Possible air intrusion?

[patrscoe]

Last week during a cold morning (35 degrees), I went out to my sailboat for a morning (cold but windy) sail. I attempted to start up the engine, normal procedures and I could not get the engine started and eventually my batteries were too low and I ended up plugging in my shore power, charged up my batteries and tried again later in the morning but I was unsuccessful.
This week I investigated what could be wrong. One thought was the glow plugs are original and it has always started a hard at cold temperatures so I ordered new glow plugs, arrived this week, replaced them this morning, and also checked the air flow (cleaned out my air intake can) and I was able to start the engine and I let it run for about 15 minutes to make sure it was running okay. I backed out of the my slip to give it a run for a bit before I went home and as I was turning in the marina, the engine stalled out. I hit the starter button and it started right back up. I put more throttle on it and it started to bogged down and stalled again. This repeated for about 5 times and I eventually coasted back in my slip (took me while as I was feathering the throttle). No throttle and just above idle, it ran fine.

I went down below and I notice my injector bleeder valve was open, maybe 3 turns. I tighten it back down (as per the attached image) and the engine seem to run a little rough so I loosen up the valve nut and saw some bubbles coming out so I bled the bubbles out. I let it run for a while and came back down and the kurl knob was loosen up again. Perhaps the spring or tension in the valve is broken. I can fix it but I had to leave and unfortunately I will not be back for a few weeks so I am left wondering.

If the injector bleeder valve was semi open, would it have this effect on the engine?
Would it allow it to run at low speeds or idle but once you put more load, it bogs down and stalls? But if this allowed air back into the fuel system, why was I able to restart the engine once it stalled out?
I am ruling out the fuel as I just recently replaced the fuel filters and cleaned the tank. I will check all my connections to make sure nothing is obvious.
Thanks!
Patrick

 

[Loren Beach]

That is the same knurled knob as my former M25XP. I used it to bleed the fuel system (up to that point), and this was all that was needed to get it running again after a filter changeout.
I have not before heard of one that vibrates loose on its own. I recall tightening it firmly by hand each time, but have no idea of how much torque is OK or how much is too much. Matter of fact, in spite of the noise from the oil low pressure buzzer back on the panel, I could faintly hear the fuel splash into the tank under our settee, with that by-pass valve open for bleeding new fuel thru the system.

 

[Dave G.]

I'm surprised the engine ran at all. That bleeder valve has to be tight with absolutely no air getting sucked in. When you changed the filters you must of blead the system to get it running yes ? Maybe while bleeding a seal or washer got dislodged and that is preventing it from locking down ? I have a 5416 and both of my bleeder valves are hex head so have to use a socket to bleed. If that is indeed a finger tighten valve then there must be a O-ring or washer of some sort I would guess.

 

[Kenneth K]

That sounds exactly like the effect an open bleed valve would have on a running engine. At any given throttle setting, you can actually vary the engine RPM a little bit by opening and closing the bleed valve. You're just robbing fuel away from the injector pump and sending it directly back to the fuel tank.

And your problem didn't have to have anything to do with air in the fuel line. It could have resulted from the valve simply allowing too much fuel to bypass the injector pump. Air in the lines would indicated a separate, additional problem.

But, as Loren said, the valve must be able to remain fully closed after just being finger tightened. If the valve has a two-party body, it could be that just tightening the two parts could compress the internal rubber washer (IF this is how the valve is constructed). If not, and the valve is just worn out, I know you can get a new one from Westerbeke.com. I think they're about $30-40.

But, wait, you said you saw bubbles. Where?

Also, the Universal manual lists a cold-start/low battery procedure using the decompression lever to get the engine up to high cranking rpms to aid starting. Never done it myself.....

 

[patrscoe]

I was thinking about this as I was writing the posts and your right, I must of adjusted or forget that I messed with it the other week when I was cleaning up from a oil change or perhaps moved it as I was sneezing my hands around the engine to remove the glow plugs yesterday. Off memory, when you don't tighten the nut down that holds the valve (which is how I bleed the air, not the knob as it seems to be more effective), the knob becomes loose.

Bubbles type fluid like dishwashing soap in water; Kenneth; when I looked at the knob and release that it seems to be partially out, I said perhaps it is sucking air in at this location so I bled the line by removing the valve nut not the knob and fuel came out but it was more like dishsoap bubbles. I only bled the line at this location. I tighten everything up and let it run but did not have time to test the engine under load.
I am planning to put her up on the hard towards the last week of December for the winter until April 1st but I would like to figure this out before I haul out.

