Something more serious

[sailaway78]

All you Yanmar experts, here is a real and not theoretical question for you. Today I was going to bleed the fuel system on a 3gm Yanmar. When getting to the injector pump I backed off the bleed screw, that is in the banjo fitting where it attaches to the high pressure pump. The bleed screw came out with my fingers, and was to my surprise very short. Not much over 1/8" long. HHHHHMMMMMMMMM A close inspection shows that this bolt was drilled and cross drilled with a small bleed hole. And where the bleed hole was drilled is where it stops. The only logical conclusion I can come to is it is twisted/broken off at this point. Replacement is not such a big deal, other than going to the local Yanmar place. But where is the broken piece? Looking at it, it doesn't seem possible for it to get down into the injector pump, as the banjo bolt is threaded it's entire length. But since I am not known as Mr.Lucky, and Mr.Murphy lives next door, I want to pull the pump to be sure. From reading the manual this appears to be a very straight forward project. The book shows the pump as coming out of the housing as a single unit, with no pieces to go flying off into never, never land. The question is, what is there, if anything that I am not seeing. Is there any trick to pulling the pump, and checking for any foreign parts, if I do not take anything else apart. I really don't want to screw up something I have never messed with before, and have no working knowledge of.

 

[Landsend]

I wouldn't pull the pump... I would replace the bleed screw

and the crush washers. You could easily change the injection timing and that would be a real mess. The bleed screw in the repair book looks very short.

 

[sailaway78]

Bleed screw

I agree that the bleed screw is short. But looking at this one it is obvious that it has twisted/broken off. But there is no sign of the end of it. I know it is not very likely that it can be in the pump. Only way is for it to vibrate down the threads the length of the banjo bolt, down into the pump body. From what I can tell from the Yanmar manual, if I can pull the pump body, very carefully, and just turn it over and see if it is in there. I don't think I can get the pump out of time by just removing the body, being careful to not turn the engine over. The thought of part of a bleed screw rattling around in there doesn't make for any piece of mind, and as I said, Mr.Murphy lives right next door.

 

[RAD]

Maybe PO replaced the bleed screw

Cause he dropped the original into never never land and Mr Murphy said go get another bleed screw from an auto parts store or a mechanics tool box and it happened to fit.

 

[Rich Stidger]

Do you have a picture?

I'd like to see what you see.

 

[sailaway78]

Nothing open tomorrow

Since nothing is open tomorrow to get a replacement, I will try to get a pic and post it up. The really disturbing thing to me is I am reasonable sure that at one time, there was another piece to that bleed screw, and I don't know where it went.

 

[RAD]

Does it look like a piece broke off?

nm

 

[sailaway78]

Broken off

Rad, yeah, the bleed screw looks like it was drilled up the centerline, and then a small hole cross drilled about 1/8 or so down from the head of it. Which makes sense for a bleed screw. Except there is nothing below where it appears to have been cross drilled. When removed it was only slightly more than finger tight, and there is no sign of the other end of it, if it was ever there.

 

[RAD]

If some one had modified that bleed screw

You would think they had already delt with the broken piece?is it made of metal? maybe a magnet? so you don't have to remove the pumpHoly S..t Mr Murphy does live next door

 

[sailaway78]

MagnetI

I did stick a magnet down in the hole where the banjo bolt is. And got nothing out of it. It is a steel bolt. Will try to post a pic tomorrow.

 

[RAD]

Great minds think alike *5

nm

 

[Fred]

Yanmar fuel pump

You will not change the timing by pulling the injection pump.It sits on a cam that pushes the pump plungers up.The timing is set by the Shims (gaskets) under the pump that control the distance from the pump plungers to the cam. Less shims, Pump plungers closer to cam, this would advance the timing(inject sooner).However; there is a collar the rides on the front of the cam where the governor weights are. You have to get this right.If the engine has been running, and there was no problem, I would leave it alone.When the bleed screw broke the piece below the head of the bolt would have still been in the threads of the bajo bolt and easy to remove with an E-Z out or even a screw driver.Unless it is still there threaded in the hole. In that case remove the banjo bolt and see what you have.fred

 

[sailaway78]

