Bad Diesel from the pump or do you have a deck leak?

[Fuss]

I just wondered how often bad diesel from the pump is the problem or is this a deck leak on the boat.
For my diesel filler cap there is an O - ring that wears out.
Just under the deck, there is a valve so that no diesel or water can get into the tank without this valve being manually opened.
This also allows me to see if the filler cap is leaking...it never seems to even when sometimes the O-ring was slightly perished.


following on from this ... What are the symptoms of bad diesel. Normally the comment is that "it was a bit rough weather and the engine stopped". As if this was a complete surprise.



Surely there were some warning signs before...assuming of course you have owned the boat for a while.


I guess the obvious is that at every filter change, it is looking not particularly healthy. So the warning signs are there.


My filter bowl is having more junk in it, but not much... I only drain it out once a year and I only look at the filter, I don't change it unless I don't like the look of it.



Anyone care to give an experience of the warning signs before the dreaded engine stop?

[Lepke]

Usually what happens is the filter flow is reduced and eventually shuts off the fuel flow. Since some contaminated fuel doesn't burn well, you can have a loss of power, the engine no longer reaches the WOT it did in the past. Sometimes the engine will increase rpms before quitting.

The best insurance against fuel problems is using an additive every fueling. A good additive will kill organisms, help a Racor type filter remove water from the fuel, add lubricity, stabilize the fuel for a year, and increase cetane rating. If your fuel sits for long periods, months or years, you need to find a way to circulate it thru your filters at the dock a few hours a month.

The next best insurance is buy fuel from a dock where commercial boats buy. Many marinas sell very little fuel over the winter. Most diesel pumps have a spin on filter mounted where you can see it. Better marinas put a date on it. The best ones actually change the filter. A friend has his boat at a marina. When I visit I check out the pump. Their diesel pump has a filter dated 12 years ago. Nobody I know buys fuel there.

[clongcor59]

After 2 years, I always learn something new about diesel engines. This may be useful for some.

I silicone grease the cap o-rings to prevent wear and help keep water from leaking past.

My Yanmar (1995 4JH2E) owner's information noted that Yanmar recommends no fuel additive. They recommend buying good diesel fuel.

Ha! Seems like ridiculous advice to me. Who knowingly buys bad diesel fuel?

HOWEVER! I checked with a marine diesel shop owner whom I trust. He called B.S. and told me there are many reasons to use a good diesel fuel additive. So that is what I do.

Fingers crossed I don't get surprised but 10 months after we left the docks and began cruising full time...no diesel fuel issues so far.

[gonesail]

if your fuel has a strong solvent or varnish odor it may be going south. put some in a clear container and see if anything settles on the bottom. your filter will be lined with red gooey junk more than usual.

[Tillikum]

Originally Posted by Fuss

I just wondered how often bad diesel from the pump is the problem or is this a deck leak on the boat.
For my diesel filler cap there is an O - ring that wears out.
Just under the deck, there is a valve so that no diesel or water can get into the tank without this valve being manually opened.
This also allows me to see if the filler cap is leaking...it never seems to even when sometimes the O-ring was slightly perished.

following on from this ... What are the symptoms of bad diesel. Normally the comment is that "it was a bit rough weather and the engine stopped". As if this was a complete surprise.

Surely there were some warning signs before...assuming of course you have owned the boat for a while.

I guess the obvious is that at every filter change, it is looking not particularly healthy. So the warning signs are there.

My filter bowl is having more junk in it, but not much... I only drain it out once a year and I only look at the filter, I don't change it unless I don't like the look of it.

Anyone care to give an experience of the warning signs before the dreaded engine stop?

How often are your tanks drained and flushed? Or, when were they last flushed?

How do you know the below-deck valve is 100% watertight?

If you want to test the valves you could play a hose over the topside valve, if you think that would duplicate to a useful extent how sea water might impact it, then immediately check the lower valve for traces of water ingress.

I have seen some extremely dirty diesel come out of pump nozzles once or twice when the pumps were probably drawing from a nearly empty tank, or perhaps one that had just been filled, but had not yet settled out the muck that was stirred up by the filling process. It's worth holding the nozzle where the stream of fuel can be seen at the beginning of every fuel up, and maybe at the end too.

