Why does my diesel engine keep dying?

[High Pointer]

[QUOTE=High Pointer;3008876]I had the same problem,after days of starting over on my Yanmar with no luck.
I ended staring at the ceiling at 1am and I figured it out,and was right.
The air intake line from the tank to the transom was really plugged with spider stuff. Removed it and transom fitting.Replaced with new. End of problem.
The engine had been running for about 10min. and died as a vacum in the tank took place as air could not replace the use of fuel.[/QUOTE I agree with
SAILON 46 As it is a good way to check lack of air supply to tank.

[Northbound44]

A good article about the reason why you shouldn’t use copper nor zinc plating with diesel fuel:

https://www.bp.com/content/dam/bp-co...age-diesel.pdf

[basssears]

Originally Posted by Northbound44

A good article about the reason why you shouldn’t use copper nor zinc plating with diesel fuel:

https://www.bp.com/content/dam/bp-country/en_au/media/fuel-news/long-term-storage-diesel.pdf

Current issue of practical sailor has a test of different metals and how they interact over time submerged in diesel too.

[a64pilot]

I didn’t read the article but it’s not the metal. I participated in Certifying a turbine aircraft to burn bio fuel. The absolute best and most complete scientific information out there is written by John Deere.
But the zinc and copper changes the fuel if left in contact long enough. We even had to change the fuel tank bungs that we were using that was bronze, because the Engineering section thought it was brass, and had us custom machining them out of steel.
Brass contains zinc and also shouldn’t be used. Now a fitting here and there I feel certain is so small that it’s simply irrelevant, but an entire copper fuel line ought to be replaced.

[smallFry]

Since you have a Racor, you can tell by looking if it’s a blocked line or a vacuum leak. Watch the fuel in the bowl as it’s failing. If you see small vapor bubbles forming in the fuel and rising in the bowl, it’s a blocked line. Otherwise it’s a vacuum leak.

If it’s a vacuum leak, there are a couple of causes other posters have not mentioned. On the Racor the o-ring at the tee handle looks like it should install opposite the way it really should. I think it’s at the bottom of the tee handle/top of the cap, but double check this with the parts diagram.

The threads on everything in the lines are designed to deform as they tighten. Put PTFE sealant (Permaflex) on the threads, tighten until you feel resistance, back off slightly, and tighten a little more.

I had an issue where a diesel mechanic talked me into replacing the tee handle with a vacuum gage. This works great if you have the new Racor with the stainless tee handle. I had the old brass tee, and the threaded receptacle was 1/10” too shallow for the gage. After eight months searching for the vacuum leak I found out from Parker help desk about the gage incompatibility and filed 1/10” off the gage threads. Perfect afterwards.

[NYSail]

When I first bought my boat, I added the Racor 500 and also changed all the rubber fuel lines (they are all rubber from tank to engine). Before I attached the fuel line coming from the tank (which was connected) to the racor filter I blew into the hose..... I felt a little pressure then heard it clear itself (was not completely blocked). After hearing this I pulled the pickup tube cleaned it out (some have screens that need to be removed) and I vacuumed the bottom of my fuel tank and got 12 years of debris out.....

Again good luck

Greg

[Northbound44]

Originally Posted by a64pilot

I didn’t read the article but it’s not the metal. I participated in Certifying a turbine aircraft to burn bio fuel. The absolute best and most complete scientific information out there is written by John Deere.
But the zinc and copper changes the fuel if left in contact long enough. We even had to change the fuel tank bungs that we were using that was bronze, because the Engineering section thought it was brass, and had us custom machining them out of steel.
Brass contains zinc and also shouldn’t be used. Now a fitting here and there I feel certain is so small that it’s simply irrelevant, but an entire copper fuel line ought to be replaced.

Briefly:
STORAGE LIFE
Under normal storage conditions diesel fuel can be expected to stay in a useable condition for:
• 12 months or longer at an ambient of 20oC.
• 6-12 months at an ambient temperature higher than 30oC.

ACCELERATED AGEING
The ageing process can be accelerated by the following conditions:-
• Contact with zinc, copper or metal alloys containing them. These metals will quickly react with diesel fuel to form unstable compounds.
• The presence of water. Water allows the growth of fungus and bacteria, these produce natural by-products such as organic acids which make the fuel unstable.
• Exposure to high temperatures.
• Exposure to dust and dirt which contain trace elements that can destabilise the fuel,
such as copper and zinc.

[LifePart2]

Ok, here is the preliminary update.

The challenge was that we have copper pipe between the tank and the Racor, which makes it difficult to attach hoses to it to suck or blow to test connections.

Also, I discovered that there is a one-way valve in the racor, so blowing IN the outlet end does not produce pressue on the inlet side, again making it impossible to test the inlet side for leaks.

So I eventually took the Racor off and did a thorough cleaning. Which it certainly needed as I found it to be FULL or old algae. I know it is old as the fuel filters are always clean these days but a few years back we did have an algae problem.

Anyway, after cleaning it all out I could actually see through the bowl! And, lo and behold, as I sucked fuel through the filter I could see bubbles coming from the intake side.

