Tick or Knock?

Greetings everyone and welcome to my first ever ls1.com post. LOL

My story involves a 1998 Z28 that I recently purchased. I bought the car from a local Chevrolet dealership for a pretty good deal. The dealer said it was a local trade in and the individual had originally bought the car from them and had all the service done there as well. I checked the car over fairly well and even had a reputable mechanic look at it. I'm by no means new to F-body’s; however, this is my first LS1. The car ran and drove great so I bought it! It was the happiest day I've had all year.

After driving the car a couple of weeks, I decided to change the oil. The oil looked fine and according to the sticker on the windshield, was NOT due for an oil change yet. But, since the car was new to me, I wanted to make sure I was running my preferred oil and changing it properly. I've heard good things about Mobil 1 and have always run it in my SUV without any problems. So I headed off to the store to pick up some oil for my new car. I saw a new kind of Mobil 1 on the shelf, High Mileage 10-40. I figured that was just perfect for my Z28 since it did have 119,XXX on the clock. I go home, drain the oil, slap on a new AC Delco filter and fill her up. Start the car, well over 40PSI at idle, and I'm as happy as can be.

Now my story changes... After driving the car for another week, I start to occasionally notice an audible ticking sound at idle. Not thinking anything of it, I continue to drive. Well... after another week or so, I really start listening to this motor... I've heard that LS1's are noisy compared to other motors, but this particular idle tick is very audible. I've poked around under the hood using a mechanics stethoscope (aka rubber hose), and it sounds like its coming from deep inside the motor, towards the middle. It’s very audible underneath the car as well. This motor makes all kinds of noises, lots of valve chatter, definitely some piston slap on start up I think (tiny diesel sound) but this other tick is very distinct. It’s not a loud thumping, but more of a loose rattling sound.

It doesn’t make this sound when you first start the car, it only does it after the car has run for about a minute. It’s very audible from outside the car, but not inside. It increases speed with RPMs, but goes away when you rev just a little, then comes right back at idle. It goes away almost entirely once the car reaches operating temperature. It’s not audible at all while driving. It’s only noticeable at idle. It’s more noticeable at idle when in gear (probably due to lower rpms). What really bothers me is that my Fiancee has a Monte Carlo with over 200k miles and it has the exact same tick or knock at idle. I always assumed hers was a slight rod knock with that many miles and I usually just change the oil a little more frequently.

I realized I’ve said a lot, but I was hoping maybe you guys can point me in the right direction. I'm pretty sure it’s not an exhaust leak. I've also checked for loose spark plugs. I don’t think it’s a loose rocker (I've had one of those before). It doesn’t sound like anything pulley or serpentine related. I've also changed the oil again to some dino Valvoline 10-40 and no change in the sound, although it sounds like the valve train quieted down a little.

Any advice is greatly appreciated. I’m thinking about draining some oil and adding a little bit of Lucas this weekend to see if it changes the sound any. Someone please yell at me before I do this!

Thanks,

Jonathan

i have the same problem,i running royal purple and its still making noise then i put some lucas in it and the sound is still there.

I didn't read the whole post but was the car originally a Synthetic car?? i think it was with the previous owner... and going back to regular oil... you could of screwed things up... you should go get some mobile 1 synthetic 5 30... and a new filter and see if that fixes anything

read the whole post... :sillyme:

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Originally Posted by 2000SuperSportMaro

I didn't read the whole post but was the car originally a Synthetic car?? i think it was with the previous owner... and going back to regular oil... you could of screwed things up... you should go get some mobile 1 synthetic 5 30... and a new filter and see if that fixes anything

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I was under the impression that most all modern motor oils are compatible with each other, synthetic or not. I believe I read a post by an oil junkie called Sarge that said that. After all, how do they make sythetic blends?

If I'm mistaken, I will IMMEDIATELY switch back to Mobil 1 ASAP. The dealer did say they had used Synthetic when it was brought in for service. I did use Synthetic on my first oil change, although it was the high mileage stuff.


BTW - the most recent oil I put in was Valvoline Maxlife 10w40 "Synthetic Blend"

synthetics should be used alone. LS1's do better with synthetics and 93 octane. :D

So it's bad for the motor to drain all the synthetic and put dino back in? Even when you first switch to synthetic, there is always some old oil that gets mixed with it. I didn't intentionally mix them together, I just drained one and refilled with the other. You think that could be a problem?

no. thats not the problem. the other poster was refering to the dino oil itself being your problem... the slight mix isnt going to affect you.

Is it manual or auto? Manual could be the throwout bearing.

It's an Auto. I've also noticed a sort of rattle sound right before it shifts. Kinda like a marbles in a can. The tranny doesn't slip or anything... it seems very solid.

Other things I've noticed is its mostly audible on a warm restart... that is until you tap the gas, then it quiets down. If I let the engine warm up, then turn it off and sit about 15 minutes, when I fire it back up, thats when the ticking is MOST noticeable. Once I hit the gas though, it goes away.

Its really baffling me.... :dunno:
I'm starting to get used to it though, so maybe thats a good thing. It doesn't bother me nearly as much as when I fist noticed it. Otherwise, I REALLY love this car. Maybe I will post some pictures when I hit... what is it, 15 posts?

You could have a bad EGR gasket or Spark Plug boots not sitting properly. Right now I am in the same position. My car has been sitting since August and this weekend, I did a plug change, removed the EGR tube, swapped all plugs and wires and now I have the tick. Tonight, I will be getting a new EGR tube gasket and see if that solves the problem. After I make sure that all my wires are seated properly on the Plugs and Coil Packs.

MY car is M6 and I had/have a similar problem to you. Mine was only ticking when I engaged the clutch, so I figured it was a throwout bearing...had a mechanic look at it and he verified my pinion so I replaced the clutch assembly, slave cylinder, pilot and throwout bearings, and the noise is still there!!!

