Engine Knock

[jsforrest]

Just got back from a 3 day weekend to the Ozarks, beautiful weather, fall color pretty much at the top of it's game. Unfortunately, my engine has developed a knock.

I started hearing it last week and over the weekend it got a lot worse. I've heard 'spark knock' before and this is exactly what it sounds like but something's different. Below 3,000 rpm and above 5,000 rpm the engine is practically clear, but between 3 - 4500 it sounds like a sewing machine coming apart at the seams.

Changed grades of gas all weekend and it had no impact.

Could the timing have slipped?

Any suggestions?

[MadMerv]

How's the temp? Oil level? Check dipstick carefully for shiny flecks. Timing should not do this. If it's getting louder and louder, I'd say it is serious....bearing? I would drain the oil and look at it very closely.

[jsforrest]

It's using some oil, but none on the ground and no smoke. I don't like the sound of this. What am I looking for in the oil?

[sammm]

What am I looking for in the oil?

Metal shavings.

[trackdog]

There is a good chance you picked up some bad gas. Normally bad gas will cause detonation at low RPM's even under mild exceleration. If you suspect this then try some of the gas additives that are used for long term moisture prevention. You could also remove a gas line and pump some into a clear glass, but take caution if you do this as the fuel comes out extremely quick.

Gary

[SPETSNAZ]

I had the same trouble last week filling up Shell on 93 octane. Same trouble again with my GMC Denali with bad gas two weeks before but different gas station.I useSta-bil gas additive in my other cars which are park for week at time & have had no trouble.