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Good Fortune 11-20-2012 07:11 PM

Troubles with Bukh
We have a raw water cooled Bukh DV20 on our Fortune 30 and we are having some troubles. The engine does not run for more than 10 or 15 minutes at a time. After that time, the engine sputters and eventually chokes out. It will start immediately afterwards, but the running time is diminished with each start.
However, if we haven't used the engine for a month or so, it can run for up to 45 minutes...but then the problems starts all over again.
One mechanic warned that the cylinder head could be warped, but we're skeptical. If it was a heating issue, wouldn't the engine have trouble starting again after it cuts out?
We've also been told that it is likely a fuel suction issue. We've disassembled both the lift-pump and fuel pump, looking for some kind of blockage, but found the innards to be astoundingly clean. And now, we're wondering what to look at next.
Any suggestions would be infinitely appreciated.

klem 11-20-2012 07:14 PM

Re: Troubles with Bukh
Have you tried running with the filler cap removed for your fuel tank? If you vent is plugged, you will get symptoms like you describe.

Two pieces of data that would be really helpful are coolant temp (I assume that you have a gauge?) and fuel pressure (you probably don't have a gauge but they are not very hard to temporarily put one on).

Good Fortune 11-20-2012 07:19 PM

Re: Troubles with Bukh
Unfortunately, we don't have a temperature gauge...only a tachometer(this leaves us pathetically ignorant, I know). But the plugged vent sounds plausible...thanks

Good Fortune 12-30-2012 12:12 PM

Re: Troubles with Bukh
We've tried removing the filler caps and it still stalls out. But we've found a pocket of air in the fuel line just below the Racor water-seperator. The fuel line is not fully primed, even when we manually prime the lift pump. The hose is brand new and we can't find any cracks in it. Does anyone have any suggestions as to where we might be able to chase down this unwanted air intrusion?

Faster 12-30-2012 02:55 PM

Re: Troubles with Bukh
Any and all connections and fittings between the tank and filter are obviously suspect.. another sneaky one I've seen is a perforated pickup tube inside the tank. Sometimes installing an outboard-style priming bulb close to the tank will allow you to pressurize your system to check for leaks. Use good clamps, though, not the generic 'snap on' clips that come with these things. We had one but I suspect it was a source of leaks itself so I changed to a primer pump equipped Racor.

deniseO30 12-30-2012 03:56 PM

Re: Troubles with Bukh
check the pick up line strainer. it's in the tank. most people scoff about it. It causes exactly the symptoms you described.

Rockter 01-01-2013 04:58 PM

Re: Troubles with Bukh
Certainly sounds like fuel starvation.

arf145 01-02-2013 09:56 AM

Re: Troubles with Bukh
I'm betting it's what Denise says--a pickup strainer.

Brett01 01-08-2013 11:43 PM

Re: Troubles with Bukh
I had the same symptoms with my Bukh DV20 here in Australia. It would slowly starve after maybe 20 minutes. I also had trouble priming it using the manual lever on the vertical lift pump, the lever felt "dead" and it certainly didn't pull any fuel through.

Checked filters etc. etc. all clean.
It ended up being "bug" (microbe growth) in the diesel tank which was a black sludge consistency. It would block the pick up line (thin copper tube) and never even made it into the first fuel/water separator. The motor stopped, suction ceased and bug would drop away allowing another 15 to 20 minutes of running before it stopped again.

It took months to figure this out and was only after we took the top off the tank (built in fibreglass) and simply scooped handfuls of this black sludge out.

Hope this may help.

John Hill 07-14-2013 02:09 PM

Re: Troubles with Bukh
We had a similar problem after cleaning a tank with an absorbant pad. Some of the fibers left behind collected in the valve at the tank and would partialy block the line causing fuel starvation and air intrusion through any fittings between the tank valve and the pump as a result of the lift pump suction.

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