Some people say dumping a few litres of isopropyl alcohol in a diesel tank can help "absorb" water. Might kill off some bacterial/fungal growths as well?

[stormalong]

Originally Posted by Tillikum

How often are your tanks drained and flushed? Or, when were they last flushed?

How do you know the below-deck valve is 100% watertight?

If you want to test the valves you could play a hose over the topside valve, if you think that would duplicate to a useful extent how sea water might impact it, then immediately check the lower valve for traces of water ingress.

I have seen some extremely dirty diesel come out of pump nozzles once or twice when the pumps were probably drawing from a nearly empty tank, or perhaps one that had just been filled, but had not yet settled out the muck that was stirred up by the filling process. It's worth holding the nozzle where the stream of fuel can be seen at the beginning of every fuel up, and maybe at the end too.

Some people say dumping a few litres of isopropyl alcohol in a diesel tank can help "absorb" water. Might kill off some bacterial/fungal growths as well?

I agree with clongcor59. Lubricate your O ring. I use teflon grease.

I would never do as Tillikum recommends. The risk of adding water to your tank is too high. If you want to know if your valve is leaking pour some diesel above the closed valve. Measure it, let it sit a while and measure again.

[skipperpete]

I’ve seen a lot of suspect or dirty diesel out of the pump or bunker barge, particularly in Indonesia, Thailand and Malaysia. Service station fuel is usually very clean but marina storage tanks are notoriously risky. In these 3 countries, the actual quality of the fuel is at odds with that of Australia and Europe, it seems to have more solvent type content than what I see in Singapore and Oz, it smells different too.
Sometimes you just KNOW that the fuel you’re getting is suspect, in Indonesia the delivery guys filter it through a layer of cotton T-shirt’s, and you can only hope they were 2 micron. In Phuket a guy in a big oily boat with plastic drums in it would come alongside and pump directly into your tanks.... no possibility of using the trusty Baha to sieve out whatever might be in that mysterious fuel.
The more sinister aspect of dirty fuel is damage to injectors and pumps from both emulsified water, high wax content or really fine dirt. The first sign of a looming problem is that the filters are dirty when you take em out at the service intervals..... next warning is when a filter actually affects the performance, bad idling, surging or un invited shutdown.....the first warning should be enough because unless you have 2 micron filtration up to the injector pump, the damage is already quietly in progress, often, as a previous post mentioned, corrosion or wear in the injector pump. I sent an injector pump that was problematic on a 400 hr engine back to Yanmar for warranty and they sent me photo’s of corrosion on the inside of the pump.... warranty declined, wet fuel. In a way, an engine that shuts down or fails to start from contaminated fuel is a good thing, but the nature of some injector pump designs is such that if a single plunger on an in-line injector pump seizes at the top of its stroke , that plunger holds the other 3,5 or 7 other plungers at that fuel rack setting and nothing other than oxygen starvation or complete fuel cutoff will stop er from going into an un governed overspeed. Early GM Detroit engine owners are usually familiar with this heart stopping event and have an air cutoff built into the engine intake for just this reason.
On the water thing, I’d heard that CAV filters are waterproof and a test established that, ....same test on aftermarket filters failed dismally... as it also did on new genuine racors

[Bowdrie]

Originally Posted by skipperpete

Early GM Detroit engine owners are usually familiar with this heart stopping event and have an air cutoff built into the engine intake for just this reason.

Well, all the 2-stroke DDs have individual injectors operated by the camshaft.
Probably the most common cause of a run-away is if a blower seal lets go.
Then they take right off and run on their own lubricating oil.
One wants to be able to trip the air-flap right now pronto without fumbling around.

[skipperpete]

Yes, you’re right about the individual unit injectors but ALL of em are connected to the same control tube and until the introduction of the spring loaded links, if one unit injector seized, all the other ones would be locked in the same rack position. 99.9% of detroit diesel 2 stroke runaways are due to a single seized injector.

[Stu Jackson]

For those with Racor 22 or 24 type housings:


Fuel Starvation and The Obscure Check Ball Valve
https://c34.org/bbs/index.php/topic,10681.0.html
and
https://forums.sailboatowners.com/th...l%20Starvation