v8nate92RS

I had my 77K mile 305 TBI Camaro in the shop yesterday for them to put in my Jet Fan Switch and Thermostat. They also replaced my whacky oil pressure unit. Ever since I got the car it has had a strange noise coming from somewhere in the engine really only audible at idle. It doesn't sound metallic, and like I said, it is heard strongly at idle sounding like a combination of a tap, tick, and puff. It does not get louder as the RPMs go, and I can't hear it during regular driving, only at idle.

My mechanic confirmed that it sounds like its coming from the bottom end of the motor towards the back near the bellhousing. My oil pressure never goes below the middle mark and at cruising speeds stays at the mark between 30 and 60psi (stock gauge). I have used 5w-30 Valvoline Max Life since I bought it. The guy gave me a can of some engine treatment that I put in to see if it quieted the sound. It quited my lifters a little more, but the noise from the bottom end is still there.

They didn't really seem too concerned about it, I was kind of in a hurry and didn't have time to talk much, so I will talk to him again today. I need this car right now until my GTO comes in, what do you guys think about this? Will I be ok, driving this car like normal?

v8nate92RS

Ahhh, no comments?

Token

At first it seems like it could be a spun bearing; is your fuel pressure completely steady at idle?

My next thought, this really sounds like a loose or missing or broken torque converter bolt. But then I see you have a manual transmission. So my third idea remains similar- it sounds like it's coming from the connection between the flywheel to the clutch/transmission.


I wish I could help.

v8nate92RS

Thanks for the reply man. Yeah, this has been eating at me since I bought the car. Its very strange, I can only hear it at idle or near idle, when I rev the car or under normal driving I don't hear the noise. Car consumes no oil, idles steady, and oil pressure never drops past the first yellow mark at idle and while driving stays between 30 and 60psi. The transmission makes all kinds of whiney sounds and the clutch needs attention for sure. So, I guess it is still a possibility it could have something to do with the flywheel, clutch, transmission to engine stuff. I have never heard a spun bearing or rod knock so I don't really know. But I thought they got louder with RPM and mine does not. Anymore suggestions from anyone?

Grizzly_Addams

My engine has a low end knock/tick, too. Since I bought it. I'm also leaking oil so I'm assuming its a rod bearing or the main bearing. I have not had it checked out yet.

sellmanb

1) Make sure your dampner is tight and not wobbling or missing a bolt or something of that sort.

2) Take off the inspection plate and make sure all the flywheel bolts are in (if thirdgen manual trans have inspection plates? Never seen them before... )


To Grizzly_Addams... an oil leak is more a sign of a gasket needing replaced than a rod bearing going out. A bearing w/ excess clearance will give you low oil pressure, not leak oil.

Check the typical places for oil leaks... intake manifold gasket, valve covers, oil pan, oil filter, and oil pan drain plug gasket.

Grizzly_Addams

I am leaking from the rear main and i have low pressure. Drops down to 20-30 at idle, goes up to 40-60 while driving.

v8nate92RS

Grizzly,

That is not low oil pressure, that is normal. Now, anybody that has had a rod or bearing knock/noise, what exactly did it sound like? Could you hear it throughout the RPM range or just at idle? Did it get louder with higher RPM?

Grizzly_Addams

Oh. Well, at least my oil pressure is OK then. But, i hear it at idle, and when I drive it gets more frequent. Not so much louder. Just seems to get w/ the RPMs.

sellmanb

Your problem sounds more like an exhaust leak my friend

sellmanb

I encountered several knocking rods actually. Mine was horrible at idle, it quieted out around 2500RPM (but made NO power) and just simply wouldnt rev out any higher then 3000RPM.

The knock sensor goes crazy if there's any knock and retards the timing like a ****....

though I gotta hand it to chevy... I dont know many other motors that with 4 of 8 rods bearings being spun could I still go 55 on the freeway and get home about 12 miles away from my house.

Grizzly_Addams

Exhaust leak? It's really a very clear knock coming from the engine. Could it really be an exhaust leak?

SLEEPER 86

sellmanb;
ditto on chevys always gettin ya home! only been stranded one time out of many!that was a thrown fanbelt in the middle of nowhere,found one in a farmers barn,and was back on the road in less than an hour!
v8nate;
go to a pharmacy and get a stehescope,pull the piece you would apply to someones heart and insert a bolt in the rubber hose(a little oil or vaseline helps).then start listeng to various areas of your motor until you pinpoint the sourse of the sound!
it's a very enlightening experience!just be VERY careful when you are around moving parts!no jewelry,loose sleeves,watches,long hair or nuthin!i've seen an aluminum flex fan do extreme damage to a friend's elbow.........
anyway i would get the cheapest one i could find,nuthin fancy needed,but if you can't find it with that,it's an exhaust leak.
Eric

sellmanb

Very possible.

The three most common "feigned knocks" are:

Exhaust leak
Flexplate/Flywheel broken
Spark knock ( too much timing, needs a tuneup, running too low an octane gas, etc)

I'd doubt yours has a broken flexplate or flywheel since you didnt say anything about it not running right, it just has a noise that you dislike...

spark knock would also make a big difference in your performance.


And while an exhaust leak will hinder your performance, it hinders your gas mileage more, and the performance loss isn't too noticeable unless it's a huge leak... most the time it's like driving around on a hot day kind of power loss... (because the air is less dense)


I'll concurr with Sleeper86 though, the best way to find out is to just get a stethescope and prod around... or take an old piece of heater hose and put it around areas and put your ear to the other side... and always use caution when working on cars, whether they're on or not... you never know when you might just happen to ground out the wrong wire or what be it and start the fan, or spin the starter on accident, etc...

Grizzly_Addams

Well, my mileage sucks ***.

My performance? Pfft. 4 cylinder cars kick my ***. It has no get up and go, especially at operating temperature.

I'll check with a stethoscope, and I hope it's an exhaust leak, because like I said, sounds very distinctly like a hard knocking in the engine.

88IROCZZ4

i had the exact same problem , turned out the bolts between the torque converter and flexplate where loose and made little egg shape holes in the flexplate so everytime i was in gear and at idle it would knock, once i was driving and everything was spinning it would stop. i see you have a manual and not auto, but it's worth taking a peek. good luck!

84z28350

You do realise this thread was 4 months old!?!?

Probably killed 2 motors since this one

88IROCZZ4

yea , but someone reading in the future may benefit ... when i was having my problem i searched all around the board and couldnt find one mention of checking the T/C bolts .. and actually found the problem by accident while under the car trying to see where an oil leak was coming from.