Isn't it possible for fuel to leak into the coolant, but the cup still passes the pressurization test? In other words, I don't think all leaks don't necessarily have to be coolant leaking into the injector bore.

That being said, it isn't difficult to change the cups, just time consuming. I did them 2 years ago on my truck and I didn't have any leaks or do-overs. You just need to take your time and clean the bores carefully of all the old sealant.

 

I used a Dremel on low speed and a wire brush attachment I bought at harbor freight. I think it did a pretty good job but I'll no for sure after I drive it awhile and see if I still have anything leaking.

 

I put a paintbrush handle in the injector hole and chipped the pieces of old sealant (it was hard as a rock)...



Then I vacuumed up the pieces, used some IH brushes along with Dremel brush attachments (similar to Obs7.3Powerstroker) to clean the seating surface. Then I swabbed the bore and seat area with 90% rubbing alcohol to make sure there was no residue before installing the cups...

 

That's a clean hole right there. If I every have to do this job again - I'll be following your lead.

 

Yes. Temperature, pressure, and other factors make it easier for fuel to leak through, but coolant 'should' also leak through when you pressurize the system.

 

Okay, so update on the injector job. Over the last several weekends I have been trying to flush out my coolant system. I have been doing this by pulling drain plugs and running a hose through and letting the water just pour out the plugs. Also mixed cascade in and drove it around for a while to get it all throughout the system, would then drain and flush with the hose again. I've done this probably ten times. But here is my concern: so I let the water run till it runs clear, I fill it up and go drive it for a while and get it nice and warm, when I get back home, the water in my reservoir is a dirty yellow, my first thought - crap its still leaking, but on closer examination and sniffing it has zero smell of diesel, just smells and feels like plain tap water. I know this probably isn't the most scientific way of doing this, but I haven't had a whole lot of time to do this, just after work and school. The next thing I was going to try was to catch the water when I drained and watch it for a couple of days and see if it separates into fuel and water. I am wondering if it could just be the rust and build up in the radiator and coolant system from 18 years of use that is contaminating the water. Or did I just screw up my injector cup job and still have the problem?

 

 

Kudos on the cup job. Thats 1 job id rather not have to wear a shirt to....i think the discolor is more of a 20yr old cadt iron block with water running thru it that has no additives or preservatives...i put water thru my system and it comes out yellow too