Mikemetham@gmail.com
Filing Flight Plan
- Joined
- Aug 17, 2014
- Messages
- 3
- Display Name
Display name:
Mike Metham
I have a friend who owns a Bulldog with an IO360 Lycoming engine.
He has been suffering from rough running and fluctuating oil pressure at running temperatures. Having tried every thing else we finally decided that the problem was with the hydraulic tappets. He has installed a complete set of new hydraulic tappets and is now checking the clearances which we note should be between .028" and .080". When checking the clearances he is having to push quite hard on the tappet side of the rocker arm (the tappets are new and completely dry) and it feels to me that he is compressing, or partially compressing the small flat coiled spring on the tappet piston assembly before being able to insert the feeler gauge. I am of the firm opinion that one should simply take the slack out of the system before checking the clearance. I would expect to be able to move the rocker freely backward and forward through the clearance and, maybe, hear a little "click" at each end of the movement.
My contention is that as soon as the engine runs, the oil will fill the cavity and, as the oil is incompressible, set itself to NO clearance and the spring will only come into play lightly when the volume of oil is adjusting. I'm sure that if the clearance is adjusted with the small spring fully or partially compressed, the idea of a self adjusting hydraulic tappet would not execute properly.
Help?
Thanks in anticipation.
He has been suffering from rough running and fluctuating oil pressure at running temperatures. Having tried every thing else we finally decided that the problem was with the hydraulic tappets. He has installed a complete set of new hydraulic tappets and is now checking the clearances which we note should be between .028" and .080". When checking the clearances he is having to push quite hard on the tappet side of the rocker arm (the tappets are new and completely dry) and it feels to me that he is compressing, or partially compressing the small flat coiled spring on the tappet piston assembly before being able to insert the feeler gauge. I am of the firm opinion that one should simply take the slack out of the system before checking the clearance. I would expect to be able to move the rocker freely backward and forward through the clearance and, maybe, hear a little "click" at each end of the movement.
My contention is that as soon as the engine runs, the oil will fill the cavity and, as the oil is incompressible, set itself to NO clearance and the spring will only come into play lightly when the volume of oil is adjusting. I'm sure that if the clearance is adjusted with the small spring fully or partially compressed, the idea of a self adjusting hydraulic tappet would not execute properly.
Help?
Thanks in anticipation.
