# Why does my LS1 sound like a diesel?!?!



## PnYeaTr (Aug 24, 2009)

I'm the proud owner of an 04 a4 with 60k. about amonth after i bought the car it made a slight knocking noise from wht sounded like inside the motor and has grown to sound like a deisel motor and the knocking has gotten pretty noticable from inside the car. It doesnt at all sound like a rockerarm or bent pushrod or any loud metal on metal on the valvetrain. Ive read about piston slap but its my understanding that it usually goes away with warm up. This noise isnt made at all on startup, but after a little bit of driving or idiling. and once in a while not at all. Also if i hold the rpms at about 2k for a few seconds then let off it stops momentarilly. Pretty rough idle as well. I'm stating to get worried and lookin for some help. Oiling issues? Motor mount?


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## vxssls1 (Sep 9, 2006)

sounds like a stuffed lifter
have you changed oils recently?


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## PnYeaTr (Aug 24, 2009)

I'm assuming it is a lifter but wouldnt it make the noise all the time? and yes i change the oil every 5k with mobilone. and have tried putting some lucasoil in with no effect.


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## PnYeaTr (Aug 24, 2009)

Nooo body has anything?! it starts when the engine is warmed up and after normal driving for a few miles, then is a constant, one speed knock. any input is appriciated!


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## Rukee (Feb 8, 2007)

bad lifter or bent push rod would be my guess.


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## QUIKSLVR04GOAT (Nov 24, 2008)

What octane fuel are you using? Ive heard fuel causing a knocking.... are u using premium?


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## PnYeaTr (Aug 24, 2009)

I've never used less than 91 octane. And if it were a bent rod or lifter wouldnt it make the knock all the time, especially before it warmed up before oil got to it? Ive never had either so i'm not sure. Motor mount maybe? the car only has 60k. I do have e couple small exhaust leaks, maybe the downpipes are knocking against something when it warms up? Thanks for the help guys. 
oh and last night i drove home from the movies via the highway and really got on it, hit about 130, and beat on it a little for the whole 10 mintue drive, and when i got home, it wasnt making any noises at all. I dont get it! its not to loud outside the car, but its definetly noticable from inside the cabin.:confused


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## QUIKSLVR04GOAT (Nov 24, 2008)

PnYeaTr said:


> I've never used less than 91 octane. And if it were a bent rod or lifter wouldnt it make the knock all the time, especially before it warmed up before oil got to it? Ive never had either so i'm not sure. Motor mount maybe? the car only has 60k. I do have e couple small exhaust leaks, maybe the downpipes are knocking against something when it warms up? Thanks for the help guys.
> oh and last night i drove home from the movies via the highway and really got on it, hit about 130, and beat on it a little for the whole 10 mintue drive, and when i got home, it wasnt making any noises at all. I dont get it! its not to loud outside the car, but its definetly noticable from inside the cabin.:confused


Yea thats all i use too. Yes if it were a bent rod it would be making the sound all the time. It could be a cheap or very expensive fix. i would suggest start out cheap, and try throwing a couple bottles of fuel injector cleaner through it. but to tell you really whats wrong with it. Somebody have to look at it unless it just magically disappears, oh yea but this aint a perfect world. HAHA id say try the cleaner. 

This is gunna sound crazy but take a screwdriver, a long one, leave your car running when its making the sound, take the screwdriver, put the tip on your motor where you think the noise is coming from, put your hand over the handle of the screwdriver and put ur ear on your hand so u can atleast locate the noise.


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## PnYeaTr (Aug 24, 2009)

Well thats just the same thing as using an mechanics stethoscope lol. which i am going to be doing, but i dont hear any serious knocking or ticking coming from the engine bay when it's running so it'd be a little hard. (with the exception of a wierd deisel sound) As soon as I get in the car and shut the doors its a noticable loud knocking, sounds like it's coming from where my trans and cats are under my dash somewhere. I just seafoamed the whole car and changed the oil, didnt make any difference, and my trans was serviced 12k ago and the fluid is still a clean red. I guess it's one of those sounds you guys would to hear to know what im talking about :/


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## wislergto (Feb 12, 2010)

I would try fixxing the exhaust leak first. An exhaust leak may cause the noise you are describing. Good luck !


