Engine Ticking Noise under load/acceleration

[goathearder]

Hey Guys,
I have a ticking noise coming from my 350 that is driving me crazy. I ONLY hear the ticking during acceleration or when the motor is under load. I.E. if I put it in park and rev the engine there is no noise, you also don't hear it at idle.

It also doesn't matter if the car is warmed up or not, it is still there. The ticking also becomes faster the higher the RPM is.

I totally though it was an header to block leak because of the location it is coming from so I added some soft aluminum header gaskets and it still leaks. I also can't "feel" any leaks around the header so I am starting to think it might be lifters.

Is there anything it could be besides lifters? Is there any way to diagnose bad lifters?

If I replace the lifters do I have to replace the Cam and pushrods at the same time?

Thanks,
John

 

[goathearder]

Hmmmmmmm, a google search for this really seems to point to a manifold leak since lifters would apparently tick all the time and not need a load present. Anyone know if that is true?

 

[80' 427]

header to pipe leak.

 

[goathearder]

I thought that too but i have "header buddies" from summit which are gasketless reducers and i can feel any leak coming from those at all.

 

[wheeler]

Sounds like pinging to me, how's your timing?

 

[goathearder]

Timing is good at 14 degrees. Its definitely not the pinging sound that I have heard before on other cars.

Has anyone ever tracked down an exhaust leak by plugging the tail pipe?

 

[mlrtyme]

Only under load

Usually this can indicate pre-detonation of the air/fuel mixture situation. Now, there can be leaks in the exhaust, true...but a quick check at idle should indicate a problem anywhere. If there is a leak, you should hear that noise consistently. If it is only under load and you do have an exhaust leak, it could be a sign of excess backpressure that should be addressed.

Lifters and pushrods don't care about engine load, per se. They care about oil pressure and RPM. If they were suspect, you would most likely hear them during a rev while not under load, since the oil pressure and RPM are the same (theoretically) at those times as it would be under load. A free check on that (or at least very inexpensive) is to pull the valve covers and rotate the engine to where you can check each rocker arm at the cam's base circle. Any undue play of a single arm would indicate poor adjustment that would cause the lifter to 'tick'. If you damage the valve cover gasket during removal, be sure to replace.

I just pulled apart a Vortec engine I purchased from someone due to knocking under load and it had leaky intake gaskets which (under load) were pulling oil into the cylinder and creating a scenario where pre-detonation existed. Pistons were covered with burnt oil, on top of the standard carbon buildup. Depending upon the exhaust and engine configuration, this sound can be different between engines. Pull the spark plugs and see if you can identify any traces of oil deep in the plug. Again, not a guarantee that pre-detonation is not your problem, but a free way to check if you are ingesting amounts of oil into your cylinders either via intake gaskets or questionable piston ring seal. A healthy cylinder should have no oil (either liquid or burnt) inside or around the spark plug threads or ceramic coating, just standard carbon buildup.

 

[y5mgisi]

Pretty much its leaky exhaust or pinging. 14 base is usually a bit into the danger zone for timing.

 

[smier]

Pretty much its leaky exhaust or pinging. 14 base is usually a bit into the danger zone for timing.

What's the specs on your truck? From the pic it looks to be a 89 to 91 TBI motor. 14* base timing? My '91 was set at 8* By the previous owner and it would ping under load on 93 octane gas. I set it back at 0*, like it came from the factory, and no more pinging under load and it runs fine on 87 octane now. It has much more power than it did before also. I've heard of guys running 6* to 8* safely, but not 14* on a TBI motor. It's worth a try setting it back to 0* at least as an experiment, you might be surprised by the results.... Oh, and if it is a TBI motor, remember to disconnect the EST(?)wire on the firewall when you go to check/set your timing!

 

[smier]

Oh, my "pinging" didn't sound like I was used to hearing in my old junker carb'd chevy's, it was much fainter, like a tic. It was quiet enough that my wife and most people wouldn't notice it until I pointed it out to them, but it drove me insane and I knew something was wrong...