<<And your problem didn't have to have anything to do with air in the fuel line. It could have resulted from the valve simply allowing too much fuel to bypass the injector pump. Air in the lines would indicated a separate, additional problem.>>
If the valve sole purpose is to bypass the fuel to the return line and somehow bleeding it at the same time, then that makes sense. If it was partially open, I was able to run but not under load as I would not have enough fuel. Yes, I agree, I mostlikely have a air coming into the lines somewhere. Doesn't sound like a alot but some. I have been thinking of that for a while and my last fuel filter change did not go well, as I slightly crushed the Racor filter because my filter wrench was at home so I made a make-shift filter wrench.
Could this valve be replaced with a bleeder bolt?

 

[Loren Beach]

I was thinking about this as I was writing the posts and your right, I must of adjusted or forget that I messed with it the other week when I was cleaning up from a oil change or perhaps moved it as I was sneezing my hands around the engine to remove the glow plugs yesterday. Off memory, when you don't tighten the nut down that holds the valve (which is how I bleed the air, not the knob as it seems to be more effective), the knob becomes loose.

Bubbles type fluid like dishwashing soap in water; Kenneth; when I looked at the knob and release that it seems to be partially out, I said perhaps it is sucking air in at this location so I bled the line by removing the valve nut not the knob and fuel came out but it was more like dishsoap bubbles. I only bled the line at this location. I tighten everything up and let it run but did not have time to test the engine under load.
I am planning to put her up on the hard towards the last week of December for the winter until April 1st but I would like to figure this out before I haul out.

<<And your problem didn't have to have anything to do with air in the fuel line. It could have resulted from the valve simply allowing too much fuel to bypass the injector pump. Air in the lines would indicated a separate, additional problem.>>
If the valve sole purpose is to bypass the fuel to the return line and somehow bleeding it at the same time, then that makes sense. If it was partially open, I was able to run but not under load as I would not have enough fuel. Yes, I agree, I mostlikely have a air coming into the lines somewhere. Doesn't sound like a alot but some. I have been thinking of that for a while and my last fuel filter change did not go well, as I slightly crushed the Racor filter because my filter wrench was at home so I made a make-shift filter wrench.
Could this valve be replaced with a bleeder bolt?

Regarding a 'bleeder bolt', the little valve present on the Universal is there to allow diesel fuel to flow back to the tank from the whole supply piping system without having fuel spill in the engine compartment.
I have watched a mechanic bleed the injectors, one at a time. Even with a rag near there is some spillage that's difficult to clean completely.

The oil attracts dirt/dust and this coats the engine parts over time.
Since most mechanics are looking for a quick way to bleed out fuel, at the final point that it's possible, and also most were trained on vehicles where a bit of leakage goes on the ground or at least a catch pad underneath, there was less worry about the escaped fuel. (that's an IMO thought)

This reminds of some knowledge gained from a mechanic of 50 years experience about the whole Return Line that all boats have. The manual for our new Betamarine calls this the 'leak off' line. This little bit of diesel that does not go thru the injection pump was always just allowed to drip... drip... on the ground by diesel engines in those big old Catapillers back in the 50's and 60's. Things changed as the builders developed an environmental conscience in the 70's, and this became something that could be marketed.
(my uneducated guess is that this little amount of diesel was always caught in a bucket or some such on boats in Ye Olden Days. ) ??

 

[patrscoe]

So it is basically a by-pass valve, allowing air to be vented out the valve's knob some how and fuel that would normally come out into a bowl while bleeding the air from the lines is now being diverted back to the tank. So I was not getting air back into my fuel system as I thought with the valve being partially-open but I was starving the engine from fuel when under load. Got it. Sounds like that was the source of my issue. I must of had the knob turn just far enough out so it ran fine but under load, it was not getting enough fuel. Also confirms that I may have a minor air leak in my fuel lines or filter that I need to find this winter.
Thanks.

 

[Christian Williams]

Tragically--and I mean it--the famous Service Department Vic's video on bleeding Kubota diesel tractors has been withdrawn from the public. There is mourning in Tractorvilles everywhere.

But here's how he (used to) recommend doing it: loosen one fuel injector just a bit and run the engine. Some fuel will come out. Tighten the injector as the engine runs. Do the same for each injector in turn. "That's how we do it here in the service department."

