1998 S-10 LS - 2.2 4 Cylinder Engine

[ominousred]

My truck makes a loud clicking noise while the engine is running. I performed a coolant flush and I replaced the serpentine belt and the water pump.

I am having a hard time identifying the source of the sound but I have noticed that the noise stops when the engine revs over 3500 rpm. As soon as the engine slows down below that the noise comes back.

The noise isn't that noticable from inside the cab but it is very noticable to anyone standing outside of the truck.

Anybody have any ideas?

I will put a video link up later on tonight so you can see and hear the sound for yourself.

[bignasty50]

i had a 98 5 speed and it made the same noise. the only answer i could get out of anyone was that it was a factory defect and not to worry. they said that it wouldn't tear anything up so i guess if you can stand it drive it.

[ominousred]

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I just took a few different angles inside and outside of the garage so you could get a better grasp on the sound coming from the engine. I bounced the symptoms off a few other gear heads in the office and most people are saying it sounds like an exhaust leak. It sounds like metal on metal to me but they say since it sounds external it couldn't be a rocker arm or valve tap. Like I said...when I rev the engine over 3500 rpm the sound goes away. If it was a leak...why would the sound go away after I rev the engine up?

Also... sometimes when I accellerate, I will get stutter. It is the same stutter you get when you try to accellerate from a stand still in second gear instead of first...you engine kinda stuggles until it gets up to speed. Would an exhaust leak cause me to do that? It normally happens when going from 3rd gear to 4th and when I am cruising at 70 and I try to punch it while in 5th gear, the whole truck just kinda starts shaking. Not violently, but noticably.

I have also developed a small oil leak. In the 5 years I have had the truck this is the first oil leak I have ever had. This couldn't be a symptom of a valve leak?

The last time I did anything close to this intensive was a timing belt and waterpump change on a Dodge Stealth with a side mounted DOHC V6. My Dad walked me through the whole thing so I only have enough knowledge about engines to take them apart and put them back togther. I have no experience or knowledge when it comes to diagnosing sounds and symptoms.

Anyway...I am gonna crak open the Chiltons and dig under the hood and see what I find but I was gonna see if any of you seasoned mechanics had any insight.

I will post a page up about the work I do this weekend for anyone else who runs into this problem.

[OverBoardProject]

Good Job, ominousred! That's just the sort of thing that we want to see done for our advice. And welcome to Automotive Forums.

I'm 1/2 thinking that youve got 1 or 2 really bad lifters. But they would have to be really bad for that I've never heard Hydrolic lifters that were that noisy.

Other than that I don't know

[RahX]

check your harmonic balancer. theyre designed in such a way that if the inner hub comes apart from the outer balancing/belt drive the thign wont fly apart. itll sound like that. it sounds REALLY loud for a lifter and too tinny for an exhaust leak. take the belt off and grab ahold of the balancer and see if it flops back and forth.

[dmbrisket 51]

i doubt he has a balencer, its an l4, most 4 bangers dont get harmonic balencers on them, the crank simply isn't long enough to need one to keep it from twisting... to me i have to agree with obp, it sounds like a bad lifter, but being over the internet on a camera i cant say that its not an exhaust leak, but a bad lifter (or 2 or 3...) makes more sence to a power loss issue over the exhaust leak

[Smokefan20]

Sounds to me like you are about 5 quarts low!

[sector95]

To me, it sounds as if the valve train is getting low or no oil pressure. There's a lot of clattering....it wouldn't be just one or two lifters that have gotten sticky causing all that ruckus. I watched the interior shot, looking at the oil pressure gauge (I'm pretty sure it's in the lower left corner of the cluster)...I also noted the truck was not at operating temp so that may be a factor in why the oil press gauge didn't seem to move when going from idle to 3500rpm.

Does the oil pressure behave normally? When the truck is @ normal ops temp, what kind of PSI do you get at idle? Does the gauge move (show an increase in PSI) in response to engine RPM?

When did the truck start to make this noise? How long has it been going on? Was something done to it just before it started making the noise?
Does the truck make this sound all the time below 3500rpm?

What weight of oil and what kind of filter are you using? When was the last time it was level checked or the oil changed? These engines usually speicify 5W30 as the oil of choice with 10W30 used under specific conditions...don't use 20W50 or even 10W40. Filters are not equal...I use a Delco filter (Purolator and NAPA Gold are also good choices). Fram is garbage... and I would be suspect of any that come from any of the "Qwik-LooB" joints.

Hope this all (as in all the advice you're getting) helps.... If it were my truck, I wouldn't be driving it except maybe to my local mech or Chevy dealer. Expect the worst and at least you won't be surprised when they lay on the bad news.

mike

[brcidd]

I once heard one like this that the steel timing chain was rubbing the timing cover- because the tensioner had come loose-- check with a long hose -held to your ear- remove serpentine belt and run the engine- see if noise persists and if it is coming out from behind timing cover- If let go it can wear clear through the cover......

[RahX]

thats a good point. the guides on the tensioner wear off and its metal to metal. as for the oil pressure gauge, i have the same dash. with the engine temp as low as it was the oil pressure would peg and stay at 60 with little or no change till it gets driven. 4cyl or not, i have yet to see an engine without a balancer of some kind.

[gmtechnician]

Knocking/Grinding Noise With Engine Running (Replace Flywheel) #99-06-01-020 - (Oct 21, 1999)

Knocking Or Grinding Noise With Engine Running (Replace Flywheel) 1998-99 Chevrolet and GMC S/T Models
with 2.2 L Engine (VIN 4 -- RPO LN2) and Hydra-Matic 4L60-E Automatic Transmission (RPO M30)
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=644992&pubid=67#ss1-644992">Condition

Some customers may comment about knocking or grinding noises with the engine running. This condition could ultimately result in a loss of drive and reverse ranges, or grinding noises during starting.
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=644992&pubid=67#ss2-644992">Cause

The condition may be caused by lack of proper alignment between the engine and the transmission centerlines resulting from improper engagement of the transmission housing on the dowel pins. This misalignment causes the flywheel to stress and crack. The condition may be aggravated by the dowel pins being pressed too far into the cylinder block.

[gmtechnician]

does this noise go away with the serpentine belt removed and the engine running? if so then spin all pulley's and feel the roughness of the bearings.
Some of these engines had timing chain noise because of the tensioner faulty. But your noise sound very loud for that.

[gmtechnician]

This engine has a solid harmonic balancer and cannot make that noise.

[ominousred]

Man... I appreciate all the feedback. I dove into it this weekend and I found a lot of sh*t. I basically have the starter halfway out of the engine after stripping one of the bolts on the exhaust.

It's along story but before I upload all the photos and text...I want to have the car running so I can tell you guys for sure what was up. i took some good photos of the whole process.

I will post them up asap. Or should I say ASATIF - AS-Soon-As-Truck-Is-Fixed.