98 Mustang GT 4.6

[bigdaddy41143]

#7 bearing spun. Put on a new crankshaft kit w/all new bearings. Torqued to specs and in order. Crankshaft will only rotate 1/4 turn. I took cam shafts off to release valves, squirted wd-40 in each cylinder (even thou I did nothing to top end). Re-checked everything and still have the same problem. Any suggestions or solutions. Transmission and converter are disconnected. 1st time this.has ever happened to me.

 

[Noobz347]

Posted in incorrect forum. Relocating to 4.6 tech forum.

Good luck with your problem. I'm sure that folks will jump in with some suggestions here shortly.

 

[trinity_gt]

#7 bearing spun. Put on a new crankshaft kit w/all new bearings. Torqued to specs and in order. Crankshaft will only rotate 1/4 turn. I took cam shafts off to release valves, squirted wd-40 in each cylinder (even thou I did nothing to top end). Re-checked everything and still have the same problem. Any suggestions or solutions. Transmission and converter are disconnected. 1st time this.has ever happened to me.

Couple of thoughts:

1) When a rod bearing spins it basically "grabs" the journal and begins to spin in the rod end. This is going to quickly eat metal out of the rod which opens up dramatically leading to the knock but it also will send metal shards and shavings everywhere. How did you clean out the oiling system? As well, did you replace the rod or at least measure the big-end to ensure it's within spec?

2) Is the engine coming to a hard-stop at that quarter turn point or does it gradually tighten up? If it's the former, check with pistons are nearing TDC and consider that one of these pistons is contacting something in the combustion chamber that shouldn't be there. If the piston on the rod for which you replaced the bearing is at TDC start there. If it's doing the latter it sounds like the bearing/journal you replaced has a clearance issue.

 

[bigdaddy41143]

Comes to a hard stop. There's nothing in the combustion chamber. Piston is within specs. It turned at first, then did this.

 

[trombonedemon]

Comes to a hard stop. There's nothing in the combustion chamber. Piston is within specs. It turned at first, then did this.

Would there be a possibility that one your piston-rings have not seated and actually come out?

 

[bigdaddy41143]

Pistons push up and pull down freely by hand in each cylinder, without any problem.

 

[bigdaddy41143]

Plus, they were never pulled out.

 

[blkstanger]

You need to pull the motor down COMPLETELY. Have your crank turned and your rods resized.

 

[bigdaddy41143]

Ordered another crank kit (2nd one), going to replace it today. See if that works. No damage to the piston arms or bearing journals or caps.

 

[Gtwo]

If it spun the bearing it generally does other damage as well. Some easily visible,some you'd never see.

Does the crank spin without the rods connected?

I would take the rods off one at a time until it freed up then would know where to start looking, if that didn't work do the same procedure on the mains.

Not an expert,but it is what I'd start with before I just started spending money.

 

[bigdaddy41143]

Took all pistons loose one at a time, crank will not turn. Pushed them up out of the way. Loosened main bearings one at a time, starting with number 5, 4, 3, 2, 1. When I freed #1, it rotated freely.

 

[bigdaddy41143]

Took all pistons off, loosened all main caps, took #5 off and took thrust bearing off and the crank seizes up again. Any possible solutions?

 

[bigdaddy41143]

No-one has any suggestions?

 

[N8Dogg98]

Throw engine away, buy MMR900 with ported heads, cams, and a PD blower... win...

 

[bigdaddy41143]

Belongs to my wife, therefore I don't want to make it a dragster. Any other suggestions?

 

[trombonedemon]

Is something different with number one piston and or number one cylinder.

 

[trinity_gt]

Belongs to my wife, therefore I don't want to make it a dragster. Any other suggestions?

Source a replacement engine from a wrecking yard.

 

[bigdaddy41143]

All pistons are ok and I have checked the rod journals, caps and have even gone as far as to take cam shafts off.

 

[Gtwo]

If there is nothing bolted to the crank,which is new and known good then there is only two possibilities...
1. Block is out of spec
2. Main caps are out of spec.


How did you check your block and caps bearing clearance?

What is it?

 

[blkstanger]

If you want to fix it right it needs to be torn down and the short block needs to be rebuilt by a machine shop. Or buy a replacement. There are no short cuts when it comes to bearing clearances. It has to be done right and done well. Your block might even need to be line bored.