Vic was a star in overalls. I don't know what happened, but we must go on.

Vic also said nobody uses the compression lever in cold weather, although that's what it's for. Open the compression lever, the engine turns over more easily and faster. When the engine starts, close the compression lever. On a tractor there's a wire control handy for the operator. We don;t have a wire, and open the lever direct by hand.

 

[patrscoe]

Conclusion:
After replacing the glow plugs, tighten the fuel lines, removed and reinstalled the filters, check for any leaks or cracks in the Racor bracket, and countless hours of removal, clean, removed hose clamps / replaced some which I thought they were leaking, removal of the air bleeding valve / cleaned it, air bleeding and starting the engine, it still performed the same. Started up just fine but only when my air bleeder knob was turned open by about 1 1/2 turns, more than that, it stalled and less than that, it stalled.
Until... I was bleeding the air out for the 4th time and my arm rubbed up against the preformed 5/16" fuel line that is about 6", goes from the fuel filter to the air bleeding valve, and when my arm slightly hit the line, a spray of fuel came out and sprayed all over. The preform hose was painted with the engine so you cannot see the crack in the line, even when I removed it - impossible to see it. The hose became very rigid and developed a hairline crack, sucking air into it.... which probably was my problem this summer when I thought my fuel filters were clogged and I did a complete replacement and fuel tank cleaning.
I purchased a 6" long 5/16" fuel line, replaced it, bled the fuel system, etc.... 5 min later after the engine got all the air out, engine sounded better and a little smoother and ran well under load.
Well, although it was frustrating that I could not figure it out sooner, glad I found the problem.

.... Anyone know where you can get the preform fuel line? You have to make a aggressive bend in the line and I can see the line somewhat collapse because of this. It will be fine for some time but I can it being an issue at some point. I looked through the internet and could not find the part.

 

[Loren Beach]

Conclusion:
After replacing the glow plugs, tighten the fuel lines, removed and reinstalled the filters, check for any leaks or cracks in the Racor bracket, and countless hours of removal, clean, removed hose clamps / replaced some which I thought they were leaking, removal of the air bleeding valve / cleaned it, air bleeding and starting the engine, it still performed the same. Started up just fine but only when my air bleeder knob was turned open by about 1 1/2 turns, more than that, it stalled and less than that, it stalled.
Until... I was bleeding the air out for the 4th time and my arm rubbed up against the preformed 5/16" fuel line that is about 6", goes from the fuel filter to the air bleeding valve, and when my arm slightly hit the line, a spray of fuel came out and sprayed all over. The preform hose was painted with the engine so you cannot see the crack in the line, even when I removed it - impossible to see it. The hose became very rigid and developed a hairline crack, sucking air into it.... which probably was my problem this summer when I thought my fuel filters were clogged and I did a complete replacement and fuel tank cleaning.
I purchased a 6" long 5/16" fuel line, replaced it, bled the fuel system, etc.... 5 min later after the engine got all the air out, engine sounded better and a little smoother and ran well under load.
Well, although it was frustrating that I could not figure it out sooner, glad I found the problem.

.... Anyone know where you can get the preform fuel line? You have to make a aggressive bend in the line and I can see the line somewhat collapse because of this. It will be fine for some time but I can it being an issue at some point. I looked through the internet and could not find the part.

Sure Glad you found the problem. Considering the other places in the fuel system where "entropy" can induce a leak, it's also great that you have upgraded the rest of the system.
About your "preform" line, I confess to puzzlement. I became rather familiar with all of these parts of my M25XP Universal for over two decades, and for some reason cannot imagine which hose this might be. I recall there being rigid fuel lines, under high pressure, from the injection pump to each injector. Up to the pump intake, tho, I recall all of the hose being flexible enough that nothing kinked; some did take some close-radius turns.
And yup, all of those OEM hoses were painted Universal bronze on our engine, as well.

When I replaced almost all of those hoses, I was using USCG-rated fuel hose with obvious layers of fabric in the synthetic rubber material. That hose will take a pretty sharp change in direction.

Thanks Again for the update. This is a real service to other owners.

Added Thought: remember that any flexible line that has to be forced into a "sharp" 90 degree turn, can, IF there is room, be lengthened enough to form a small circle and then be sent in the new direction. You end up with a 'curly cue' standing out a bit, but this solves the problem of possible kinks.

