knock type noise

[gabbin]

I hear a knock type noise, and I've gotten underneath the truck to listen to the bottom end and it doesn't seem to be a low end knock in the engine. It's a 63 with a 327 and 700R4. What kinda ideas you all have??

I'm tending to think it might have a cracked flywheel?

[Chevy Fleetside]

Originally Posted by gabbin

I
I'm tending to think it might have a cracked flywheel?

Probably this.

[gabbin]

TY Fleetside, I'm going to rotate it around and see what I can see, also the water pump pulley makes a slight knock when you grab it and rock it back and forth. (Brand New) no fan blade. This is when I don't have it running.

Def. gonna check/inspect that flywheel, just for piece of mind.

[forestb]

You might also try checking under the valve covers. I don't know how lowed it is but it might be a pushrod.

[66customcamper]

Those stethoscopes you can get at the parts store work pretty darn well identifying noise sources. Wooden dowel or a piece of vacuum hose or even a long, wooden handled screwdriver also can help pinpoint where it's coming from.

[BR3W CITY]

Instead of a cracked flywheel, check and see if a flyhweel bolt is loose or has backed out and is ticking against the shield. If its loose a while, it can oval the hole out.

[gabbin]

I had checked the torque convertor to flywheel, but that's a good idea I hadn't checked the actual flywheel to crank bolts. Thanks for the insight!!!

[gabbin]

Everything seems good to go on and around the flywheel. It is very light knock noise, when I had to replace the valve cover gaskets because they were leaking, I didn't have 10W40, I had some 5W20 that I used to top it off until I was ready to do the oil change. I will get the oil and filter today, I think the 5W20 might be a bit too light.

[BR3W CITY]

Unless that knock sounds like its coming from your rods (if its "low") or lifters (more tap, less knock) , light oil won't usually make a motor noisy.

[gabbin]

I guess that's why it is concerning, it sounds a good bit like a diesel when it idles, it is mild, but I can hear it, I adjusted the valves good, I've even removed the belts from the Alt and power steer pump. I haven't listened at the timing chain cover or taken it of yet to see if that is stretched. Also, it goes away after you get the throttle up and going, and generally a rod knocking doesn't go away, it will maintain the knock

In my experience to date.

[gabbin]

Ok, quick update, I changed out the oil, and it is still a knock at idle, but seems to go away as rpm increases. I took an old long wooden handle screw driver and used it as a stethoscope, and it sure sounds like it's in the water pump, that's were you can really hear it, I tested around from the timing chain cover and oil pan and side of the block, front of the block, and it gets pronounced at the top of the water pump, where the plug is in the top. Also, I have an electric fan, so no fan on the pump. When you grab the pulley, and jiggle it, it does have some lash, and you can hear kind of a knocking type noise, can't duplicate the speed by hand. It is a new water pump, but it seems that it may not have been set up right when built. I also have quite a bit of belt that goes around the drive, water pump and Alt. due to it being an old style head (no front holes on the head) so the alt. is mounted on a bracket on the headers. With that whip of the belt and the idle of the engine, I'm thinking this is what is producing the knocking. The pump doesn't leak, so I'll run it until I can get a pump. Can someone, grab ahold of their water pump pulley for me, and see if you have much lash, forward and aft? Thank you. Here's a quick set up of the engine bay, just for GP.

[geezer#99]

Check the short bolts you have holding the pulley onto the pump.
One just a touch long can make a noise if it contacts the pump.

[Chevy Fleetside]

One more... Did you put a new fan belt on? If so, is it tight enough? Sometimes a belt can make a knocking noise. Just one more thing to check out.

[gabbin]

OK, I'll check the bolt length, and the belt is nice and snug, and it is new, that was a thought, since the belt is quite long, it can vibrate pretty easy.

[gabbin]

Quick update, not sure on the bolts holding the pulley on, but will tomorrow as the pump is sitting on the timing chain cover, Right on it. Not sure if you can tell much from my above picture. Does anyone have a good overhead shot of their 327 I could see just for comparison please? I have another pump that came off a 350, and from mounting point to flush it is approx. 2 1/2 inches, this one that is on the truck measures 2". I'm sure that would give me the depth, and from over all measurements , the pulley should still ride in the correct location.

[gabbin]

Well I found the culprit, the water pump that had been instaled must have pushed the timing chain cover, allowing the cam gear bolts to contact the cover. So I massaged it out and reinstalled everything. Thats a major load off my mind for sure.whew!

[BR3W CITY]

Originally Posted by gabbin

Well I found the culprit, the water pump that had been instaled must have pushed the timing chain cover, allowing the cam gear bolts to contact the cover. So I massaged it out and reinstalled everything. Thats a major load off my mind for sure.whew!

Thats a first.