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## PnYeaTr (Aug 24, 2009)

Thats my plan, just ordered the flowmaster catback/xpipe and will be deleting my resonators. I'm starting to think it is an exhaust issue. Since it is a wood on wood like knock and doesnt seem to fluctuate much with rpm. Just really hoping it's not a lifter or rod.. do NOT want to pull apart an elsewise perfectly good LS1! Especially considering you have to pull the heads on the stupid motors just to get to them. Oh and another addon, when it is making the noise i can turn the car off and start it right back up and it wont make the noise for a minute or two. I wish I could get a sound clip :/ thanks for the input everyone!


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## QUIKSLVR04GOAT (Nov 24, 2008)

PnYeaTr said:


> Well thats just the same thing as using an mechanics stethoscope lol. which i am going to be doing, but i dont hear any serious knocking or ticking coming from the engine bay when it's running so it'd be a little hard. (with the exception of a wierd deisel sound) As soon as I get in the car and shut the doors its a noticable loud knocking, sounds like it's coming from where my trans and cats are under my dash somewhere. I just seafoamed the whole car and changed the oil, didnt make any difference, and my trans was serviced 12k ago and the fluid is still a clean red. I guess it's one of those sounds you guys would to hear to know what im talking about :/


Yea its the same as using a stethoscope. but im country and dont have them fancy tools... lol. but The ticking is probably from an exhaust leak. If the ticking sound speeds up with the RPMs then i would bet its from a Exhaust leak. Probably headers or near the cats or the resonators. Good Luck! my buddy had an F150 that had that same sound. It was an exhaust leak from the headers. If thats the problem it wont take but 10 mins to fix.

Good Luck:cheers


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## FastFrank (Jun 12, 2009)

The symptoms you are describing sound to me like it could be a part of the exhaust is actually banging against the car somewhere. That would definitely be more pronounced inside the car, and may only happen once the exhaust has heated up the metal has expanded a little. Check your exhaust from front to back, and make sure that there is sufficient clearance between it and any part of the car.


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## PnYeaTr (Aug 24, 2009)

As soon as my exhaust comes in this week I'll get under the car and get a real good look at everything when I put it on. I'm still assuming it's an exhaust issue as well. I'll make sure all my manifold bolts are tight and so on. Thanks for the great input everybody.


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## PnYeaTr (Aug 24, 2009)

Just Took out my midpipes and inspected everything today. No noticable issues with exhaust. Everything put back together tight and RTV'd. Guess it's gonna be worse than just an exhaust issue. Motor mount maybe? It does speed up slightly with rpms, but doesnt really fit a bad lifter or rod description..


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## Rukee (Feb 8, 2007)

a motor mount is not going to cause a RPM related ticking. Can you post a video of the engine running and the noise you are describing?


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## PnYeaTr (Aug 24, 2009)

I made a video from inside the car and you cant hear it on my camera. But the video I made of the engine bay was very good, But it wont upload, it just says uploading for about 5 mins and then says invalid file. Is there any other way to get the video posted?


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## Rukee (Feb 8, 2007)

Upload it to youtube and then post a link. :cheers


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## GM4life (Mar 18, 2007)

PnYeaTr said:


> I made a video from inside the car and you cant hear it on my camera. But the video I made of the engine bay was very good, But it wont upload, it just says uploading for about 5 mins and then says invalid file. Is there any other way to get the video posted?


I use photobucket.


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## PnYeaTr (Aug 24, 2009)

best heard towards end of clip. I wish i couldve gotten a sound of the inside knocking. thats the one i'm more worried about.


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## PnYeaTr (Aug 24, 2009)

Well I just finished installing my new exhuast. didnt notice anything unusual under the car that would knock. It actually starts knocking sooner now and doesnt wait til the car warms up. I have a nasty burning smell coming from under my car, hoping thats just the new exhuast and vht paint breakin in.


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## PnYeaTr (Aug 24, 2009)

So basically my question is, What kind of knocking can be heard from inside the cabin but not outside? Anyone?


