re-using bolts in engine rebuild

**clubagreenie** · 15-12-2007, 09:34 PM

Contrary to most here, important bolts. Head, rods, main brgs, flywheel I've always replaced. Mind you I've not rebuilt anything redlined under 8000

**DX20VT** · 15-12-2007, 11:40 PM

Originally Posted by duff_boy

Well i work at cummins diesel and i rebuild diesel engines all day long. In the case of these big engines you _never_ have to replace the bolts at all, unless the thread is fucked out or(if you can be bothered measuring them) they are stretched beyond the given specified length. Type of tightening method doesn't really matter tbh, infact most of the important ones - ie mains, bigend and head bolts - they're torque + degrees method. Regardless of the bolt being old or new, they're tighten to the same torque. They seem to withstand several builds no worries, even when they're tensioned to 300ft/lb + 90degrees in some cases.

Originally Posted by clubagreenie

Contrary to most here, important bolts. Head, rods, main brgs, flywheel I've always replaced. Mind you I've not rebuilt anything redlined under 8000

Exactly,
How many of those cummins diesel's do 8000 rpm +?
and I bet they dont have 8mm rod bolts, lol.

**duff_boy** · 16-12-2007, 05:02 PM

Originally Posted by DX20VT

Exactly,
How many of those cummins diesel's do 8000 rpm +?
and I bet they dont have 8mm rod bolts, lol.

try the 1000's of NM of torque these motors put out, might only rev to 2000rpm but have a massive stroke, piston speeds would be pretty similar i'd say... And afterall, the size of the bolts are proportional to size and output of the engine yeh?

Hey, im not saying im "right" but im just using it as an example.