Weird valve train noise problem - a riddle

Brian D · 2004-06-17T04:59:40+00:00

Truck: 1997 4x4 K1500 heavy chassis with 5.7L Vortec V8, 75000 milesI bought this truck new and for years told everyone how they should'vebought a Chevy ...perfect all the time. In the last year however, I've hadto replace the alternator, serpentine belt, idler pulley, intake manifoldgasket, fix the hose fitting (crusty) on top of the manifold, egr valve,replace front discs, calipers and pads etc. Whew!Then, since the idle was ever-so-very-slightly rougher than when new, I rana bottle of Lucas brand fuel injector cleaner through it (full tank). About1/4 of the way into the tank following that, I started getting very loudlifter knock (scary loud) on the passenger side of the motor. Oil level wasfine and looked OK. Always have used Mobil 1 Synthetic, 5-30W as spec'd,changed at 3k mile intervals. This oil was about 500 miles from a change.The lifter noise would quiet down after running for awhile, or driving veryslowly with a very light pedal. Note that the coolant level was low and Ihad not filled it since I was out of Dexcool, but the temp gauge said theusual 185 F or so just like always.Over the next week, it got worse to the point where you could hear loudnoise from the entire valve train under the valve covers on both sides ofthe motor. So far, my mechanic (non-dealer) and the dealer had no clue andneither did I. I was so busy listening to the noise (and worrying to deathabout thousands of dollars in taking motors apart becoming necessary etc)that I never did think to check oil pressure so I have no data on that, evennow.On a whim, I changed the oil with my usual Mobil 1 and put a new filter likealways (Purolator Pure One), filled the reservoir with Dexcool. The motorstill knocked and made noise. When shutting down, a bunch of the coolantchugged into the motor so I refilled it. Again, a bunch of it went into themotor. Topped off with water and it's been stable and quiet (no gurglingnoises) since.The next morning, the motor started up and sounded...

Jun 17, 2004 20 Replies

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Demon 22 years ago

Funny oil analysis story. A diesel came into the shop, failed, the owner of the trucking outfit had a oil analysis done. Turns out the driver ran it out of oil and siezed it, dumped in whatever he could get his hands on. Cause the lab called back and asked if they usually run hydralic oil in their engines................... Busted. LOL

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