I then disconnected the inlet pipe and put my thumb over the connection. When I sucked through the filter, no bubbles, and a nice suction on my thumb. So that, at least, told me that the Racor was not to blame, and the leak must be either in the connection of the pipe to the Racor, or further upstream towards the tank.

I then reconnected the pipe to the Racor and disconnected the fuel tank end of the pipe. Then I put my thumb over that end, and sucked through the Racor. This time we had bubbles again. So there must be a leak somewhere along the pipe, or the connection of the pipe to the Racor.

But I still have not positively found the leak despite lots of soapy water.

No matter, it seems the next step then is to replace the copper pipe and fittings with a rubber hose. That is cheap and not too difficult to do (once I get somewhere where they sell the stuff) and should solve the problem.

But one question remains. Is there a reason why there is a copper pipe (not rubber hose) between the tank and the Racor? The length is about 4m. Being on the suction side, is there going to be a problem with the hose collapsing and impeding fuel flow? I note, however, that between Racor and fuel pump there is rubber hose, albeit only about 2 feet long, and that seems to be fine.

Any more thoughts from anyone? Can I replace the copper pipe with rubber?

Thanks
Noel

[undercutter]

IMHO long exposed runs of unprotected rubber hose are an accident waiting to happen.


Just my opinion.

[undercutter]

Originally Posted by undercutter

IMHO long exposed runs of unprotected rubber hose are an accident waiting to happen.


Just my opinion.

Especially if they run through bulkeads or turn sharp corners.

[Northbound44]

Originally Posted by LifePart2

Ok, here is the preliminary update.



The challenge was that we have copper pipe between the tank and the Racor, which makes it difficult to attach hoses to it to suck or blow to test connections.



Also, I discovered that there is a one-way valve in the racor, so blowing IN the outlet end does not produce pressue on the inlet side, again making it impossible to test the inlet side for leaks.



So I eventually took the Racor off and did a thorough cleaning. Which it certainly needed as I found it to be FULL or old algae. I know it is old as the fuel filters are always clean these days but a few years back we did have an algae problem.



Anyway, after cleaning it all out I could actually see through the bowl! And, lo and behold, as I sucked fuel through the filter I could see bubbles coming from the intake side.



I then disconnected the inlet pipe and put my thumb over the connection. When I sucked through the filter, no bubbles, and a nice suction on my thumb. So that, at least, told me that the Racor was not to blame, and the leak must be either in the connection of the pipe to the Racor, or further upstream towards the tank.



I then reconnected the pipe to the Racor and disconnected the fuel tank end of the pipe. Then I put my thumb over that end, and sucked through the Racor. This time we had bubbles again. So there must be a leak somewhere along the pipe, or the connection of the pipe to the Racor.



But I still have not positively found the leak despite lots of soapy water.



No matter, it seems the next step then is to replace the copper pipe and fittings with a rubber hose. That is cheap and not too difficult to do (once I get somewhere where they sell the stuff) and should solve the problem.



But one question remains. Is there a reason why there is a copper pipe (not rubber hose) between the tank and the Racor? The length is about 4m. Being on the suction side, is there going to be a problem with the hose collapsing and impeding fuel flow? I note, however, that between Racor and fuel pump there is rubber hose, albeit only about 2 feet long, and that seems to be fine.



Any more thoughts from anyone? Can I replace the copper pipe with rubber?



Thanks

Noel

Most sailboat use rubber hoses approved for fuel. These hoses will not collapse and should be sized according to the engine specs.
I’ll also recommend to replace the existing old shutoff valves and sealing all threaded connectors with the appropriate sealing compound.
Finally, check the condition of the diaphragm and the strainer in the lift pump (low pressure) and also the condition of the banjo bolt ( purger) on the secondary fuel filter ( engine mount) , sometimes when over torqued it could create a crack.

[kenbo]

Many previous posters have said do not use copper for diesel fuel lines. I don't understand the reasoning of this. Most if not all home heating oil tanks are plumbed with copper tube to the burner with no ill effects.

The issue with copper or any metal, rigid tube is fatigue do to vibration. But from a stationary fuel tank to a stationary filter a well supported copper tube is in my opinion an excellent material. Just make sure that long flare connections are used.

Flexible hose from the primary to secondary filter is best due to vibration.

[LifePart2]

Thanks guys,

As soon as I can source some hose and fittings I will do those replacements and, hopefully, solve the mystery leak.

The copper pipe does have compression fittings on each end which, I believe, are often a source of problems. So switching to rubber would resolve that too.

Thanks so much for all the suggestions.

I will update when I know what the outcome is.

Noel

[NYSail]

My opinion use rubber... anywhere it has a chance of chafing protect it just like you do with all others hoses on the boat. Problem with a boat is that there is significant vibration and with that comes issues with using copper in my opinion.

There is a reason I have NEVER seen coppwr fuel lines used or heard a good mechanic recommend it when delivering fuel from tank to engine

Also I would remove and clean the check valve...


Good luck!.

[jamhass]

I would suspect (but have no real data) that an objection to the use of copper tubing would be it's tendency to work harden from repeated flexing or vibration.

Note that my Volvo uses copper coolant lines (both coolant and raw water) but these are all "firmly" secured to the engine, thus "theoretically" subject to less vibration.