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Bleeding your Yanmar Engine

47K views 41 replies 29 participants last post by  illanrob 
#1 · (Edited)
Tutorial: Bleeding your Yanmar Engine

Introduction and Disclaimer:

This is a picture tutorial of how to properly bleed your Yanmar Diesel engine. It will also cover other maintenance issues as well, and is provided with no warranties or thought of accuracy. Use this information at your own risk, and is merely provided to assist others that are like me, a bit mechanically challenged. A good portion of this tutorial is from knowledge gleamed from "You can call me David", and other forum members.

When do you need to bleed your Diesel?

1. When you change out any parts related to your fuel system. Such items may be, fuel lines, various fuel filters, mechanical pump, injector pump etc.

2. When you have run out of fuel and refill after such. Note: If you run out of fuel, you will positively realize the effects of algae and other sludge in your tank, keep an eye on your Rancor fuel filter, and I personally recommend when re-fueling after exhausting your tank - do it with the pump handle set at the slowest pump selection possible as not stir up residual sludge at the bottom of the tank.

3. Anytime that the engine appears to cut-out, as this may be an indication that there is a leak in your system that air can be introduced.

WARNING:

Anytime that your engine is not able to turn over after 2 or more tries, and if you have not done so - locate your water inlet valve for your Engines water intake and TURN IT OFF - until the engine is running. If you do not you RISK ruining your engine as it will be likely that you will siphon water into your engine and since water is not easily compressionable by your engine - you will blow out gaskets, ruin cylinders and if water sits in there - will rust out your engine quicker than you can say duh.

When starting the engine, it is important that the water shut off is done, but also do not try to start the engine for more than 2-5 seconds at a time, without allowing it (the starter) to cool down in between. Trying to make it start by holding the starting button for long periods of time will cause your starter to overheat, and you risk a possible explosion or start of a electrical fire. Patience is the virtue that must be practiced with this procedure.

Starting at the front of your Engine.

Auto part


In the picture above, you will note one item that probably is not part of your normal Yanmar engine setup. That will be the Facet electric diesel fuel pump. This is a mod I added to the fuel system, to allow me to bleed the fuel lines without requiring me to run up to the cockpit to turn the engine over, or manually depress the mechanical lever on the Yanmar's fuel pump like a crazy man.

This particular pump is easy to install, and when not powered is passive, which means it can remain inline of the fuel line going to the engine as it will not restrict the flow of fuel once powered off. In the installation pictured, there is a push / pull switch that I installed into the bilge (not pictured) that allows for easy access for powering it on and off, when I am required to bleed the system or in the event that the mechanical fuel pump fails underway.

The part is $124 from Napa, and the push / pull switch is about $9. You may also need additional fuel line and adapter barbs if you locate the pump elsewhere. But for less than $170 bucks, less than an hour install time, a worthwhile mod to make to your system.

You will notice that the picture above, also denotes where your water intake valve is. On my vessel it is located forward of the engine. SHUT IT OFF and do not turn back on until engine is running.

I also annotated where the bleed valve for the Rancor is. Water is heavier than fuel so it is important to check the Rancor filter to make sure that the bottom of the clear portion of the filter is not filled with debris etc. To drain any water there is a little twisty at the bottom that you unscrew. Unscrew and keep a fuel/oil mat or rag underneath, and it will drain. When red dyed diesel comes out - screw back in.

At the top of the Rancor is a vent valve. I find with the electric pump installed there really is no need to open this, but officially, this is the first place to start.

Starboard side of the engine:

Auto part Engine Fuel line Technology Electronics


In the picture above, you will see that I have annotated fuel related components. Starting aft (the left in the photo), we see the Yanmar mechanical pump. This is the part I replaced because the outlet side was leaking and the outlet screw piece was stripped on the original part. The part is around $70-130 depending on your make and model of your diesel. MAKE SURE, you get a gasket with the new part as they do not come with one. The gasket is around $2, and you can not re-use the old one. If you simply bolt it on without one, you will find that your engine will run well once bled but will leak oil like a banshee into your bilge - and it won't be long before you get oil warning lights and alarms.

