Contour Enthusiasts Group Archives Forums Modifications 3.0L Duratec How to fix a block with spun bearing?

I want to know if a block has a spun rod bearing but everything else is fine, what do I need to fix it? I know that I'm going to need new rod bearings with the right clearance, but do I need to get the area that the bearing was resurfaced? Or what do I need to do? I'm going to be using another crank that didn't go through spun bearing problem so the crank part will not be a problem.

Should be nothing wrong with the block as long as the old crank didn't do a melt-down near a main bearing journal. A new rod and new crank should pretty much solve the problem along with good bearings.

where have you been by the way and what happened to your car?

warmonger

More times than not, a spun rod bearing block will also have heavy scoring on the mains as well, including the block. The problem stems from the oil supply and crank whip issues as the one or two rods try to twist the block apart, as the mains try to hold itself together. The main bearings end up walking around a bit. It really just depends on how much the engine was run while the bearings were seizing up.

Check the mains of the block for any grooves. If there are any, the block will need to be align bored. Color it cheaper to find another block in many cases...

I agree with Brad. If you are gonna go through the hassle to replace the crank, why not just get a nice 0 mile block? It seems like the peace of mind alone would be worth it. If you miss any signs of damage you could end up putting it back together again only to have it POP again. Just playing Devil's Advocate.

You both suck.

Its a matter of saving money. Obviously you inspect the block and mains for damage and as I said...assuming it didn't cause damage to the mains then you'd be ok. (that's what "...didn't melt down next to a main.." sort of means)


Either way, if you take the normal precautions like put the mains together and re-measure the bore of each main from two axes, then you'll know if damage took place.

I personally would go the cheaper of the two routes, crank then block UNLESS the cost was about the same. However, from my own personal experience a newer used engine is the cheapest way to go in almost all cases.

Tom

It's not just a matter of saving money to me right now. I'm going to have to either fix the block with spun bearing, or fix the one that blew some pistons. I still haven't pulled the 3L out of my car so I don't know how bad the cylinder walls look. But I want to do whichever is cheaper and easier. I need to get the car back on the road soon, winter is just a few months away. I can only ride my bike up til it starts snowing.

If you can't get the block out of the car yet, at least pull the plugs on it if you haven't. That will give you a better idea what the cylinder walls look like as well as if you'll need to redo the heads too. Of course it won't give you a solid answer, but at least an idea to work with. Plug gaps that are closed, usually means chunks of piston are flying around... That means a full rebuild is in order, probably including at least a cylinder hone or overbore. Unless, of course, you already have new heads to put on the next block and/or the spun bearing block has no main damage.

The plugs in the front bank all have mechanical damage. There were definitely signs of stuff flying around. The plugs on the rear bank on the other hand looked almost as new as when I put them in. I don't know if the 3L block with spun bearing has any problem with the main bearing... I guess I won't know until I disassemble everything.

How many miles you have on that?