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Removed 4-6 bank camshaft assembly and was surprised to see significant wear on one of the exhaust bearings
This is on the "outside" edge of the bearing at the end with the timing chain..."inside" edge appears OK
Camshaft itself shows minor wear.
Engine has 41k miles.
Now I need to decide:
repair: would only be able to sand the damaged bearing area to prevent further wear/metal particles since entire head and cam cover is one matched set
replace: I have another head + camshaft assembly that I could swap out from another engine. Do I absolutely need to get the block resurfaced before installing a new head gasket (would be logistically challenging)?
Shouldn't need to resurface block but check it for straightness. Recommend you take the head to Costa Mesa R&D in Costa Mesa - Orange County to have it checked & rebuilt.
You are right tt9714 the damage to the bearing/head is significant. You mentioned the engine had 41k miles. The pitting on the camshaft (where the bearing meets cam) is also significant. That pitting of the steel is usually caused by corrosion which can be present in engines with low miles. There are other variables that can cause the corrosion also.
Your are *not* going to fix that mess by sanding. The bearing clearance is opened up and this represents an internal oil leak which will result in this bearing running with less oil and oil pressure than is acceptable. The problem is compounded by the fact the bearing has lost considerable area and those areas that still have the factory clearance will be subjected to extra pressure due to the reduced load carrying/load supporting surface areas of the damaged bearing.This can only lead to further deterioration of the bearing with the risk of more serious damage to the engine when this occurs.
You are faced with finding a shop that can repair this: This requires the cam cover be bolted to the head and the bearing machined oversize on probably a horizontal boring milling machine, then fit a split bearing, properly pinned to the head and camshaft cover to keep the bearing halves from moving, and with the groove and hole machined into the bearing shell before it is cut in two and the halves fitted to the head and camshaft cover, then finish the job by boring this "sleeved" bearing to the proper size, finish, and clearance, then replace the camshaft and any other collateral damage (like possibly one or more lifters: The top of the lifter in the pic doesn't look so hot...).
While the above can be done it requires a shop that has done this before and knows the full procedure. This will probably be expensive.
As long as the block and head check out flat and straight to spec, neither the block nor the head need resurfacing. If either is not flat or straight there's not much metal that can be cut away to bring these into spec. I have no info on what amount of metal can be removed before this can impact the chain slack or other things that are highly dependent upon the amount of material at the block and head surfaces.
If you can't find a shop or the shop declares the situation hopeless, you will have to replace the head with another intact and needless to say in good working order head.
Almost certainly replacing the head is the easiest and less costly and least risky way to address the problem.
And a replacement engine may be better still. The concern is what else is lurking in that engine to bite the engine and you when you fire it up after fitting the new head?
Macster's answer is pretty good. Those dimples in the lifter are pretty ominous. I think I'd do like Macster says and put a replacement head, cam, and camcover on the engine. And I'd be pulling the oil filter and the sump for some inspection, and cleaning. That's a bad breakdown, might be better to find a replacement engine.
04-28-2019, 01:03 PM
Camshaft bearing damage -> repair or replace?
Not good.
