Tweet
Well, my idle was always kinda noisy, but seems to be getting worse. I guess the best way to describe it now is that it sounds a bit like a diesel when I first start it up. Sometimes after driving it quiets down, but always seems to come back. The engine runs fine as far as I can tell and it still getting good gas mileage, its just the idle that is loud and a bit rough and wonky. It started after doing the last oil change, I started the car up and I'm pretty sure one of the pistons slammed against the head. Anyone got any thoughts on what it is?
-
Last edited by Sidewinder; 06-25-2009, 12:40 AM.
Dual Outlet Exhaust with Resonator Delete, Front STB, Rear STB, GMPP Trailing Arms -
Sound more like valve train or deep knocking?
Deep knocking - mine has some piston slap on start up, only can hear it if you get your head down to the ground.
Other sound, it went away when I changed the timing chain and guide. Before I thought it was lifters..
I doubt the piston hit the head unless it broke off... lolsigpic
New 2010 project (click image)
1994 3100 BERETTA. 200,000+ miles
16.0 1/4 mile when stock. Now ???
Original L82 Longblock with LA1, LX9, LX5 parts
Manifold-back 2.5" SS Mandrel Exhaust. Hardware is SS too.
-
Sounds more like valve train, I'll get a video of it tomorrow when its not 1am just so you get an idea of what it sounds like. The piston hitting the head was the best way I could describe it because that's what it felt and sounded like. When I started it up it jerked and it sounds like a piece of metal slamming into something, after that its been loud. Its always had some noise but its much worse now and its idling rougher than usual as well. I've had a few cases of random really rough idle recently where it sounded like something had broken inside and was slamming against another part of the engine, then it smoothed out and was fine.
Hopefully some of that will help too.
Dual Outlet Exhaust with Resonator Delete, Front STB, Rear STB, GMPP Trailing ArmsComment
-
Here is a video of it, fyi that's my neighbour talking to me:
Dual Outlet Exhaust with Resonator Delete, Front STB, Rear STB, GMPP Trailing ArmsComment
-
They make an inexpensive automotive stethoscope that can help isolate questionable engine noises and narrow down the area and problem. Some experienced mechanics can even dial in on the mechanical problem with the risky tactic of using a wooden rod held close to their Mastoid Bone (held directly behind the ear) while touching the opposite end on various parts of the engine, using the same listening tactic to isolate mechanical noises in the valve train and engine block. The attached videos may seem off topic, but listening to these motor sounds and reading the response comments to the videos might give you some other things to look at for EFI/Firing/Sensor Timing/Odd Clicking or Piston Slap noises on similar motors and see whether they resemble what you are experiencing to help narrow down the problem:
Comment
-
sounds like valvetrain, pull the valve covers and see what's going on. could be collapsed lifters...Comment
-
That sure sounds like the timing chain slapping the guide. Everyone said to me it was lifters. After I replaced the chain/guide, the motor is whisper quite. You can hear the injectors fire on mine now LOL.
Mine was loose, and the rubber on the guide had hardened into plastic.
Sounds just like mine did, even sounds louder when you get to the passenger side. And when you rev it, it puts more tension on the chain/speed which makes it quieten down some.
As for that other loud noise you had on startup, no idea.Last edited by IsaacHayes; 06-25-2009, 11:01 PM.sigpic New 2010 project (click image)
1994 3100 BERETTA. 200,000+ miles
16.0 1/4 mile when stock. Now ???
Original L82 Longblock with LA1, LX9, LX5 parts
Manifold-back 2.5" SS Mandrel Exhaust. Hardware is SS too.
Comment
-
This would probably have to be the rarest event to explain the racket in your motor , but I read somewhere recently about the bolt(s) holding the large gear on the camshaft of the timing set being under-torqued and coming loose enough to walk forward at various RPMS to make contact the inside of the Timing Chain Cover in a weird way, causing similar knocking and squealing noises in time with the raising and lowering of the throttle.Comment
-
Well I don't think the timing chain has ever been touched, could be that or the lifters I suppose. What would happen if I didn't get to those any times soon?
