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Well my SBC 350 is making a knocking noise.:mad: I believe it is coming from the motor:HMMM: but if you put your ear on the fender you can hear like a rattle.:confused:
I tried adjusting the timing and when advancing the knocking would go w/ the RPM's and then it would soon turn into a whistling noise :eek: until I retarded it, then it would go back to knocking. :confused:
I do not know what this could be be, any help would be appreciated
Thanks
51 Chevy 350/350:3dSMILE:
Just a guess here, a vacuum leak causing a cylinder to lean out and run hot enough to detonate. You can find a vac leak, or at least narrow down the area by using a 3 or 4 foot piece of heater hose or something close to that size. (Section of the neigbours garden hose!) Hold one end up to your ear, and use the free end to listen for the whistle. The hose cuts down all the other noises that are going on, and concentrates on whats close to the open end.
I found a vacuum leak on my old bronco with a bottle of carb cleaner (or starting fluid? I forget now). Sprayed short bursts around the engine, when it got sucked into the leak, the motor would rev up.
Be careful to keep the burst short or it could get dangerous.:eek: File that under redneck mechanic.
starting fluid works great, too bad i get in trouble everytime i light a customers car on fire :LOL: .... they made me get a smoke machine, works really good though.... even though cars on fire produce enough smoke as is :LOL:
Ok tried the starting fluid and it did nothing and I also hooked a vacuum guage up to the manifold and am getting readings around 12 and it moves like it is scenario 11 on this web page http://www.secondchancegarage.com/public/186.cfm but from 12 to 11 to 13 I tried adjusting the timing but it still does it. Also its got an HEI ignition
Ok well I've got it narrowed down to it only starts to knock after the car has warmed up, during the warm up when it is cold, no knocking noise???
Broken flexplate?
Is it more like a mechanical knock or a preignition knock? Sound like one cylinder or many? Could it be a spun bearing? Is the oil clean? Any smoke? Look for any sparkles or water on the dipstick.
-Chris
Not sure what kind of knock, sounds maybe more like a mechanical??? Just did a check by pulling plug wires and none of them stop the knocking. The oil is perfect, no metal specs or anything and nice and clear, no smoke, just did an oil change about 2 or 3 weeks ago
Ok well its wierd, I just did another check by putting the car in gear and it seems as if the knocking goes away. I also had the car revved up to about 13-1400 RPM's while in gear and holding the brakes and it didn't come back, but as soon as it was put back into park, the knocking came back
I am stumped
The bolts on the flexplate to converter are tight but I just disconnected the belt to the alternator and water pump and it seemed not to make any noise, could an alternator make a knocking noise, I replaced the water pump not to long ago so I don't think it would be that???
The plot thickens... if it's alternator or water pump, I wouldn't expect the noise to go away in gear(?) What about motor mounts? I was with Denny and or Corvette64 with loose converter bolts or flex plate problem but apparently that's not it.
You can try free-spinning the alternator pulley with the belt off to see if it makes any noise... Can try the same with the water pump pulley too.
Ok well I took it off, started it no noise, put it back on, knocking, took it off again, no noise, put it back on, knocking.
I tried free spinning by hand and it doesn't feel like its binding anywhere, but if I shake it back and forth like to and from the alternator i can get a clicking noise, water pump makes no noise and I just replaced that not too long ago
Ok just came out from under the car and the bolts are tight and the plate and converter have no play in them. From what I can see I can't see any cracks unless their small or I missed them.Quote:
Originally Posted by DennyW
My next question is isn't there a certain way the converter is supposed to be mounted to the flexplate?
If that was wrong could it cause this noise??
Oh yeah forgot to mention I did find some chipped teeth on the flywheel
Ok well I recorded the flywheel and it doesn't seem to have too much wobble in these videos so I guess its okay , I recorded once in park and once in drive, you can also hear the knocking in the video if anyone's got a really good ear maybe can tell what it is???
http://vids.myspace.com/index.cfm?fu...deoID=14416834
http://vids.myspace.com/index.cfm?fu...deoID=14417585
Whatever it is, better start taking things apart and checking before the engine gernades and starts kicking parts out the pan or something.... You could try pulling the plug wires one at a time and see if you can isolate it to a specific cylinder....
