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#2 ex valve sticking, no surprise

sansoneservices

sansoneservices

Well Known Member
Pulled jug, not a big fan of the rope trick. #2 is easy on the IO-360. Upon assembly notice no valve to rocker clearance. Yes deflated the hydraulic unit, and I'm asking the group if you order shorter pushrods, maybe ship my pushrod to a shop and let them send a shorter one? In the past I had access to a dozen or more at my buddies shop but now I'm hesitant to purchase multiple new pushrods at about $60 each.
 
For my engines, I go to the auto shops that make custom pushrods. I send them my existing rods with notes on how much longer or shorter to make them. Don't forget the math to factor out rocker ratio when dtermining the new length. .040" short on the valve side is NOT .040" short on the pushrod side. One downside is that the wall thickness is greater on the auto stuff, so doesn't bend as easy, which is a damage mitagation thing when valves stick. Not sure this would be a meaningfull savings for one pushrod.

Do you know why the gap closed up? Valve recession possible? Sure you got the spring fully seated in the plunger body? Did the ball rattle after cleaning? Maybe a piece of crud at the bottom of the lifter body?
 
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lr172 said:
For my engines, I go to the auto shops that make custom pushrods. I send them my existing rods with notes on how much longer or shorter to make them. Don't forget the math to factor out rocker ratio when dtermining the new length. .040" short on the valve side is NOT .040" short on the pushrod side. One downside is that the wall thickness is greater on the auto stuff, so doesn't bend as easy, which is a damage mitagation thing when valves stick. Not sure this would be a meaningfull savings for one pushrod.

Do you know why the gap closed up? Valve recession possible? Sure you got the spring fully seated in the plunger body? Did the ball rattle after cleaning?
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If the previous leak downs showed no leakage past the valve, I would be concerned that something is off with the re assembly. Valve recession usually takes a lot of time and can't think of another reason why the gap reduced, assuming you know it was right in the past. Poissible the plunger has a flaw and not fully collapsing.
 
Good tip on the auto pushrods. Back when I assembled this engine after installing a new cam, I noticed clearance was at minimum. Ran great for 50hrs and recently experienced "morning sickness" cold engine only, cleared up in 2 minutes, but after brief trouble shooting found the sticky EX valve. The seat needed lapping or replacement. I'm ordering a cylinder but very long lead time for this angle valve engine. The seat is probably why the clearance changed. It's my personal plane so I'm either going to have a new seat installed or your auto pushrod option.
 
lr172 said:
If the previous leak downs showed no leakage past the valve, I would be concerned that something is off with the re assembly. Valve recession usually takes a lot of time and can't think of another reason why the gap reduced, assuming you know it was right in the past. Poissible the plunger has a flaw and not fully collapsing.
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Credit due to lr172.. as I stated, after installing the new cam deflated clearance was at minimum (50hrs ago). This time after reaming the guide, lapping the valve/seat reinstalled the jug. Somehow the hydraulic unit partially filled with oil after deflating and installing it. My guess is the limited prop rotation partially filled the hydraulic unit. This repair was done in one day so oil quickly flowed with limited hand rotation of the prop. Clearance still at minimum but flying again
 
sansoneservices said:
Credit due to lr172.. as I stated, after installing the new cam deflated clearance was at minimum (50hrs ago). This time after reaming the guide, lapping the valve/seat reinstalled the jug. Somehow the hydraulic unit partially filled with oil after deflating and installing it. My guess is the limited prop rotation partially filled the hydraulic unit. This repair was done in one day so oil quickly flowed with limited hand rotation of the prop. Clearance still at minimum but flying again
Click to expand...
That darn oil; always going where you don't want it ;) glad you figured it out!
 
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