172k LS1. Just started to get strange engine noise

**ScrapMaker** · 10-19-2008, 02:07 PM

Hey guys,

I have had pretty good luck with this engine. 172k and still running strong.

A few days ago, I drove with the windows up, and the A/C and blower completely off, because it got a bit cool outside.

I haven't done this since last February, probably. I either had the A/C on, or the windows down.

I am hearing a slight vibration/whooshing/detonation sound from the passenger side firewall. This is ONLY happening under heavy load--like accelerating in high gear, and not letting it downshift (A4.)

It is slightly possible that it is making the noise under heavy acceleration, but I cannot hear it over the engine and exhaust.

I cannot hear it without load. I have tried everything to reproduce the sound in the driveway, and I cannot. -- Also, it seems to get worse after my engine has warmed up.

I have caused the sound to happen in 2nd, 3rd, and 4th gears, but holding in those gears and accelerating under load. Under normal acceleration, I hear nothing out of the ordinary... Only under heavy situations, where I know my car is on the virge of wanting to downshift.

The noise has gotten significantly worse in the last few days, as I have been driving more and more with the windows up, so I can hear the sound.

The noise is not high-pitched like a normal ping, but it's more like an exhaust leak. I have never EVER heard of an exhaust leak that only leaks under load, and not idle/high RPMS.

I can cause the noise any time the car is under load, even at 80MPH, if I give it just enough gas to hold it in gear.

It's easier for me to hold the gear in my A4, because I have had it rebuilt for drag racing. Wider bands, shift kits, etc...

Anything you guys recommend? I am running seafoam through my car again, but I am so worried when I do it, because when I take off the break booster vacuum line, my car starts to "putter" and detonate... REALLY FREAKIN' BAD... I have never had any other car do this when I take off the line. Plugging it with my finger fixes the problem. -- I am not sure if this is somehow related, but it definitely does not seem normal.

The car is VERY due for plugs and wires. I have about 50-60k miles on a set of delco iridium plugs, and delco wires. (Recommended.)

The car is not running the best right now--has a bit of a rough idle, which I blame on the plugs. I had the intake removed and cleaned at the same time as my last plug swap.

I had my fuel filter replaced about 25k miles ago, and I ran SeaFoam through the brake booster vacuum line about 10k miles ago, hoping to improve some of this rough idle. When I first did this, is when I noticed the car acting up, severely after removing the booster line. After running the SeaFoam, the car started detonating like crazy, and would not turn off at the ignition. I thought it was a bit strange, but I turned the key back on and gave it a little gas, trying to clear up whatever was causing it... It stopped detonating, and I turned off the car.

So the seafoam really didn't do much on that last run, but I am trying it again, because I have had it work on other vehicles, and it's been almost 10k miles. I figured that maybe I put in too much seafoam last time.

The car still detonated like crazy when I pulled the booster hose, but I was able to pull on the throttle to keep it from detonating while I poured in the seafoam. I put in less than half the can, and stuffed the hose back on. The car was running nice, with a really low idle. I let it run for about 10 seconds, and turned it off.

I am about to go out and start it. (Which reminds me, last time I did this, the car pinged like crazy for about 20 miles of driving. This is after I let it smoke in my driveway for a while...

If you guys have any thoughts on the noise-under-load, or anything else that might help me with my high-mileage LS1, I would really appreciate it!

-Steven

**ScrapMaker** · 10-19-2008, 02:49 PM

update: I just drove around and it was pinging pretty bad, due to the seafoam, but once that subsided, I could still plainly hear the noise under load. I could describe it better by saying the car vibrates more during this sound, and its a low-rumble, mixed with a sort of 'whooshing' sound... like a mix between an exhaust and vacuum leak. Strangest noise I've ever heard. It's quite obviously coming from the passenger side... There are no traces of the sound on my side of the car... I can't hear it with the hood open, standing there, because other stuff is too loud.

If it's coming through the firewall mostly, and not reflecting off the ground, does that rule out exhaust leak? Could this be the passenger-side catalytic converter somehow? I know they run up in front of the firewall (sort of,) and I have thrown a code that claims my cat is bad, but I don't understand why this would happen under load only.

This might also help any of you clever folk--but a friend rode in my car last week, and said, "hey, you need your motor mounts replaced. My truck felt the same way, and when I did change them, it felt brand-new again."

