Valve problem

Ed Pitts

Ed Pitts

Well-known member
I have an issue with an exhaust valve that just started sticking. This is a new build that has about 30 miles on it. Has been running great. At 1500 rpm, the lifter starts clattering and the engine misses. I can goose it and it quiets down. No noise at idle. Ran a compression check this morning and all cylinders are 120 psi. Temp runs at 150 degrees. I need some suggestions on this one.
Thanks, Ed
 

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Usual cause for a "sticky" valve is a weak or broken valve spring and/or a valve guide which swells enough when hot to grip the stem. A valve spring retainer that is not properly seated may also be a cause. In our rebuilds we use solid guides and straight stem valves, and never have a problem.
 
"In our rebuilds we use solid guides and straight stem valves"
That's what I use in my rebuilds as well. Never a problem before this one. May have to pull the intake to see what is going on. Put the MMO in the gas and it's seems to be helping. Thanks Ron.
Ed
 
I have problems with sticking valves on some of the helicopter engines I maintain. It usually happens with in the first 60-hours after O/H and was generally due to the cylinder shop or manufacturer not sizing the guides to the correct clearances (we have to remove the valves to check them now). They carbon up real fast and then start sticking. On those big stem guides, we ream them & polish them to get the clearance back and it doesn't happen again. That's what happens when there are two different tolerances depending on application. Some one always gets the wrong one now and then.

For flatheads the fix was already mentioned.
The Marvel Mystery Oil is a life saver on the old flatheads. Running at proper coolant temp is a very good idea as well so I can't add anything there.
 
Ed Pitts said:
"In our rebuilds we use solid guides and straight stem valves"
That's what I use in my rebuilds as well. Never a problem before this one. May have to pull the intake to see what is going on. Put the MMO in the gas and it's seems to be helping. Thanks Ron.
Ed
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I have heard or read recently on the "magic" of bronze lined valve guides for a flathead. I don't recall seeing them sold anywhere, but if I remember correctly there was a company said they could do that to a set of stock solid guides. Thoughts?


"Hard tellin' not knowin!"
 
Gary "GOSFAST" on this board has a company that does them. I have never used his guides, but have gotten a few other things from him and he really knows his stuff.
 
Any machineshop can stick a bronze liner in a guide...the size is the same as for a SBC so not uncommon.
I ream mine in the lathe...install....trim...and hone to size in the Sunnen.
Honing them is not needed if you arent to picky.
 
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