replacing fuel filters

bcarli · **Joined:** 02 Oct 2011 20:39 **Posts:** 49

Hi
We have an external Racor fuel filter plus the main engine fuel filter. I wonder if anybody has had problems with air getting into the system when replacing these filters. I have found that bleeding our engine is a real pain compared to diesels we have had in the past...Any tricks regarding filter replacements...
thanks
p.s. This form has been a wealth of information to us...thank you all

jvoelxen · **Joined:** 21 Oct 2006 15:36 **Posts:** 268

I'm assuming you have a W50. It's not too bad if you take a few simple precautions. I 've installed an electric fuel pump that I use during the bleeding process which makes things a lot easier, but the following process will still apply if you use the manual lift pump for filling/bleeding the system.

The first step is to fully bleed the air from your Raycor filter after you've replaced the filter. I do this be keeping the Raycor cover slightly cracked open while I fill the filter assembly. When fuel starts to over flow, close and tighten the cover. Next move on to the engine mounted primary filter. Just a word of caution around installing the new filter. Make sure you get the rubber gaskets installed correctly. I'm not sure how I did it but one year I did it wrong, and the gasket totally blocked the fuel flow. Anyway, now bleed the system through the bleeder (banjo) bolt on top of the filter assembly until it appears that the fuel is air free. Take a deep breath, and bleed it again, and perhaps a third time. A couple of times, I was too cocky or impatient, didn't fully bleed the air out, and sent a slug of air into the fuel injection pump. You don't want to do that! Once there is air in the fuel injection pump, the bleeding process is long, painful and something to avoid when possible.

Good luck! It's not all that bad, but certainly err on the side of over bleeding.

Velera · **Joined:** 29 Dec 2006 09:38 **Posts:** 656

I do what Jim does with an electric pump in line, but before I had one, I was able to fill the Racor with a cup. Key thing I have to remember I to turn off the fuel at the tank before breaking the fuel system open. This keeps fuel from running back into the tank and minimizes the amount of air you have to replace when bleeding. Also, I found that it was faster to not mess with all the little bleed screws and just loosen an injector nut while cranking. Remember to shut off the raw water while cranking---I watched a neighbor bend a rod in a brand new Yanmar because he filled the engine during prolonged cranking on initial startup. In my T 37 it is a lot easier to bleed the system with the tank full.

My new Yanmar is self bleeding so all this is historical now that I think of it.

Ray

Velera · **Joined:** 29 Dec 2006 09:38 **Posts:** 656

Jim is right that you would not want to run the injector pump dry to fill a completely dry line and empty filters ---it needs fuel for lubrication. i recommend using my process (bleeding at the injectors) only if you turned off the fuel line pror to breaking the system and filled the filters some way.

Down2TheC · **Posted:** 02 Dec 2012 12:25

The W50 manual makes that point that for a filter change, if you're careful, you can get away with bleeding only at the banjo bolt on the secondary filter and possibly the entry point to the injection pump. There's no reason to let air into the injection pump for a filter change. Sometimes if a little gets in, we get away with bleed point D only as a short cut. That prevents that tiny bubble from making it into the injector lines. For filter changes we never get as far as the injector lines. She's always running by that point.

Now running the tank dry is a whole different matter.

puffcard · **Posted:** 02 Dec 2012 12:26

My Racor is located under the raw water pump. I shut the fuel off, open and replace the Racor filter (10 micron). Keep the top off, open fuel line and if I have more than a 1/4 full tank the Racor will fill up by a gravity feed. Let the filter completely fill and re-install the cover. I do the secondary filter, but use the hand pump to fill that one before tightening the top nut. Then crack the nut on the front injector and bleed the air out. The trick is to minimize the amount of air you get into the system. I also only replace the secondary filter every other time, that I do the Racor. Most of the time she fires right up, it does seem easier since I rebuilt the motor and the fuel pump.

Timshel · **Joined:** 29 Dec 2010 10:24 **Posts:** 191

I fitted a 'pump bulb' in the fuel line between the tank and the Racor filter, a few squeezes and the filter is full, I filled it with a cup before this,messy ! Bruce.

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replacing fuel filters

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