Forward in the photo (to the right) is the injector and it also has a small fuel filter as well, located at the bottom of the unit. If you are changing out your Rancor, this would be a good time to replace this one as well.

In the photo I have numbered the bleed points for quick visual identification.

NOTE: Place a fuel / oil absorption mat or rag under the areas as you bleed to catch fuel.

To pressurize the system, manually cycle the mechanical fuel pump lever up and down or turn on the electric pump (if you have installed one). Starting with #1 to #3, one at a time, crack them open using a crescent wrench of proper size. When I state crack, just enough to unseat the bolt. You will see air bubbles escape through the fuel. Keep cycling the fuel pump lever until nothing but fuel comes out. Once you have nothing but fuel coming out - tighten the bolt - be careful not to over tighten them as if you strip them, it means replacing the part.

#1 through #3 are part of your low pressure fuel system. If these are bled successfully, most of the air that you should be worried about will be in your HI pressure system, which I will cover next.

HI Pressure System.

In the same picture above, note where the HI Pressure relief valve is. WARNING - wear protective goggles and loosen slowly as fuel can spray when under pressure and cause injury.

Use a properly sized crescent wrench or flat head screw driver and crack this nut ever so slowly. You will get a bunch of air escaping and remember this is under pressure. Remember you have to manually depress the fuel lever to pump fuel or rely on the electrical diesel pump if you have installed one. Be patient as it will take some time. Use a large fuel / oil absorption mat under it as more fuel than not will come out with the air. When no more air is escaping re-tighten.

Auto part Engine Fuel line Machine Automotive engine part


Next locate the other hi pressure relief point on the starboard side - forward of your engine. This one is illustrated in the photo above and will be on the top right of the photo. Using a phillips head screwdriver or crescent wrench - repeat the same process you did with the previous one.

Now, we need to move to the port side of the engine. Repeating the same processes as before, and release the air out of the fuel intake of the cylinders (again HI Pressure).

Auto part Engine Automotive engine part Vehicle Car


Locate the three HI Pressure nuts on the port side of the engine as per the above photo. Notice that I annotated the LO pressure side as well, you will most likely not need to touch these as they are fuel return and do not impact air in the fuel / starting or engine running problems. Repeat the same process we did on the previous ones, starting with the most forward one (#1) and working your way back to #3, ONE AT A TIME. Remember - this is the HI Pressure side and protective goggles are suggested.

Wahoo! Am I done now?

Maybe. Now is time to crank the engine. Keep the water intake valve SHUT for now. Try starting the engine.

1. It doesn't start after 2 tries.

Repeat the above process on the high pressure locations only. Start on the starboard side of the engine and work your way around. We may need to repeat this process several times as you will be surprised how much air is in the system.

2. It runs. Turn on the water intake valve now. Check to make sure your are getting water out of your exhaust. Now put your engine under load by putting your boat in forward or reverse and give it throttle. If you are tied up at the pier, prior to make sure your lines are properly properly secured. Run under load for 5 minutes or so.

If its hums along, you may be done, but if the engine sputters and dies out. Repeat the process again, shut off the water intake valve down below, and bleed the hi pressure locations described starting on the starboard side working around to port.

So, there you have it. A pictorial tutorial that should allow the true mechanic in you to come alive.

I hope you find this helpful and that the mysteries of "bleeding" a diesel are de-mystified. You should probably print this out and keep it on your boat in the event this happens while you are underway.

NOTE: I may have made some technical labeling errors in some areas, and will correct as needed, however - this document gives a very elementary overview of how to do the task.
 
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#3 ·
I think we need a boat maintenance and repair tutorial forum. Either that or a reference forum. Halekai's waxing and polishing post, crimping post, and through-hull post should be there too.
 
#7 ·
I guess you never spoke with a mechanic, as there is a much easier way and cheaper and less complicated, one just needs bleeder screw, and hand vaccum pump down stream to accomplish all that you have show.

There is also something else sailors should be aware of is that there is out there diesel fuel with fish oil in it, which has been the cause of the last three engines that stop running, which I had to get going. The only thing that put me on to it was the smell, it didn't.
 
