91.5 beater

I have had a few people tell me to replace my head bolts after 252,000 miles of runnin, is this necessary or not? This motor has not really been run hard. Should i replace them when going to a stage IV? And one other thing do you all recommend pinning the kdp in? how hard is it?

Dean Snow

i wouldnt replace the head bolts unless it was needed, and yes pinning the kdp in is fine. its not that hard.

G1625S

I know Wanndiesel helped Pred put a HG on recently and they reused the headbolts...I think Pred's truck is a high-miler, but I'm not sure. I do know that Cummins didn't skimp on the fastening hardware. I'm doing a HG in the next week or so and plan to re-use the bolts 'cause I can't afford studs right now

1stGen545

Mine were fine at 300k

marksmith

My 95 was OK with re-used bolts.

I torqued to 120ft-lbs. If one wanted to twist off..... I put another used one in its place.

This truck held 55psi on a new marine (+.020) head gasket with 20* timing.

My 02 held 60psi with a drag comp.


When I do my first gen... it will have re-used head bolts and they will be torqued to 120ft-lbs (I have a box of used head bolts) Suspect it will hold somewhere between 50-60psi and a little timing.

wannadiesel

The Cummins test for head bolts (really, I'm not kidding) is to hold them head down at arm's length and drop them on a concrete floor. If they ring, they are OK. They also have a cardboard stretch gauge that comes with the head gasket. High tech stuff, huh?

91.5 beater

So its really nothin to be worried about?

93beater

with the condition your truck is in i would proably replace them, and the kdp is a must do!

ChrisLib

Wow, and I thought Mitsubishi`s method was "high tech". For the con rod bolts they have you spin the nut down by hand and feel for any stiffness which would indicate excessive stretch.

CaptainChrysler

Here are some specs from the Cummins book:

Head bolt strech gauge (included with head gasket or upper engine gasket set) P/N 3823921

Maximum length for head bolts:
Short
71.5mm OR 2.815in
Medium
122.1mm OR 4.807in
Long
182.9mm OR 7.201in

As long as they are not pitted or overly stretched they can be reused for the life of the engine.

Torque specs:
Lubricate bolt threads and under head with clean engine oil.
Install all 26-12mm head bolts and 6-8mm rocker pedestal bolts finger tight
Tighten all 26 bolts to 66 ft-lb
Tighten 6 long bolts to 89 ft-lb(these are the bolts that are under the valve covers and hold on rocker assembly's)
Tighten all 26 bolts to 66 ft-lb again because of head flex
Tighten 6 long bolts to 89 ft-lb again because of head flex
After that you have to turn all the bolts 90*
The heads are marked with a dot on one "point" and a "window" or range 90* from that. You are supposed to mark your socket to match the dot on the bolt head and then 90* from it. Put socket on bolt and mark head, then turn to second mark on socket. I used a Lisle torque angle gauge to do ours.
Then you can torque to 8mm bolts to 18 lb-ft.

If anyone can get around the security on the PDF files I would be happy to post all of this.

CaptainChrysler

Oh yeah one other thing.
The book warns against using pre 1991 bolts in newer engines because of the length of the threaded portion. You can use new(er) bolts in 1991 and older engines.

91.5 beater

My trucks in better shape than yours 93beater, look who's trucks in the shop cause it don't start! Hee Hee

schamran

Can someone put these specs in the sticky!? Been looking all over for em! Thanks.