Problem with my new truck..

derek_silverado · April 10, 2004

The deal on this truck is not finalized so I wanna make sure this is nothing major before papers are signed.

99 1500 5.3L - 75K

I start it up and it sounds fine. The problem comes when it is in any gear (including park and neutral) and I lightly touch the throttle there is this little tinkly sound. Kinda like a couple washers clinking together, or just a rattle maybe. It isn't very pronounced, but if you are listening you hear it. It seems to occur between 700-1000 rpms.

If it was an exhaust leak, it would be heard all through the rpm range, and not have such a "thin metal hitting together" sound - right?

The engine is still strong and the transmission seems to shift fine. The oil was changed 1K ago, and I just changed the plugs. The "hook" on the plug was fine, no deposits or corrosion, but the center electrode seemed very worn down. What does this say about the engine? Does this have anything to do with anything. I'm worried this sound could be a spun engine bearing or something. If it was a spun bearing wouldn't it sound god awful all trhough the rpm range?

What could this be?

-Thanks in advance

derek_silverado · April 10, 2004

I know this really isn't a big problem, but the fact that its my "new" truck and has a lil sound bugs me. Somebody has to know what it might be...

jobee454 · April 10, 2004

If it had a spun bearing it would be knocking and the rods would be trying to exit the block. My 2000 5.3 auto has the same sound. It sounds to me like its coming from the exhaust on the drivers side, right under your feet. I think its something in the cat on that side or a shield that is slightly loose. If the oil pressure is good and the oil is clean I wouldnt worry too much. I think other people on here have talked about this same noise.

derek_silverado · April 10, 2004

I had my dad listen to it and he said, "just low octane gas."

Think it may be pinging, I've never really known what pinging sounded like.

asepgrad98 · April 10, 2004

try to de-carbon the engine with some Sea-foam

Boogity3 · April 11, 2004

It could be a worn out fly wheel (really gets cranking at low RPM). Is it a manual or an auto? And about the plugs, they're just worn out. They get that way with hard driving after 50k miles. Doubt it's a blown engine bearing.

silveradodude · April 11, 2004

Does it have headers?

Plainsman · April 11, 2004

try to de-carbon the engine with some Sea-foam

Or your foot on the interstate

p3tweet · April 11, 2004

Can't say I've ever heard pinging in neutral or park, just under the load of acceleration.

When I picked up my truck the dealership was nice enough to put some "cheap" gas in yet I only knew it when I accelerated. Try a grade higher octane and see if you still hear it. I have no problems with 89 octane.

One thing it might be (this happened to a friend) is that the catalyst in the catalytic converter has come loose. You may be able to test this by rapping on the "cat" with a rubber mallet.

As an afterthought, the noise of the engine may be overcoming the "tinkling" sound after a certain rpm so unfortunately the noise might not be going away, just getting masked.

Let's hope it's just the gas!!

derek_silverado · April 12, 2004

Thanks for the replies.

It is an automatic to answer some ones question.

Sea foam huh? I don't think we have that around here, what's another effective decarbonation product - and are there any potential side effects?

And now it doesn't have headers, I do know that they can cause that lil pinging though b/c of unequal pressures (that is the cause - correct?)

Hope its not the flywheel - is there anyway to tell w/o ripping the starter off and turning it?

As far as a catalyst or baffle being broken in the cat:

That seems possible. Are their any oxygen sensors at the cat or after it? I can have it removed if thats the case, but I think the 99 would have a sensor at the cat. What if I removed it anyway and got an oxygen simulator? What problems would have the potential to arise with no cat and a o2 simulator?

Thanks

-derek

JamesB · April 12, 2004

A buddy had a similar thing happen on his Suburban, I think it was a '94. Turned out to be the heat shield on the catalytic converter. He just tack welded it back on.

James.

pacodiablo · April 12, 2004

It isn't worth the trouble to run w/o a cat. Replacements are under $100 (for many vehicles) and the truck will be able to run the way it is meant to. Not to mention cats clean up a lot of crap from the engine.

Like others have said, what you are hearing could be pinging. The Ranger does it, partly because it is only run on 87. Our old Ranger did it too on 87 (we usually ran it on 89). It really isn't a big deal unless it really bothers you.