Learned to bleed injectors

[JohnEasley]

Last weekend, I did full oil and filter changes and fuel filter changes. While doing an air bleed on the port engine, I discovered the manual priming pump was leaking badly when pressed. Replaced it today, bled the system, and then had my wife crank the starter while I cracked open the injectors. First time doing this. Kinda pleased with how it went, overall. The engine fired up and took over after bleeding the second injector. Pretty cool. It’s something I’ve been wanting to learn to do, anyway.

Think I’m gonna pick up a couple of spare injectors. In case one goes out while we’re traveling, I now have the skills to swap it out and get us operational again.

‘Twas a good day.

John

 

[Comodave]

Good for you. Nice when things work out.

 

[Jeff F]

It is pretty cool. You've gained a very useful skill.

 

[psneeld]

For anyone not sure of their engine requirements.....some engines don't require injector bleeding.....some do.....make sure you know your engine.

If your does.....a great thing to master...especially if you are a single.

 

[Gulf Comanche]

How would you know when or which injector goes out? I have a spare injector but no idea how to tell if one is bad.

 

[psneeld]

If an injector is out or is going bad ......often the engine will tell you that it's not happy by running rough for giving another symptom. You crack each injector and when there is no change in that unfamiliar engine pattern.... that's the bad injector.

Hopefully a better mechanic than me can explain it better

 

[twistedtree]

And another caution under the “know your engine” category....

Cracking open injector pipes and fittings on a high pressure fuel system like a common rail can be quite dangerous since the fuel is under such high pressure. This is a well know hazard when working on higher pressure hydraulic systems. The stream of ejected fluid can be very hard to see, and can pierce your skin and inject you with fuel or hydraulic fluid. It apparently requires immediate surgery to save the limb or other body part. Very nasty stuff, and worth a google to fully appreciate.

 

[JohnEasley]

If an injector is out or is going bad ......often the engine will tell you that it's not happy by running rough for giving another symptom. You crack each injector and when there is no change in that unfamiliar engine pattern.... that's the bad injector.

Hopefully a better mechanic than me can explain it better

That's pretty much how it was explained to me, too. A bad injector will run rough, similar to a bad sparkplug on a gasoline-powered engine. With sparkplug, you'd pull each wire one at a time. If you pull the wire and the engine runs even rougher, it's not that one. When you pull a wire and it still runs the same, that's the bad sparkplug. It's the same with diesel injectors. Loosen the fuel line nut on one injector at a time. When you loosen the one that doesn't make the engine run any rougher than it already is, that's the bad injector.

 

[JohnEasley]

And another caution under the “know your engine” category....

Cracking open injector pipes and fittings on a high pressure fuel system like a common rail can be quite dangerous since the fuel is under such high pressure. This is a well know hazard when working on higher pressure hydraulic systems. The stream of ejected fluid can be very hard to see, and can pierce your skin and inject you with fuel or hydraulic fluid. It apparently requires immediate surgery to save the limb or other body part. Very nasty stuff, and worth a google to fully appreciate.

Heard about that. I pre-loosened the first three injector fuel nuts and then barely snugged them down. Wifey turned the key up at the helm station after I had a wrench on the first injector. I was able to stay back a safe distance and observe the fuel spray (which was smaller than I expected and took a few seconds before it spurted) before tightening the nut. About as safe as it can be made.

 

[High Wire]

If anyone has never bled a mechanical diesel injection system before, I would urge you to find someone who has and go through the drill while in a safe dock. Its not hard or complex. Having a mentor will take a lot of stress out of cruising. Sooner or later you will need that skill.

 

[JohnEasley]

If anyone has never bled a mechanical diesel injection system before, I would urge you to find someone who has and go through the drill while in a safe dock. Its not hard or complex. Having a mentor will take a lot of stress out of cruising. Sooner or later you will need that skill.

Wholeheartedly agree. I’m lucky to have a local mechanic that has taken me under his wing and has been generous with his time. Equally, I over tip him a bit when he does larger jobs for us and take him to lunch now and then. He has become a friend.

