'99 Chevy 350 engine noise

[captmello]

I'm looking at a project truck. Its got 170,000 miles. Here's the issue.

When you start it up, it has a loud tick or tapping sound, I think its a valve train noise. usually after it starts the noise goes away but sometimes it doesn't. Sometimes you drive it a couple miles and the noise goes away.
Oil pressure is good according tho the dash gauge.

Any Ideas?

Thanks.

 

[TilliamWe]

Re: '99 Chevy 350 engine noise

Valve lifter? Slightly plugged up pushrod allowing a rocker arm to clack a little?
Also, sometimes the fuel injectors are quite clicky.

 

[captmello]

Re: '99 Chevy 350 engine noise

Valve lifter?

That seems to be the common thought. Sticking, I wonder if an oil additive might help? Maybe some seafoam to try to clean up the system.

Slightly plugged up pushrod allowing a rocker arm to clack a little?
Also, sometimes the fuel injectors are quite clicky.

I'm going to find out where the noise is. If it upper, heads, rocker and injectors, lower noise, lifter issue.

Thanks for the input.

 

[KYBOY]

Re: '99 Chevy 350 engine noise

check the timing chain, those click and clank sometimes to

 

[Bob_VT]

Re: '99 Chevy 350 engine noise

Be very carefull using stuff to clean the sludge in that engine. Loose sludge will block that oil pick-up screen.

My bet is on weak lifter or worse .....piston skirt.

 

[truckermatt]

Re: '99 Chevy 350 engine noise

my 98 chevy truck doess the same thing when temps are below 40 degrees... i was told a lifter or valve.... mine is on the drivers side...

I tried seafoam and oil change.. it went away for a while, but is back.... It only happens when the engine is cold.

 

[MikDee]

Re: '99 Chevy 350 engine noise

I heard it was piston slap? Don't know for sure.

 

[gss036]

Re: '99 Chevy 350 engine noise

Piston slap would be my choice. My 1999/early 2K had the same thing. I put up with it for 15K before I could get GM to exchange the engine. They tried to rebuild the engine, but w/new crank, etc, still did not go away. Put in a fresh factory crate engine and it went away. They were notorious for the piston slap.

 

[windsors03cobra]

Re: '99 Chevy 350 engine noise

Pretty sure the slappers were the LS based engines and not the old school 350 in this case. Any possibility its an exhaust leak ?

 

[TilliamWe]

Re: '99 Chevy 350 engine noise

I thought of the piston slap issue before I commented, but I certainly wouldn't described it as a "click or tapping sound", as mello did. That's why they call it "slap".
I agree with Bob_VT, be careful with engine cleaners, especially if you have any reason to believe the motor is sludgy inside.

 

[captmello]

Re: '99 Chevy 350 engine noise

I haven't heard of piston slap. What causes that? I'm going to listen to the motor this afternoon to see if I can tell if it's in the head or block.

If it was a "weak lifter" like Bob VT mentioned, What makes them weak. What could be done to check it? Change to a heavier oil? 20-50 maybe, see if that quiets it down?

The noise is definitely worse when the engine is cold.

Instead of seafoam, maybe some frequent oil changes with a lightweight oil, 5-30 to try to clean it up a bit.

Thanks to all for the input.

 

[Vlad D Impeller]

Re: '99 Chevy 350 engine noise

" Instead of seafoam, maybe some frequent oil changes with a lightweight oil, 5-30 to try to clean it up a bit."


I could'nt agree more, Seafom and other alike additives does a good clean-up, however they can sometimes play havoc with your emission cortrol systems.

 

[MikDee]

Re: '99 Chevy 350 engine noise

IMO, putting thinner oil in a worn engine is not a good idea, you just lose the lubricating properties as the engine gets hotter, nor is putting thicker oil in, binding up with the sludge already in there, so it can't get to vital parts when the engine is cold. I'm a firm believer in 10-30W winter, 10-40W summer, in my vehicles. Marvel oil, & Seafoam, as an additive, does loosen up sludge, & carbon, and keeps it in suspension, but not enough to cause engine failure. It also lubricates where regular oil cannot get to.

 

[Arabian180]

Re: '99 Chevy 350 engine noise

I had the same problem on my 98 Vortec 5.7 @ 96,000mi. Low oil pressure caused roller lifter to collapse & seize. The low oil pressure was caused by the intake gasket leaking coolant into the crankcase. (common problem on 5.7 Vtecs).
It is a PITA job to do, but pulling the intake and servicing the lifters is not something someone with a little mechanical ability couldn't do.

With 170,000 on the clock I would bet you're having the same issues.

Good Luck.

 

[windsors03cobra]

Re: '99 Chevy 350 engine noise

Badly designed o-ring on plastic frame gaskets and dexcool strike again huh ?

Castrol 20-50, a set of lifters and a lower intake mani gasket job. :redface:
Should the obligatory $700 dollar injector spyder be done as well.

