Change filter and bleed. Scared!

[Jon Hacking]

Joe, our Yanmar 4JH2 (c1995) engines have a bolt on the top of our on-engine fuel filters that we can use as an air bleed. We fill the filter with clean fuel, screw it on, then loosen that bolt (to let any air out) & pump the manual lever on our mechanical fuel pump (on the side of the engine) until fuel starts coming out that loosened bolt, indicating all the air is out (I suppose we could remove that bolt & pour fuel in until it's full, but my way's simpler). Then we tighten the bolt & restart the engine. Never had this fail (in 5,000 hours of changing the fuel filters for 2 engines).

But if you get air into the injector lines (usually from removing the injectors or the head to have them worked on), then they probably will have to be bled. Just loosen the nuts on the tops of the injectors & crank the engine until they're all squirting fuel out. Stop cranking, tighten the nuts back up, & away you go! Once you get into it, it's pretty simple.

Good luck!

[MerMike]

Originally Posted by joeniver

It took 40 or more pumps and finally bubbles and fuel started to come out. Just surprised it took so many pumps.

Yep it takes a lot of pumping on my 3GM30F. I've had fuel delivery issues (finally found a cracked banjo fitting on the lift pump intake side) so I've had lots of practice. Hopefully back to routine maintenance now.

[sailingharry]

We have a 1998 4JH2E Yanmar, new to us. I intentionally allowed it to run out of fuel (run on Fwd tank when safe, run on Aft when needed) partly so I could experience an out-of-fuel incident on my terms (I also needed that tank empty for other reasons). I have an inline Facet electric pump. I switched to the aft tank, turned on the electric pump, listened for the pump to change tones, ran another 30 seconds, and started the engine. Super easy. No tools, no fuss.


If you don't have an electric pump in line, or at least an outboard bulb, do it!


Harry

[EmeraldCoastSailor]

Originally Posted by MerMike

Yep it takes a lot of pumping on my 3GM30F. I've had fuel delivery issues (finally found a cracked banjo fitting on the lift pump intake side) so I've had lots of practice. Hopefully back to routine maintenance now.

At about 900 hours - 9 years the washers around my fuel related banjo fittings needed replacing. It wasn't something I was paying attention (like the banjo fitting related to coolant routed to hot water heater) so I had a bit of leakage.

[sudarkoff]

I haven't seen anybody mention this—but I'll also admit that I haven't read every single response—run the engine for 30 min after replacing the filter. If the engine does not stall, you can have a pretty high level of confidence that it won't quit on you because of the air bubbles when you come out for a sail next time.

[MerMike]

Originally Posted by sudarkoff

I haven't seen anybody mention this—but I'll also admit that I haven't read every single response—run the engine for 30 min after replacing the filter. If the engine does not stall, you can have a pretty high level of confidence that it won't quit on you because of the air bubbles when you come out for a sail next time.

X2. Under load at the dock if possible.

[parkstone bay]

I've not seen these points mentioned. 1. Do remember to turn off the fuel before playing with the filters. (or you can land up with a bilge full of diesel very quickly). 2. Do have plenty of rags/absorbent materials to hand. (You WILL leak fuel!) 3.Wear protective gloves. 4. Don't forget to turn the fuel on when you have finished (or you get 100 metres from the berth, and the engine stops). 5. RTFM, and it's in fact very easy. Good luck on the job!

[joeniver]

Everything went very smoothly! Thanks for the post.
Why under load? If the only connections that were touched are the fuel filter cup and 1 bleed screw, how can more torque show a different outcome?

[sailingharry]

Under load increases fuel flow. So in 5 minutes at load you get the flow of 15 minutes at idle. Probably overkill -- as you point out, it's not like you did an engine rebuild.

[Velella99]

At least you are striving to gain independence and self-reliance. It might surprise you the number of people who claim to be coastal Cruisers but do not know how to change filters and bleed their fuel system to restart their diesel. One told me "that's a mechanic's job".

[Pizzazz]

You are too cautious. Unscrew filter housing, take out the old filter, put in the new filter, screw in the housing.

1. If you feel like it, you may bleed at the filter screw, it is not necessary

2. If you feel like it, you lift the decompression levers and turn the engine with the starter for about a minute (4-5x 15 sec with breaks). It airs everything out. It is not necessary.

Start as normal. The whole procedure takes 2.5 min.

SV Pizzazz

[boatpoker]

Originally Posted by Velella99

At least you are striving to gain independence and self-reliance. It might surprise you the number of people who claim to be coastal Cruisers but do not know how to change filters and bleed their fuel system to restart their diesel. One told me "that's a mechanic's job".

I agree.
I deal with a lot of new boaters and tell them they should never leave the dock until they know how to set an anchor, bleed their engine and change an impeller. These two gremlins always seem to raise their heads as you exit the breakwall.

[Tanqueray]

I worried about changing filters on my 2GM20, but finally decided I needed to tackle it.

I shut off the fuel valve and pulled the Groco primary first, filled the cup with clean fuel and closed it up. Moved to the filter on the engine, replaced filter and filled cup.

Fired up engine, made sure I s was tied up tight and put her in gear for 15 minutes or so at the dock. Engine never stumbled,

Way easier than I thought it would be.


Greg

[MerMike]

Originally Posted by sailingharry

Probably overkill -- as you point out, it's not like you did an engine rebuild.

True it is overkill, but I have had several exciting moments as I learned about the fuel system and searched for an air leak. Like having the engine sputter and die just as we crossed in front of the ferry dock. After we drifted out of the way, we dropped the anchor for the first time while I went below and sorted it out. Or when we were motoring, mastless, back to the marina and the engine died again. Or another time just outside the fairway to the slip...But that's all behind me now . Still, whenever I mess with the fuel system now I test it, at the dock, under load, for 15 minutes or so just to be sure. I'm sure I'll slack off as the memories fade, but that leak caused some serious cussing and sanity questioning.