I have a lot of vibration at a stop light, with the car in gear, but when I put it in neutral the car feels great again. This has become increasingly worse over the years... I suppose it could be the motor mounts? I am not sure if it would relate to this noise under load though...

So, thanks in advance if any of you can help me--I know it's a bit long, and I have multiple problems, but I'm looking to hold onto my baby until I die, whatever it takes. I just hope this isn't the sign of a bearing of some kind going out, because that happened to my 1990 V6 Firebird. One day, I started hearing this same 'whooshing' sound (like a wire brush, but THIS noise I am hearing now, is no where near as intense, and not as consitant.) Either way, within 4 days of hearing that sound, my engine spun a bearing and had to be completely rebuilt. Not much fun..

So thanks

-Steven

**JoshieDoom** · 10-19-2008, 03:19 PM

Plugs Wires and fuel filter would definately help. I have somewhat of the same issue and my tranny/torque converter is toast. It wont shift into second at WOT. I do have a drivers side cat and the passengers was cut off. Do you have any check engine lights on?

Does you engine flex a bunch when you rev it up?
Do you know if your tranny mount isnt broken? (common thing)
Do you run 93/91 octane gas?
Have you have your MAF cleaned?

Maybe you had an impeller or something break in the torque converter?
A lot of possible. Try having someone drive your car while you ride in the passengers seat and listen for the noise.Or have someone brake stall the car and get on the ground and listen for the noise(carefully.. lol)

It could be a lot of things.. I know I stay busy on my high mile LS1 as well... Two things break for every one thing that you fix.

**ScrapMaker** · 10-19-2008, 03:48 PM

Originally Posted by JoshieDoom

- Plugs Wires and fuel filter would definately help.
I should get this done ASAP, but I didn't see how it could cause this out-of-the-blue noise under load.

- I have somewhat of the same issue and my tranny/torque converter is toast. It wont shift into second at WOT.
I had the tranny/converter rebuilt 18k miles ago, so hopefully that's not my issue

- Do you have any check engine lights on?
I have a light that says my cats have failed. I have had this light for months. This noise under load is very recent, and scary

- Does you engine flex a bunch when you rev it up?
Yes, I don't know if it flexes abnormally, but the whole car swings left and right when I rev it, like all other V8's I have owned

- Do you know if your tranny mount isnt broken? (common thing)
I am 99% the tranny mount isn't broken, because I have had it recently replaced (for the 5th time.) I believe that my engine mounts could be broken, but when I get the shop to look at them, they say it's fine. I really don't think they look hard enough, but they are the stock mounts.

- Do you run 93/91 octane gas?
If I don't, I get detonation.

- Have you have your MAF cleaned?
Not that I know of. Is this something I can do myself rather easily?

- Maybe you had an impeller or something break in the torque converter?
I hope not, since it's just been rebuilt in the last few months

- A lot of possible. Try having someone drive your car while you ride in the passengers seat and listen for the noise. Or have someone brake stall the car and get on the ground and listen for the noise(carefully.. lol)
Sigh, I might just have to take it in... I have to take it in to get the plugs changed anyways, because, for the life of me, I have never found an easy way to change the passenger-side plugs... They are difficult to even see

- It could be a lot of things.. I know I stay busy on my high mile LS1 as well... Two things break for every one thing that you fix.
But it's so worth it!

I'm just concerned as this noise didn't really start up until the temperature change. It started a few days ago when it got (relatively) cold here in Texas. It has not gone away since, even though temperatures have risen again.

The sound is obviously coming from the passenger area.

What's crazy is that the SeaFoam did not put out ANY smoke from my exhaust. I have heard that means that it is really clean, or something. I might try running some more through, but I am petrified to hear my engine detonate like that...

**JoshieDoom** · 10-19-2008, 03:50 PM

How much flex? Mine does a bit but its to be expected with a high mile bird... I got a set of poly mounts to go in it...

**chuckie669** · 10-19-2008, 04:47 PM

I wouldn't keep running seafoam through your motor. I hear it's good sporadically, but you might end up doing more harm than good if you keep using. Maybe I'm wrong, but I thought that it's harsh and would be bad for seals.

**thearborbarber** · 10-19-2008, 04:57 PM

Exhaust leak possible (manifold to head leak)?

