Sticking Exhaust Valve - Diagnosis and Fix! - Page 10

Dayz · #91 05-01-2020, 09:11 AM

Guys. Need help with securing the valve through either the plug hole or the exhaust hole. My 4 finger pick will not grab the valve enough or right. Can you post a link of what you are using?

Also, the fishing line is too thick to pass between the valve and the guide. I was thinking of using the magnet. I am scared that if I drop the valve, I won?t be able to pick it up.

This is for a parallel valve 360.

Thanks
Erik

bullojm1 · #92 05-01-2020, 02:18 PM

Quote:

Originally Posted by Dayz

Guys. Need help with securing the valve through either the plug hole or the exhaust hole. My 4 finger pick will not grab the valve enough or right. Can you post a link of what you are using?

Also, the fishing line is too thick to pass between the valve and the guide. I was thinking of using the magnet. I am scared that if I drop the valve, I won?t be able to pick it up.

This is for a parallel valve 360.

Thanks
Erik

Hi Erik,

I used a popsicle stick with a notch carved out of it to lift the valve, and help align it with the guide:

Dayz · #93 05-01-2020, 06:43 PM

Ahh. I read the post many times, clearly forgot the popsicle stick. Will post back tomorrow with how it went, which me luck.
Erik

Bill.Peyton · #94 05-05-2020, 10:29 AM

I used a piece of small rubber hose with a loop of safety wire through the tubing. I loop the safety wire around the valve stem and use it to hold the valve and reinsert it after the guide has been reamed. I do this through the exhaust port

scard · #95 05-05-2020, 10:46 AM

And you CAN pretty easily fish a valve out of the bottom of the cylinder (pickup fingers, safety wire, magnet pickup, etc). For your own piece of mind, find a local shop that has a trash cylinder lying around and prove it to yourself. Once you've done it a few times on the bench, that particular fear melts away.

ian_mac · #96 07-22-2020, 05:17 PM

awesome thanks for sharing

Saville · #97 08-05-2020, 02:10 PM

So I was ground testing a new propeller today and the engine is having some trouble:

O360-A1A

Starts up fine.

At idle the engine has a lot of afterfires - some loud.

Run the engine at 1500 rpm and all 4 CHT's and EGT's some up together. Engine runs smoothly.

Between 1200 and 1500 you start to get engine stumbles. CHT-3 and EGT-3 start to come downbelow the others

Between IDLE and 1200 more stumbling and more afterfires.

Worst at IDLE - there is more stumbling and more afterfires. Some loud. EGT-3 drops rapidly to a point 300 degrees below the other three. CHT-3 follows suit only more slowly. It ends up about 50 degrees cooler than the other three.

Come back up on the throttle to 1500 rpm and it all smooths out. CHT-3 and EGT-3 temps come back up even with the rest.

Behavior is the same whether on LEFT mag, RIGHT mag or BOTH.

Things tried:

Compression on #3 cylinder was measured at 77

#3 Intake gasket was brittle so it was replaced. The other 3 intake gaskets will be replaced.

#3 Intake line inspected for cracks - none. Made sure it was tight.

#3 Plugs were swapped with another cylinder.

All Rocker covers removed and valves inspected while turning the prop - all worked fine. All rocker gaskets replaced.

None of these ideas worked.

I'm getting the impression from reading this thread that this might be a sticky valve.

Any other possibilities?

Bill.Peyton · #98 08-05-2020, 02:37 PM

How many hours on the engine? This usually starts occurring north of 500 hours. To verify your assumptions you will have to do either a wobble test which requires a special fixture, or remove the springs and check with a ream.
Does this happen with the engine cold or at temperature?

Saville · #99 08-05-2020, 02:43 PM

Quote:

Originally Posted by Bill.Peyton

How many hours on the engine? This usually starts occurring north of 500 hours. To verify your assumptions you will have to do either a wobble test which requires a special fixture, or remove the springs and check with a ream.
Does this happen with the engine cold or at temperature?

About 400 hours.

The stumbles and backfires started at once with the engine cold but through the day we ran it several times so it was well warmed up. No change in behavior.

Bill.Peyton · #**100** 08-05-2020, 02:53 PM

Either you have bad intake leak in number 3 or your ex valve is sticking. I have seen on two occasions, engines with 400 hours have a sticking valve. I am leaning towards the valve. It is not that hard to check the valve. I usually pull the exhaust stack and hold the valve with a short piece of tubing with a length of safety wire looped though it and around the valve stem to hold the valve. If you find one that’s in need of cleaning, I would do them all .