Briggs 22hp Intek bent rods

[Jim68]

I have a 22hp intek with about 650 hours on it. It wasn't running right. I toke it in to John Deere and they said the rods were bent. They replaced them and the new ones bent right away. They said it may be cam. I tore motor apart and cam looks fine to me. It's not bent and nothing looks damaged. When I move the things the rod connects to(rocker, valve) they don't give more resistance than I think there should be. I did clean the carb out a few months before this. One of the plugs looks dirtier than the other. I really don't know what I'm doing if that's not obvious any help would be appreciated.

 

[bertsmobile1]

Take both rocker covers off and measure the length of the fully compresses valve springs.
Chances are the ones that keep bending the pushrods will be shorter than the ones that don't when fully compressed.
You can double check by trying to slip a 0.002" feeler between the coils of the springs when full compressed.
If you can not the spring is effectlvely coil bound and will cause the pushrod to bend.
This happens because valve guide slips down inside the head.
And that happens because the head gets too hot.

 

[Tinkerer200]

Well that is a little different experience than I have had. I have only heard of one valve guide slipping down into the combustion chamber. All I have experienced the guides slipped up into the rocker arm chamber. The guide should not extend more than 1/8" above the head casting in the rocker arm chamber. As said, a cooling problem usually causes valve guides to move but some say ethanol fuel is causing valves to stick resulting in guides moving. I have a fix if that has happened. Also, I can send you a Service Manual IF you like. Address below, put in proper format and remind me engine model number and what you want.

Walt Conner
wconner5 at frontier dot com

 

[motoman]

I have heard that the Intek rods are weak. But maybe smart engineering - just strong enough for 3000 rpm? Anyway, you pros should weigh in on valve interference with a rising piston. How could that happen on a pushrod motor? Hmm wrong assembly causes wrong valve phasing? Not sure if a pushrod could resist enough to bend a rod. When I first read this thread I thought maybe jest? What about hydraulic lock- gas fills cylinders?

 

[bertsmobile1]

No valve doe not hit the piston, the spring fully compresses so the spring is coil bound but the pushrod is still trying to compress it.
So the pushrod bends
One of the reasons for using alloy rods is to remove as much of the inertia in the pushrod which pushes the rocker harder after the cam has already gone past peak lift.

 

[Tinkerer200]

I have heard that the Intek rods are weak. But maybe smart engineering - just strong enough for 3000 rpm? Anyway, you pros should weigh in on valve interference with a rising piston. How could that happen on a pushrod motor? Hmm wrong assembly causes wrong valve phasing? Not sure if a pushrod could resist enough to bend a rod. When I first read this thread I thought maybe jest? What about hydraulic lock- gas fills cylinders?

I think you are mis-reading the post. All references are to *Push Rod* not connecting rod. Also, as said above, there is a reason the push rods bend and if they didn't then much more serious damage would result.

Walt Conner

 

[motoman]

yes, I did misread it. thanks

 

[Jim68]

Well that is a little different experience than I have had. I have only heard of one valve guide slipping down into the combustion chamber. All I have experienced the guides slipped up into the rocker arm chamber. The guide should not extend more than 1/8" above the head casting in the rocker arm chamber. As said, a cooling problem usually causes valve guides to move but some say ethanol fuel is causing valves to stick resulting in guides moving. I have a fix if that has happened. Also, I can send you a Service Manual IF you like. Address below, put in proper format and remind me engine model number and what you want.

Walt Conner
wconner5 at frontier dot com

It looks like what I am guessing are the valve guides have both pushed up on one side. I sent you an email for a service manual. Can you send me the fix? Thanks!

 

[BlazNT]

The fix is a new head.

 

[Tinkerer200]

The fix is a new head.

Well that's fine for you, for others they can fix it for less than $10 and dozens have over the last several years using my method. Let us know how things work out Jim.

Walt Conner