How to remove diesel injector

[mowerandy]

A month or so back my old Yanmar single cylinder diesel refused to fire up despite good looking fuel at pressure from the pump, apparent compression and a decent spin. It has always been completely reliable, so upon noting the above points I thought a tap with the "encourager" on the injector might help, and sure enough she fired up right away after a couple of good wallops.
Cut to yesterday, and she doesn't want to fire up again. Hammer treatment ineffective this time.
I am betting there is something going on between the high pressure line and the piston so decided to try to get the injector out - not a mechanic by any stretch - therefore failed ignominiously
So I am hoping that someone can suggest how I might take this forward...
The engine is a YSE12(hp), and has a single injector thingy mounted to the cylinder head and apparently retained by two bolt studs with a collar torqued down above. One of the studs has been replaced by a bolt, but the other stud is rusted in place and only the top nut easily removable. The trouble I had was that the whole assembly starts to unscrew out of the head until the fuel line input hits the bolt stud preventing further rotation.
I was hoping to remove the whole assembly since the chances of losing some vital part in the bilge are rather high, but I am wondering if it is possible to service the injector without removing the whole injector body - maybe by locking it down with the collar and unscrewing the doohickey with flats on the side that protrudes through the collar?? And if so, will the naughty bits come out with it?
Alternatively, how might one go about removing that frozen stud so as to be able to unscrew the whole thing. I am thinking to try to find an extra nut to lock onto the stud real hard against the original nut and try to unscrew it that way - not terribly optimistic though.
Any thoughts will be appreciated :-)

[Diesel Bill]

Good grief, I hate to post 1st on this but here goes. please don't wack your injector with a hammer no matter how badly it misbehaves. It's just not acceptable in polite society.
You mentioned adding another nut onto the stud and jamming it against the other nut.
This is normally done in this situation to remove a stud. I'm assuming (bad to do) that you removed the high pressure fuel line and leak off line from the injector. After removing these and the stud and bolt and hold down collar you would use a crow foot pry bar to gently pry the injector out of the head. Others will add more specific details.
Please be gentle as you can do much damage if you go country on it.

[mowerandy]

Thanks Diesel Bill! I was hoping you might chime in, having just read (and filed) your reply about diesel smoke!
You are absolutely right about "going country" on the old girl - cost me a new water pump not long ago, and Diesel Neil at Minnards said much the same thing at the time...unfortunately I am a slow learner, but hopefully have stopped short of doing any serious damage this time
Alright - I will focus on getting that stud out, after which the injector body will unscrew apparently, rather than needing prying out. I put a spanner on the flat sided thingy after removing the (high pressure line, fuel bypass banjo thingy, and) collar and the whole lot wanted to unscrew from the head quite easily, but was stopped by the rusty stud.
Assuming I can get it all out, is there anything I can do for it (with or without a hammer), or should I just send it to Diesel Niel?

[Wotname]

Originally Posted by mowerandy

Thanks Diesel Bill! I was hoping you might chime in, having just read (and filed) your reply about diesel smoke!
You are absolutely right about "going country" on the old girl - cost me a new water pump not long ago, and Diesel Neil at Minnards said much the same thing at the time...unfortunately I am a slow learner, but hopefully have stopped short of doing any serious damage this time
Alright - I will focus on getting that stud out, after which the injector body will unscrew apparently, rather than needing prying out. I put a spanner on the flat sided thingy after removing the (high pressure line, fuel bypass banjo thingy, and) collar and the whole lot wanted to unscrew from the head quite easily, but was stopped by the rusty stud.
Assuming I can get it all out, is there anything I can do for it (with or without a hammer), or should I just send it to Diesel Niel?

Send it to Minnards. These guys do good work and provide excellent advice - maybe not as good as when Mr Minnard was still around but pretty good nevertheless.

[Jim Cate]

For removing the rusty stud, try Reducteur H-72. Magic in a spray can! Might even help with the injector itself.

REDUCTEUR H-72 RELEASING AGENT 300GM P/P (0101 7372)

Often available at Bunnings here in Oz

Jim

[Wotname]

Another vote for Reducteur H-72

[mrm]

Injector assemblies are often stuck a bit, due to carbon (soot) build up. Besides penetrating oil, the usual trick is to use a slide hammer, like shown here:

https://www.youtube.com/watch?v=JyD81685Lo8

You will need some free space along the injectors though.

