My 97 Cad Catera has a knock. My mech. says it's probably a rod bearing, piston hitting head. Any other ideas?

Question

Can a loose timing belt alter the timing enough for the pistons to hit the valves? Engine runs smoothly and has good oil presure.?.

Answer 1

The cateras are know to be reliabilty nightmares, sell that can as sonn as you can.

Answer 2

I highly doubt that the piston is hitting the head. I'd suggest you get a new mechanic; that one's skills are suspect.

If memory serves, that Opel engine in your Catera uses a timing chain, not a belt. Timing belts don't stretch really; they break. Suddenly. Usually with catastrophic results. Timing chains can stretch but if the engine has been maintained properly it should outlast the engine. The auto tensioner will prevent any valve timing shift.

Without hearing it, it's hard to say what it is for sure. A slightly muffled knock under acceleration that goes away under slight deceleration is probably a rod bearing. If it's a continuous sharp knock that doesn't change with engine load, it's probably a failed camshaft.

Whatever it is, you need to get it tended to quickly. It's throwing junk into your oil system and clogging the oil filter in just a few miles after it's changed. Once that happens, the bypass valve in the oil filter will open and the crap will circulate through the engine and quickly grind everything else to bits. The best bet would be a factory-overhauled replacement engine. But do it before you have a catastrophic failure. If you throw a rod, there won't be any refund of the core charge on the old engine -- that could be close to a grand with that motor.

Answer 3

Possible but not likely. There would be other indications of failure as well.
Without actually hearing the noise, I have to rely on what you were told, so if your mechanic is reputable, you certainly do have a problem.
My recommendation would be to replace the engine with a crate engine complete. The cost for the engine is substantial, but when ALL the labor and incidentals are considered, it won't be all that much more than repairing the one you have, and the warranty will be MUCH better.

Good Luck