Bill.Peyton
Well Known Member
I'm looking for the procedure to bleed the new style Lycoming roller lifter. I want to check the dry tappet clearance.
Vic, I agree with you in principle. But what is your experience, since you do a lot of work observing others, in practice? My thinking is for us amateur mechanics, that the chance of a screw up in pulling,bleeding, reinserting a lifter (along with push rod and rocker arm) likely exceeds the chance of an inaccurate reading done by bleeding in situ? Especially for a field check?
I suppose this is relative to how tight the lifters are (I am sure there is some variability in the tightness / bleed down rate). In my engine, they will not fully bleed down with just valve spring pressure. I have to use extensive mechanical leverage just to get the rockers back on. I would have no confidence that they are fully bled down for a lash check after this though. Other than using a magnet to get the plunger assemblies out, not sure there is much to screw up. Once out, they are easy to bleed down and not many ways to damage them, unless you take them apart.
Larry
Vic, I agree with you in principle. But what is your experience, since you do a lot of work observing others, in practice? My thinking is for us amateur mechanics, that the chance of a screw up in pulling,bleeding, reinserting a lifter (along with push rod and rocker arm) likely exceeds the chance of an inaccurate reading done by bleeding in situ? Especially for a field check?
The roller tappets are totally different than the flat tappets, At least that's the way it appears. The rollers tappets have a small oiler assy that fits over the end of the pushrod. This oiler fits into the hydraulic lifter. The lifter itself does not want to come out of the bore easily. I am very familiar with the removal and bleed down of the flat tappet assy., but this looks completely different, and does not want to come out. The bore has two flat sides to keep the roller lined up. Am I missing something here with the removal.
I bore scoped my cylinders for this last annual and found a valve on it's way to failure, so I replaced the cylinder. Only 680 engine hours! Lycoming may warranty it even though it is over 2 years, so I am sending the cylinder back to them for evaluation. I want to be sure I have the minimum tappet clearance before I button it up.