What is This sound from my engine?

[Michigan]

Hello everyone, here I am again

So I just recently posted in a different thread about a leak as can be seen here http://www.tahoeyukonforum.com/threads/help-with-leak-please.85548/#post-1032136

I recently purchased a 2003 Tahoe z71 with 178k miles on it. I knowingly made a mistake of buying on a rainy day and basically took no time inspecting the truck or having it inspected by a shop. I have little knowledge of inspecting on my own anyways but I took the guys word for everything being solid since I know some of his relatives. Figured he didn't want to screw someone he knows. In a separate thread that i posted the link to above I noticed a leak days after I bought it when the rain finally stopped.

In this thread I am asking about a sound my engine is making. I have not been driving the truck since i have not put plates or insurance on it yet. It's going to be a secondary vehicle for me in the winter.

So since I have not been able to drive it for long distance I do not know if the noise goes away but as of right now I can hear this noise when idling and I also hear it while driving around the block and stepping on the gas.

From listening to other videos on YouTube it sounds similar to other videos of lifter tick

My questions are.

1. Does it sound like a lifter tick?

2. If it were a lifter tick, can you usually hear the sound while driving or does it go away while driving?

3. Can this be a rod knock or exhaust manifold bolt that came off?

Sorry I know so many questions but I think I may have bought a lemon. The truck does look good cosmetically but seams like it has some issues. Hopefully not major.

Also if it is for sure in fact a lifter tick can I just keep on driving or does something need to be fixed? From research I see this is super common but not sure if most people just keep driving or try to fix. I plan on using Mobil 1 5-30. Previous owner just changed the oil with pennzoil synthetic 5-30

In the video you can hear the tick most from 26 to 36 seconds coming from the passenger side of engine.

 

[iamdub]

Too difficult to ascertain from that video. It sounds a bit too "deep" to be a lifter tap, but then it also kinda sounds not deep enough to be a rod knock. There's too many possibilities: lifter tap, piston slap, rod knock, spun bearing...

 

[Tonyrodz]

Doesn't sound like a rod knock or lifter tap .Rod knock I think would be much louder and lifter tap would be more like a tick, tick, tick .Can you tell if it's coming from the upper or lower part of the motor?

 

[ISU-152]

Listen for the knock with a stick of wood held to the motor in various places and to your ear. 2x2's work well but anything will do

 

[benski]

They also sell mechanic's stethoscopes for this purpose, about $20.00. But a piece of dowel or a long blade screwdriver will do wonders, and for less money.

 

[Larryjb]

Check your exhaust manifold bolts. They do make ticking sounds when loose or broken, and this problem seems so common I'd now check this out first. I've ordered 2 Kral kits for myself for 2 broken bolts.

Larry

 

[iamdub]

^^^ All good points. I have a mechanic's stethoscope I bought from O'reily Auto for around $10. I've seen the same at Harbor Freight for around $5. It's MORE than paid for itself at even the parts store price. After going as far as removing the dash and hood while trying to track down a loud chirping that sounded like it was coming from behind the radio, I left my truck at the dealer for 3 days/2 nights. After they gave up, I bought the stethoscope and had my girlfriend drive while I poked around with it. I pulled back the carpet and touched the tip to the trans tunnel and was almost deafened by the chirps when she started hitting reflectors in the road. We went home and I looked underneath where the firewall met the trans tunnel and heard the chirp when I bumped a heat shield. The edge of it ever so slightly scraped the firewall like fingernails on a chalkboard when the truck's body vibrated from hitting bumps. I bent it to have about a 1/2" of clearance and it never chirped again.

So, invest the $5-$10 and try to narrow down where the sound is coming from.

 

[sumo]

Could also be noisy injectors

 

[Michigan]

Doesn't sound like a rod knock or lifter tap .Rod knock I think would be much louder and lifter tap would be more like a tick, tick, tick .Can you tell if it's coming from the upper or lower part of the motor?

Thanks for all the replies

It sounds like it's coming from the upper side of the engine on the passengers side

 

[Michigan]

A little information to add

I just got in the truck and started it up after not starting it in two days I believe. It's 50 degrees outside and the sound was pretty loud (should have made video)

Anyways I drove it around the neighborhood for about 10 minutes and and the noise was obvious while accelerating. The warmer the engine got the quieter it got while accelerating but can still be heard but nowhere near as loud.

Oil pressure has been at 40 during idle and consistent while cruising around 25 mph. I seen it get up to about 60 psi when stepping on the gas a little.

By the time I got back home and let it idle it can still be heard but again nowhere near as loud as the cold start.

Does this rule anything out to you guys?

I've heard if it's a lifter tick then it goes away as the engine warms up but a buddy said if it were a lifter tick you should not hear it while accelerating. Not sure how accurate that info is.

Unfortunately whether this is serious or not I still have an oil leak to deal with. May be rear main seal or pan gasket from replies in other thread. I don't want to fix an expensive oil leak if my engine is not healthy but obviously won't fix anything till I get both diagnosed by a shop. In the meantime just trying to get as much info and education I can before I take it to a shop so I have an idea of what's going on and it looks like I have some knowledge so I don't get ripped. Lol

Thanks again

 

[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.