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2005 Saab 9-2x (Impreza) Engine Problem

I recently had the following work done or replaced on my 2005 Saab 9-2 X -

Timing belt kit and water pump replaced
A/C Belt
ALT/P/S Belt
Front Camshaft seal Kit
Front Camshaft seal

Everything was fine for a couple of weeks. A few days ago my car started shuddering on the highway and the check engine light came on. I was out of town at the time and took my car to a different service garage. They found that “Cylinder #3 was miss firing and had very low compression, only 20 psi” They suggested I may need to find a used motor to have installed…

I arranged to have the car transported home and dropped of at the shop that performed the original work.

Is it possible that the current problem could have been caused by the previous work being done incorrectly?
Or should this possibility of this problem been noticed when the previous work had been done?

Thanks for the help.

It would help to know if the 20 PSI compression was due to a valve problem or piston ring problem.
It would also help to know if the belt replacement was done as part of a normal maintenance procedure or if it was done after a timing belt broke.

Generally speaking, a problem with very low compression that develops suddenly is due to a problem in the valve train. It could be that a valve tightened up due to tight valve lash and this problem may not be related to the timing belt job at all.
Assuming for the sake of discussion that this is a cylinder head valve problem that is certainly no reason to replace the entire engine. If there is damage to a valve face/seat due to incorrect lash this could possibly be corrected by setting the valve lash (intake valve) or by possibly performing a complete valve job. The latter would be true in the case of a tight exhaust valve.

With some blanks filled in it’s possible to be a bit more precise in any advice but hope some of this helps.

ok4450 - Thanks for the reply!

The timing belt was replaced do to an oil leak from the cam seal. Oil was leaked onto the timing belt and it was ruined…

I’m really not sure what is the cause of the low compression. All I have is the brief note the service tech left on the invoice. I’m pretty car illiterate, that combined with the potential of being stuck carless hundreds of miles from home meant I didn’t really follow what they were saying was wrong with the car. The shop seemed to be a bit unsure as to what the problem was and I wasn’t prepared to pay them to investigate further.

Mostly I wanted to try to gather some info so that I felt a bit more educated on what could possibly be going on when I take the car back to the shop that replaced the timing belt. I wanted to make sure that if they told me the previous work and this current problem were in no way related I could follow what they were saying and feel comfortable in moving forward.

Thanks again.

If the shop went so far as to run a compression test and tell you that the one cylinder had 20 PSI then they should have carried this a step further and determined why it was 20.
This would have only taken a few more minutes.

If the 20 turns out to be correct then I would inspect the valve lash and adjust as needed. If an intake valve has tightened up this is often surviveable once adjusted. If an exhaust valve has tightened up then it’s debateable as to whether the engine’s top end survives even if adjusted to specs.
It doesn’t take long for valve face or valve seat damage to occur with a valve held open a few thousandths of an inch. Once adjusted the engine may run fine but it’s unknown how long this will be so as that microscopic damage will likely grow over time and miles until the compression drops again.