why did my engine die?

[rogerroger]

had first engine failure on Sunday. It ran beautifully on the mooring for 15 minutes (no smoke; cooling water circulating) then chugged away quite happily through the harbour for another 20 mins before the revs suddenly dropped and it stopped.

went through basic check list -

Fuel in tank - yes

Tank turned on - yes.

Check primary filter - there's not one in there (engine serviced by Marine Power at Bursledon last year who never bothered to put one in).

on openning the drain screw there was an air sound but we don't know whether it was inhaling or exhaling.

Check secondary filter - hoping / expecting it to be filthy to explain failure but despite over 130 hours of running without a primary filter it was spottless (it looks new).

Put a new O ring on secondary filter; bought a primary filter and put back together.

Bled system but final bleed screw broke and couldn't be replaced on a Sunday / BH Monday.

So - will replace bleed screw and hope it works.

It doesn't seem like it was dirty fuel so air must have got in - I'm reluctant to fix the symptoms without tracing the problem as I dont' want it to die in a worse place.

are the washers around the banjo joints compression washers that need to be replaced?


Your thoughts will be most appreciated

Roger Holden
www.first-magnitude.co.uk

 

[pvb]

Just a thought...

I had similarly bewildering engine failure a few years ago. After hours and hours of checking everything, I finally found that the fuel pick-up pipe in the tank had a fine metal gauze filter on it, and that this was completely blocked with crud.

Also, it's a good idea to replace the copper washers on banjo fittings if you're disturbing the fitting for any reason.

Finally, you should also check the tank vent, to make sure that running the engine isn't causing a vacuum in the tank.

Good luck!

 

[rogerroger]

thanks

That's a great help - I'm hoping to get a list of all these little areas to check so that's a great start.

Regarding checking the tank vent - we did take the breather pipe off the secondary filter and blew through it - is that sufficient ?


Roger Holden
www.first-magnitude.co.uk

 

[ParaHandy]

Re: thanks

Hopefully, with all the work you've done this winter, problem is air leak from "disturbed" connection. Check for disturbed joints in the fuel line - presume as Burseldon lot did service - it's Yanmar 2gm/3gm? Is fuel tank level above/below fuel pump and is engine pump only pump?

Check fuel return is air-tight, not restricted. The return should run from the banjo on top of the injectors back to the tank. Blow through it at injector end - ugh! - and you should hear it bubbling in the fuel tank.

Replace all copper washers on joints released.

Presume fuel pump OK (no sudden increase in oil level which happens if diaphgram is pin-holed) since you got her bled except for last bleed screw?

Be careful with another filter in the line. You will be sucking thro' this (coarse) one and pushing thro' the fine one? Water separator might be more use than such a primary filter. I'm assuming you call the coarse filter the primary filter? It could, indeed, be water that stopped her.

Good luck and what a b*gger.

 

[pvb]

Tank vent...

There should be some vent system which allows fresh outside air to flow into the tank as the diesel is used up. If this is blocked, running the engine will gradually build up a vacuum in the tank which could stop the engine.

 

[Trevor_swfyc]

Roger,

Sounds like you have an air leak on the pump suction side of the system. Eventually enough air gets in to stop the engine. A good test to eliminate the tank breather is to run the engine with the diesel filler loosened, if it runs ok with this loose and stops after it is screwed tight then its a blocked breather. Condensation and diesel may have produced bugs which have blocked it over the winter layup. Does this pipe have a loop which may trap diesel? if it does remove it, buy a new pipe and run it so that it runs continually up hill to the breather. Also have you put more diesel in the tank since launch and washed down into the tank same rubbish from the filler pipe which again can be prone to bugs developing during the winter layup.
All the best, good luck
Trevor

 

[summerwind]

I vote for the blocked inlet pipe from the tank. Why? Because of the sound of air rushing through the vent when you opened it. If you had an air leak on the suction side of the lift pump, air would be in the system already. (You are hardly likely to get air pressure on the suction side of the lift pump.)

Secondly, you had no fuel on the suction side of the lift pump when you opened the drain.

Thirdly, when the engine was ticking over on the mooring, enough fuel was getting through the blockage. Once you increased the load, more fuel and muck sucked through partial blockage to complete the blockage. Engine used fuel in pipeline, then stopped because of starvation. Delay with engine stopped allowed blockage to sink back down feed pipe inside tank and loosen up. You could therefore bleed system and run engine again.

Finally, I suffered from exactly the same symptoms and muck in the fuel feed pipe inside the tank was the cause.

Short term cure - blow back through fuel feed pipe from primary filter to tank. Long term answer - thorough cleaning of tank.

Good luck.

 

[brian_neale]

I agree - sounds like blocked tank breather. However, my 1GM used to suffer from similar stoppages, eventually tracked down to air getting into the feed pipe somewhere. Fix was regular bleeding (every 2-4 weeks), but never did find the leak.