Fuel Injector service

[Reefgeorge]

Everything is now going back together. Some observations:

The silver flexible dremel attachment in post #47 works well. As fishtales said I used the cup shaped wire brush for the bottom of the holes (they get shiny and really clean) and the wire wheel for the sides and threads. You still have to do some scraping on the sides with like a small screwdriver first but the wire wheel helps further clean it up and really gets the threads for the castle nut open and smooth. I used a wire bore brush for gun cleaning for the very bottom opening for the injector tip. Vacuum with a piece of hose attached to your shop vac. Last check is that an injector dry fits with no issues and a dry threaded collar spins all the way down with no issues. Then get out the anti seize and your torque wrench and go to town. Don't forget new copper seal washers (make sure the old ones came out, if not press a large screwdriver into the center and lift the old washer out) I inspected each hole with a boroscope to check progress, especially on the holes I couldn't see from the top. Lastly I spoke with the anti seize tech support. They said that the silver colored aluminum paste is fine and used a lot but the nickle based black compound is better for less galvanic problems especially if salt water becomes involved around the cooling pipes. They said that if you really want to use the best they have an upgrade based on synthetic grease. I used the plain nickle and man are those threads buttery smooth when you tighten everything back up.

George

[Avenger]

Use some discretion when torquing the hold-downs. Never Seez is a pretty good lubricant and you can overtorque things easily with that on the threads.

[Reefgeorge]

If you are a ble to get a torque wrench on do you change the spec?

[krush]

Clean threads with anti-sieze I'd say 25-50% lower torque. But that's just a WAG

[Reefgeorge]

The man manual shows applying anti seize to the threads upon re assembly so I don't know if they took that into account when they published the 93 ft lb spec. I called the engine distr who has need very helpful and they said oh we don't use anti seize on the threads do that didn't help. They also didn't agree with man corporates coolant recommendation.

George

[Reefgeorge]

In the absence of a consistent answer (even the anti seize company said just use your judgement) I went old school. I torqued the injector down to spec dry. Then I put anti seize on the threads and re torqued to the exact same nut position which implies the same holding force against the copper seal washer. Fudging a little for the likelyhood that the copper waisher probably got a little compress, I needed 12% less torque with anti seize brand nickle based compound. I suspect that other compounds will produce different results. It probably also related to thread pitch, cleanliness etc. since I don't know if my spec is dry or lubricated threads I sm going to split the difference so I won't be more that 6% off.

Here we go again with "nuts" trying to disprove science. :-)

George

[krush]

The real truth is that torque is a horrible indicator of bolt stretch anyway. But it's easy to measure, so that's why it is used on things like engines.

More important bolted joints are checked with bolt stretch or compression (squish washers...some even squirt ink out).

[Reefgeorge]

And I could not torque two of the anyhow. No combination of oddities would fit so they are my best guess with a not so special wrench.

George

[Reefgeorge]

All back in. Some final thoughts. Make sure that Tha flat seal surface at the bottom of the hole is clean. Drop the copper seal washer in and check that's it's flat and it's dead clean on the bottom. Dry fit the injector and pressure screw. Make sure the injector is loose and clinks on the bottom. Spin down the dry pressure screw and make sure it captures the injector and that the threads are clean enough. Remove apply anti seize and torque to spec. If you have to add a crowd foot. Shorten your grip for the same effective torque wrench length or lower the setting according to the formula. I also put small pieces of tape over the return holes and peeled them off right before attaching the return rail to keep anti seize out. Happy injecting.

George

[Reefgeorge]

Here on the East coast Diesel Injection of Martin County are the best. Ask for John, (772) 283-8999

Thank you for the recommendation, John was easy to work with and very responsive on every single call I made to him. I have not run the boat yet at full tilt but the injectors are working great at lower RPM's (completely solved my low RPM smoking condition) and his pricing was very fair.

George