Air lock?

[storyinframes]

I have a Perkins 4108. Today I changed the oil and all the filters. After that I started the engine. It did fire and started but died within 5 seconds.

Is there an air lock in my fuel line?
Can someone advise me how to bleed the line and which line?

What other problem could be there?

Thanks

Prashantt
Green turtle cays


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[Cheechako]

I always filled the engine fuel filter housing whenever possible when changing filters. For bleeding I never had to bleed anywhere but at each injector starting with the first in line.

[skipmac]

When you say "all the filters" I assume that means fuel filters as well as oil filters. If you did change the fuel filter then the symptom you describes is almost certainly air in the fuel lines.

Most boats have two fuel filters. First thing, as Cheechako says, when you change the fuel filter fill the housing with diesel before trying to start the engine.

Depending your engine and the location of the fuel tank this might be enough. Since you tried to start it and it died you probably sucked more air into the lines and may have to bleed the fuel lines. Are you familiar with this process?

[sparrowhawk1]

If your exhaust is raw water cooled as most are be careful not to turn the engine over too long without starting, the exaust will fill with water. Shut off the raw water intake, make sure your filters are full of fuel, crack the fuel injectors, turn the engine over for no more than 15 seconds then let rest for a few minutes so you don't overheat your starter.

[NoTies]

Filling the engine mounted fuel filter from a jug instead of using the priming or lift pump can lead to dirt entering the injector pump.

[cheoah]

Good point, no ties. Cool to fill the racor (primary) with a jug but anything going into engine mounted secondary needs to be filtered. Baja is fine.


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[Cheechako]

Whatever you put in the filter should be clean. If you don't know then "yer doin it wrong"! :>)

[NoTies]

I see plenty of examples of damage to common rail fuel systems here from people following the practice.

[DougR]

Here is the 4-108 bleed drill:
1. Fill the Racor or equiv. with fuel.
2. Loosen the following:
- Bleed bolt on the top of the on- engine fine filter, or the return line banjo bolt if no bleed bolt.
- governor bleed bolt on the injection pump body ( directly below the throttle actuator arm/ cable attachment)
- fuel return line attachment nut between the high pressure lines at the aft end ( high pressure end) of the injection pump.

3. Using the hand primer pump ( lift pump) lever, pump fuel until air free fuel comes out of the bleed bolt on the fine filter, then close the bleed bolt or tighten the banjo bolt. If no fuel comes out, rotate the crankshaft one turn to get the lift pump off its drive cam lobe.
4. Move to the injection pump and continue pumping with the lift pump until air free fuel comes out of the bleed fitting on the inj. Pump body. Tighten the bleed fitting.
5. Continue pumping with the lift pump until air free fuel comes out of the return line attachment at the high pressure end of the inj. Pump, then tighten up that nut as well.
6. Give the lift pump another 2 dozen strokes just for good measure.
7. Loosen the high pressure injection lines at the injectors, put the throttle lever to full throttle, make sure the stop cable is not pulled, and crank the engine over with the starter motor. Do this for 8 or 10 seconds at a time until fuel spurts from the high pressure lines at the injectors. Stop cranking and tighten the high pressure line nuts at the injectors. The engine is now ready to start. Leaving the throttle setting at full throttle, crank the engine and it should start. If not, repeat all of the above!

If it still won't start, and you flatten your batteries, you can follow the advice in the Perkins Operator manual and " look to your flare locker".

DougR

[berniekatchor]

perkins engines one and only one way to bleed. Squirt wd40 into air intake and start engine on it keep squirting with throttle full open to run engine on propane in wd40 until engine screams
rush to slow it down never fails often perkins engines are stubborn to bleed and this method is used by many professionals

[GILow]

Originally Posted by berniekatchor

perkins engines one and only one way to bleed. Squirt wd40 into air intake and start engine on it keep squirting with throttle full open to run engine on propane in wd40 until engine screams
rush to slow it down never fails often perkins engines are stubborn to bleed and this method is used by many professionals

I think I remember reading that this could crack the rings? Or was that some other kind of aerosol? The reasoning was that the aerosol explodes rather than burns. I thought at the time it was sound logic from someone who knew their stuff but I can't find the thread now to confirm.

Matt


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[berniekatchor]

that was ether based sprays propane is more gentle and many trucks and cars run on it

[GILow]

Originally Posted by berniekatchor

that was ether based sprays propane is more gentle and many trucks and cars run on it

Ah, good to know, thank you.

Matt

[storyinframes]

Everyone thank you very much for the reply!
and I am sorry for the absence here.
I will explain you what was the problem apart from the air lock.
after bleeding the fuel lines, the problem still persisted.
I remembered a Cuban Engineer in Rybovich categorically warning me NOT to put a gasket in the secondary fuel filter. I had simply forgotten about it after a month and i did put the round gasket on the circumference of the filter. This blocked the fuel supply from the sides.
When I removed the gasket, bled the lines again, the engine started. :-)

[GILow]

Well great to have it sorted and good luck to make the mistake when safely at dock, not in the middle of an ocean somewhere.


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