torque specs for injection pump cam gear

[Eric Selinger]

I need to know what the torque specs are for the fuel pump driver gear that bolts to the cam. It does not give a specific in thedieselpage R&R manual for a 1994 6.5L diesel.

Anyone know where to find torque spec listings on the internet?

Thanks!

Eric

[More Power]

As listed in the R&R Guide and in the torque specs page in the Member's Area Reference Section: Camshaft sprocket bolt (pump drive gear) 65-125 ft/lbs

Fuel injection pump (driven) gear to pump 13-20 ft/lbs

Through about 1996, the cam bolt was torqued to 65 ft/lbs. GM apparently experienced a number of cam bolts coming loose in the electronic era, which resulted in an upgrade to a grade 10 bolt and the torque was increased to 125 ft/lbs.

Clean the threads on both the bolt & threaded hole with solvent, then apply a thread-locker when torquing the cam bolt.

The 6.5 Project 6.5's cam bolt was torqued to 65 ft/lbs more than 5-years and 150,000 miles ago. The DS4 could put more rotational torque on the cam, which may explain why GM upped the bolt torque.

MP

[damork]

Eric,

GM did publish specs to go to 125 lbf-ft on the cam gear, and I really questioned it.

I asked several engineers I work with and did the baseline calculations and could never come up with a justification for that much torque on that bolt. 90 lbf-ft was much more in line with the size and grade of bolt.

After checking in with some engineering groups online, I found material design engineers that supported what I found. I looked at the existing bolt, bought a new bolt, checked the hardness and in the end I torqued mine to 90 lbf-ft with Loctite 271 on the threads. I've got over 30,000 miles since and no problems so far.