I've driven it since then, and it just seems to be getting worse. I can now notice it at all rpms even when driving...and it still sounds like a valve/lifter tap....not loud enough to be a rod knock imo...I'm gonna be changin lifters in a month or so and since I've had 3 mechanics tell me the same thing, it better be F#$*%@ right this time!!!

Also, mine used to just brely make a noise at idle, but now it makes noise at all rpms, and the weird thing is it goes away with a rev, but immediately comes back.

Good luck, cause this has been going on for me for abou a month and I'm getting a little flustered lol.

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Originally Posted by 01ws6er

MY car is M6 and I had/have a similar problem to you. Mine was only ticking when I engaged the clutch, so I figured it was a throwout bearing...had a mechanic look at it and he verified my pinion so I replaced the clutch assembly, slave cylinder, pilot and throwout bearings, and the noise is still there!!!

I've driven it since then, and it just seems to be getting worse. I can now notice it at all rpms even when driving...and it still sounds like a valve/lifter tap....not loud enough to be a rod knock imo...I'm gonna be changin lifters in a month or so and since I've had 3 mechanics tell me the same thing, it better be F#$*%@ right this time!!!

Also, mine used to just brely make a noise at idle, but now it makes noise at all rpms, and the weird thing is it goes away with a rev, but immediately comes back.

Good luck, cause this has been going on for me for abou a month and I'm getting a little flustered lol.

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Was the pilot bushing or bearing replaced when this was done?

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Originally Posted by FORD RECOVERY EXPERT

synthetics should be used alone. LS1's do better with synthetics and 93 octane. :D

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[B][/:true::true: BUT YOU WANT TO GO WITH 10/30 SYNTHETIC & STAY WITH IT.

Hey Guys,

I figured I would post a little update. I've done about 4 oil changes over the past few weeks "experimenting"

I've decided the noise is definitely something internal in the engine as the brand and weight of the oil does make a difference. Here's some of my results with different oils/additives:

Original oil in car when I bought it (unknown): No noticeable tick when I first got the car. When I changed the oil it did not seem thicker than your normal 10W30. I've bought cars in the past and when I did my first oil change it looked like syrup coming out.

Mobil 1 10W40 High Mileage: First noticed the tick with this oil... seemed to progressively get worse.

Valvoline Max Life 10W40: Tick seemed slightly more noticeable at idle. Still no tick at higher rpms and goes away once warmed completely.

Valvoline Max Life 10W40 w/ Lucas Synthetic Oil Stabilizer: CONSTANT TICK! The tick would NOT go away no matter how warm the engine was. Even with increased RPMS it was still noticeable! Needless to say I was a little concerned after a day of driving and thought the Lucas was going to FUBAR my motor. I decided to change the next day.

Penzoil Platinum 10W30: By far the best thus far. I barely notice any ticking and my oil pressure is actually a little better than with the Mobil 1. I just changed to this yesterday so I'm going to keep a close ear on it for the next 2 thousand miles or so.

In summary, I was thinking that the "thicker" oil would quiet down the motor some. That’s always been my experience in the past; however, it would seem the opposite is true with this LS1. Maybe I should opt for 5W30 my next oil change? Wouldn’t that be crazy if the GM recommended weight oil was actually the best for the motor?

My car has a slight tick as well but I think its a lifter. It only does it on start up then it goes away. I think that when the car sits the lifter empties out or something. Using thicker oil may be harder for the lifter to fill, just a thought. I'm pretty sure mine is a lifter though. Good luck guys

My '01 SS does the exact same thing described above... I think mine's a lifter. It does it while warming up, and thumping the throttle makes it go away for a few seconds. My first oil change really made it noisy (with Mobil 1 10W30), but after a little more use, it quited back down. No lack of power, no real issues at all other than the tick.

Mine also will get noisy at about 1300 rpm... and it's most noticeable under the hood slowly opening the throttle by hand.

I've also heard these engines are noisy, but it just seems a little excessive. I'm going to be cutting my oil filter open this weekend just to be sure nothing is tearing itself apart inside the engine.

No suprise with the Pennzoil Platinum....highest HTHS of all the oils you mention.....in other words...thickest film strength.....
I am curious though if you are hearing piston slap? Slap is built in at the factory due the piston skirt length being so short it allows the piston to "rock" in the cylinder....of course as oil film is built up it lessens as the engine warms up....if your hearing lifter "tick" I would AutoRX it....we ( folks at LS1.COM and me personally) have had excellent results with AUTO RX curing this.....follow the instructions to a T.....
http://www.auto-rx.com/

sorry tell you bro it has nothing to do with the oil what you have is bad rod bearing it needs to be replaced before you wear something else out. i bought my 98 Z about 6 weeks ago from a private seller on the internet, the motor was strong as could be and had 88k miles on it since new, i got an oil change and used 91 octane the highest i can find 'round here. About a 2weeks into i noticed a small ticking as well and that did the exact same thing as your quieted down with acceleration but got louder as you slow down so i drove about another week but then took it to the chevy dealer and they told me that it was the crank but that it would be 3500 i said that too much so i left and check in to a couple of shop around here and found out it was the rod bearing, so i got that replaced as well as a complete rebuild it was supposed to be back on sat. but i will get it back by this thursday. got to get ready for the cruises and the shows this memorial day weekend is la invasion may 23rd -26th in los angeles, ca.

I will say that when I first read the description and you said it sounded deep inside the motor I was thinking rod bearing but I don't wanna send you on an expensive goose chase especially without hearing it in person because it could be a couple different things. Have you had any mechanics listen to it and see what they think? What's the speed of the tick? Is it in sync with the top end of the motor or lower end?