**ScrapMaker** · 10-20-2008, 06:51 AM

I just thought of something else..

The same EXACT day that this noise started, I also began to notice a strange vibrating/clunking sound when I start my car. It doesn't happen EVERY time, but about a third of the time. It's a metalilic rattle/clanking... I just assumed that my starter was on it's way out.

I wonder if it could be related?

Maybe it's not the starter itself, but a component that is dying, and vibrates/rattles at certain loads/RPMs...

ugh.

If it were the exhaust leak, wouldn't I hear it at other RPMs/loads?

**ScrapMaker** · 10-21-2008, 08:34 AM

I just found a shop around here that will swap a motor for $1200. They are Henderson Performance.

I told them my idea of the crate LS6 with a modified cam, and they told me that they would easily be able to do the EGR delete, as well as a dyno-tune. $350 for the tune.

So it looks like I'd pay about $3500 for the LS6 longblock, and another $2500 for the swap, cam, and other other foreseeable costs...

So, that would be $6000 for a 400(base) hp, and depending on what cam I get, it could be much more.

That is less than the dealer wanted to put in a replacement LS1...

**andrew rs** · 10-22-2008, 03:18 PM

Originally Posted by ScrapMaker

I just found a shop around here that will swap a motor for $1200. They are Henderson Performance.

I told them my idea of the crate LS6 with a modified cam, and they told me that they would easily be able to do the EGR delete, as well as a dyno-tune. $350 for the tune.

So it looks like I'd pay about $3500 for the LS6 longblock, and another $2500 for the swap, cam, and other other foreseeable costs...

So, that would be $6000 for a 400(base) hp, and depending on what cam I get, it could be much more.

That is less than the dealer wanted to put in a replacement LS1...

if your spending all that I would go 408 LS2...

**JoshieDoom** · 10-22-2008, 05:52 PM

408 LQ4... That is...

**ScrapMaker** · 10-23-2008, 12:37 PM

The guy at the shop actually mentioned the LQ4 as well.

$5-6K is really my limit. How much would it cost to get that other engine?

I'm looking for something that can be done quickly, and will put down 400rwhp with headers and good exhaust. Supposedly the LS6 can do that with the Z06 cam that comes in it.

I figured I would do the LS6 engine/intake, new injectors, (172K on them,) and move over my coil packs.

What would you guys do? Would the LQ4 work with my current computer/etc?

Thanks!

edit: keep in mind that I cannot/won't be doing anything myself. Just drop off the car, and let the magic happen. I don't have the time or the expertise to do anything like this...
-Steven

**bballking_2007** · 10-28-2008, 04:05 PM

how much for your old motor.

**ScrapMaker** · 10-30-2008, 08:31 PM

Originally Posted by bballking_2007

how much for your old motor.

They said that there are no core charges... if that is what you mean...

As far as I know, I guess they aren't offering anything for the old one... hrm... damn fine question...

**squee** · 10-30-2008, 10:19 PM

It could be the motor mount, but its unlikely. I'd say if it was, the reason its pinging and such is the motor is loose and the vibration/rattles set off the sensors. I've heard of the sensors being set off by stuff like that, so its possible. If you can, replace the motor mounts. $50 is better than $5000.

**bballking_2007** · 10-31-2008, 04:52 AM

are you willing to sell me your old one? was my question. lol

**RedVertTA** · 11-06-2008, 12:19 PM

With that many miles can't say I'm surprised.

Could it be a spun bearing of some kind? They're high pitched like what you were describing to be the sound.

**ScrapMaker** · 12-07-2008, 09:33 PM

Originally Posted by squee

It could be the motor mount, but its unlikely. I'd say if it was, the reason its pinging and such is the motor is loose and the vibration/rattles set off the sensors. I've heard of the sensors being set off by stuff like that, so its possible. If you can, replace the motor mounts. $50 is better than $5000.

Yes, I do have a bad motor mount. I swore up and down that my mount was bad, and the shop checked it once before. I sat there while they tried the "gas and break(brakes heh)" trick, and it looked fine, (even by my own eyes.) I told them that I was really, really sure it was bad--from my experiences. They got under, used some crowbard, and worklights, and it was obvious it was trash. So that could be causing some vibrations.

Originally Posted by RedVertTA

With that many miles can't say I'm surprised.