Oil pressure reads perfect when at idle and goes up as you raise the throttle, no fluctuations at all, I've tried pulling plugs to see if it was a specific cylinder but no change with each plug I pull.
The flywheel has no play in it and neither does the balancer on the front.
I guess I will have to pull the valve covers and check things out underneath em
Also this motor only has about 2,000 miles on it. This was done during the rebuild 350 .030 over,4 bolt main, pop-up high compression pistons ( I think 11:1), Torque Cam, Z28 valve springs, High volume oil pump, Heads have been milled, Factory Corvette intake, 780 cfm carb., 3500 stahl converter. 3 angle valve job.
Not sure of that will help any but just throwing it out there
Sorry not meaning everything is perfect, but the oil pressure at idle is about 25 steady and goes up as the throttle goes up without any sort of fluctuations. I'll check what it raises up to next time I start it.
By no play I mean I can't really get any movement by moving it by hand, but I could be doing this wrong, I don't know.
Just let me know what to check and how to check it and I will
By the way all this help is greatly appreciated so far
take a broom stick,rake handle, hold one end near the pan, or where you think the noise is coming from, the other end to your ear, and you should be able to hear the noise. its a cheap stethescope(sp). good luck.
Ok I got some numbers on the oil pressureQuote:
Originally Posted by DennyW
Cold engine 40 PSI in Park/ 35 in drive
Hot engine 15 PSI in Park/ 10 in drive
its about 27 PSI at 1500 RPMS and about 37 PSI at 2000 RPM's
Alright recorded a new video with variations in RPM's in this video you can the slight wobble I mentioned earlier in the thread
http://vids.myspace.com/index.cfm?fu...deoID=14590492
Also did the stethoscope idea and I get three places that seemed the loudest 1.) The Alternator itself 2.) the front of the left valve cover 3.) the front of the oil pan
I also unbolted the torque converter to check again for cracks, again couldn't find any and when flexing only the outer part flexes, but I'm guessing(don't honestly know) thats normal since its called a flex plate.
Also took some pics of it to see if maybe someone can see something I didn'thttp://img231.imageshack.us/img231/1945/0000225mg8.jpg
Shot with KODAK Z730 ZOOM DIGITAL CAMERA at 2007-07-31http://img231.imageshack.us/img231/4779/0000224fg6.jpg
Shot with KODAK Z730 ZOOM DIGITAL CAMERA at 2007-07-31http://img58.imageshack.us/img58/5115/0000223tx5.jpg
Shot with KODAK Z730 ZOOM DIGITAL CAMERA at 2007-07-31
http://img58.imageshack.us/img58/4823/0000222ax6.jpg
Shot with KODAK Z730 ZOOM DIGITAL CAMERA at 2007-07-31
http://img58.imageshack.us/img58/3373/0000221jz1.jpg
Shot with KODAK Z730 ZOOM DIGITAL CAMERA at 2007-07-31
http://img66.imageshack.us/img66/8177/0000220tx0.jpg
Shot with KODAK Z730 ZOOM DIGITAL CAMERA at 2007-07-31
http://img66.imageshack.us/img66/3124/0000218fa0.jpg
Shot with KODAK Z730 ZOOM DIGITAL CAMERA at 2007-07-31
http://img58.imageshack.us/img58/2028/0000217ao2.jpg
Shot with KODAK Z730 ZOOM DIGITAL CAMERA at 2007-07-31
Also tried prying on both ends of the crankshaft and virtually has no play on the balancer side or the flexplate side unless you really pry on it, you can move it a hair
ok ya i see what you mean....what does that MEAN???....That the bearings are worn out?????????????