Not in the banjo

Fred, Looked really close at the diagrams in the Yanmar manual, and it looks to me like some of the bleed screws, coming from the lift pump are cross drilled, but it doesn't look like the one at the high pressure pump is. It appears to be really short. The others look like there is a small hole cross drilled between the bolt head and the start of the threads. I pulled the banjo bolt and there is nothing in it. That was my first thought, that the rest of that bolt was in there. I have been studying the Yanmar manual, and I do not see the collar you refer to. The only thing that looks like it could be disturbed is what Yanmar calls the fuel control rack. Looks like this just drops into a slot in what they call the fuel control lever, when you put the pump back. The engine has been running fine, but now after sitting for about three weeks, it wouldn't start. Has done this before and after bleeding the system it started and ran fine. So I am beginning to think this is the cause of the problem. But the thought of a piece of screw floating around in there just scares me to death.

 

[fred]

Yanmar fuel pump

I found my manual.I called what the rack lever slides into a collar, Yanmar calls it a sleave. The governor is attatched to the sleave. The sleave moves forward and back on a shaft to control fuel. So the throttle applies spring tension to pull the fuel rack towards more fuel delivery and the governor counters that to control fuel and then limits fuel to limit max RPM. I seem to recall the type of bleed screw in the bajo bolt at that point as being different, just a short bolt with a slot in the threads instead of cross drilling. The slot does not continue all the way to the head of the bleed screw. So as you loosen the bleed screw the slot allows fuel / air to escape. My manual shows a very short screw in the banjo bolt at the pump.It shows a longer cross drilled screw in the fuel filter.Yes you are right about the no start after it sits for a day or so.Air is getting into the fuel system, letting the fuel drain out into the fuel return, or the valves in the fuel pump are leaking letting fuel run back.Sealing the bleed screw may fix this. You can have air get in at rest but it may not leak fuel when running, strange I know. Don't worry, be happy... that you found your no start problem.Good job!

 

[jimbooth]

Probably got over tightened & broke

On your boat, isn't the pump right there in front of you w/easy access? You could pull it or work right there. First I'd make sure that the broken end isn't still threaded in the hole, if it is, it'll probably thread out fairly easily, an easy out works best, but the wrong end of a file will usually grip enough to turn it out. I have made bleed screws with a drill press. Figure out the size: I believe it is a 8mm x 1.25 - 13mm length bolt(it might be fine thread 1.0) just get a bolt that threads in the hole. drill up the middle then slot with a hack saw or cross drill. I set the stop on my drill press so I couldn't go too deep. Do the threads go all the way to the bottom of the hole? I don't think the broken end could go all the way into the pump.

 

[s sauer]

Bleed Screws

The bleed screws on our 2Gm20F ate drilled and cross dilled near the top.I wouldn't mess with the High Presure Pump; the shims do adjust the timing.You should be able to insert a pin probe in the screw hole and feel if the remnant is in there; if it isn't hasn't it already dropped thru?The 'Easy-Out is probably a good idea if th remnant is reachable, just don't screw up the threads.

 

[sailaway78]

More inspection and a decision

Sorry but I couldn't get a decent enough pic of the screw to post up. I have looked and inspected more and come to a decision. What I have figured out is that this screw is different from the others. The bleed screws that are cross drilled are drilled in the little bare area between the head and the beginning of the threads. This one has no bare area before the threads begin. But it has definately been cross drilled. What I have left is a 6mm screw, only about three or four threads long, broken off where it was cross drilled. I don't see any possibility of the rest of it getting into the pump. Because it would have to get through the banjo bolt from the vibration of the engine running, and the banjo bolt is approx. an inch long. Before it could get that far through there, it would have to restrict the fuel supply and the engine would at least loose power if not totally quit. So I am going to do the big no no, and make the assumption that it isn't and can't be in the pump. Where is it. Not a clue. But I have poked around as best I can with a magnet and found nothing. Don't see any way it could get down in there. I am also assuming that I have a better chance of screwing something up by pulling the pump than the chance of this screw being in the pump. So, just going to replace the screw and see what happens. I sincerely appreciate all the comments, ideas and help from all of you, and will post up with the results when I get this thing back together and fired up.