 

[patrscoe]

Loren: it is the rubber fuel line that is only 6" long. It goes from the fuel filter at the engine to the knob air bleeder valve which is before the fuel injectors. Mine was rigid because it was old but it is preform, as it heads out of the filter then needs to curve up and under the manifold.
See attached. Red arrow and yellow highlight is the fuel line.

 

[Kenneth K]

That may not be pre-formed hose, it could just be old and stiff. It is a tight bend from the engine mounted filter to the injector pump. The original hose on mine was a bit collapsed due to the bend:



The real fix for me was to remove the fuel filter bracket from the engine and mount it somewhere where it's more convenient to change the filter. Then I was able to install a new hose without much bend at all. After all you went through to find the leak, you're probably not looking for another project, but if you move the filter, you'll thank yourself the next time you go to change it:

 

[patrscoe]

Kenneth: that's a good idea.

 

[Loren Beach]

Good Ideas!
Further -- a clean engine is much much easier to maintain and to spot and fix any problems.

I know of an early 80's 33RH with a remote oil filter mount (aftermarket). I never thought of relocating that engine filter on our M25XP. Then there are owners that have remote-located their heat exchanger. That filter was pretty easy to get to in our particular engine space, luckily.

Perhaps useful to remember that there is no special design magic involved in the factory engine layout -- idea was (and still is for all builders) to have an engine package that drops into the boat with minimal external parts to attach and run wires & hoses to. No matter what brand, the builder wants to drop it in and hook it up with minimal labor cost.

(The ultimate result of this thinking is the number of sail drives you see nowadays in new boats -- terrible maintenance $$ down the road starting at 7 to 10 years, but the owners are being conditioned to view this expense as 'normal yachting expense'.
The OEM builders love the reduced labor cost to build out, and the younger buyers seldom know what questions to even ask.

 

[Tom Metzger]

Bend a piece of copper tubing and use the rubber hose to make the connections.

 

[1911tex]

Bend a piece of copper tubing and use the rubber hose to make the connections.

Now how great an idea is that!!!

 

[ToddSullivan]

ANY ADVICE AND COMMENTS WELCOME!!!!!!
Sully here - New Owner MaineSail - a 1985 E35-3. Currently in New Buffalo MI. I crossed Lake MI on May 5th from Racine WI to New Buffalo. 11 hour Motor sail - 85 miles. After trouble starting my engine on a cold 40 degree morning, we finally got going after bleeding the fuel line at the injector pump. The engine was solid all day on the crossing but definitely was dripping diesel. I am about to attempt a repair on my M25. SCARY but necessary as it is hard to find anyone to do this work. I have ordered the correct Bleed Valve, screw and gaskets. I am having difficulty starting my engine and MUST bleed the fuel line everytime in order to get it started. I believe that the Bleed Valve gaskets are old and compressed - allowing air to enter the line after the engine is turned off and sits. The engine runs great once it is up and going but is dripping diesel at the fuel inlet joint and bleed screw. After reading previous comments here- I will replace the 6" fuel line that drops down to to the filter from this point - COPPER TUBING IS THE REC?. Gold Oainted Fuel Line looks originaland could be cracked underneath. Fingers crossed that this will allow my engine to fire up right away and I will stop dripping diesel!!!! ENGINE PIC BELOW IS From the EY.O post.

 

[Loren Beach]

Sully here - New Owner MaineSail - a 1985 E35-3.

Sounds like you have done your research well and are getting into maintenance stuff that might well be overdue.
When I replaced the factory fuel system hoses and copper tubing in about 2008, that stuff was over due.... the old copper tubing looked like someone had beat it with a hammer when it was installed in 1988.
I never did have any air ("vacuum") leaks in the little valve or fitting parts, but rather had one in the OEM smaller three-section Racor filter. I replaced that one with a similar newer model.
When we put in the new Beta, in 2018, we installed a new Racor 500, which greatly reduces potential places for leaks to occur.

Good luck and keep the comments coming.

 

[Christian Williams]

Sure the fuel bleed will drip--that's how you know the air is out of the line. It's probably just old--no problem, and replacement is the answer .

But there are more common ways for air to enter the system, all of them well known here, so if the new part doesn't solve it something else will.

 

[Dave G.]

Welcome Sully ! I'm just 100 miles up the coast from you on beautiful but still kinda cold Lake Michigan.