6.9 idi injector return cap leaks

[Clb]

Stop tossing parts at things and figure out what’s wrong

How

 

[Kdo58]

The hoses are larger so it has less pressure on the return caps, but you will have to make a adapter to replace the one near the back of the motor, which goes back to the fuel tank.

 

[Cole_Sudeyko]

Just a different co figuration of caps. Tees and elbows in different spots. Same diameters for O rings.

What are you lubcricating your o rings with? I will either buy a harbor freight box of misc o rings, or get a set from a vendor, and I lube them up with a glob of vaseline. Rarely have one leak.

I was just using some lubriplate assembly grease

 

[asmith]

Try vaseline. that has seemed to work the best for me. Also I haven't seen it mentioned yet, and maybe you are already doing this, but just in case. put the top oring on first then GENTLY roll the bottom one over it into the bottom groove. This can help prevent them from getting nicked.

 

[Cole_Sudeyko]

Try vaseline. that has seemed to work the best for me. Also I haven't seen it mentioned yet, and maybe you are already doing this, but just in case. put the top oring on first then GENTLY roll the bottom one over it into the bottom groove. This can help prevent them from getting nicked.

I’ll give that a try thank you!!

 

[Nero]

Vaseline, and Super Lube synthetic grease are what most people use.

 

[scsmith42]

I use Dupont Molykote 55 o-ring grease with all hydraulic and fuel system o-rings. It's made specifically for lubricating 0-rings.

Although I buy it from my local industrial supply house, it's available on Amazon.

Amazon.com: MOLYKOTE 55 O-Ring Grease 5.3OZ D632745 : Automotive

Buy MOLYKOTE 55 O-Ring Grease 5.3OZ D632745: Grease Guns - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[nelstomlinson]

CDD and R&D both sell return kits that should be the best quality available.
Dregs Garage occasionally makes a run of very nice brass return caps. I've had excellent success with those, but they're expensive, and shouldn't be necessary.

 

[Tod Rockstead]

Ok, assuming you've obtained all the correct parts... let's talk about how you're installing them.

​

1. Remove everything. Pull both sides of the entire fuel‑return assemblies. Replacing one or a few caps is pointless.
2. Get supplies. From NAPA:
   • Clear diesel‑rated return hose (correct size)
   • 1 quart ATF transmission fluid
3. Rebuild the return assemblies. Use the old assemblies as your guide. Lubricate each cup nipple with ATF before installing the new hose.
4. Prep the injectors. Remove both O‑rings from every injector. Wipe each injector clean.
5. Prep the new O‑rings. Pour some ATF into a small cup. Drop all new O‑rings into the fluid so they’re fully coated.
6. Lubricate the injectors and cups. Generously coat:
   • The tops of all injectors
   • The inner surfaces of all return cups with clean ATF.
7. Install the O‑rings correctly (corrected). Place the first O‑ring into the first groove of the injector. Install the second O‑ring below it.
8. Seat the return rails. Set the rails over the injectors and press firmly until you feel the cups fully seat.

The clear line helps diagnose air intrusion. Do yourself a favor and ditch the mechanical lift pump. I replaced mine after 2 bad pumps back-to-back from AutoZone with an Edelbrock Green Micro E Pump for diesel fuel.


1986 Ford F250 XLT SC LB 6.9 IDI Banks Sidewinder Gen1 C6 Auto 4x4 with GearVendor OD 74K original miles only. 6" lift & 34" all terrains on American Racing "Outlaw 2" wheels