Knocking Sound?

deekster_caddy wrote:

Could be something like a worn control arm bushing. Mine do that, plus I get an annoying vibration at a stoplight in gear. Plus a little clunk when I shift to reverse. Plus a little creak/squeak when I start from a stop...

I know my right two control arm bushings are gone, one of them is pretty bad. I have new control arms to go in next weekend, hopefully that'll take care of all my weird creaks and groans.

Did the new control arms help with the noise?

jrocha wrote:

Excuse my ignorance, but was does KR stand for?

https://rivperformance.editboard.com/information-directory-f50/automotive-acronyms-t480.htm

Ok.. well i understand this engine is supercharged and all.. and could account for some of the noises... ive noticed a sound coming from the engine.. you can hear it slightly when the radio is off.. when i lightly press on the gas to accelerate, i hear a knocking sound that progresses faster as i put my foot on the gas. Its not very loud but its a deep sound. When i have my hand on the valve cover and pull the throttle cable i can feel the vibration in sync with the knocking sound..I'm not sure if since its a GM and it just makes this sound b/c it feels like it or if i have a serious problem. I only have 54k miles on it but ive noticed this sound ever since i bought the car with 34k and thought nothing of it.. Also.. on a side note. My supercharger makes a squealing sound from the nose next the the pulley. Should i have my whole nose replaced ...replace the bearing..or just leave it?
Thanks guys

Inspect your belts. Do they look to be in good shape? Are you sure the squealing is coming from the blower?

Check supercharger oil level. How's engine oil level?

If you've gone 20K then it's doubtful it's a bearing in the bottom end. They shouldn't last that long.

Trace and fix up the other items, and let's see if any of that helps.

Well... i replaced the belt about 5,000 miles ago, and the tensioner pulley as well. I checked the supercharger oil and its up the the brim and still clearish pink ( i think it was that color, it was kinda dark out ) and the oil is at a normal level. When i place my head right next to the spinning supercharger pulley its squealing enough to annoy me But yes i have gone about 20 k and the noise has always been prevlivent. I have even opened the oil cap and listened to see if it was a valve tap but all i hear is the vibrating of the rocker arms. The noise is best heard outside of the engine and inside the car. Is there anything else i should check for either of the noises?

Thanks again

Are you sure it's not coming from below/behind the SC? Loosen your belts and spin and try to wiggle all the pulleys that could be going. I found the accessory tensioner pulley going bad when I thought the sound was coming from the SC or the alternator.

Well after listening to 1998riv... i took off the supercharger pulley and ran the engine. I heard no squeaking.. so i shut off the engine and got the trusty ol bottle of WD-40 and put the nozzle on and sprayed in each of the SC pulleys til i found out the bottom stationary one ( the one next to the engine mount ) was squeaking. Sooo im leaving that one alone But i did find out a few things about my main concern which is that knock... While the engine was running without the SC the engine knocking sound didn't sound very loud if not at all. But once i put the belt back on the knocking sound was loud again and you could feel it pulsing on the valve cover. 2nd, you can only hear it if i rev the engine quickly.. not too high but just a quick tug on the throttle cable. And 3rd the knocking sound is the loudest when i put the car in reverse or drive and you can hear it very clearly from inside the cabin.. Which makes me think is it being caused when the engine is put under stress... if any of this makes sense.. this sound is really freaking me out...
Thanks again

If you heard it all the time (Including driving down the road) I'd say it could be your fuel injectors. That's what happened to our GTP, one of them got clogged up full of crud and wasn't firing much or at all. The car made a kind of sputtering sound the entire time it was driving down the road and sounded about like it wanted to die at idle but never did. It felt like it was in the SC snout but it wasn't.

Just speaking from a recent experience, it may not be your problem but it's a possible explanation.

did you check your motor and transmission mounts?

Albertj

Hmm well i plan on taking out the injectors soon and trying each one to see if they are all working. I think ill get to that tomorrow. But for what i checked out today, all the mounts seem to be in pretty nice shape. I did try a neat trick my neighbor told me about. I got a long screw driver and put the flat head end on random parts of the engine and put my ear on the plastic part.. its amazing all the sounds u can hear! i was about to narrow down the knocking sound to around the valve covers. I placed it on the supercharger ( heard the swirling on the compressor ) and fuel injector rail ( heard the ticking of the fuel injectors ) and other places. The knocking sound was pretty much non heard. but i could hear it on the valve covers and heads... soo i don't know what that could narrow it down to? Ill update if the injectors are the culprit tomorrow though..

i checked all the injectors and they are all firing nicely. The noise sounds isolated to the front passenger side piston. Other then that im pretty stumped as to why its making this sound... everything is in tact and nothing else is loose on or around the engine too

Before the car was working okay everything fine only thing diffrent is a new down pipe and cat. but all of a sudden the engine is starting to make this rattling noise like a loose piesce is bouncing around in the engine but it also sounds like the piston is hititng the cylinder head which when i lift up the hood and press the throttle body you can hear the noise speed up. however im confused bc i only use 93 and 93 octane. and i know all my fuel lines should be clean which they did last year and i have done the whole seafoam to the car to get the crap out. the only thing that i think could be causing it is a somewhat loose water pump and coolant leak other than that im not sure. i might try tommorow and change out the performance plugs with new ones and ignition wires although they are pretty new. the car accelerates fine but im scared to really get it up in the upper rpms with the sound. this has never happend before and was wondering what you guys think, i have already looked at some other posts about enigne knock however im still confused of what could be my engines problem.
thanks.

