Purging Injectors - Confused

[ImaginaryTango]

I have a BX25D. I've cleaned the fuel tank, but there's still some fuel in the line. (I replaced the filters earlier, as part of the troubleshooting, so I think there's a good chance they're okay.)

I have seen a few sources, including Messick's, say that to purge air in the fuel line, there is no need to actually open up injectors so air can be forced out. On the other hand, I have friends saying, "Oh, no. That could really mess things up."

Which is true? Do I have to manually purge the injectors? I hear it's easy, but, I also need help with finding them. I know it's a 3 cylinder engine, so I assume there are 3 injectors. Are they sticking out from the cylinders or beside them? Where are they and is purging a matter of turning a valve and waiting until some fuel spills out instead of just air coming out? (That's how I've been told to purge them.)

 

[John T]

when I had the injectors tuned up on my New Holland skid steer....
I put them back in, and fired it up.
The way I understood it, the injector pump feeds the fuel and the return line brings any exess back to the tank .... air too, I would imagine.

Maybe I'm off base/not sure if the bota engine is the same....... but I had no issues.

 

[North Idaho Wolfman]

I have a BX25D. I've cleaned the fuel tank, but there's still some fuel in the line. (I replaced the filters earlier, as part of the troubleshooting, so I think there's a good chance they're okay.)

I have seen a few sources, including Messick's, say that to purge air in the fuel line, there is no need to actually open up injectors so air can be forced out. On the other hand, I have friends saying, "Oh, no. That could really mess things up."

Which is true? Do I have to manually purge the injectors? I hear it's easy, but, I also need help with finding them. I know it's a 3 cylinder engine, so I assume there are 3 injectors. Are they sticking out from the cylinders or beside them? Where are they and is purging a matter of turning a valve and waiting until some fuel spills out instead of just air coming out? (That's how I've been told to purge them.)

You need to read the WSM! And learn the engine operations and components before you do something dangerous or damaging to the tractor or to yourself!

You should not have to deal with any of the high pressure side of the system in order to get it to run.

 

[ImaginaryTango]

You need to read the WSM! And learn the engine operations and components before you do something dangerous or damaging to the tractor or to yourself!

You should not have to deal with any of the high pressure side of the system in order to get it to run.

So you're saying if I don't know what I"m doing, don't even try to purge the air from the injectors?

 

[whitetiger]

So you're saying if I don't know what I"m doing, don't even try to purge the air from the injectors?

What North Idaho Wolfman is saying is don't just start fiddling with things you do not understand. There is no need to loosen any injection pipes.

With fuel in the tank, turn the key switch to the Run position to activate the electric fuel pump. Let the pump run for 30 seconds, turn the key switch to the Glow position for approx 5 seconds, and then start the tractor.

If it does not start within 10 seconds, stop cranking the engine, let the pump run for another 30 seconds, activate the glow plugs again for 5 seconds, and start the engine.

 

[North Idaho Wolfman]

So you're saying if I don't know what I"m doing, don't even try to purge the air from the injectors?

We have a winner!

Follow the above information.

 

[ImaginaryTango]

We have a winner!

Follow the above information.

Actually, the information in your first post was more useful than the attitude in this one and I am still not sure about just exactly what you are saying in that first one - that I don't need to bleed any air out at all?

I'm really trying to get clarity here, but I'm still not sure exactly what is being said.

 

[North Idaho Wolfman]

Do not mess with the High pressure side of the fuel system.
This is everything from the injection pump and beyond.
So, DO NOT mess with any of that side of things, the air will bleed itself out on that system.
DO exactly as @whitetiger said in post number 5

 

[EPIC]

Older diesels would occasionally require bleeding injectors when changing the fuel filters or other fuel components.

However, as I understand it newer diesel engines work at a much higher fuel pressure and are designed to self bleed.

I believe this is why you have seen conflicting information because both are true in some circumstances.

In any case don’t mess with injectors unless you know what you’re doing because it can be dangerous and expensive if you don’t do things correctly.

 

[ImaginaryTango]

I had been hoping to finish and get the tractor running "that day," on both Saturday and Sunday, but that wasn't happening. Since I was confused by what I read here, on Sunday, I spent the afternoon adapting the seat I bought so it can fit on the seat base. Today (Monday) I called the mechanic from the dealer, who has worked on my tractor and knows me and what I can handle for clarification.

