Re-Torquing STOCK Head Bolts Questions
 

had an experience tonight, i want to ask some questions, get some answers then i will go through what went down.

1. Is it "OK" to re-torque factory installed head bolts?

2. If it is "OK" to does mileage have any affect on them?

3. What is the acceptable ft/lb of Tq that you can torque the bolts to?


:pca1:

I have never done this my self because you can only stress a bolt so much before it breaks

Everyone I have talked to about it takes them to 135 ft/lbs

you can
140lb ft

i forgot to add,

4. what is the correct sequence of doing the re-torque in ft/lb steps?

start in the middle and work your way out in a circle I did this with mine this summer and there still holding.

only time i have retorqued a head bolt is during installation of head. always checked torque twice just to check myself than ran engine to operating temp check for leaks and any extra rattles and then shut off and let cool and then check torque again but i dont think checking them is a bad idea especially if your comfortable doing it and stretching your head bolts will only happen if you take them to a higher torque value then they were at or from the factory http://www.dieselpowermag.com/tech/d..._to/index.html see if this will help with your questions

well here is what happened,

all the :":big guys:": in the diesel scene that live around me (not calling names but one has a pro-stock truck and one has a green "street" truck) all say to re-torque the head bolts up to 130 ft/lbs. we installed a set of 370 marines, and bumped the timing to 16*, decided since the injection lines were off that we would re-torque the head.

for the record this is on a 96 ram 2500 with a little over 420K miles. anyway, in the middle of re-torquing the head one of the bolts broke off in the block. we torqued them to 130 ft/lbs. we broke each bolt lose one at a time before re-torquing them.

this is an announcement, by me, take it as you will, if you are going to take head BOLTS above stock specs, BUY A NEW SET and install them one at a time, and then torque them to a higher setting.

I WILL NEVER RECOMMEND RE-TORQUING OLD STRETCHED HEAD BOLTS DUE TO THE POSSIBILITY OF THEM BREAKING.

pictures will be posted later of the broken bolt. luckily we were able to remove the offending piece in the block without having to remove the head and replaced it with a lower mileage head bolt out of my truck since i am upgrading to studs.

Attachment 50189

Attachment 50190

Attachment 50191

Attachment 50192

:argh:

wow, that really twisted before it broke. At least you were able to get it out. I would have to say that when re-torqueing head bolts age and milage are key deciding factors.

D'oh! :argh: Atleast you were able to get it out w/o taking the head off.

Bolts stretch, thats how they hold. When a bolt stretches too much it looses it strength. There is a Cummins procedure that is very technical for seeing if they can be used. Drop them head first from shoulder height onto concrete, if they ring, they are good, if they land with a thud, replace them... :D

Mine are down to 135 ft/lbs...

:argh:

i called and checked w/ cummins a while back and was told by their people to NOT REUSE THE OLD HEAD BOLTS, they are a one time use and need to be replaced whenever you pull the head, or loosen one off, they are only about 3 bucks each, :c:

well after talking to a machinist he said that this bolt had stretched and was bottomed out in the block, or so he said.

diesel power mag did a write up about this and they said to soak the bolts in oil over night and make sure the threads on the block and bolt are perfect and clean then from 100lbs up do it in 5lbd incroments up till 135lbs. i think im going to get all new bolts and torque them to 130. that should be more then enough to hold 40psi

this is what the shop manual says

step ......... torque value
1 ........... 40 Nm (29 ft lb)
2 ........... 85 Nm (62 ft lb)
3 .......... 126 Nm (93 ft lbs

there is a sequence but the picture of it is bigger than allowed for uploading

AERA SAYS 66, 89 FT/LBS +90 DEG SEE TB 909

909 SAYS TORQUE TO YIELD IS AT 100 FT LBS

I wouldn't condone it.......
But I have heard of guys using Grade 10 or 12.9 Socket head bolts.

BTI