Main bearing cap screw

[DosGatos]

MY 2009 871:
Rolling in new bearings. Ordered new main bearing cap screws 4966356 through the dealer. Part number in quickserve did not resolve. After a call to Cummins bolts were ordered. What showed up were head bolts 3678506. Apparently same dimensions but different markings.

Different angle markings. I don't see a problem but thought I'd put it out there just in case.
Thanks

[Signature620]

I thought main and head bolts were the same part.

[DosGatos]

They are now

[Rawze]

It is my understanding that one is designed for a 180 degree stretch,.. and one is only designed for 90 degrees. It is even stamped into the bolt head by the bolt manufacturer,.. not cummins.

That would tell me that they are of 2 different designs, rated for 2 different stretch/torque specs. + have different metallurgy. - Only way to know for sure is to get in touch with the bolt manufacturer and ask them for the interchangeability at maximum holding force, and how far to turn one vs the other before worrying about distortion or damage.

Not trying to over-think it,. but it is a critical part of the engine, and if it were my own truck, I would not rest until I had a clearer answer than simply "use this part instead of this part bla bla BS".

[Hammerhead]

(07-18-2019 )Rawze Wrote:  It is my understanding that one is designed for a 180 degree stretch,.. and one is only designed for 90 degrees. It is even stamped into the bolt head by the bolt manufacturer,.. not cummins.

That would tell me that they are of 2 different designs, rated for 2 different stretch/torque specs. + have different metallurgy. - Only way to know for sure is to get in touch with the bolt manufacturer and ask them for the interchangeability at maximum holding force, and how far to turn one vs the other before worrying about distortion or damage.

Not trying to over-think it,. but it is a critical part of the engine, and if it were my own truck, I would not rest until I had a clearer answer than simply "use this part instead of this part bla bla BS".

Can't see bolt manufacturers putting different markings on the same bolt.
I 100% agree that I'd be telling Cummins to get the correctly marked bolts, or put me in touch with the bolt mfgr to get some documentation confirming metallurgy/stretch/strength characteristics. An additional 90° of rotation is a significant difference in torque! I don't think I'd be comfortable using a 25 IPO a 33, nevermind double!

[DosGatos]

(07-18-2019 )Hammerhead Wrote:  

(07-18-2019 )Rawze Wrote:  It is my understanding that one is designed for a 180 degree stretch,.. and one is only designed for 90 degrees. It is even stamped into the bolt head by the bolt manufacturer,.. not cummins.

That would tell me that they are of 2 different designs, rated for 2 different stretch/torque specs. + have different metallurgy. - Only way to know for sure is to get in touch with the bolt manufacturer and ask them for the interchangeability at maximum holding force, and how far to turn one vs the other before worrying about distortion or damage.

Not trying to over-think it,. but it is a critical part of the engine, and if it were my own truck, I would not rest until I had a clearer answer than simply "use this part instead of this part bla bla BS".

Can't see bolt manufacturers putting different markings on the same bolt.
I 100% agree that I'd be telling Cummins to get the correctly marked bolts, or put me in touch with the bolt mfgr to get some documentation confirming metallurgy/stretch/strength characteristics. An additional 90° of rotation is a significant difference in torque! I don't think I'd be comfortable using a 25 IPO a 33, nevermind double!

Understood. I'll call cummins tomorrow. The head is 300ftlb plus 90 degrees. The main is 110ftlb plus 180 degrees. Which is the greater final torque?

[Rawze]

(07-18-2019 )DosGatos Wrote:  Understood. I'll call cummins tomorrow. The head is 330ftlb plus 90 degrees. The main is 110ftlb plus 180 degrees. Which is the greater final torque?

It works out to very similar torque actually, from what I have measured out of curiosity in the past... . Problem is that can one be exchanged for the other, and if so, what is the starting torque, and ending rotation.. and are they compatible. I am thinking the bolt manufacturer would be the one to answer that and not some damn cummins shop, unless there was an official document stating as such, so that one's own arsse is covered in the event of failure. It is unlikely, but a failure of the crank retaining bolt(s) can lead to engine lock-up and sudden loss of control of an 80,000 lb vehicle.

again,... not trying to over-think things,.. just sh$it that comes to mind ... the beer is talking tonite lol

[Mr Hagg]

Quote:d. I'll call cummins tomorrow. The head is 330ftlb plus 90 degrees. The main is 110ftlb plus 180 degrees. Which is the greater final torque?

When did the head bolt go to 330 ft lbs We do it 300 plus 90

[DosGatos]

(07-19-2019 )Mr Hagg Wrote:  When did the head bolt go to 330 ft lbs We do it 300 plus 90

The head bolt went to 330 when I was typing on my phone with fat fingers. Previous message corrected. Sorry