While it's possible to hear knock, it isn't likely in the upper RPMs. There're just too many other sources of noise, so it's masked. The knock sensors can pick it up, because they're tuned for a specific frequency.

How long after installing the downpipe and cat did you notice the noise? If immediately, I'd assume it's a leak, or part of the heat shield vibrating against the pipe. Maybe something else that's loose? Try hitting with a hammer and listen. Also could be the braided flex pipe is allowing the dreaded "tick" sound to escape.

could be exhaust leak making a poping/ticking sound. OR it could be your s/c coupler is rattling. when you say press on the TB, you me open the TB plate?

AA wrote:

While it's possible to hear knock, it isn't likely in the upper RPMs. There're just too many other sources of noise, so it's masked. The knock sensors can pick it up, because they're tuned for a specific frequency.

How long after installing the downpipe and cat did you notice the noise? If immediately, I'd assume it's a leak, or part of the heat shield vibrating against the pipe. Maybe something else that's loose? Try hitting with a hammer and listen. Also could be the braided flex pipe is allowing the dreaded "tick" sound to escape.

thats what i was thinking maybe the new down pipe is vibrating against the heat sheild or that they didnt tighten something all the way which i got it installed about 4 days ago and it didnt make that sound right away it just started as of today. but right when i start the car it makes that rattling sound and when i apply throttle when i open the hood and open the TB plate i can hear it speed up but not as much when im driving and apply throttle it seems to go away however when i get off the throttle when im driving it will make the sound. it almost sounds as if its coming more from the passenger side of the car but im not completly sure which my mom thinks it could be the belts but i dont know if i should listen to her since she knows jack about cars.

sounds even more like a bad coupler
take the s/c belt off and rock the s/c pulley back and fourth feeling for play

Matthew i think you may be right. i researched a little bit and looked at ZZP site to see how much a new coupler might cost if it may be the case and i found this and they quote "The ZZP Supercharger Coupler fits the entire line of Eaton Blowers from 1990 to present. A Worn Coupler will cause a rattling noise at idle". Thank god it dosent cost much to replace and they have a set of instructions to install since im already out 400 dollars for having to put back on my cat which my mom made me do when she finnally found out what a catalytic converter was. ill just take it to a shop to verify the noise and if thats it for sure to save money ill order one and do it myself but in the mean time take the belt off the s/c pulley and run N/A until the part comes in. hopefully its the s/c coupler b/c i cant think of any reason for my engine to create a sound other than that especially engine knock.

Actually, I think there are lots of things under the hood that will make clicking/ticking noises other than spark knock. Knock is not a common thing to hear because the PCM usually takes car of it before you notice. Now that you're saying it happens more at idle, it almost certainly isn't knock, as you're not hearing it under load.

If you run N/A without SC belt, remember you can't really take the belt off without cutting it. You'll need to slip it around the engine mount bracket and tie it to the side of the engine bay - not a good idea for more than a day or two, imo.

yah after looking under the hood i dont know if it would be a good idea i just took it to the Mr.Tire down the shop to get it taken a look at. i called my dad up to tell him he will have to give them his credit card number and he told me not to be suprised if its about time to scrap the car. he thinks to many things are going wrong with the car or its too much to take care of. however im trying to tell him thats what you get with a high millage car and if you keep up with the maitnence the 3800 should have tons of life left. theres no way in hell im letting that happen or at least i should store the car and only take it out in the summer since its my DD.

Sure, It could be time to scrap the car, or it could be a $35 fix. Or, it could be a noise that goes on for some time without compromising the function or reliability of the vehicle.

Keep in mind, if you let the car sit, you will likely have more problems creep up than if you drove it every day.

turned out not to be the sc at all it was the alternator and a cracked balancer pulley cost 640 something dollars. thats 1,000 something spent on the car in the last couple of weeks, although the first 400 dollars was my fault. anyway the people who worked on my car really adrmire my car and always have something to say when i bring it in. i told them how my dad wants to get rid of it because of the high maitnence which they agreed with me that my dads being rediculous. they said that the rivieras are classic cars and that most people who have one talking about the 95-99 gen dont use them as thier daily driver and are usually have them as a collectors car. but if i was to ever sell it sell it to a car collector in which i could get alot more money out of than selling to a dealership, however i have no plans in selling my rivi and plan to keep it. my parents are about to the point of agreement that i should get another car and store the riv. but ill take it out every month to drive it but definitly take it out in the summer ill just miss the car too much.

The more it sits the more problems it will have. Use it at least once a week. I drive mine every day...

Drive it.

Bert

yah i guess you guys are right, i might just miss my car too much. however i just dont like racking up the miles on the car since it dosent have much. although i could just drive the car until the engine dies and then that will be my excuse to put a series II in