Injector Installation In Chassis

[Keith Browning]

Well I finally got around to performing my one and only 07T07. For those of you techs that have done this SSI and anyone from Ford watching, I have a serious question. Installing injectors in a 6.4L requires that the injector and it's fuel supply tube be installed in sequential steps of tightening from pre-assembly, pre-torquing, torquing and then a final turn on the fuel tube nuts. SSI 07T07 instructs us to use the procedure in the service manual and pays the technician 2.9 hours to complete the installation of injectors #1, #5 and #7. This tells me that it has to be done in chassis without removing anything that is not listed in the procedure.

 

The issue: getting a torque wrench to fit in the space between the injector and the cowl and A/C box. None of my toque wrenches fit, let alone adding a Crow's foot to the end. Second, if you could get your wrench in there, you do not have any room for the wrench to swing. We are instructed to keep the crow's foot in line with the extension of the torque wrench and many people think that using extensions will affect final torque values. I have read several writings that this is actually not true.

 

The question: is it allowable, permissible or otherwise acceptable to -

• rotate the crow's foot on the end of the torque wrench?
• use an extension between the crow's-foot and torque wrench?
• replace injector #7 with injector #5 out of the head for access? The manual notes to install from the inners to the outers.

I agonized over this for a short period of time and decided to do what I have to to get these injectors installed properly. See the photo below which shows what I deemed necessary to install #7. I know that the job was done right and I performed the high pressure leak test which passed easily. Is what you see in the picture a bad idea, what would YOU do or is this acceptable considering the low torque specifications involved? If I did not get the fasteners torqued to the *exact* spec, I am sure I got damn close.

 

[Jim Warman]

Considering that the torque wrench is going to have it's own accuracy issues (I can't remember what SnapOn promises for a dial reading wrench) and parallax is going to enter into the issue at some point and that what ever may or may not be on the threads is going to have an effect on clamping force.

 

I don't see recommended torque specs as being absolute and fudging a little bit one way or the other isn't going to be the end of the world.....

 

FWIW, last I saw, many race engine builders were torquing connecting rod caps by measuring rod bolt stretch to determine clamping force... now THAT'S anal....

[DwayneGorniak]

I consider it very acceptable Keith. What I don't consider acceptable is the stupid ass fuel lines they are using. Why the hell couldn't they have designed these injectors with a different style friggin line like a banjo fitting or something else like that? And yeah I know there are all kinds of excuses for their reason of thinking: not enough space, location, sealing factors and whatever the hell else they can think of. But then again they will also come up with an excuse for shoe horning that big ass engine into that tight ass compartment and dressing it with a whole lot of crap as well. Is that acceptable?

[Brad Clayton]

It's not hard for engineers to come up with those torque specs./techniques with engine on stand, but out in the trenches it's a diferent world.

[GregH]

Ok, this may not be the best advice in the world, but here is what I did for the 4 or 5 recalls I had to do here.

 

When you look at the torque sequence, and feel how the connections are fitting together at the various stopping points, it becomes clear what the intent of the torque sequence is.

 

At the final stage, the male fitting is in it's final position in the injector and manifold fittings. The little acorn shape isn't supposed to shift anymore during this sequence. The last torque that is peformed ensures that the acorn is hard against the manifold and injector fittings, but is not yet crushed. The final 60 degree turn provides the required amount of acorn crush.

 

I used a torque wrench on the first injector. I did not use a torque wrench on the remaining injectors.

 

Mine passed the high pressure tests too, and as of Friday, none of them have come back in for injector or oil/fuel related concerns.

 

Am I playing with fire? Yes. I am fully aware that I did not follow the proper procedure. Will it bite me? maybe.

 

How big is the acceptable margin of error? Did Keith get any closer to the proper specification than I did? How close to specification is it when the truck leaves the factory?

 

As a side note, I'm curently working a 6.4 with fuel in the oil. The field service engineer and I put oil dye into the fuel and ran several high pressure tests in a row with the valve covers off. We have yet to locate any dye. But, to verify that dye was getting to the injectors, we cracked the supply line for #2. With less than 1/4 turn, the fuel spray was pretty big. I tightened the line back up and we continued diagnoisis. The line continued to leak a small amount...

[HGM]

Some other MFG's are claiming that with the crowsfoot at 90* to the Tq wrench you do NOT need to do the equation to recalibrate the wrench.

 

The only concern I have with your picture, if you used the equation, it was probably a low Tq value to start with. Then adding the extension(torsion bar) length might lower it a bit more.. Cant knock you at all for doing what you had to do, just keep this stuff in mind next time.. Good luck..

