Hi all-

My wife's 97 LX (100K miles) makes an awful knocking sound for the first few minutes until it's warmed up. The mechanic says its piston's slapping around but I'm not sure I believe him. It's had a recent tune and valve adjustment, and that didn't have any effect on the sound. Anyone have any ideas? Is this a common issue? I'm thinking of running a can of Techron through it, giving it an oil change and maybe trying a different viscosity. Any help would be appreciated.

 

I would argue against piston slap because piston slap is very difficult to year, & if it's producing the sound levels you're indicating the skirts would've shattered by now. My guess would be a rod knock. To test for this start the engine up & while it's making noise pull plug wires one at a time until the noise stops. Then repair accordingly. I don't know what Techron is but I assume it's some sort of oil treatment, motor honey, something like that. Sometimes these products work, there's no harm in trying. A heavier oil can help as well. I use 15w40 diesel oil in mine to reduce oil burning. while it didn't completely eliminate it I went from burning a quart per tank to 1/2 a quart every two so I'm happy with that. You might even get away with 20w50 depending on how cold your winters are. Another possibility is a bad oil filter. Oil filters have a one way check valve in them to prevent the oil passages from draining while the motor is off. This is done to reduce cold start wear. So i'd try that first, then do the plug check, then switch weights, then try the additive. If nothing helps you can either rebuild it or run it until it blows.
Let us know what you find out.
xmctech

 

Thanks, xmctech -- that's some great advice on what to try. I'll give it a go and see what happens.
- Rich

 

i would make sure that the timing was right.
a wrist pin will make an intermittant noise; dont know if its one that will go away when the car gets warn though.