injector issue, truck in pieces HELP

[funvtec]

hey guys i'm in the middle of changing my fuel injector o-rings and thekit i bought as only 12 brown o-rings, the injectors have a different black o-ring for the fuel rail side, however everywhere i call has the same kit of 12 brown o-rings. Are these an updated set? they look way different, the ones on the fuel rail side (black)have flat sides and the ones on the intake manifold side(brown) are your normal round.

anyone have a part number for NAPA for these or any suggestions
90 4.0
TIA

 

[langer1]

hey guys i'm in the middle of changing my fuel injector o-rings and thekit i bought as only 12 brown o-rings, the injectors have a different black o-ring for the fuel rail side, however everywhere i call has the same kit of 12 brown o-rings. Are these an updated set? they look way different, the ones on the fuel rail side (black)have flat sides and the ones on the intake manifold side(brown) are your normal round.

anyone have a part number for NAPA for these or any suggestions
90 4.0
TIA

The flat sides is why there bad.

 

[funvtec]

they're just that wore out?

every writeup i've read said they come as a kit with 6 of each
i believe you i'd just hate to be leaky again

 

[funvtec]

well you've been good to me before i'll take your word for it and replace all them with the brown ones

 

[old_man]

Langer1 has it right. Make sure and lube them before installing. I use vaseline but oil will work fine.

 

[funvtec]

how sure are you guys? upon removel of the old ones I really think they are diferent, I don't want to seem ungrateful and your help is very appreciated however the dexterity of the rubber copmared to the brown and black of the old ones is way different, the brown are very stiff and not brittle and the black ones are very plyable and easy to break. all i'm gettin at is they seem completely differet the new brown ones i have are exactly the same as the old brown ones as far as shap and dexterety. once again i really do appreciate your help and i do trust your judgement but this one seems iffy to me, i'll see if i can take a picture to show you guys what i mean

thanks again i'm not trying to seem rude and ungrateful but i'll show you what i mean

 

[casm]

the brown are very stiff and not brittle and the black ones are very plyable and easy to break.

The difference you're seeing here is x years of underhood heat and vibration breaking down the black ones. Go ahead and replace them, and keep the old ones aside if you're worried. You can always go back to them later if there really is a problem with the brown ones, but you should be OK.

 

[funvtec]

ok in the first pic you just see the color difference no bgie

in the sond one you see a height difference


if this dont sway you guys into thining i got some strange set up their goingin LOL

 

[T&A-XJ]

I remember seeing the same thing when I replaced my injector o-rings a few years ago, Im thinking they just made it more universal. The injectors will fit TIGHT with the new O-rings on the fue rail side so make sure you lube them.

 

[funvtec]

this one is a good one

 

[funvtec]

ok i'm replacing them

if they leak i'll hunt you all down


:firedevil:

J/K thanks everyone

 

[langer1]

ok i'm replacing them

if they leak i'll hunt you all down


:firedevil:

J/K thanks everyone

I have replaced 100rds of old o-rings and the old ones always look flat if there more than a couple of years old.

 

[funvtec]

ok NO LEAKS

everything looks good, but i did run to the parts store to buy a new quick disconnect that i broke and noticed in the help section they had an injector o-ring kit kind of a universal type and on the back it said it was for bendix injectors, sure enough they had 6 brown o-rings and 6 black squared orings

all in all i don't really care it works fine the way it is and i would deff. tell others to do the same you all instructed me to do.

so thanks a million you were all right and I was just unsure

never fails me :lecture: when will I learn

 

[xjbubba]

My experience doesn't make it so--but last set I bought from the Jeep people were all brown--they said it's the new and improved design. I installed them, and have not had any problems. As it's been noted before, lube well (not silicone) before installing.

 

[WVridgerunner]

I was replacing the o-rings in my 87XJ and I went to the Jeep dealer and they said that the BROWN o-rings are the same for the top and the bottoms of the injectors, the old kits were two colors and they changed to Brown o-rings and they are all the same and Will fit both the tops and bottoms.
I went the 5.0 Mustang Injectors and they fit in with NO problems. I will let you know how they do on the MPG and the Power.
Use a good lube and they also siad the rings should be soaked in gas for a short while too, prior to install.
Thanks for the info and the Great site for the XJ's

 

[LazarusMJ]

The reason the new ones are brown is that they are made of a different material. They made the brown o-rings that color so you can identify them from regular o-rings. The brown o-ring material is made to withstand higher pressures.