#8 · (Edited)
I guess you never spoke with a mechanic, as there is a much easier way and cheaper and less complicated, one just needs bleeder screw, and hand vaccum pump down stream to accomplish all that you have show.

There is also something else sailors should be aware of is that there is out there diesel fuel with fish oil in it, which has been the cause of the last three engines that stop running, which I had to get going. The only thing that put me on to it was the smell, it didn't.
We would enjoy the write-up if it makes things that much easier. The instructions come from my experience with a mechanic. And actually the method works relatively quickly. I do not see how suctioning with a vacuum would do the trick. But you seem to always just throw ideas out there in my last two threads on the topic, none of which contributed anything positively to them.

If you have a faster and better way - then follow my lead and actually post the details of it and illustrate it. Otherwise... all I smell is something fishy...

Thanks to everyone else for the wonderful feedback - it is much appreciated.
 
#9 ·
Suction is wonderful, but a hand job is safer. I've had success with a simple manual sqeeze bulb (like those used on outboards) between the tank and the filter. After changing a filter, a few pumps sends fuel to the high pressure pump. If I haven't run it to empty that's usually sufficient. Theyre' made for gas, not diesel, so I keep an eye on it to make sure it doesn't disentrgrate, but at a few $ each, theyre easily repalced. Beats the hell out of that silly lever on the low pressure fuel pump.
 
#10 ·
ROFL... You might want to rephrase that a bit... People might get the wrong idea... :rolleyes:

Suction is wonderful, but a hand job is safer. I've had success with a simple manual sqeeze bulb (like those used on outboards) between the tank and the filter. After changing a filter, a few pumps sends fuel to the high pressure pump. If I haven't run it to empty that's usually sufficient. Theyre' made for gas, not diesel, so I keep an eye on it to make sure it doesn't disentrgrate, but at a few $ each, theyre easily repalced. Beats the hell out of that silly lever on the low pressure fuel pump.
 
#12 ·
The instruction for the vaccum pump procedure is with a bleeder screw installed at the return line, using a vaccum pump, one draws the fuel through a hose immersed in a container of fuel and as you vaccum the fuel through the system you watch for bulbs, if now showing you stop vaccuming and watch to see if you have flow, with the thought that the fuel tank is higher than the engine. Using this procedure I find 90 percent of the faults. There was once when this really didn't work well and knew there was a leak so I introduced a die, same as we use in airconditioning, and with the use of a black light was able to find a crack in the fuel pump body.
 
#14 ·
Good job. Even though I have a Perkins 4-108.

I do have a question about the electric fuel pump being used.
I also have one on my boat. Not sure if it is a Facit brand or not - I also got it at NAPA. It is a little square job. From looking online, the difference I see is a small difference in the output pressure.
The square one works for me, but is noisy as it operates, making a clicking sound. Does the cylindrical one make the same noise?
The one I have on my engine doesn't bother me, but I have used the same type pump for just transfering fuel between tanks, or emptying a tank, or in a fuel polishing system I made. After a while, the clicking tends to get on your last nerve.
 
#16 ·
I think this is a good start - very nice effort. However, I think there might need to be some refinement. Every bleed point from the lift pump point up to the low pressure inlet into the injection pump is a low pressure bleed points. The high pressure connections are at the top of the injection pump and the injector ports (on the side of the injectors). I think some pictures are not labeled correctly.

You don't have to bleed the high pressure side when replacing fuel filters. You only need to do that if you introduce are into the high pressure side.

Low pressure points need to be opened until you can see the hole or slit in the bolt on the threaded part. Just cracking them loose will make it much harder to do a hand job. High pressure points should be opened 1 full revolution for bleeding.

You do not need to bleed the high pressure line one at a time. Just open them all crank the motor until you get fuel at each one. Then re-tighten. The fuel will not flow back and introduce air.
 
#17 ·
Sorry to be a party pooper here, but the more I look at this first post, the more problems I see. I think it's a great concept and I applaud the effort that went into it. However, I think the document is not usable in it's current state. For example the item the second photo labeled injection pump is actually the secondary fuel filter. There are many other problems as well.
 
