What is This sound from my engine?

[retiredsparky]

Does not sound like piston slap or rod knock. I am betting on either a sticky valve or a faulty lifter, especially since you said it sounded like it was high up in the engine. Weak valve springs will also cause this. If the oil was not changed frequently enough, a lifter or valve is the common result. You could try Mystery oil or other oil additive for 50 miles, then change the oil to see if a lifter is not pumping up all the way.

You can add a fuel additive to attempt to clean the valves chemically, if a valve is sticking.

If a previous owner has added a "Teflon" or other other type of oil additive that leaves deposits, noisy lifters are common. Those types of additives should be illegal! Mystery oil or other type of cleaner in the oil will help to remove this type of contaminant over several hundred miles. Teflon tends to clog small orifices like what is in lifters/lash adjusters.

 

[Michigan]

One more thing

When I put it in neutral and revved the engine, I can not hear the tick.

Just did some more research and in post 2 of this thread. The person says that would eliminate lifter tick. Idk http://www.gmtruckclub.com/forum/threads/strange-ticking-noise-during-acceleration.64129/

Looks like his problem ended up being manifold bolt. I'll have to further check mine. I looked at it and seen all the screws. Should I just check too see if their tightened?

 

[Tonyrodz]

Can't hurt. Give it a shot.

 

[Michigan]

If it's piston slap, is that a serious issue?

I've been trying to do as much research as I can on this. It's sounds like a Diesel engine basically as others have put it. On start up while idling and during acceleration it sounds like a Diesel engine throughout.

i don't know much about timing, I believe we have timing chains in a 2003 Tahoe? If so can this relate to timing needing attention possibly?

I'm going to get plates and insurance pretty soon and try a higher octane gas. Maybe 93 or just stick to regular 87 with either a gas cleaner like gum out or stp fuel injector cleaner. Anyone have one they recommend? Marvel mystery in the fuel maybe?

 

[SLCHOE]

Welcome to piston slap. Enjoy your stay!

 

[jfoj]

Look for the bolt heads at both ends of the exhaust manifolds. I would be the rear most bolts on each side of the engine have broken, the bolt heads will be missing. But also look at the front of the engine as well.

Exhaust tick is more prone when cold and on the throttle, some goes away as the manifolds warm up, some just quiet down. Usually hard to hear at warm idle, but will be obvious when slightly accelerating.

I had this happen on my 2005 Denali and bought the brackets to clamp the exhaust manifold rather than fight trying to remove the broken bolts.

 

[Michigan]

So I have some new details

Today I got insurance and plated the truck.

When I first started it in the afternoon it made the same tapping diesel like sound that it's been making

I drove it to work. I work 29 miles from home. Takes about 30-40 minutes without traffic. About 20 miles of it is freeway

I pumped fresh gas near my house and filled up the tank and threw some gum out fuel cleaner since I had one laying around. Not sure if any of this has anything to do with anything. Lol also I averaged 18.1 mpg on my trip to and from work. 58 mile trip so I guess the problem is not causing poor gas mileage

Anyways what I noticed is that the sound is pretty much gone when the engine is warm. When I got off the freeway I came to a light and when accelerating from the light I was listening for the sound and it may have been there somewhat but pretty much gone I would say.

Would this indicate or narrow down any problems you guys think this could be. That the noise goes away when engine is warm?

Did not have time to get it into a shop today

 

[jfoj]

Did you bother to pop the hood and just look to see if there is a bolt head on each side of the the exhaust manifold at each exhaust port?? Just count, should be 8 bolt heads on each exhaust manifold, the front and rear most bolts tend to break first. Usually the rear most exhaust bolt on each side of the engine.

So simple to rule in out out as a problem, not sure why this was not checked by now?

 

[Michigan]

Did you bother to pop the hood and just look to see if there is a bolt head on each side of the the exhaust manifold at each exhaust port?? Just count, should be 8 bolt heads on each exhaust manifold, the front and rear most bolts tend to break first. Usually the rear most exhaust bolt on each side of the engine.

So simple to rule in out out as a problem, not sure why this was not checked by now?

Yes i did check and looks like they are all there. I'm almost starting to think this sound is coming from underneath the engine bay. Probably not a good thing

 

[jfoj]

"Looks like they are all there". This does not sound very convincing, but you are in charge of collecting the info.

I would rule out any sort of exhaust leaks first, where broken manifold bolts, cracked manifolds, leaking pipes at manifold.

It could be piston slap or something else. Very hard to tell over the Internet without hearing anything.