will a burnt exhaust valve pushrod cause loss of compression or even low?? i don't get how that would work.. someone help me understand this and picture it thanks..

 

Yes a burnt valve can cause a loss in compression.

If you have a burnt valve or bad piston rings that don't allow the cylinder & combustion chamber to seal completely there will be a lose of compression. This happens when the intake charge of air is pushed out through the gap created by the burnt valve or passed the bad rings on the compression stroke. There has to be some of the intake charge left in the cylinder when it gets to TDC in order to have any physical compression.

The greater the volume of intake air you can keep in the combustion chamber, on the compression stroke, the closer to your static compression ratio you will be.

 

no i know that much but on the test it asked if a "burnt exhaust valve pushrod" the word pushrod is what threw me off.

 

What test?

The C27A1 is the only Honda engines that I know of that used a push rod. In all honesty I don't know how one of them would get burnt though. They are in the top of the head and go no where near any exhaust gasses.

Or are they referring to the adjustable valve tappet as a push rod? Ether way I can't see how they would get burned.

But if one was to somehow get burned. It would have to burn in a fashion that material (carbon) would fuse to it. Increasing it's length, therefore not allowing the rocker arm & valve to return to the fully seated position. That would be cause for a low compression situation.

 

ase testing and yes to other your other compression.

scenario was tech A said intake valve burnt will cause loss of compression. tech B said a burnt exhaust valve pushrod will cause lose of compression. I know tech a is right but B is confusing. either way i failed the Engine repair ASE test.

 

Ah multiple guess tests.

Sorry to hear that you didn't pass.... If you go to take it again I wish you best of luck

 

The correct answer to that question is Tech A only...stupid ASEs, always trying to confuse you. If you come across another question like that, dont over think it. You were right on the money when you thought "how does an exhaust valve pushrod get burnt". the answer is "it doesnt" therefore tech B is wrong. They like to see if you know which parts are which, where they are located, and what function they perform ... Ive got my L1 this spring and then I am done for about 2-3 years. unless I take a few of the new hybrid / alt fuels tests. Good luck next time