Dual Outlet Exhaust with Resonator Delete, Front STB, Rear STB, GMPP Trailing ArmsComment
-
If you had a collapsed Hydraulic Tappet (Lifter), it might be possible for the push rod to get loose and bang hell out of the rocker arm and even transmit all that energy through the bad lifter and damage the camshaft lobe underneath, even if the push rod guide was able to hold it in the general area.Originally posted by Sidewinder View Post
In the case of a really badly worn Timing Set of worn cogs and a super-loose Timing Chain...Your engine could suddenly start doing "The Hucklebuck" at idle when you find yourself in the middle of heavy traffic when the motor relaxes torsional tension and "Jumps Timing" because of the excess slack in the worn out Timing Chain. If this happens, a whole cascade of bad things will follow after the valves open and close at the wrong times and the pistons hit them...you could "lunch" the entire motor in very short order!
To spare yourself this nightmare scenario, getting a new Standard Timing Set runs anywhere from $35.00 for the stock flavors to over $100.00 if you decide to go the performance route of installing a "True Roller" TS with cam and crank dual sprockets/rollers of the "Bicycle Chain" style design.
If you would like to see first hand what this looks like when installed, please visit my photobucket here for the step-by-step how-to images and product comparison side-by-side between an old, worn out stock TS and a brand new, "True Roller" component set. I show the tools and the shop manual removal/install views that will be generically similar to what you will encounter on your engine. You will need the correct ones from this site/forum, a Haynes or correct car line series shop service manual for your own specific vehicle to follow the right bolt patterns and torque values. Sometimes, eBay has a full set of factory OEM manuals available for some lucky car owners to purchase for not too much money:
You'll need a Harmonic Balancer Puller, a Three Prong Puller with Flat Tangs on the adjustable arms to remove the small gear from the nose of the crank and a Crankshaft Gear installation tool which might be available for loan or purchase from your local Autozone or the like...and of course ...removing whatever is in the way on the front of the engine to do the pull and re-installation with the necessary room to do this replacement along with a new gasket kit, leak sealers and you might as well spend a few more bux and get a sleeve kit for your Harmonic Balancer and a new Timing Case Cover Seal as well to do the complete job properly. Don't wait too long...and...
Good Luck with the Fix!
--==Bob==--Last edited by 60dgrzbelow0; 06-26-2009, 11:51 PM.Comment
-
new to forum -- first post.
just curious if the chisel+hammer method for removing the lower/crank cog is still okay? Risk of shattering something else or harming crank?
My son just changed his 1993 3.4 firebird engine oil and a noisy-lifter or chain condition started up. Possibly the prior owner was running 20w50 and he put in 5W30. 144K on the motor. 2 plugs were finger-loose when changing them on Friday with autolite platinums, EGR gasket was 1/2 missing (fixed) and the vacuum harness had cracked rubber (replaced -- $13 at dealer). now the car has mild chugging on acceleration sometimes and loud to not too loud ticking noise. running 93 octane and chevron cleaner now, with new fuel filter this morning. Gas in old filter was milky in color (water in gas)?
added 1 qt of lucas oil additive to help lifters. did seem to quiet the engine somewhat. engine was 1 qt low -- possibly not enough added at change. couldnb't tell until today because they broke dipstick off.
did find a tricky way to remove the dipstick. drilled out center of plastic and used a long deck-wood screw to pry and pull out what was left, taking car to pull out shavings first. JB weld to the rescue I guess.
will try to post engine video soon.Comment
-
posted video here -- first 2-3 seconds have the clacking engine noise. .mv4 format via a mac -- let me know if you all can hear it..
Thanks,
CSComment
-
-
Cold Surfer...
Hammering on any crankshaft can de-tune it at best ...and at the worst, ruin it completely for the need to get the harmonic damper/balancer back on and center bolt re-installed. The attached images show an easier way to get the hard-2-remove timing gear off. Please visit my Photo Bucket site below for more images on Timing Set replacement and installation data on the GM L-32 3.4L 207 CID engine. The clacking noise could be the stretched-worn out timing chain clattering on the slack side of the timing set rotation and be involved in the hesitation from the mis-reads on the timing gear sensors to the ECM. Your description of the poor engine condition indicates the 144,000 miles on it may have been very hard ones. Putting the super-high viscosity motor oil in the engine is reminiscent of that old trick of dumping saw dust into gear boxes to quiet them down and make selling used cars with them less suspicious.
(A pretty damned, mean trick to be played on your son, if you ask me...)
BobAttached FilesLast edited by 60dgrzbelow0; 07-06-2009, 06:38 PM.Comment
-
-
do we really need to remove lower gear?
if we are replacing the chain and top sprocket -- do we really need to replace the lower? I know it's recommended given the miles -- but it is the chain that's stretched... I've always wondered about the real need to replace the gears if they aren't VERY worn...
consider that the cam/lifters/everything else is stretched/worn...Comment
Comment