1BIGJIM

iTrader: (1)

After spinning a couple rod bearings I stroked my 454 to a 496. It Ran great all year. Oil temp and pressure never changed from day one. I cut open the oil filler last fall and found some bronze metal flakes. Tore the engine down over the winter and found the THRUST BEARING clearance at .020. Replaced it and down to .004. clearance. (Nice and snug the way I like bearings and women )
Every rod and main looked great just like the day they were installed.

The only think I could think of is, I changed the crankshaft and the shaft from the outdrive was pressing against the crank forcing pressure against the thrust bearing.
I ground about .020 off the drive shaft. If it was tighter than that I would not think the outdrive would bolt up tight. The splines are and coupler are perfect. I even went as far as to replace the gimble bearing. The alignment tool slide in and out and in and out nice and smooth.

I cut the filter open after 20 hours this year and I am starting to see the same damn thing.

Any idea of what else could be causing this problem?

I am going to continue to run it until the end of August. Just no long 30 mile trips!

GOODT

did you mic the clearanses befor instaling the crank ?????

Ive never seen a drive cause this....how did you install balancer ...hammer or installer


sorry stupid questions but need to be asked

SB

iTrader: (1)

Another basic question - who's crank + which model and was it gone over with a fine tooth comb ?

1BIGJIM

iTrader: (1)

The first time my machine shop I have delt with for 20 years put the bottom end together because I did not have time.
Everything was mic'd crank was turned down to give me the clearence for a boat.

I stopped using a hammer to install balancers 10 years ago

I put the last thrust washer in personally. Yes I know how to install them.

I have never heard of a drive causing this problem, but something is pushing or pulling on that bearing.

I have seen cars do this with aftermarket cranks. I saw one a couple months ago on a manual transmission that the pilot bearing would not seat all the way in the crank because it was not counter bored enough.

This is why I am STUMPED

88Fount33

I know spinning rod bearings does occur, but I feel that what you are seeing is related to the earlier problem. If the block was not properly machined could be the rod bearings spun as they were the weakest link, then you "fixed" them and the thrust bearing became the weakest link. I would check the block's bore alignment and trueness. It is very unlikely given the spline fit of the drive to the coupler that enough force is transmitted from the drive to the crankshaft to cause this kind of wear.

razor1115

Something else that would be easy to check, not sure if it could lead to your described problem: Are the accessory belts aligned properly. This could, concievably, place a load on the crank pully and "walk" the crank. If all is well with the block machining and the crank, somehow a load is being placed on the system. I am assuming it is the rear crank thrust bearing surface since you were asking if the outdrive shaft could cause this...

Zack

cstraub

The thrust itself could have a high spot. Just ran into this on a crankshaft. Endplay was good when checked but after engine came down thrust was out of tolerance.

Put a dial indicator on the face of the thrust and check it.

1BIGJIM

iTrader: (1)

Chris, what do you mean the engine came down?
Yes that will have to be the first think I check.

The block was alignhoned(sp).

88Fount33

Align-honing the mains will true them up, that is correct, but what I was referring to was the trueness of the bores to the crank centerline. I do not know if a resize of the cyls. was done with the conversion. Crank high spot is another very strong possibility.

cstraub

Jim,
The customers engine was still running it just had .100" worth of endplay. So before it let go he pulled the engine. The front side of the thrust was eaten up. Customer was then informed that this had been found in some aftermarket import cranks.