Diesel return line repairs

[cathead]

Yesterday's project was to remove the injectors from my Iseki diesel tractor as I was having major difficulties getting it started in the morning.
It would fire and emit lots of black smoke, then white smoke. After about four tries to restart, it would finally catch on and run perfectly.
This tractor has a loader on it so no easy job to get at the top of the engine. It took most of the day with a lot more disassembly than
just unscrewing the fittings and pulling the injectors. Also my assortment of tools was somewhat limited so that wasn't much help either.
By five o'clock I removed the last injector but not without breaking off the end fuel return line.

This morning I disassembled all the injectors and cleaned them up. All looks fine but I have no pop tester to know for sure. Anyhow, it
looked to me that the last person that worked on the injectors had not tightened the injectors as they were all loose. I would expect that
they should tightened to somewhere near a hundred foot pounds. The other interesting part was that the return lines were tightened to
a hundred foot pounds! Another thing I noticed was that the return line assembly is not at all in a straight line so I have that situation
to look at when I reassemble the thing. My feeling is that the last person before me to work on the injectors was inept.

The other morning project was to machine a small steel fitting to make the return line long enough to fit properly. I used the Springfield
lathe which is set up for collets so the machining part was pretty easy. After that I had to silver solder the little fitting onto the pipe and also
silver solder the fitting to the ring that fits over the rear injector. I'm thinking I will have to go to town and get a 27mm 12 point wrench
to put the injectors in properly, maybe a 12 point socket too. I don't know but I would think that unseated injectors would cause hard starting.
Time will tell on that.
There's the little fitting machined to make it fit together in the middle.
That's the whole return line ready to be silver soldered.
This is the injectors and repaired return line ready for install.


My guess is that the "mechanic" either forgot to torque the injectors or simply thought that tightening the nuts on the top of the injectors would
be sufficient. I would be interested to hear your thoughts. Thanks for reading along.


I don't know what the specs are but the injectors are going to be torqued to 100fp and the return line at 20fp.

 

[Lo-Fi]

My guess would be that someone inexperienced was told to "torque down the injectors" and merrily went on their way torquing up the return line bolts...

Nice repair!

 

[FOMOGO]

Nice repair. Hope that solves the hard start issue for you. Mike

 

[ddillman]

The hard start portion of your problem may be the lift pump losing prime after sitting overnight or a long period.

 

[davek181]

If you have any leakage in the lines or fittings it will allow the diesel fuel that would normally be captive and unmoving to siphon back to the tank or some other lower point, causing hard starting and/or erratic running cold. A loose injector might leak a little compression, but if you cant hear it popping it isn't big enough to cause starting problems.

 

[aliva]

This may help for future diagnosis

Causes of Diesel Engine Smoke - By Color - Capital Reman Exchange

www.capitalremanexchange.com

 

[cathead]

The hard start portion of your problem may be the lift pump losing prime after sitting overnight or a long period.

Thanks for posting. It isn't that because it is blowing a lot of smoke so I know it is getting fuel.

 

[cathead]

If you have any leakage in the lines or fittings it will allow the diesel fuel that would normally be captive and unmoving to siphon back to the tank or some other lower point, causing hard starting and/or erratic running cold. A loose injector might leak a little compression, but if you cant hear it popping it isn't big enough to cause starting problems.

I had four LOOSE injectors.

 

[Nutfarmer]

The loose injectors could cause loss of compression. That in its self could cause hard starting. Let us know how it runs when back together.

 

[cathead]

The injectors were reinstalled and I ended up torquing them to about 70 foot pounds which seemed like plenty. It did start
a little better but still not what I would like to see.

I had an old hydraulic jack that was pretty much for parts so did some work on it to make an injector tester. It looks like
it will work so need to pull the injectors again and test them for atomizing spray and pressure. A fitting was needed to
go from 1/4 NPT to metric 12x1.5 so did a bit of machining and brazing to make one up. Just for fun I did the brazing with
some copper solid house wire #12 and some flux for brass. There wasn't much room to hold the middle of the fitting
so I drilled out a 1/2x13 nut to half inch and brazed it to the middle of the fitting using the copper wire.
Brazing the nut on to the fitting was a lot easier than machining down one solid piece. It's not something I will use a lot of anyway.


After a little plumbing, it was ready to test.


Here the gauge is reading 1800+ PSI. I think the pop off pressure is supposed to be 1700PSI on these pintle injectors
so it should work to test them and add some shims if required.


It's another cold day about 10 below zero F and snowing to boot. Visibility is about a quarter mile or so at present. I don't
have much else going on today so might as well get on with it and pull the injectors again. Thanks for following along.