 

[Pete Meisinger]

My F.L. was just not running quite right. Ruff idle mostly. The admiral was on the front deck and I bled the injectors one by one. When I got to the one which was air locked I saw her through the window. She asked what I had just done because the engine sounded totally different. She really has a good ear but the change was night and day once I got to the right injector.

pete

 

[Gulf Comanche]

That's pretty much how it was explained to me, too. A bad injector will run rough, similar to a bad sparkplug on a gasoline-powered engine. With sparkplug, you'd pull each wire one at a time. If you pull the wire and the engine runs even rougher, it's not that one. When you pull a wire and it still runs the same, that's the bad sparkplug. It's the same with diesel injectors. Loosen the fuel line nut on one injector at a time. When you loosen the one that doesn't make the engine run any rougher than it already is, that's the bad injector.

Thanks for the explanation, I figured it had to be something like that but wanted to hear it from someone who knows. I’ve bled the injectors several times after the fuel filters were changed, no big deal but a skill that you should have.

 

[ktdtx]

Cracking open injector pipes and fittings on a high pressure fuel system like a common rail can be quite dangerous since the fuel is under such high pressure. This is a well know hazard when working on higher pressure hydraulic systems. The stream of ejected fluid can be very hard to see, and can pierce your skin and inject you with fuel or hydraulic fluid. It apparently requires immediate surgery to save the limb or other body part. Very nasty stuff, and worth a google to fully appreciate.

Absolutely agree--do not mess with the High Pressure common rail injectors.
Pay someone else to do it.

 

[Xsbank]

I believe that a Lehman should have its injectors checked every 1000 hours. It will give you slightly less vibration and run slightly smoother. The motor will still rattle at too low an idle and it will still put fuel in the water. The best place for injector repairs is a farm shop, anything that says “marine” or “Lehman” will charge you double or triple. All that happens is an injector is put in a jig and the pressure to make it pop is measured and the pattern looked at. If substandard, the tip is removed and replaced and the spring is replaced. If its a good shop they will test them again. When I had my boat I sent my injectors to a fellow in Wisconsin who did mainly combines. $25 each.

Don’t forget to replace the washers or anneal the old ones. I’m pretty sure that the Lehman/Ford has self-bleeding injectors?

 

[FlyWright]

If anyone has never bled a mechanical diesel injection system before, I would urge you to find someone who has and go through the drill while in a safe dock. Its not hard or complex. Having a mentor will take a lot of stress out of cruising. Sooner or later you will need that skill.

+1 My buddy taught me the skills early on at the dock. I've had several opportunities to practice those new skills in the past 12 years. Adding inline electric fuel pumps and having a remote start switch have made it much easier to do single handed.

 

[Steve DAntonio]

And another caution under the “know your engine” category....

Cracking open injector pipes and fittings on a high pressure fuel system like a common rail can be quite dangerous since the fuel is under such high pressure. This is a well know hazard when working on higher pressure hydraulic systems. The stream of ejected fluid can be very hard to see, and can pierce your skin and inject you with fuel or hydraulic fluid. It apparently requires immediate surgery to save the limb or other body part. Very nasty stuff, and worth a google to fully appreciate.

Well-said Peter, and I'd add that's a risk with any diesel fuel injection system, even conventional systems are under very high pressure, high enough to inject fuel under one's skin.

For those who haven't done it, this video walks would-be bleeders through the process https://vimeo.com/153401032

 

[Boatcrazy]

Out of curiosity....is it "typical" for just a single injector to go bad, or, under normal ops, would the whole set go bad at the same time? ie, is it OK to carry only 1 or 2 injectors, and save the $$, or to carry a whole set as spares?

 

[Pete Meisinger]

Carrying one spare injector, to me, sounds like a waste of effort and money. Do you carry a spare spark plug for your car? If you have an injector go bad, there is a good chance they will all show some signs of fouling.

If you even have a tiny suspicion of a bad injector, pull them all and have them rebuilt and put them back in. It will give you a couple thousand hours of peace of mind.

One new injector for my F.L. is probably $300 - $400. Some are far more, some less .That is why they are almost always exchanged or rebuilt. For the cost of one new injector to carry as a spare you can probably have all 6 or 8 rebuilt.

Not a bad home mechanic job either. What is nice about it is that it is right on top of most engines, no need to slither around on your belly like a reptile.

Go For It.

pete