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DeValency 14-02-2021 06:45

Re: Mechanics Time for Replacing Injectors
Thatís very impressive Dr. Injectors!

I could use your knowledge on a last year passage from St Lucia to Sint Maarten, where an old diesel bacteria partly glued the non return ball at the primary filter. Three mechanics couldnít trace it as it was not a permanent clogging....

Nothing like daily, delicate manual work on a bench to treat arthritis :)


Originally Posted by oldcal46skipper (Post 3342593)
I have been rebuilding fuel injectors over 40 years, after completing "Marine Diesel Engine" school. Now due to age 82 & various health challenges, like arthritis in my hands, that's about all I can do. I do not crawl around in boats anymore, so you bring our injectors to me & you are welcome to witness my test, no charge so far.

Perkins 4.108 Lucas or CAV injectors.

For the Perkins 4.108 removal, the "bridge" that holds the injector in must be removed. Be careful as it is cast iron and breaks easily. Then using a removal tool that bridges the injector and screws into the return line fitting on top. Sometimes it is necessary to soak them (PB Blaster or similar) for several days if they are seized.

Mr. Perkins says this should be done each 1,000 hours of running time. Check your engine builders manual.

After testing, I apply paint remover, wait, clean with wire brush all paint from exterior, as the cleaner I use is $80 a gallon.

I take the injectors completely apart, carefully examining all parts. The flats that mate are all surfaced, using 500 grit wet sandpaper, splashed with mineral spirits. Each flat is given 5 "Lazy Eights" 12,3,6 & 9 O'clock. Then examined with magnification.

The parts are rinsed with solvent, (paint thinner is okay) and placed in the chemical cleaner for at least 24 hours. The strainer container is drained and the parts rinsed with solvent & placed in a small container of solvent.

I have my air hose ready as I remove each part, blow it off and place into my stainless steel assembly bowl that is partially filled with clean diesel fuel. With my rubber gloves on, I assemble while in the fuel. Then I torque the nozzle holder and insert fitting for fuel in.

I immediately tighten the adjustment screw to approximate pressure for the 2,200 PSI for Perkins 4.108 fuel injectors. They are placed onto the tester, I prefer the old manual tester, and pumped and adjusted to design pressure. After observing the spray pattern, I pump to almost opening pressure and observe for leaks.

If all is well, I clean any fuel or solvent off, using masking tape I cover the input, low pressure return opening and nozzle holder. I first put them upside down in a cardboard box bottom with appropriate sized holes.

I use a very good spray paint that is rated 500 degrees F, Three coats of primer, then 3 coats of Perkins Blue or _____?

I caution the installer to clean the surface where the injector crush washer seats. Use a bowl brush the correct size, then vacuum and rust or debris. Always use a new crush washer and torque the hold down "bridge" very carefully and evenly to 12Ft Pounds.

I charge $75 each which includes a new nozzle.

I have previously posted my directions, "Diesel Fuel Systems on Sailboats" I'll Email a copy on request. I wrote this after some customers used dirty, old diesel fuel and damaged their high pressure pump and/or injectors.

waterman46 14-02-2021 17:00

Re: Mechanics Time for Replacing Injectors

Originally Posted by rbk (Post 3341654)
Really depends on the shop rate. Part4engnes has 4108 injectors for (USD) $70 each TAD is around $90 and there's a place in Oregon that has them for $60. Most are rebuilt but I think TAD has brand new ones for a bit more each (like $100-120).

OP wanted to know how much time for removing, cleaning and re-installing the old ones.

I'm a total amateur, but I've had to R and R an injector now and then. I can't see how the remove/replace for 4 cylinders on my Perkins would take more than 30 minutes, maybe an hour if I wanted to impress my wife and have a cup of coffee halfway through the job. That includes finding my torque wrench, etc.

Even if you include travel time and the cleaning, 6 hours is really stretching it. You can buy an ultrasonic cleaner for much less and DIY there is nothing to adjust or worry about other than replacing the compression seals.

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