Should I replace Main Bearing Cap Bolts?

[aclayton59]

Rebuilding a '93 4.0 OHV. Until today, I've not seen anything that says to replace the main bearing cap bolts. But today, reading the factory service manual, in big bold letters, it says NOTE: New bolts must be used for assembling main bearing caps.

So, who has or hasn't replaced them and have you had any problems?

I'm also not finding them from regular sources (rock auto, Advance, O'Reily's, etc..) Anyone have a source, or is this a dealer part?

 

[Dirtman]

Have you tried looking for them directly from ARP? I'm not 100% sure but they may be TTY bolts which means yes, they absolutely must be replaced. Best way to check that is to look at the installation procedure. If it gives you a torque spec AND a degree spec, they are definitely TTY bolts. (For example torque to 80ft lbs and then turn 90 degrees)

It's always wise to replace main, rod, and head bolts no matter what. But tty bolts are a must by design.

 

[aclayton59]

Thanks Dirtman. I don't believe they are TTY. Procedure is a single tightening to 66-77 lb-ft.

So I did a little measuring and searching.

Bolts are M12x1.75 x 93mm - Dorman sells a 90mm (Part #99127090.) A buck eighty nine at Advance Auto.

The fun one is the 4 that hold the "Crankshaft oil windage baffle", Ford part #FOTZ-6345-A. Of course they are no longer available. I found some NOS on e-bay for (ouch) $10.00 each. Hurts a bit, but the $40.00 is worth the peace of mind.