[Matsubob]

Yanmar injectors have a top and bottom. That is the only part with threads. The injector simply sits in the injector port on the head and the studs nuts press the injector down into the port with pressure from the hold down. But, if the oring banding the injector basehas failed, rust might be the cause of the injector not coming out easily.
The injector can be easily disassembled, and, as long as the orientation of the tiny internal parts is recorded and it is reassembled exactly as it came apart, it will work. Assuming that it was emitting the correct fuel spray pattern before. (hitting it with a hammer could have easily altered all of that!) The parts in an injector are very delicate. The passageways and orifices are tiny and can easily become clogged with sediment from contaminated diesel fuel.

[AZ-Oldguy]

Is this stuff available in the US?

[01kiwijohn]

Some injectors were held with bolts, some with nuts. Both do the same job. If the stud begins to unscrew just work with it and let it come out. You can always put it in a vice and deal with it in the shop. Sometimes, you have to use a hooked end pry bar to get the injector to come out. Use new studs and/or bolts when reinstalling but coat all threads with "Never-seez" to eliminate future problems of this sort.
You may not have to remove that stud. If you can get the injector out, leave it there, clean it up and protective coat, re-use.
Servicing the injector is a job for a proper fuel injection shop. They are a very simple injector but they need to be specially cleaned and the cracking pressures set precisely to insure easy starting and great running performance. (I get these type of injectors rebuilt for about $40 each, in Tacoma.)
These are a "pre-combustion" type engine, if I recall correctly so the pre-cup may come out with the injector. there are two copper seals down there so they should be replaced, if disturbed. (I have restored them, by carefully annealing with a welding torch). Make sure you clean out the injector bore, in the head, and the seal seating areas. Use a small shop vac, with a piece of plastic tubing duct taped to the hose, so you can keep any debris from falling into the cylinder.
Take the injector line off, do not bend it out of the way.
When reinstalling, torque the two bolts, holding the collar, evenly, to the specified setting. (I coat the injectors, on my 3GM, with neverseez too.)
Don't panic, use common sense & do not take short cuts. You'll end up with an excellent repair job.
Let me know if I can help further

[grantmc]

The two studs are easily bent and without being perfectly straight the injector wont seat correctly. The injector is sighted in a precombustion chamber. And the injector itself is precision engineered. Nothing on a Yanmar YSE will respond well to the hammer treatment for long.

I have a digitised copy (PDF format) of the service manual if it would be helpful. If so PM me with an email address.

A common fault for not running well is that the head gaskets don't last. Possibly because the piston moves horizontally and with them being raw water cooled, with a water jacket through the head, then tiny bits of salt seem to creep in and corrode the gasket. So some owners change the head gasket every couple of seasons as part of their preventative maintenance.

I'm sure you know that a YSE 12 is a very old motor, great old bangers for sure, but parts are now very expensive.

[boeing1]

one other point, clean around the injector prior to removal to prevent foreign mater falling in your cylinder when you remove the injector

[leftbrainstuff]

Injectors dont like hammers, dirt or being dissassembled. They are not field serviceable.

You need to be obsessively clean. Before you remove it ensure all dirt and dust is absent. Plug pupes and ports.

Removing frozen threads is accomplished by using locknuts to unscrew, stud extractors or drilling out.

I usually just drill them out. Cobalt drill bits or center drills help greatly.

You should be avle to extract the injector along its main axis. You'll need appropriate pry bars. Be gentle.

[BruceS]

The important part is that the injector does not screw in. It just sits in the hole. What you are probably doing is unscrewing the tip / nozzle. You don't do that! Let the injector shop do that bit!

[capt-couillon]

Carbon and additional smut on the lower part of the injector can cause it to be difficult to remove. No threads, pulls straight out when clean. Puller tool available from mfg, or slide hammer as mentioned earlier. Sometimes (if you are lucky) rolling the engine over will generate enough compression to pop out the injector. Leave the retaining ring loose but in place. Otherwise the exiting injector can launch itself into uncomfortable places.

High spring pressures and close tolerances preclude diy rebuild. Take to diesel shop for pop test and rebuild. Use new copper seals and torque retainer ring to spec on reassembly. Bleed per specs.

Picky but not rocket surgery...