And I got an answer different from any so far: Take off the line going into the distributor pump, purge the air from there, stick it back on the pump, then start it.

Did that - it wouldn't start, even with the jumper pack, but lots of clicking, so I got a new battery and, after installing it, it started right up and ran immediately. I suspect that while trying to start with the weak battery and jumper pack (and I'll be checking the battery in the jumper later this week), that the first few times it tried to start (before it was reduce to only clicking) pumped fuel into the injectors. That was not much time, but maybe it was enough. Or maybe, just having fuel actually in the pump was what did it.

Either way, it didn't take long for it to start up once I bled the air before the injection pump.

Older diesels would occasionally require bleeding injectors when changing the fuel filters or other fuel components.

However, as I understand it newer diesel engines work at a much higher fuel pressure and are designed to self bleed.

I believe this is why you have seen conflicting information because both are true in some circumstances.

In any case don’t mess with injectors unless you know what you’re doing because it can be dangerous and expensive if you don’t do things correctly.

Thank you for a good, complete, and clear explanation of what was going on and why I was getting contradictory information. This also is a flag, to me, to talk to my neighbors who offered to help to bleed the injectors, that on some systems you just don't do that. After I bled the injection pump, I looked at the injectors and I'm not sure there was even any way, on them, to bleed them. At least not something I could easily see.

 

[Trash Panda]

Actually, the information in your first post was more useful than the attitude in this one and I am still not sure about just exactly what you are saying in that first one - that I don't need to bleed any air out at all?

I'm really trying to get clarity here, but I'm still not sure exactly what is being said.

There is no attitude.

People here are just trying to prevent you from getting into a situation that could possibly be beyond your depth.

 

[Killer Bee]

maybe I can help clarify a little bit.

first of all, consulting the manufacturer's service/repair manuals is the best advice anyone can give you. following generic advice without the appropriate level of experience can be dangerous to personnel and/or lead to catastrophic failure.

as for generally when to bleed or not to bleed..

when older mechanical injectors get air bound, cracking fuel lines may be necessary. while they often do still have a return system, it's frequently not high enough volume to clear large amounts of trapped air on the delivery side.

as mentioned, follow the applicable manual. but typically, start with closest injector to to the pump. crack fuel line b nut a turn or two (do not remove), crank engine in brief intervals (to avoid overheating starter) until solid stream of fuel is visible without bubbles, tighten b nut immediately. repeat for remaining injectors or until engine starts.

if engine starts and runs rough after only bleeding one or two injectors, let it run at low idle no load and it should clear the rest of the air on it's own. if not, continue bleeding remaining lines and engine will level out. again, this is generally not necessary though after engine starts.

now, common rail high pressure systems can run at 30k - 40k psi, DO NOT open these lines. there are specific air purge procedures for these engines, often as simple as cycling ignition switch or occasionally with diag software on a laptop or scan tool. again, always consult applicable manual.

a couple of tips to prevent or at least minimize air intrusion, never run fuel tank empty and always prefill fuel filters when replacing. again, consult applicable manual, but after filter service, some engines have low side bleeding procedures to keep air out of the high side.

so the tl/dr - rtfm!

good luck!

 

[ImaginaryTango]

There is no attitude.

People here are just trying to prevent you from getting into a situation that could possibly be beyond your depth.

I'm only speaking as a former special ed teacher who dealt who taught English for many years, as well as addressing issues like context or why, sometimes, there are gaps in communication, or other issues, so what the heck would i know about a line like, "We have a winner" being distracting and more about sarcasm than about directly addressing what to do and not to do. Honestly, I was not 100% sure just what was going on or just what was said about the issue until @EPIC spelled things out clearly about the issues. @Killer Bee also did a fine job of addressing the issues involved and clarifying things.

Related to that, my comments were also an attempt to keep the discussion on the topic, to focus on what is going on, and on clear and informative answers, as opposed to short comments that are not as helpful, or sarcastic reactions.

I also found @white tiger's information useful. All of these gave good useful information, but those posts also took time to go into what is going on and provide more depth for context and background on what's going on - taking the time to spell things out clearly and completely.

 

[GeoHorn]

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