I am starting to notice delayed starting after the motor is warm. Last time this happened, my work order mentioned they replaced the STC fitting. Where is this? And why do they fail so much?

 

It connects the HPOP to the rest of the high pressure oil system. The fitting has been upgraded from the original problematic design. How much of a delay are you talking about?

 

I have not heard anything about the updated stc fittings failing. How about you Tim?

 

there have been a few. they all have failed with in a few 100 miles of install. I think what happens is the o-ring gets hung up and cut. other then that all has been good with them.

 

I've noticed a little longer (1-3 sec) hot crank times lately. I attribute it to the weather being rediculously hot and running the a/c full blast, really hot engine = really hot/thin oil. I think it's taking just a couple sec longer to hit 500psi on the ICP. Take it for what it's worth...it's just common sense deductive reasoning.

 

A hard start can be more than an STC fitting. It can be attributed to many different components of the injection pressure system. Depending on how long ago you had your STC fitting replaced, you may have already had it updated. The newest one (which actually deletes the STC is a solid o-ring boss T fitting) is the final fix which is probably the strongest point in the system now.

The update before this one was a bracket that kept movement and vibration induced by the branch tube and the pump to a minimum. The STC fitting was still incorporated in this update, so they also failed quite a bit because of the nature in which the STC was being used in conjunction with the branch tube.

Other components contributing to hard start (especially hot) can be an Insufficient pressure from a worn high pressure oil pump, sticking IPR (Injection Pressure Regulator) or broken IPR o-rings, an STC fitting (or the o-ring in the updated fitting), cracked branch tube, leaking case to head tubes (between branch tube and oil rail manifold, a leaking injector puck (mounts in the oil rail manifold), a leaking off injector o-ring, a leaking off injector.

Obviously there are some of these that fail more often than others, but they all have the likelihood of failing. In a hard start situation especially, any one of these things can cause this type of problem where a small leak can be all it takes as opposed to a sudden failure of a component causing the engine to die and never restart.

 

To answer your question titled... it is at the back of the engine under the HPOP cover. Requires turbocharger/turbo mount bracket removal, HPOP cover and HPOP removal. It screws into the HPOP and bolts to the branch tube.