I learned this while working on diesel engines. If you put a standard black o-ring in a diesel fuel rail it will blow it rather quickly.

 

[wilcharl]

When i did mine i 1st bought aftermarket replacemnt rings... They were all the same ... I went with an OEMR part and found low and behold there were 2 dif. seals

Go the OEMR route on this one

 

[funvtec]

already done guys

it works fine with the brown ones all around

 

[cknott]

I should be able to provide some assistance here. I used to work for a company that manufactured these orings for Chrysler, in doing so I(we) designed and manufactured the orings in your Jeep motor.

To conclude, you should use the new brown ones.

When the motor was originally manufactured, polymer manufacturers such as Dupont and Ausimont, produced only a certain variety of polymers that oring manufacturers could use to manufacture rubber. Well, rubber compounds are designed for a specific application. The orings used on the fuel injectors of a Jeep motor....any motor for that matter, have to deal with several things. On the intake side of the injector(the lower side), the oring will see more heat due to the temperature of the head and will not see direct fuel exposure. As such, that oring material must have better compression set(the resistance to becoming flat over an extended period of time) at higher temperatures, yet still be able to seal at temperatures as low as -20 F. On the fuel rail side of the injector(the upper side), the oring will see less heat, but will be directly exposed to pressurized fuel. Believe it or not, rubber is permeable, and the exposure to the fuel will cause the oring to swell. Therefore, at the time the engine was manufactured, polymer manufacturers did not have a cost effective polymer that oring manufacturers could use on both ends of the injector.

However, in the mid 90's Dupont(as well as other polymer manufacturers) started producing Viton(Dupont tradename) B polymers which could be used in oring materials at both ends of the injector in a cost effective manner that also satisfied the design requirements.

This only lasted a while though, OEM's started requiring that all suppliers produce systems that would seal to temperatures as low as -40F. Believe it or not, Ford/GM/ Chrysler beginning around 1998 would enclose a first run vehicle in an environmental chamber at -40 F for 24 hours, and then they would crank it, and it better not leak, or for that matter, vibrate loose. This resulted in the development and manufacture of the Dupont GLT polymer, which is typically an ocean blue color. Therefore, as folks start replacing the seals in Jeep 4.0 motors in 1998 and later, they should see a brown oring on the bottom, and a blue one on top. By the way -40F is really cold.

 

[Dave in Eugene]

Just like everybody else says, use the brown ones if they fit and work, and chances are you'll be okay. Just look/smell for leaks 'til you're sure.

Black o'rings are usually (but not always) plain nitrile rubber, and probably on the top of the nozzles not an especially hard cure.

Brown o'rings are usually (but not always) Viton rubber, a more specialized material designed to maintain it's physical properties in more harsh environments. A Viton seal is an excellent material to use for fuel. If you remember the days of carburetors, the needle valve tips were almost universally made of Viton.

It's not at all uncommon to pull an old used o'ring and see it flat on one side or otherwise conformed to the shape and contour of the groove in which it is installed. We in the trade call that "heat set", where heat and pressure over time cooks the material beyond it's original cure and makes it, at the same time, weak and brittle.

Now, if you see a new seal that has a flattened or otherwise odd shaped cross section, it is not an o'ring (which is, by defenition, round). So can you replace such a seal with an o'ring? That depends. In the top of that particular fuel nozzle you have a fairly small diameter static seal with a fairly low hydraulic pressure pushing on it, so the total available force, trying to extrude or otherwise deform the seal to get around it, isn't powerful enough to get past much of anything. So mostly, you depend on chemical properties that survive gasoline on one side and air on the other, and Viton is an excellent choice.

Why they originally used a D-ring (or whatever it was) originally is something you'll need to ask someone above my pay grade. But if I had to guess, I'd say whatever they were putting in originally was selected for it's cost (in the '60s Ford started usung plain plugs instead of zerks to save 10 cents a car) and it's ability to perform reliably through the original 50K emission warranty and not necessarily any longer. And they probably came out of the third world (Pakistan comes to mind).

The flip side of the coin is that those upper seals may well have been made of a flame retardant material (a legitimate concern here), and Viton rubber is NOT such a material, but is indeed a very fast and hot burning material :flame:

Whatever you use, know who made them so you'll know who to sue.