|
Aircraft parts |
|
Home | Software | Knowledge Base | Customer service | Products |
|
Home> Continental & Lycoming TroubleShoot
Hydraulic lifter malfunctions in Continental and Lycoming aircraft engines
a. Too rapid leak-down. b. Ball seat worn out of round. c. Fouled or damaged ball-check valve. d. Deformed or weak spring. e. Lifter face scored, pitted, spalled, or excessively worn. f. Plugged oil passages. g. Check valve ball magnetized. This problem is more common than you might think. Often when we found a lifter that was not holding pressure we would demagnetize it and instantly restore its operation. Types of Hydraulic Lifter Noises in Lycoming and Continental aircraft engines
There are a variety of things other than the hydraulic tappet which can cause the trouble: such excessive clearance between the valve and guide, eccentricity of the valve seat, broken valve springs, etc. In cases where this type of noise is made by the unit itself, it is due either to a leaky check valve or a plunger having too much clearance in the bore
A hydraulic plunger has become sticky or tight in the bore to such an extent that the plunger spring will not move the plunger in the bore. Units may stick from a build-up of oil varnish or from dirt.
Insufficient oil is being delivered to the hydraulic units. Possibly the oil pump is taking in air on the intake side.
This type of noise will usually occur when the engine is brought down to idle from high speed, or on starting and is due to air in the oil delivery system to the hydraulic unit.
Hydraulic Lifters Pumping Up Valves can leak if the hydraulic lifters pump-up. This may result in the situation where the compression check is good, the engine starts to run OK but then a cylinder drops-off or the engine becomes rough. This happens when the hydraulic lifter pumps up and holds the valve open. An example of this happening is on the Continental A-75, A-64 engine installed in an aircraft that originally used an oil cooler. Then the engine is removed and installed in an aircraft without an oil cooler. Now the engine drops two cylinders and runs rough because two hydraulic lifters on one side of the engine are pumping up and holding the valve open. The reason its doing this is that the 22130 sleeve (oil restrictor) was not removed from the crankcase. This oil restrictor diverts some of the oil thru the oil cooler. If you remove the oil cooler and don't remove the restrictor then pressure builds up on one side the the crankcase and the extra oil pressure causes the hydraulic lifters on that side of the engine to pump up and hold the valves open.
|
Copyright 2003 by
Sacramento Sky Ranch Inc. All rights reserved. Prices subject to
change without notice. Not responsible for typographical or misprint. |
