Posted: 5/12/2005 7:46:51 PM EDT
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I'm looking for info on a knocking noise in a 1990 GMC Suburban 1500 4x4 with a 5.7 V8. The noise is not terribly loud and is most noticeable when driving slowly by a wall, window down, where the sound bounces back off the wall. I have been told it may be piston slap but I haven't found any recalls or info on that year having this issue. I have found a whole lot of info on later modelGMC/Chevys having bad problems with this issue. Specifics on this vehicle are, it has 38,000 original miles, has always been well maintained, never abused, little or no off road use, no towing, a true "cream puff". The noise is evident at idle both cold and warm. It is most noticable when coming slightly off idle, raising the rpms. It runs and drives great, doesn't use any oil and the noise goes away or just isn't evident at higher rpms and cannot be heard while freeway driving. I probably shouldn't worry about it and several people have told me just drive it or turn up the radio etc.. but it just bugs me even though it really isn't causing any problems. Any suggestions ? |
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There have been complaints that are diagnosed as piston slap, but the noise is only noticable when the engine is cold. As an example, one of my vehicles is a Chevy Tahoe that I bought new in 1997. The first start of the day on colder mornings, I hear a slight knoccking noise that goes away once the engine warms up. GM says this is normal due to different metals and the rate they expand with heat. I have put over 150,000 miles on this truck with no engine problems so far. The noise is still there on cold mornings, but it does not seem to be a problem. You have to look at the history of the vehicle. Is this something new? If not, then use the standard ways of tracing engine noise. IM me if you need further info. |