I recently purchased a 2004 Discovery II with approximately 84,000 miles. The engine ran great and did not have any tapping sounds at all. However, I discovered coolant leaking from the left rear between the block and the head. So, I proceeded to pull the heads and decided to follow the recommendations of several owners and pull the oil pan and front cover to inspect the oil pump and timing chain. When we pulled the pan we noticed part of the thrust washer in the bottom of the pan with chunks of bearing in the oil pick up. So, we pulled the engine for a full rebuild, but we question what caused the issues with the Thrust Bearings. Is there an option for enhanced bearings or is there an issue with the torque convertor or driveline? Suggestions are welcome

 

Could be a sign of an engine that did not receive regular oil changes. I've seen the middle bearing worn almost to the point of coming apart but never have seen a running engine with bearing pieces in the pan that was not ticking and overheating.

To my knowledge there isn't any bearing set that differs from the original design although there are some major differences in quality. Needless to say go for the good ones. Check the crank journals carefully and if they're okay have them polished and put things back together. Don't forget new rings, con rod bearings, cam bearings, lifters, pushrods, valves, valve guides, seals, rockers and rocker shafts.

 

I've never seen any engine with rubbished thrust bearings, worn ones, yes, but never disintegrated. It does sound like an amateurs engine rebuild or possibly run clean out of oil. It does sound like the whole engine needs rebuilding and careful checking for other issues.

 

I'd think that a bad thrust bearing (you just have one in the center of the Mains) would be due to either/both low oil level/pressure or else from a worn crankshaft that is now out of round.

Of course, an aluminum block *could* possibly warp a little if it ever overheated such that even a straight crankshaft could prematurely wear/grind apart your Main/thrust bearing.

There is a special bar of metal that you can buy/rent/borrow from many shops which is *perfectly* straight that people use. They lay it across the block where each head would attach and then stick feeler gages under the bar, or try to, to see if there is any warpage, then the same trick is repeated while the bar is resting inside the block where the Main (and thrust) bearings would reside, and again for where the camshaft goes.

You want to verify that your block is straight/square both internally and on top where the heads go... before spending your money+time on your heads, machining your crankshaft, buying a new cam+lifters, bearings, etc.


When you are rebuilding your motor you will test for "float" for your crankshaft and for your camshaft (well, really, just buy a new cam instead of trying to reuse some old worn one...a stock cam for the 4.6 Disco2 motor is just $90 on eBay, sponsors, etc.).

If the "float" is too much then you have to machine the crank or use a better block. Well, you can *test* your block with that perfect metal bar and feeler gages first before you are out time+$.

Float will eat up bearings in mere miles and completely ruin all of your rebuilding work+$.

 

Ok dumb question...what is the trust bearing? Guess I could just Google it..

 

What they are talking about are crankshaft bearings, specifically the center one, and the block side half.
That bearing half has sides to it.
If you look through the 2nd main cap in this picture, you can see where the bearing on the 3rd extends over the edge of the block where it sits, as opposed to the others that are visible and do not.

 

So that piece that hangs over broke off into the pan as i read? Geeze what would cause that?

 

Yes, apparently.
I don't know the cause, other than a factory defective bearing(weak spot, etc), poor installation and assembly, or maybe it got dropped and damaged.
You could run the engine with no oil, lock it up, and that bearing should stay intact.
Who knows.

 

Nice work cv!!

 

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