I don't see any place for the o-ring to go but OUT.

 

If it goes OUT, you've over torqued it.

They should also be lubed before they are torqued.

 

Loctite doesn't care, it seals up no matter what you do.

 

Really?
Even if you don't get all the oil off before you loctite it?

 

The ORB fittings at the head do not require LocTite. I have never used it on the heads and have never needed it. I do not include the LocTite 680 with the head o-ring kit for that reason.

The main reason that the HPOP hose fittings require LocTite has to do with the coefficient of expansion of metals. On the HPOP you have a steel fitting screwed into an aluminum pump body. Both expand and contract at very different rates unlike the heads. The one main exception is the IPR that does not require LocTite. If you look at the IPR seat for the o-ring in the pump, it is designed very differently. Once the IPR is seated, the o-ring can not be seen at all. With the design of the IPR o-ring seat, it is rare that you can over torque the IPR and cause damage to the o-ring.

As long as the proper type of LocTite is used on the heads, it will not hurt anything to use it but a simple o-ring torqued properly will work very well on its own.

 

In all honesty I have seen it done before and work. But the threads should be cleaned first. I am just saying I see o-rings fail ALL the time hence this thread. I have NOT seen loctite fail.

 

No locktite on mine....and i can park anywhere without fear of leaving a mess. no leaks at all!!!

just dont overtighten and should be fine.

 

Loctite is a good product, but I don't believe it should be used to replace good practices. You can see from the OP picture that the o-ring was WAY over torqued.

 

Good practices or not I use it to prevent break downs. Like I said o-rings fail if they didn't fail we wouldn't have to ever tear into the top end of a 7.3. toctite is like a safety harness for the o-rings. In our family business we cannot have break downs and I have learned over the years how to avoid the unexpected break downs and use these tricks every day and it has treated me very well.

If vehicle manufacturers did everything right the first time from the factory there would be no parts stores.


DieselO-rings: I just have to say the very very minimal expansion rate differences between the steel fittings and aluminum body are not enough that the o-rings should be effected, if it were enough the loctite as well would fail. With as small as the fittings are we are talking about a expansion difference being only .0006" over a 250f degree range. That is less movement/change then the cast iron block flexes while running.

If the movement difference was such an issue between steel or cast iron and aluminum pretty much every mechanical thing in the world would fail. Aluminum heads on iron blacks would break their fasteners off, aluminum tranny cases would outgrow their steel internals and all those little steel ***** used to seal up drilled oil passages in aluminum would fall right out.


Here is a little reading on expansion rates of different materials.

Coefficients of Linear Thermal Expansion

Temperature explained

 

Thanks for chiming in. With regard to different o-ring applications, that sure clarifies things.

 

My factory installed ORB fittings without loctite have run 285,000 miles without failure. I'm sure glad I wasn't smart enough to worry about them failing all this time, I'd probably have ulcers by now.

 

With an ORB port, the o-ring will actually engage in the bevel of the "properly" machined port.

 

After a quick call to Bob at Diesel O Rings I found out that I should still have some orings left from a kit I bought a couple of years ago. Dug around and found them. Got it cleaned up, decided to put some 680 on the threads as a backup and snugged the fitting down with the new oring. I don't know what was there before but I certainly wasn't the right thing. The new oring fit like a champ. Looking closer, there IS a bevel in the head port that will accept the oring without spitting out the edges. Going to let it sit for 24Hrs before leak checking it. Should be back to a dry machine again!
Thanks to Bob for looking it up and the advice and to Clay at RiffRaff for the offer of sending out some new ones.

 

Some guys say they get 300K+ miles on 6.0's without problems too.

I'm not looking to argue, I agree that yes the fittings should work with just the o-ring. But I'm just saying a drop of loctite won't hurt anything and can only help against any "possible" problems.

You don't have to change your oil till 7500 or more miles but I still change mine at 3K just because. Its one of those kind of deals.

 

I saw that when I had my fittings out, it just didn't totally satisfy me.