My '96 cruiser with 287,000 has a knock bad enough to throw a code for a knock sensor. The knock is rhythmic and increases on acceleration. In trying to determine if it's a bearing or something in the top end, I listened to the engine using a stethescope and a long screwdriver. My assumption is that if it's a worn bearing, I'd hear the ticketing on the low end, either by touching the block near the low end, or touching the upper oil pan cover.
Is this a correct assumption?
However, the ticking is loudest at the top end, specifically, the valve cover closer to the front of the engine. So I'm thinking it's something on the top end. (Valve clearances, something going on with the timing chain, etc.) I also listened to a few fuel injectors and they're loud when you listen to them through a stethescope, but I doubt it's enough to set off the knock sensor.
Other tests I've run:
Head gasket test: OK.
Leakdown tests: 5% - 7% leakage on all cylinders (which I interpret as good).
Visual inspection of oil - no evidence of bearing particles
If the problem is on the top end, I'll probably fix it myself. But if it's a bearing...not sure what I'm going to do. I know the definitive test for a bearing problem is to check each cylinder by rotating the piston just beyond TDC and pressing down with a screwdriver. If it "clunks", it's a bearing problem. If it doesn't, it's OK.
Just thought I'd ask people's opinions before I do that. What do you think?
Thank you.
Joel
Is this a correct assumption?
However, the ticking is loudest at the top end, specifically, the valve cover closer to the front of the engine. So I'm thinking it's something on the top end. (Valve clearances, something going on with the timing chain, etc.) I also listened to a few fuel injectors and they're loud when you listen to them through a stethescope, but I doubt it's enough to set off the knock sensor.
Other tests I've run:
Head gasket test: OK.
Leakdown tests: 5% - 7% leakage on all cylinders (which I interpret as good).
Visual inspection of oil - no evidence of bearing particles
If the problem is on the top end, I'll probably fix it myself. But if it's a bearing...not sure what I'm going to do. I know the definitive test for a bearing problem is to check each cylinder by rotating the piston just beyond TDC and pressing down with a screwdriver. If it "clunks", it's a bearing problem. If it doesn't, it's OK.
Just thought I'd ask people's opinions before I do that. What do you think?
Thank you.
Joel
