This Knock is Driving Me Nuts

[kodachrome9319]

The Wednesday before Thanksgiving I got gas at a Chevron, I bought 89 octane, full tank. The next day, when driving to my fathers house for Thanksgiving, my check engine light went on. I got to San Jose (like 40 miles), and when my brother opened the passenger door, I hear a horrid knocking sound. Mind you, the engine has been running for a hour at speed and is well warmed up.

I checked the oil level, it had some oil in it (not terribly much, unfortunately), but it was dirty. So, I got home, and went to a gas station, got a quart of oil, and put it in. The knock continued and the CEL light was on still. The next day when driving home from my grandfathers house, the check engine light magically went off, but the knock still existed. So, I got an oil change since it was due, hoping it might solve the problem. Nope. I went out for the day, did some photography crap, and talked to TangoBravo about it. He invited me over, and he checked it out.

He had no idea, except maybe its a bad tank of gas and the #1 spark plug wasn't firing properly...

The knock is nonexistent when the engine is cold, but once warm, it will knock at idle. I'll accelerate, and it knocks really loud between 1700 and 2200 RPM, then quiets down closer to 3K. Once past 3K, the engine noise is too loud to hear the knock. It also knocks really loud at freeway speeds and I take my foot off the gas to coast at 1800-2200 RPM.

I've got the gas light on and will fill up with 91 octane at a different gas station tonight, hopefully it'll solve the issue.

Any ideas? Tango told me about the bad cylinder sleeve issue, I sure hope that's not it, even though the whole truck is under warranty for another 7000 miles.

Thanks guys!

[Trail X]

What was the code?

[kodachrome9319]

What was the code?

I don't have a scan tool or anything and have been in a pinch to find free time to get it checked out.

[SteveTB03]

BOOM!!

My lil brothers TB had that problem also his engine blew up, had to get a new one.

[irishboy02]

BOOM!!

My lil brothers TB had that problem also his engine blew up, had to get a new one.

Love the positive encouragement

On that note, yea no its not a good idea to keep driving like that. Sounds like you have a bad knock which will only get worse. If you still have warranty take it to them asap (and by asap i mean make time, dont say your going to go after work).

Is it more of a high pitched tic or a bang kind of knock? Higher pitched ticking would probably be a valve issue or top end. Louder lower could be rod or seized piston or something in your block. You notice any power loss when driving or no?

[TangoBravo]

To me it sounded like a lifter knocking, I was hoping that he maybe picked up a tank of bad fuel but the knocking noise was really isolated to the front cylinder. So my other thought was maybe it is bad fuel and it fouled his plug they do need replacing anyhow so it is possible. Awhile back with my TB I did get some nasty fuel and three of my plugs were spent when I pulled them, my TB sounded like a diesel truck like a friken semi to be exact not the little diesel truck they normally sound like. After replacing the plugs I was good. His sounds different to me though, I hope it's nothing too major. Any help would be good thanks guys.

[SteveTB03]

Well I hope my post was a little encouraging to have him make time for his TB if it wasn't then it deserves to blow up on him.

But my brother got his knock one day (didn't tell me) and drove it for awhile with the knock and his description sounds exactly like yours does. Well he decided to check his oil and it was low so he bought some more filled it up and wasnt leaking. So he drove it and all of a sudden the knocking was followed by a river of oil and a big bang.

Just hope that if you don't have a warranty your problem is top end and not bottom end.

[kodachrome9319]

Love the positive encouragement

I was going to say that.

On that note, yea no its not a good idea to keep driving like that. Sounds like you have a bad knock which will only get worse. If you still have warranty take it to them asap (and by asap i mean make time, dont say your going to go after work).

I'd hate to keep procrastinating but I can't make any time, I'm taking care of my grandfather who had surgery a few weeks ago, and was just released last week. I've got this weekend free...

Is it more of a high pitched tic or a bang kind of knock? Higher pitched ticking would probably be a valve issue or top end. Louder lower could be rod or seized piston or something in your block. You notice any power loss when driving or no?