Could it be a spun bearing of some kind? They're high pitched like what you were describing to be the sound.

This is going to sound crazy, because it did to me--but the catalytic converters were STOCK on the car, with nearly 175K miles, (now,) and apparently they were beyond SHOT.

What's scary, is I came in for an oil leak AND the noises I was hearing. The oil leaks were CAUSED by the bad cats. Apparently if the cats go bad, they can cause intense back-pressure, and it does some wonky stuff in the engine. I had a dash light telling me they were bad, but I didn't know that meant it could make backpressure--I figured I would just fail the sniffer inspection test.

The worst part is that the cats are DEALER-ONLY, and I had no choice, so I ended up paying nearly $1,500 to get them both replaced. Once they were done, the car really had no more noise. It's whisper-quiet--well, except the the power steering pump and the water pump going out

The backpressure ruined my valve cover gaskets, I believe, because the leak started around the same time. It continued after the cat replacement, so I had to get that replaced too. I looked in the engine bay, and it looked like one hell of a job--and not being a mechanic, I decided I didn't want to tackle such an overwhelming job myself. It took the techs 3-4 hours to replace the damn gaskets... So many things had to be removed and set aside...

I am used to working on older cars... on my brother's 74 Nova, that would have been a 10 minute job.

So, 175, and my car is still going strong, but my Springs are awful, and I get a weird binding/grinding sound when I gun it from a stop. I believe it is related to the motor mounts and something in the drivetrain binding. I know it's nothing in the tranny, because it did it before AND after I had it rebuilt to drag racing standards.

I figure it's the motor mounts--moving the driveshaft to a strange angle, causing it all to bind, slightly--enough to make some noise. It is enough to keep me from ever doing it though. I get on my car all the time, but NEVER from a stop. I haven't burned out in 2+ years.

In unrelated news, my tires have lasted nearly 50,000 miles already.

**ScrapMaker** · 12-07-2008, 09:39 PM

Originally Posted by bballking_2007

are you willing to sell me your old one? was my question. lol

haha, sorry I didn't see this.

IF I end up going the $7k+ LS6 route, I can definitely sell this motor

I can't believe how beautifully it still hums along, and how much power I have on tap just crusing the highways--even without burning out or really dogging it from a stop light... I always have to get it going a little bit before I push it down about 75%. Any more than that and I break free and my suspension/drivetrain/mounts/bushing/who-knows gets very mad at me.

This car is fun, but definitely NOT cheap. I should have probably waited to get it when I was a bit older, and had more money to throw around. I find it is quite a bit of my income to keep this thing going. Although, as long as I don't have to replace the engine or differential any time soon, I should be set for a while.

I've owned it about 3 years and 1 month, and I've put on 90,000 miles. I've enjoyed every single mile.

**squee** · 12-07-2008, 10:23 PM

Originally Posted by ScrapMaker

What's scary, is I came in for an oil leak AND the noises I was hearing. The oil leaks were CAUSED by the bad cats. Apparently if the cats go bad, they can cause intense back-pressure, and it does some wonky stuff in the engine. I had a dash light telling me they were bad, but I didn't know that meant it could make backpressure--I figured I would just fail the sniffer inspection test.

The worst part is that the cats are DEALER-ONLY, and I had no choice, so I ended up paying nearly $1,500 to get them both replaced. Once they were done, the car really had no more noise. It's whisper-quiet--well, except the the power steering pump and the water pump going out

The backpressure ruined my valve cover gaskets, I believe, because the leak started around the same time. It continued after the cat replacement, so I had to get that replaced too. I looked in the engine bay, and it looked like one hell of a job--and not being a mechanic, I decided I didn't want to tackle such an overwhelming job myself. It took the techs 3-4 hours to replace the damn gaskets... So many things had to be removed and set aside...

To be honest, the crazy part is you actually PAID them that much to do that. Not being a mechanic and all, you could have easily bought a couple used cats off here or Tech and changed them in a couple hours. Its pretty damn simple really. Or, if you just HAD to spend $1500, you could have also bought a set of LT headers and a catted Y (yet again, a VERY simple bolt on thing) and said to hell with the stealership. Not to mention, I believe GM is supposed to cover the cats for 10 years. I've seen numerous people get them replaced for free from the dealers.