Which bearing is subject to the most wear?

[rvanderpyl]

I have a 2.4T I am going to be using for a while until I build up a new motor. I am considering getting one of the 2.4 E Piston Cylinder sets off of ebay to bump up the compression a bit (I have an E cam I cam use), but I don't want to do a complete teardown. I would like to remove one rod just to make sure the bottom end is OK. So the question is, which one is most likely to have an issue if there is one?

[cstreit]

The one with the least oiling?

Seriously though I don't know if there is such a thing, however if I was going to "logic" my way through it I'd suggest #2 or #5. Reasoning being that area is the last in the oil-circuit.

#3 and #6 is the area where builders tend to put the heaviest piston/rod assembly.

Anyone else got theories here?

[304065]

We know that the "center" bearings are the ones that get starved for oil at very high RPM, because the crank is drilled with passages that feed #2 and #5 from the ends. A known modification for engines that see high RPM use is to drill the crankshaft to allow the center bearings to feed oil.



That being said, it's entirely a question of that particular engine, and if you are going to the trouble to pull off one cap, you will have to replace the rod bolts and nuts and properly re-torque. If it were me I would split the case, particularly if you don't know the engine's builder.

[rvanderpyl]

Engine builder is Porsche , this case has never been opened, has around 80,000 miles on it, and is a T so very low stress. Reason I don't want to open it, is that it is still a Mag Case, so if I break the case there is a good chance I will have to deal with all the normal Mag cases issues of machine work etc before I put it back together. If I have to do that I might as well build my new motor and forget about using this one. And the early engines, especialy the T's were supposed to be able to go for a 150,000 plus miles on the bottom end. Since I don't know the complete history of the motor I just want to check what I can to make sure there has never been an issue with it having been run low, or on dirty oil which damaged the bearings.

[Steve@Rennsport]

Robert:

Mister Cramer offered very sound advice but if you do not wish to split the case, I would pull #1 and # 5 rod caps to look at the bearing shells.

The rule of thumb is that oil contamination affects the end rod bearings first, and oil starvation affects the center rod journals (2 & 5) since these are the last parts of the engine to receive lubrication. You'll need to replace the bolts and nuts of course,.....

[cstreit]

Sound advice, I do recall that 2 and 5 are oiled the least. (edited to reflect this )

Now which area in the engine sees the most heat, 3 an 6 right?

[rvanderpyl]

Thanks guys, I'll have to think about this, I might just use the engine as is for this summer and leave any upgrades to the next owner.