bad injectors?

reggie1086 · Sep 22, 2014

So.. I have a International 606, 236 IH diesel 6cyl..

Its a recent new to me project, purchased from a estate inop 10+ yrs before I got it.
Was at shop when I picked up, for unknown reasons..
Brought it home, rebuilt injector pump and she fired right up! After using a bit around the place and a couple road travels, it would start to act up like it was dropping a cyl or 2 even.. But I can throttle up, or drop to idle for a min and it would come out of it.

Seems to be getting worse, thinking it's poss dirty injectors.. So if so, how would I find the bad one? Can I test them at home?
If not what's the cost of sending them to a shop to test or overhaul?

dej(Jed) · Sep 22, 2014

I have a diesel fuel hydraulic test rig that I can hook one injector up to. I pump it up by hand and check the pop off pressure. (It has a gauge on it.) At the same time I place a white paper towel under the nozzle end. I was taught that you should get a circular spray out of the nozzle. The spray should be even and if it isn't , you need to remove the injector tip.
You can then clean it in a sonic cleaner and reassemble it and test it again. If necessary repeat the process untill you get a nice circular spray at the pressure required for that injector.
The testers aren't too expensive.

MN Scott · Sep 22, 2014

First make sure you don't have a restriction in the fuel supply, filters, tank intake, fuel cap ect. A plugged fuel tank cap vent will cause those symptoms. Bad injectors would not cause those symptoms as they would not suddenly get better. If all checks out then I think your going to have to pull your pump and have it looked at again. Its always a good idea to have your injectors rebuilt when you you have your pump rebuilt as they work together.

pete 23 · Sep 22, 2014

If you can catch it while it is misfiring and certain it is on a particular cyl, not sputtering around on different cylinder, you can feel the lines. If one is warm, you found your leaker. With engine shut off, pull injection line off that nozzle, crank engine with starter, fuel shut off and if compression comes out nozzle, you have a leaker. Low fuel pressure due to pump problems, fuel filter problems etc will cause scattered misfires and auto advance to not advance causing same thing.

Dieseltech · Sep 22, 2014

If the filters and fuel cap vent is OK the one way check valve in the bottom of the tank that the return line goes to may be plugged or restricted with old flex ring bits from the pump. A quick check is to loosten the timing cover screws next time it acts up, if it speeds up and sounds better the return needs attention. Happens to any Roosa/Stanadyne injection pump, worth a look.

mkirsch · Sep 22, 2014

Have you dumped massive quantities of diesel injector cleaner in the tank and run it?

We use the Diesel 9-1-1 product in the red bottle, at about 3X the recommended dosage once or twice a year. It makes an amazing difference in how the tractor starts and runs, particularly on the 856. That tractor goes from needing 10-15 seconds of cranking and sometimes a puff of ether to firing the second you touch the button as soon as it gets some 9-1-1 in its system.

bad injectors?

reggie1086

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dej(Jed)

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MN Scott

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pete 23

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Dieseltech

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mkirsch

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