Inliners International Forums General Discussion Engines 292 Making Knocking noise

Hello,

Just looking around the net for help with my motor and came across your site. I have a 1969 GMC 1/2 ton pickup with a 292 and 4 speed MT. Last week I had the head rebuilt because I had a burned valve. On top of the head I pulled out the lifters and they didn't look too bad but I decided why not through in a set of lifters and a cam while I have it all apart. Anyways I got it back together and when i fired it up I heard a knocking sound that I had never heard before. I thought maybe the lifters hadn't pumped up yet so I let it run for a little bit but it was still there. I set the timing and the carb and all that good stuff to see if that helped but it didn't. I pulled the spark plug wires off one at a time to see if I had a stretched connecting rod but the noise was still there. I tried running it without the fuel pump. And I even tried putting in another set of new lifters. Nothing seems to help and I'm running out of ideas. When I use a broom stick to try and isolate the noise it seems like it is running down the cam side of the engine and it is really bad when you place the end on the timing cover. I cant believe timing gears would make a knocking noise like that. The only other thing i can think of is two of the rocker arms shoot oil with quite a bit of pressure out hole on the rocker arm. But i looked at all the wholes and none of them lined up so i didn't think that was a problem. Anyways any help would be greatly appreciated.

You replaced the cam? Were the cam bearings ok?
Did you degree the cam? Reset the distributor
after finding TDC? This is general stuff. 292
owners will be more specific.

I replaced the cam and the bearings seemed to be ok at least to me. I reset the distributor and found TDC and set the timing. When you get the RPM's on the motor low enough the sound goes away completely but when you give it a little gas it comes right back. I dont know what you mean by degree that cam. Thanks

I had a cam gear come loose on a 292. It made a knocking sound like you describe. The engine ran fine but knocked. Not common, but maybe.

OK I have The Biggest Answer or Question for YOU. WAS The Gear Heated Before Installing It on the Cam.?? IF Not Then That was and IS you Problem. If You had a New Alum Gear Installed on the Cam and It was Not HEATED The Gear Walked Off The End. AND NOW Your cam is walking Front To back. This is why You hear what you do on the cam side of the block and More so Under the cover. So this may Or may not be your Problem Depending on what Your answer is. But if Your answer Is Yes a new gear and Not Heated.Then I'd pull the timing cover and Look at the gear.

What happens when The Gear Is not Heated before installing It will Shave Out the Inside of the Gear. and Then Becomes a Lose Fit ( No Longger a Tight Press Fit like it should be)

The Best way to fix this is issue is to have a New Gear installed AFTER HEATING IT. 2) is to press the gear back to where it should be and Then drill where the two meet Tap for a pipe plug (1/4in) and reinstall the cam. THIS IS NOT THE BEST WAY.!! INSTALLING A NEW GEAR IS.!!!!!!

Hope this helps }[oooooo]

The cam gear was heated before it was installed and I pulled of the timing cover to check in the oiling plug wasn't plugged and the gears looked fine. What I am thinking is that the cam bearings are just worn out and they aren't a tight fit. This engine has had probably 150,000 probably closer to 200,000 since it was rebuilt in 1980.

What is the oil pressure? If it is good the cam bearings are probabley all right.

The oil pressure is a little bit above half.

humm any scrap markes on the inside of the cover?
HUmmmmm another thought Here maybe?? you are hearing a wrist pin rattle/knock. This would not effect oil pressure. Have you tried to listen to this sound at the Base of the dist. housing To see if it is any louder their. To me this still pretty much sounds as if the cam is walking. double check the cam retaining plate screws.? Or look for a Cracked plate?? We can't hear this So kinda hard on Us. So hope this all helps Just let us know what you find out. }[oooooo]

Ps hum small brain fart here Check the dampener as well to make sure it isn't lose by any chance. It may also make a knock with change of rpms so would a lose flywheel. Just a little more food for thought.

I never heard cam bearings knock. It might happen ,but I never heard it. I still think the cam gear may be moving. Did you try pulling on the gear when you had the cover off?

The same cam grinds can be different right out of the box so the process of degreeing a cam is an accurate way to determine if the cam is opera-
ting the valves in proper timing with piston travel.The info you collect can help you get the most power from your engine by adjustment of cam
and ignition timing. Your new cam should have come with a cam card detailing its specs. That being said, installing the cam correctly and
matching the crank and cam gear timing marks most
likely you'll be fine and no further measuring would be needed. It's just that cam degreeing helps accuracy in tuning your motor. If you ever install a "performance" cam this will definitely be something you'll have to do.I think you're getting the best advice fron Twisted6 and popa-
banjo.

Is the noise constant/consistant regardless of engine temp? In other words, does it get louder as it warms up, or quieter when it warms up, or no change at all?

yes it is a constant noise. It doesn't get louder or softer it just gets faster or slower depending on how much gas you gve it. But if you turn the idle way down it goes away but if you step on the gas at that point it comes back.

Just wondering if the heads of the bolts used in the cam retainer plate are hitting the cam gear. Paul

I've heard a strange knocking noise from a 292 which was caused by the pan getting hit by the rotating stuff. There isn't much room in the forward end and if an unplanned dent got there during the rush...well you know.

Doing a valve job on a worn engine can bring out many new problems. Now that the head is sealing well, possibly the increased compression is bringing out piston slap or rod knock. With 150K plus miles, it would probably be wise to check and maybe replace the rings, rod and main bearings...

Well we figured it out. My father put the timing gear on backwards when we put the motor together last week and it didn't have holes for a puller so we had to pry it off. And in the process we fouled up three of the teeth on the crank gear which in turn fouled up some of the teeth on the cam gear. These two sets of gears hitting eachother caused a terrible knocking noise. So when we put a new set of gears on the sound was gone. Just wanted to let you guys know what the deal was. Thank you for your help.