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## Rukee (Feb 8, 2007)

Is this your noise??

http://www.gtoforum.com/f3/knocking-19145/


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## 740tank (Mar 23, 2009)

I have a 04 gto the sleeve around the piston meesed up. the ring couldnt scrape all the oil off the sleeve on the way down so when it came up oil gathered on the piston and burnt off. couldnt hardly smell anything. oil sensore never went off so I didnt know it was low on oil. got low enough it scarred the crank shaft. if its just starting there is oil at the bottom end so it wont make no noise. but once warmed up oil leaves and gives the crank no oil. metal on metal doesnt do good with no oil.had to take the whole block out and have it resleeved. and fix the crankshaft. it would religously start knocking at 2,000 rpms good luck


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## PnYeaTr (Aug 24, 2009)

Sorry to hear that lol, but I dont think that's my problem, as I check my oil religiously and it's never low, and it knocks at all low rpms. I'm sure I'd hear it from outside the car as well. And no that knocking isnt similair to mine, I've read through that thread many times haha. Its a constant knock, not just 4, and it sure isnt coming from anywhere on the rear of the car. Thanks for the suggestions though, I know this prolly sounds confusing, thats because it is :confused. I have a feeling it's a transmission related issue, since its so easilyheard in the cabin but not outside. I have had the tranny slip on me a couple times..


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## PnYeaTr (Aug 24, 2009)

I just read on a bmw forum of a few people having a very similar sounding issue, ended up being their driveshafts, as they have rubber joints as well. Im going to check mine out tomorrow. Does anyone think this sounds plausible? It does made sense as to why I would hear inside more than out.


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## Rukee (Feb 8, 2007)

I wouldn't expect a driveshaft to make a noise when the car is parked and just reving the engine.


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## PnYeaTr (Aug 24, 2009)

Yes I thought of that after I made the post lol. Stupid me, obviously the driveshaft wouldn't made any noise when the car is in park. Flywheel or TC is my next venture to explore..


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## Rukee (Feb 8, 2007)

Maybe there's nothing wrong with your car and you just 'think' you hear a noise?
As long as this thread has been going....if there really was something wrong it would have failed by now, no?


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## GM4life (Mar 18, 2007)

I had a '84 Trans Am with a 350 in it that did the samething as you discribed. My ex-girlfriend overheated it by not listening to me(b#$$&). Well mine came from the bottom end like a rod or crank bearing. The thing would idle quiet and run smooth, but after the oil warmed up it had a random metalic knock just as you discribed. I drove that car for along time with a knock, just like it never had it. When I pulled the engine apart shure enough the bearings were trashed.


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## PnYeaTr (Aug 24, 2009)

The cars been making this sound for a while now, and no I'm not just hearing things, People that have gotten in my car with no more knowledge than how to gas up a car have asked me what the hell that noise is. But thats a good point, if it were serious it wouldve done something by now, as i drive it like normal every day. Which is why its more than likly something other than the motor. I've had a bad rod bearing before as well, and thats def not it. This is just one those annoying knocks you have to hear in person to have any idea what i mean i guess lol


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## Rukee (Feb 8, 2007)

Here's a thought, take it to a mechanic.


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## taz4141 (Nov 6, 2006)

sounds like a broken valve spring. be carefully you'll drop a valve on a piston game over. take the valve covers off. and inspect each valve springs. your looking for separation or fractures in the spring. also wiggle the rockers and see if any are lose. if you have a torc wrench remove the rocker arms and inspect each rocker one at a time.(RETORC AT 22 FT LBS) don't mix them up. and see if the lobs and rollers are still round. make sure a roller bearing didn't brake. this is the simple and easiest way to check for this noise. also before you take the rockers off wiggle each push rod up and down see if there any play. you should be able to inspect each side in 20-30 minutes. so plan on some time. also look at the oil reservoir and see if there's any metal flake or chunk's lying on top of the head. if there is don't start that engine again.


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## GM4life (Mar 18, 2007)

Rukee said:


> Here's a thought, take it to a mechanic.


:agree

People can keep throwing stuff at you all day and if you keep saying no thats not it. Then, what is it?


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