Ask Tango about the sounds, I've never heard any other knocks to compare it to... No power loss, which REALLY has me confused. I have a warranty, and I'm currently reading everything about it. I guess I'll give the dealer a buzz tomorrow. Really hope its nothing serious, it looks like I'll be moving in January...

[SteveTB03]

To me it sounded like a lifter knocking, I was hoping that he maybe picked up a tank of bad fuel but the knocking noise was really isolated to the front cylinder. So my other thought was maybe it is bad fuel and it fouled his plug they do need replacing anyhow so it is possible. Awhile back with my TB I did get some nasty fuel and three of my plugs were spent when I pulled them, my TB sounded like a diesel truck like a friken semi to be exact not the little diesel truck they normally sound like. After replacing the plugs I was good. His sounds different to me though, I hope it's nothing too major. Any help would be good thanks guys.

It could be an exhaust or intake valve that is bent and its causing a ticking sound. And your lack of oil proli jump started it even faster.

You should take off the head and see how it looks along with the springs, rods and all of that.

[TangoBravo]

I should note that I took his oil fill cap off and with the engine running you can see a bead of oil flowing as it should, the interesting thing is everytime that bead would pulse it was intune with the knock if that makes sence. And if you have ever heard a lifter knock that's really what it sounds like and with the fact that it is intune with the oil flow I was kind leaning that way with it. I am not a professional mechanic but I have built many a motor been doing it since Jr High so fixing things I am good with the diagnosis part not so much.

Also with the fact that he did tell me that he had a warrenty I wanted both him and I to do some research before we went any further ie. removing the head or anything that may void the warrenty.

[kodachrome9319]

Well, just called the local GM dealership, will bring it in tomorrow morning. Luckily its only a block away.

[TangoBravo]

Well, just called the local GM dealership, will bring it in tomorrow morning. Luckily its only a block away.

Oh good man, keep me posted.

[irishboy02]

Thats good that you can get it addressed quickly. If you werent able to get it done, i was going to suggest to run injector cleaner with octane boost to help clean it out a bit. Keep us posted and let us know how it goes!

[kodachrome9319]

Thats good that you can get it addressed quickly. If you werent able to get it done, i was going to suggest to run injector cleaner with octane boost to help clean it out a bit. Keep us posted and let us know how it goes!

You betcha... I do need to get gas, its below the E... I'll put 91 in and buy some injector cleaner.

Thanks again, guys.

[bartonmd]

My guess is cam chain tension...

Mike

[kodachrome9319]

Okay, post-half tank of gas update... Chevron 91 octane, and the knock is quieter. I'm almost tempted to drive it just a mile or two from home to see if it'll go away, and that it might've just been gas...

[MrSmithsTB]

I doubt it is the sleeve issue, but it's always a good idea to be cautious. The cylinder sleeve recall was only for 02 model years within a certain VIN range. Mostly ones that came off the line between Sept 01 and Jan 02. I fell within the range, and thought I had dropped a sleeve at one point. It turned out to be three failed plugs and a bad coil. I was bummed cause I kinda wanted a new motor.

[irishboy02]

Yea winter gas sucks. See if you can get your hands on a bottle of octane boost too, that can boost you up to around 103 youl get a better detination and maybe clear out some of that gunk. See what chevy says tomorrow.

[kodachrome9319]

I doubt it is the sleeve issue, but it's always a good idea to be cautious. The cylinder sleeve recall was only for 02 model years within a certain VIN range. Mostly ones that came off the line between Sept 01 and Jan 02. I fell within the range, and thought I had dropped a sleeve at one point. It turned out to be three failed plugs and a bad coil. I was bummed cause I kinda wanted a new motor.

See, I wasn't too sure about engine dates, mines a February 2003 build, on a 2003 model, so maybe... I dunno. Like the dude said, we'll see what GM says tomorrow.

[kodachrome9319]

So, due to family issues and financial reasons, it was put off until today, but the TB is over at FH Daily Chevrolet in the Goodwrench store... I'm looking forward to hearing what happened.