[Keith Browning]

The only concern I have with your picture, if you used the equation, it was probably a low Tq value to start with. Then adding the extension(torsion bar) length might lower it a bit more..

When I thought about it, I quickly concluded that 18 lb-in was so low of a torque reading, the 3/8 extension really was not a factor at all. After reading Greg's post, it really seems to me that the initial torque of 18 lb-in is arbitrary in the sense that it really plays little or no role in the final tightness of the nuts. The sequence in it's entirety looks more like it's keeping the fuel tube aligned and squarely seated where the back of the mushroom and the inside of the nut mate. The turning the nut one flat provides the force to crush the mushroom, form a seal and keep it there.

 

Also, Greg's observation of the tiny fuel leak from re tightening the loosened fuel line underscores the need to heed the warnings and instructions not to loosen or re-use them. EVER!

 

Originally Posted By: HGM

Cant knock you at all for doing what you had to do

Which brings me back to my original post, what has everyone else done and why is this the first I have heard of this little dilemma? Surely the engineers that researched this recall tried actually performing it... or did we just assume it was straight forward and decided to instruct the technicians to replace the injectors "following the procedure in the service manual?" For me it was pretty easy to figure out but this has the potential to screw somebody up... and a few engines.

[Jim Warman]

That this conversation is even taking place indicates that, while one might assume this is throwing caution to the winds, a lot of thought is going into the process....

 

How close is "close"... how close is "close enough"? Faced with this dilemma, someone with several years of checking torque on fasteners should have developed a pretty good feel and should be quite familiar with the tools they use on a daily basis....

 

Judging by the number of fasteners that I encounter that have obviously been run down until the air ratchet stalls, tightening these with "an experienced hand" isn't good... it isn't proper... but it is, quite likely, adequate (heavy on the "experienced hand"). Personally, I don't feel that there is an "absolute" torque spec.... The state of the art as far`as metallurgy is concerned is going to back that up.....

 

As long as we meet minimum clamping force requirements without exceeedng fastener load capabilities, will there be a problem?

 

Disclaimer.. unlike a cylinder head, manifold or road wheel, there is no requirement for either repeatability or even clampng force.... close is probably quite good...

 

Point to remember.... before this stuff gets to the print media stage, an engineer has to sign off on it. Every last engineer is looking at job security, he's not about to risk that on anything less than "the perfect spec"...... I'm just waiting for the day when I see a torque spec of "72.499562 ft/lb".....

 

On the subject of torque specs..... anyone ever seen the torque to yield portion of a head bolt torque sequence performed with an impact wrench???? Seems to work - but it still makes my teeth itch...

[HGM]

When I thought about it, I quickly concluded that 18 lb-in was so low of a torque reading, the 3/8 extension really was not a factor at all. After reading Greg's post, it really seems to me that the initial torque of 18 lb-in is arbitrary in the sense that it really plays little or no role in the final tightness of the nuts. The sequence in it's entirety looks more like it's keeping the fuel tube aligned and squarely seated where the back of the mushroom and the inside of the nut mate. The turning the nut one flat provides the force to crush the mushroom, form a seal and keep it there.

Also, Greg's observation of the tiny fuel leak from re tightening the loosened fuel line underscores the need to heed the warnings and instructions not to loosen or re-use them. EVER!

 

Originally Posted By: HGM

Cant knock you at all for doing what you had to do

Which brings me back to my original post, and why is this the first I have heard of this little dilemma? Surely the engineers that researched this recall tried actually performing it... or did we just assume it was straight forward and decided to instruct the technicians to replace the injectors "following the procedure in the service manual?" For me it was pretty easy to figure out but this has the potential to screw somebody up... and a few engines.

 

 

I totally agree with the statements in the first paragraph.

 

I would just do what I could as far as the Tq. I have asked several people about the combination of tools needed to properly perform the Tq procedure. I have yet to get a specific answer. I'm hoping to eventually see a suggested tool kit for this operation. Remember necessity is the mother of invention /forums/images/%%GRAEMLIN_URL%%/grin.gif( /forums/images/%%GRAEMLIN_URL%%/banghead.gif).. We all know the importance of Tq when it comes to injectors, the 6.0L was the hold down bracket(6.4L too) and now we have the lines to keep in mind. Just thought I'd add that info..

[Tony302600]

I always torque down 6.0 intakes, I always torque down injector hold downs, no if ands or buts. I cant even count the amount of things i use my electric 3/8 impace from matco. I've never had a problem. Things become so repetitive that we know my experienced had whats good enough past the spec with the tools we use. I get laughed at sometimes when I take out my torque wrench when doing some of the things I do. I even sometimes go over by 1-2 lbs/ft or in, depending on what I am doing jsut for extra security.