

So, I still have two questions:

-Is there an easy way to re-time it without removing the belt, or is that a requirement?

-I need to do some more digging, but right now I don't see how the belt could've jumped. I forgot to mention that of course the aux belt was also replaced when the timing belt was replaced (and the belt tensioner, idler and tensioner pulleys as mentioned, 7k miles ago). The aux belt also spins fine while cranking with no plugs and the throttle closed.

 

The only way I know how to properly re-time it would be to remove the belt. I know that is time consuming but it is the best and safest way I know. The only way I know of that it could have jumped time is that the timing belt tensioner failed or was loose.

 

yep, first inspect the timing belt (or consider replacing - Conti's go for $15...) then you will want to replace the tensioner then follow the procedure for setting the timing when replacing the belt.