Hi, I have a 2000 p71. Lately, ive been noticing a ticking noise when the engine is cold. It is not constant, just when getting rolling. I baby the throttle when its cold, yet i still get this noise. My truck makes the same noise when i am lowing a heavy load and have not filled up on premium. Could this be preignition or something worse? I have always ran regular gas in this car and have never heard this sound. Do i need to run premium? I dont think i bought a bad tank of gas, as it came from mobile. I'm at a 1/4 tank right now and plan on filling up with premium tomorrow. Is there anything else i should look for/worry about?
It may be a slight exhaust leak. See if you can duplicate the noise when setting still by holding the brake an slightly accelerate. If you can,Llsten with a piece of hose near the exhaust manifolds and see if you hear it there. You shouldn't have to use anything but regular. I have a 2000 and I always use regular. They have not been known to ping.
Ok. I checked for exhaust leaks and I cannot find anything. The noise comes and goes, with drive cycles. I drove it yesterday and it was making a racket, but today it was quiet. Yesterday, however, it is was making these noises through all temperature ranges and it seems to be getting worse. Basically, it sounds like someone is shaking a spray paint can under my hood with any kind of acceleration. Even just a slight tap of the accelerator will cause a racket that can be heard over the blower motor on high. There is no noise when the rpms remain constant for a period of time. Any other ideas?
Have you checked for any codes? Autozone will for free. That may get an indication of what it could be. I've never heard a 98>up ping, but have had some exhaust leaks, though rare. Another thing can happen is the catalytic covertor fall apart inside. You can bang on them with a rubber mallot and see if you hear a rattle. Engine off.
Let me guess, the colder it is the worse it gets? Sounds like a diesel with any acceleration for the first minute or so after start up? Sound does not exist when outside temps are warmer?
Sounds like the same problems I've had with my last 2 GMC trucks. Bought my 98 with 100+k, drove me nuts the first winter I had it. General Motors told me it had to do with the aluminum pistons. They say the properties in the aluminum will change in cold temps, and will actually shrink the pistons, allowing the piston to rock in the bore. When the engine is started, the combustion chamber will warm the pistons and they will expand back to normal. Sounds crazy huh?
My 01 GMC has done the same thing since new. They say its normal...
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