 

[Arabian180]

Re: '99 Chevy 350 engine noise

Badly designed o-ring on plastic frame gaskets and dexcool strike again huh ?

Castrol 20-50, a set of lifters and a lower intake mani gasket job. :redface:
Should the obligatory $700 dollar injector spyder be done as well.

Exactly! Dexcool and plastic gaskets don't play well together. Let's not discuss the spider injector clusterfu*k going on under a two piece plastic meets aluminum intake. For 700 bones to upgrade it to something not much better. Why not? What the heck it's only money, If not the upgrade at least a new fuel pressure regulator as long as you get BOTH O rings seated properly. *sighs... Yep....
What the heck was GM thinking? I have been a GM fan for 40+ years but it's stuff like that, that makes me want to go another direction. If it weren't for emissions inspection that junk would be in the trashcan and a good ole 4150 DP 650 carb would be on it. Oh, And the ignition,, geeeez. Let's spit on GM ignition system for a few words.. Since when do we need a camshaft position sensor, a crankshaft position sensor AND a computer to tell when it's time to put the fire on the wire? Heck, With a slightly modified HEI you can spin that sucker to the moon and never worry about it.

Valvoline 10/40 and Lucas. My last Chevy. 68 swb ss had a million on the clock and was running when it left. I sure miss that truck. I hope my 98 ends up being as good. (wishful thinking? yeah,, I know)

 

[captmello]

Re: '99 Chevy 350 engine noise

I had the same problem on my 98 Vortec 5.7 @ 96,000mi. Low oil pressure caused roller lifter to collapse & seize. The low oil pressure was caused by the intake gasket leaking coolant into the crankcase. (common problem on 5.7 Vtecs).

I should have coolant in the oil if the intake gasket was bad, right? I'll have to check on that.

This is getting more interesting...why would one need to change out the injectors? $700??? For god sake this isn't a boat!

If there is no sign of coolant in the oil I'll start with some frequent oil changes.

thanks for the comments.

 

[MikDee]

Re: '99 Chevy 350 engine noise

Exactly! Dexcool and plastic gaskets don't play well together. Let's not discuss the spider injector clusterfu*k going on under a two piece plastic meets aluminum intake. For 700 bones to upgrade it to something not much better. Why not? What the heck it's only money, If not the upgrade at least a new fuel pressure regulator as long as you get BOTH O rings seated properly. *sighs... Yep....
What the heck was GM thinking? I have been a GM fan for 40+ years but it's stuff like that, that makes me want to go another direction. If it weren't for emissions inspection that junk would be in the trashcan and a good ole 4150 DP 650 carb would be on it. Oh, And the ignition,, geeeez. Let's spit on GM ignition system for a few words.. Since when do we need a camshaft position sensor, a crankshaft position sensor AND a computer to tell when it's time to put the fire on the wire? Heck, With a slightly modified HEI you can spin that sucker to the moon and never worry about it.

Valvoline 10/40 and Lucas. My last Chevy. 68 swb ss had a million on the clock and was running when it left. I sure miss that truck. I hope my 98 ends up being as good. (wishful thinking? yeah,, I know)

I Feel Your Pain! I had a 96' S10 pickup Vortec 4.3 V6 with all those issues myself, plus a balance shaft? Who needs a balance shaft??? the early V6's didn't have it?

 

[Arabian180]

Re: '99 Chevy 350 engine noise

I should have coolant in the oil if the intake gasket was bad, right? I'll have to check on that.

This is getting more interesting...why would one need to change out the injectors? $700??? For god sake this isn't a boat!

If there is no sign of coolant in the oil I'll start with some frequent oil changes.

thanks for the comments.

It may or may not be apparent or obvious on the dipstick. look on the bottom side of the filler cap for milky oil or water residue. Check the oil pressure while it's good and hot. If you can drive it for about an hour that would be just about right. It may show 40 or more cold but as it warms up and the oil thins out it will drop. If the cam bearings are worn it will drop alot when it's hot. I have run old 350 Chevys with as little as 8lb idle oil pressure but engines are alot different now. A hyd roller motor may not like 8lbs
The least I would be comfortable with in a vortec is 20lb hot idle.

The injectors don't have to be replaced or even touched. You can pull the intake without having to split it in half. (This is a Vortec right? )

With 170k on the clock it's hard to say if it's a keeper just by talking about it on a message board.

It may be a dynamite truck that just needs a lifter replaced or heck it may just need adjusting and not need any of this extra stuff that's been brought up. Anyhow replacing a lifter still requires the intake to come off.

Let your conscience and your abilities be your guide.
Best Of Luck.

 

[captmello]

Re: '99 Chevy 350 engine noise

Ya, its a vortec. It's in a one ton crew. Its underpowered but has been a good runner.

This truck had a valve job at 100k so those gaskets and orings are 70k miles old, right?

I hope its a sticky lifter.