Oiling problems to #4 rod journal?

[Tim_K]

A couple months ago when I pulled the balance shafts out of my 89 Turbo Spirits' 2.5 motor, I was checking the rods by shaking them, and noticed that the #4 rod had some clearance (play) in it. But it's still running fine.

I have a 150,000 mile 2.5 turbo short block at the machine shop right now, and the machinist (who has built a lot of quality race motors and a few for me) said the #4 rod journal on the crank was messed up. But on the low load side. With the piston all the way up in the cylinder, it'd be the side of the rod journal closest to the ground.

Anyone know why this is? I told him to drill the main oil galley to main bearing oil feed holes one drill size larger than whatever they are right now. To get more oil to the crank / rod bearings.

[Tim_K]

Anyone? I saw the block today, and the machinist said he drilled the oiling holes out to 9/32", but that it wasn't much of a change. I want to have him drill the holes more, like to 5/16" or 11/32" or so.

When I build the engine it will have full groove main bearings, so being able to get enough oil volume to the mains and rods is a big concern.

Maybe I should go even larger than 11/32"?

The crank had to be cut 20 under on the mains and rods because of wear and rust pitting.

[Turbofreak]

could it be a problem of not enough side clearance on the rod??? Something that was causing an oil shortage/starvation to that journal?

How did the bearing look on that #4 rod? Completely eat up or decent condition? Have you had the crank tested for hardness? Maybe it has a soft spot or is defective?

Maybe the main jornal that feeds the #4 rod bearing with oil had a blockage in it of sludge or something??

GOOD LUCK!!!

but you shouldn't have to do any mods to the stock crank.... check your block closely and make sure it doesn't have any dried up sludge in it that might cause a lack of oil to that one bearing....

RYNO

[turbovanman]

Your post is confusing but alas, anything could have happened to mess up the crank surface, bad oil, coolant, detonation, crap assembly etc, so I wouldn't worry about that. Did he redo the whole crank or that one throw, if he did only one, that will totally throw it out of balance. As for drilling out the crank, agreed, there is no need plus you weaken it. As for side to side clearance, your supposed to have some, the spec is .005-.013". If this is too much, it will affect oil pressure as too much bleeds off. If it is too large, the rod could have been machined to thin or ditto with the crank journals on the side.

[Tim_K]

What's confusing about the post?

I know there has to be a small amount of rod side clearance, but I haven't measured it yet. Too much clearance will let the oil out of the rod bearings too easily.

I never said anything about drilling the holes in the crankshaft. I was talking about drilling out the oiling holes in the BLOCK. The oil holes that run from the main oil galley to each of the 5 main bearings to supply the mains and rods with oil.

I saw the crank after it was machined, and it looks very nice. It was cut on all mains and rods. They were all cut 20 under.

[turbovanman]

Quote:

Originally Posted by Tim_K What's confusing about the post? I know there has to be a small amount of rod side clearance, but I haven't measured it yet. Too much clearance will let the oil out of the rod bearings too easily. I never said anything about drilling the holes in the crankshaft. I was talking about drilling out the oiling holes in the BLOCK. The oil holes that run from the main oil galley to each of the 5 main bearings to supply the mains and rods with oil. I saw the crank after it was machined, and it looks very nice. It was cut on all mains and rods. They were all cut 20 under.

Sorry, I thought you mean't the crank, I am confused about the piston with the rod all the way up?????????????? what do you mean? has nothing to do with oil clearance.
I hope you find your problem,

[Tim_K]

I meant when when the piston is at top dead center, the segment of the crank's rod journal that is on the bottom of the circle (of the rod journal).

[Tim_K]

No one has answered my question yet. What do you think of enlarging the holes (in the BLOCK) to provide extra oil volume capacity to the mains and rods?

[glhsken]

There might be a reason no one's replied. Oiling is NOT an issue on these engines.

[turbovanman]

Quote:

Originally Posted by Tim_K No one has answered my question yet. What do you think of enlarging the holes (in the BLOCK) to provide extra oil volume capacity to the mains and rods?

I did, I guess in another post of yours and said it wasn't necessary. I have beat the crap out of mine for 25K and not a mark on any bearings. Its a 2.5 in a heavy van btw.