Worn Cam
Mechanic didn't notice problem with oil pump, causing his repair to cause damage to my cam lobe. His fault?
I have a 2000 Jeep Cherokee that had an apparent engine skip. My mechanic replaced the lifters, a bent push rod, the head gasket, and rocker arms for $1300. A week later: check engine light back on and loud clicking from the engine. Mechanic said oil pump was gone and full of "sludge" and caused the prior problems. Replaced it for an additional $400 but couldn't get the symptoms to stop. Then he said that, because the oil pump was bad, the lobe on the cam shaft was deformed/bent out of place from too much friction with a new lifter, which was worn down and uneven on the bottom. They reassembled my car but said that I probably don't have much time before the friction from the now deformed cam lobe wears away at the new lifter they put in.
My questions: They said the deformed cam lobe was a result of them installing a new lifter without them knowing about the bad oil pump (they didn't check) . They say it's not their responsibility that they didn't know about the bad oil pump. Yes?
Right off the bat it's normal procedure to check camshaft lobe lift when ever new lifters are installed. This way if the cam had worn lobes it should have been changed along with the lifters before the car was ever delivered to you the first time. There's no doubt in my mind that the initial wear on the camshaft lobe was due to the old initial cupped-out lifter. Camshafts don't deform or bend either. The journals and lobes are induction hardened. When the thin outside layer of the hardened steel lobe wears away they wear very fast. In fact, a camshaft will twist and break but never bend. The fact that you had rocker-arm and push-rod trouble also leads me to believe the oil pump was at fault but did not cause initial damage to the camshaft lobes.
The hydraulic valve lifters are pressureized through an oil gallery mid-point of the lifter body. The entire upper valve assembly including pushrods rocker arms, rockerarm shafts and valve springs and valve stems are lubricated by the small hole on the top of every hydraulic valve lifter.
Guess where the lubrication to the cam lobes come from? The pressurized oil splash squeezed out between the main and rod journals. If the oil fed main or rod bearings didn't spin from lack of oil pump lubrication how do figure the oil pump ruined the camshaft and lifters?
I'm only giving you food for thought. Your first and second issue conserning the worthless oil light could have been avoided if Chrysler installed real oil pressure gages as most trucks do. Low oil pressure means two things. Low oil in the crankcase or an oil pump deciding to lay down on you.
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