After swapping in a ZF5 and changing to a different turbo I'm having air intrusion problems. Saw one wet return cap/injector and replaced o-rings but still hard start after sitting overnight. Took me three times replacing return cap o-rings after changing injectors and pump to get it all sealed up, I'd like to avoid doing that again now or any time I touch anything. I recall someone here has one piece return rails, maybe IDIoit. Do they seal better? Where can I get a pair?

 

R&D makes them. Idiperformance.com
Look under injectors

And it sounds like you're plastic return caps have swelled

 

Injectors




Charlie

 

I have individual aluminum return caps. made by a OB member on a fancy CNC machine.
R&D has the ones youre talking about, I would like a set of those too, but I don't have another running IDI, yet.

 

I hate to say it, but trying to fix 'air intrusion' by sealing all the return caps is foolhardy.
The return system should /not/ matter to getting air into the supply system.
The only reason it does so is if you haven't deleted the return line from the fuel filter.
This line is supposed to have a check valve in it, which breaks down over time, allowing air back into the system.

Ford even released a TSB to delete that line for exactly that reason..

Possible options are:
1. Delete the return line from the fuel filter.
2. Fix the check valve in that return line(or add one inline)
3. Install a check valve right before the fuel filter(I use a primer bulb on my trucks. Works perfectly - they have two check valves built in).


Also, when it comes to leaky return lines(simply because leaking diesel is bad for fuel economy), my solution is simple: Lithium wheel-bearing grease.

A little bit of lithium grease inside the cap, and on the O-rings before install and you will solve your return line leaking issues, even if you use bargain-basement return caps.

I've done this many times with excellent results - the Lithium grease lubricates and will not melt in the high temps of the engine. It also won't cause issues with the Viton O-rings.

Also, Vasoline does /not/ work for installing return line caps, no matter how much it's 'recommended'.

 

I do not recommend omitting the return line from filter head as it is the return that allows constant metered ( small orifice) flow back to the tank and any air from tank slosh is routed back to the tank before it gets near the ip. the fuel heater in the top of filter head is the culprit for air intrusion often, adding fuel check valves is a good idea.

 

I have a 6.9 filter head, no heater or extra points to leak.