#18 ·
Feel free to PM me with suggestions for improvement (would be appreciated)- I am no mechanic and the intent was DIY laymans way of tackling it, and for my own reference since David spent so much of his free time to make it easy for me understand. Hence the pics and at least laying it out - even with inaccuracies - you can get it done relatively painlessly.

To answer the wiring. I ran the wiring to the push/pull switch from battery directly, then the output of the switch to the positive lead of the aux Facet Pump. I did this as it was the easiest to do, no intentions of leaving the pump running. The switch is in the bilge and I used a electrical sealant to insulate the wires and the back side of the switch. I'll probably change that out and put a dedicated switch on the Nav panel later, since I am running new wires all over the boat.

To address the noise - the cylindrical one that I have is quiet. You do not hear it running if the engine compartment is insulated / sound dampened and barely if you have the compartment opened.

PM me with suggestions and later next week I'll do an edit on it with proper credit :)

Thanks for the input.

.
 
#31 ·
Well I had my first problem about a year ago. The little hand pump that's built into the Yanmar engine is pretty terrible too. I went to the marine store, bought one of those squeezy-bulbs the outboarders use, and spliced it in the line downstream of the fuel filter, but before the engine. Five or six good squeezes and I could hear fuel dropping back into the tank from the return lines, and the air was bled out. Piece of cake.
 
#22 ·
On my Yanmar 2QM15 engine the return fuel line doesn't run to the fuel tank, but to another input connection to the Yanmar's local fuel filter housing assembly. When I had a mechanic service the engine after buying my boat, he bled the fuel system by simply using a hand held pump like he used to extract the dirty oil, and connected it to the end of the return hose. As he applied suction, the fuel was pulled from the tank, through the fuel line, through the new Racor assembly, through more fuel line, through the Yanmar fuel piping system and out the return line. Once he saw some come out the return line, he just connected the hose back to the fuel filter assembly, tightened the hose clamp, and the engine fired right up on the first try.
 
#24 ·
Any

Any of the three models they sell will work - I opted for the largest for optional ability to do fuel polishing if the need arised. I install after the Racor because the racor is designed to be the primary fuel filter. The Facets do also have a fuel filter - but not nearly the capacity ( < 5% of the Racor) - so I suggest putting it afterwards...
 
#26 ·
Great post. I have the squeeze bulb installed before the Racor, works great and for $13 what a value. Whether electric pump or squeeze bulb, they both make bleeding so much easier than the little manual actuatuion of the Yanmar lift pump.
 
#27 ·
Great post. I have the squeeze bulb installed before the Racor, works great and for $13 what a value. Whether electric pump or squeeze bulb, they both make bleeding so much easier than the little manual actuatuion of the Yanmar lift pump.
JIM-- I keep meaning to do this because of your prior recommendations. This will go on the winter project list. Thanks!

Mitch
P-33-2 #146
 
#28 ·
The pictures were a great asset to the description. However there is one small error. The last picture posted is labeled with "hi" and "low" side backward on the injectors. The fuel lines entering the side of the injectors are the "high side" (17mm) and the banjo bolt (14mm) on the top of the injectors are the "low side" return.
 
#29 ·
I'm sending this to build up my posts so I can see the pictures. I guess that's how it works. Going to change the filters on my 2GM this weekend and keep reading about the horror stories of getting air in the line, lol. I think I'm going to run it, change out the primary, run it again for 1/2 hour, then change out the primary, then run it again for an hour to make sure it's not going to stop on me. Gotta move my Watkins 30 down the TN river this weekend.
 
#34 ·
Sellongitab is correct in pointing out that the article and photos incorrectly identify low pressure bleed points as high pressure ones.

The fuel is pressurised by the high pressure pump after which the fuel lines are all metal pipes not rubber hose and there are no bleed nipples. If you need to bleed the high pressure side you need to crack open each injector feed pipe.

If this could be edited a good article would become even better and less likely to cause confusion to newcomers.
 
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