Cleaning injector tips: Good or bad idea?

[CHRISEEBOY]

I have recently had to remove all four injectors from my 4/98NT engine. Unfortunately, the sleeves came out with them but that's a another story and a different thread.

My next question is in regard to cleaning the injectors whilst they're out. Is this a good idea or a really bad one? As far as im aware they were all working properly prior to being removed so I could just leave them as they are, but as you can see from the photos, they are very dirty.

I attached the fuel inlet hole to my compressor air gun via a small piece of (spotlessly clean) hose pipe that I first filled with a small amount of diesel. My plan was to place my thumb over the run off hole and force the deisel through the injector with compressed air and see if all four holes squirted out fuel. My plan did not work and I ended up with a face covered in diesel and a bad taste in my mouth. I am reluctant to clean the tips if I am unable to observe that the holes remain unblocked afterwards. Your thoughts would be appreciated.

[CHRISEEBOY]

[Jeremy Rowland]

Chris my suggestion would be to clean the injector tips in some clean diesel with a soft piece of rag, before you put the injectors back in you can connect them back up to the high pressure line and get somebody to spin the engine over. Obviously make sure that the engine is complete first and with lube oil back in it after its strip down, and more importantly don't get any part of your body near to the spraying injector as it is capable of penetrating the skin.
You should be able to observe an even spray pattern for each injector, also make sure that the tip of each injector is dry after the test, hope that helps.

Jeremy

[CHRISEEBOY]

Great, thanks Jeremy

[gecko.cx]

My plan did not work and I ended up with a face covered in diesel and a bad taste in my mouth.

That was to remind you not to do it again!
An air compressor is typically set to 120 PSI (approx 9 Atmos)
The injectors on a 4/98 should start to open at 175 Atmos (~2600PSI)
There is no way you will achieve anything with an air compressor (or your thumb)


http://vieux.tracteurs.free.fr/pdf/Manu ... _498NT.pdf
Page 7 2-3
(there is a 4/98 manual in the download section - that may be better)

[CHRISEEBOY]

2600 psi!

Ok, well I assume I dont have to worry about clogging up the holes with carbon if the diesel comes out so fast it can pierce skin?

[gecko.cx]

True!
Pretty well self cleaning in terms of external build-up.
Anything that gets past the fuel filter is a different story.
(it's why you need to be so careful to keep everything clean when playing with the fuel system)

[TrevorJ]

Depends on the type of injector, the newer types would have me very nervous putting anything of a mechanical nature (cleaning) near the outlet holes. Yes I've seen people run a rotary wire brush right over them ... mostly it's not anything I was dealing with, and ... someone else problem if they ignored my "be caref ... too late" and it'll probably run even if the spray pattern is a bit funky.

Some penetrants also decarbonise but I usually opt for a gasket stripping spray. The active chemical I favour is also found in many paint strippers and oven cleaners but they are usually thicker gels and don't work so fast if at all.

I've noted in recent times it feels like the products have been watered down a bit I've used a couple different brands of DCM based [DiChloroMethane (METHYLENE CHLORIDE)]

Loctite have moved from their DCM version now going the way their "Chisel" product was iirc. It is not DCM based but supposed to work as well if not better, but I don't trust marketing hype that much.

https://crcindustries.com.au/products/ds/sds-5021.pdf


Anyhow the bottom end of an injector could or should sit well in a cup of thick paint stripper. Depending on how baked on, it may take a day. Then it's a simple matter of using an air kero cleaner or a soft paint brush or tooth brush in solvent to remove the softened carbon. It may take two or more times soaking to get the baked stubborn carbon off, and resist the idea of using a fine wire to pick carbon out of the holes ... old injectors that was part of servicing but I've no idea how touchy laser cut or etched holes are.

Simple injectors aren't too hard to set either ... or simply test to see if they are dripping or the spray pattern is passable.

I made my tester from an old jack, braised in a suitable pipes, filter on the inlet, small hydraulic flow control valve inline on the output, and purchased new pipe and end fittings ... for the few different injector fittings that popped up.

P.S. pulling down old easy injectors to replace nozzle. Do the assembling in a tub of very clean clear diesel or similar suitable fluid (no doubt clean hands and tools too) ... just what the really old books I read on the subject, stresed. I don't know why, when an injector gets air in it ...

[MrF]

For the price of the cheap chinese/indian injector pop off testers I could have made my own but for under $100 I can be off making something more interesting or difficult to obtain instead. Yes I needed to fettle it slightly as various joints weeped slightly out the box because of poor assembly, but only a few minutes work. I was however surprised to see the one I had bought had 6 adapters in the box, which when I came to do the kubota's injectors (I bought one to set my jcb ones up) came in handy as I already had the correct fittings to hand.

Quick example, sure you can find one more local to avoid shipping costs etc :-
https://www.ebay.com/itm/203625132639

Just remember to keep away from the spray path when your testing/observing. I use a clear glass container on the bench sitting around the suspended injector to spray/observe through.

Now if only they didnt start making cheap injector testbenches with a drive to rotate the whole pump, test tubes to measure the output and gauges to monitor calibration and phasing for a few hundred euros/dollars/whatever. Though I keep seeing testbenches come up for sale for 7-800e I have convinced myself that I can do same with the lathe, a aux diesel tank and some test tubes and Im struggling to justify the floor space where my machine tools live for a real one...

[TrevorJ]

Nice and compact and 6 adapters, worth it. The one from link posted probably have a shut off so one can test for leakage, just my eyesight is poor these days.

Hardest part using an old jack is fixing the valve (replacing it) if it's been a bit leaky. I recall some days spent chasing down the brass valve bit, no doubt common to many jacks, just the area's stores didn't keep them ... or have any idea what I was on about.

I'll have to redo mine ... I made it with an adapter so I could run a couple of different fittings ... one of my family's nuts didn't ask to borrow it, didn't notice I had fashioned an adapter, removed the whole end and placed one on for a ford ... I was of course pretty livid especially when they didn't know anything, shrugged with a couldn't care less ... oh I grabbed it back right after they were done with it, it's ugly but handy ... funny thing a year later they asked me where it was, eh I don't know, maybe lost

Setting pumps is a bit past my mere abilities and tools ... and with the little time I had back when I was fairly involved fixing stuff almost on a daily basis.