I am troubleshooting, trying to verify if the tap i hear is a bent pushrod, loose rocker, or exhaust leak. If I pulled both pushrods on that one cylinder to check for bend, and then left them out and turned over the motor (to check for exhaust leak, no gas in, not explosion, no exhaust, no tap) would this be hard on my cam or any other part of my engine? Probably pull that plug wire as well for safety. I would only have to have it running for a couple seconds to be able to verify that is exhaust leak or not. Or should I just pull the plug while it is running?
I don't recommend this long term... However, when I was in High School, my best friend's dad (seriously country folks) had a piston go bad on his 318 in the old Dodge farm truck. He pulled the pushrods and spark plug wire, then drove it as a 7 cylinder for several years. Last I saw that truck, it was still a 7 cylinder.
Shoot the lifter out? Wouldn't it hit the bottom of the intake manifold and stop. (I am trying to picture in my head how the lifter valley and all that would look assembled) Besides, it would literally be for just a few seconds, maybe 30 seconds tops. Just to eliminate any flow through that cylinder to cancel out exhaust leak as a possible reason for the tap. I guess if the plug doesn't fire off that cylinder, it will just come out unburned and squeeze past the exhaust gasket, not making the tap sound. I could do this first and if the tap goes away, I can leave the pushrods alone. Unless the extra pressures in the cylinder onto the exhaust valve during the explosion might be leading to the tap. (would the lack of high pressure change the tap if it is a pushrod issue?)
If you think you have a bent pushrod just pull them and roll them on a pane of glass. You should be able to see and feel if they are bent.
I actually think I have just a leak at the header gasket, but if I don't verify that, I will pull off the valve cover and get deeper...
Correct. That is why I am leaning toward it being an exhaust leak. The spacer is just an old header flange with the tubes cut off. I have in this order...head-gasket-spacer-gasket-header When I got the header flange, it was quite old and a little rusted, and I think it might be leaking at the 8th cylinder (or is it 5th, the one in the back driver side) since there was a little metal missing there from the rust. If I verify that it is an exhaust leak, should I even worry about it?
Well, took the car out today and verified that some of the tap is exhaust leak by pulling that spark plug. But I hear a tap at the back on pass side also, and I think the rocker is hitting the baffle in the valve cover. Looks like a nasty job ahead as I run the engine without the cover on, and get oil all over EVERYTHING. Then pull rockers if I need to and verify that none have worked loose.
this may be a little late but a good tip to rember. I use a pice of heater hose to find exhast leaks. hold one end of the hose to your ear and pass the other end around the header flange and you will hear the leak loundest when your close. you can also use a long screw driver or socket extention to listing to the rocker arms. just hold one end aginst your ear and touch the other end to the valve covers. It will get louder the closer you get to the noisy rocker. There are mechanics stethiscopes (sp) that are very expensvie at auto part stores that work well but the othe methods are free. hope this helps
I am going to start a new thread now that I have taken the valve covers off and have a new issue... I have verified that the header is leaking on that back driver side since that tap goes away when I pull that plug wire. There are a couple other taps I need to work on now.
noise My guess would be an exhaust leak which can certianly sound like a lifter/rocker problem. mechanics stethascope I bought was less than 20 bucks and work great . A bent pushrod will usually result in a bad and progressivly worse noise. Additionally, if there is a valvetrain issue it will result in a noticeably poor running motor , especiallly under a load. I expect you will discover an exhaust leak, block the exits one at a time with a piece of cardboard,plastic or wood block and then listen to each side.
With a stock-ish camshaft, especially a flat-tappet, as long as you don't rev it too much, the lifters generally won't come out.
