Engine "cold" makes grinding-like sound...

[viperct2001]

Engine \"cold\" makes grinding-like sound...

This may just be the nature of the "beast", but I have noticed my 2001 RT/10 makes a quick 0.25 second "grinding" or "pinging" sound from the engine if I go WOT before the oil reaches "nominal 190 degree temperature". Actually, I can go 1/2-3/4 throttle and it does this as well. It only seems to do it for first 5 minutes of travel whenever I floor it, then it stops once the car has warmed up.

The sound is like if your car's timing is off or the sound you hear when you have "bad gasoline", i.e. pinging in the engine.

Although pinging is usually more continuous, whereas this only does it for a split second when I floor it. It's almost as if the same cylinder is firing again too quickly.

Best analogy I could make is that it sounds like the "crunching of dead leaves".

Any ideas? or is this normal

p.s. Yes, I know I should wait for engine oil to warm-up before getting crazy. And I do for the most part. But honestly, it seems to happen even if I only "mildly" push the accelerator to just 3900RPM.

 

[Steve-Indy]

Re: Engine

I cannot REALLY answer your concerns...but would add that oil temp lags WAY BEHIND water temp in my experience driving high performance cars with BOTH gauges...(Ferrari's, Viper SRT-10). Specifically, on a day with ambient temp 50-70 degrees, driving in the neighborhood slowly in first gear with 1500-1800 rpms, water temp reaches 190-200 degrees within first minute and a half, while oil temp does not move. With ANOTHER 20 minutes around town (up to 2500 rpm), oil temp reaches 160-180 degrees. In other words, seemingly rapid water heat up in aluminum engine (our Gen II's warm water faster than Gen I's) may give one a false sense of comfort as to the temp "engine innerds". This makes quite a difference to me personally as to long term engine health.

Can't help but remember the Beechcraft checklist warning concerning WAITING for oil temp to rise BEFORE applying take-off power !!!

 

[Ron]

Re: Engine

My engine does not ping ever (93 octane), however if you vary your octane on your next partial fill, (up or down) and notice any changes you'll see if it's really pinging or not.

Would think that you would be more likely to experience predetonation when hot rather than cold. Maybe it's a loose heat shield. Try a cold rev or two in neutral with the hood up and someone listening for location.

 

[Jack B]

Re: Engine

I have to second that, 4000 rpm (3900) on a cold engine is pushing the envelope. Here is a stretch, clogged fuel filter that initially restricts the fuel flow (enventually starts to flow). The PCM is asking for an initial rich mixture and the pump cannot supply the fuel under acceleration and you get detonation prior to the PCM retarding the spark.

 

[Viper Specialty]

Re: Engine

I have a Ron Davis Rad with the internal heat exchanger, and Oil temps keep up pretty steadily with the Water temps now. However, as a rule of thumb, I always wait for the fan to kick on at least once before I take the car out and drive it anymore than 2K RPM or so.