Main bearing Cap going bad. Can I fix it without pulling motor?

[Carparooni01]

I have a 2007 Mustang GTCS with 128k miles. I just got the entire clutch system done and main seal by a shop and they told me my engine is going bad because of the main bearing cap that is worn to hell on one side, basically holding on by a thread. They said it’s possible to replace it without pulling and rebuilding the engine by pulling the pan and tranny and replacing the part. My question is, is the part replaceable with a OEM part or similar? Or does this part have to be custom made to my engine? Couldn’t find anything online or from an auto parts store. Kind of stuck… considering spending the money on a brand new 4.6 crate engine but don’t want to someone lmk thanks.

 

[lwarrior1016]

Oh man. That is not good. Yes, it is possible to replace the one cap, but it will not be right.

The right way to do it is to pull the engine and tear it down. Replace the cap, and get the main journals line honed. Something has gone wrong and ate your thrust bearing. Did you have a really aggressive clutch in it before? Ever run it low on oil?

 

[JC SSP]

I wonder what the other main bearings look like? Also cylinder wall wear from the back and forth motion.

 

[86GT351]

Like stated above. Do it right the first time.

 

[Dino Dino Bambino]

Something has gone wrong and ate your thrust bearing.

Good call. If that's the case, there'd be excessive crankshaft end float. This video will be helpful in diagnosing it (i know it's a 5.4 but the principle is the same on the 4.6).

At 07:20 of the video, Brian uses a pry bar to test for end float. If yours is as bad as that, the thrust bearing is toast and that could be the reason why the rear main bearing cap has uneven wear. You might also want to borescope the cylinders to see if there's scoring on the thrust side of the bores.
Unfortunately this would be terminal damage for your short block.

 

[86GT351]

Bottom line is there is NO quick fix for this. Just repairing the one will be like putting a small band aide on a big cut. Will end up costing you more in the long run.

 

[Midlife Crises]

Replacing a main cap requires complete engine disassembly and line boring the new cap to insure the bore is round and in line with the other journals.
I would avoid a mechanic that suggested this could be done with the engine in the car.

 

[MrBhp]

Check out this.

Catastrophic engine damage?

I bought an 09 mustang engine with 199,005 miles. I’ve completely disassembled the engine and found the following things: The crankshaft had eaten through the main thrust bearing and had been scoring the block/main caps for many miles. (Snout of the crank below) Oddly, the main bearing...

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