First racor change

Just finished my first filter change on racor 75/900 filters, 2 per engine.
1. As the attached pic shows there was lots of sediment in the bowls and the filters were black although the vacuum guages read zero up to 1500 rpm. Is this normal?
2. Watched you tubes on filling up to brim with fresh diesel to avoid air pockets but port side filters were tilted so when aft side of housing was filled to the brim, there was about a half inch gap on the opposite rim. Do I need to remove that air and if so how? At the secondary? How would that remove air at the top of the racor?
Many thanks for any help.

The sediment isn't uncommon but shoukd be cleaned out with the filter change, as you did.

The air does need to be "bled" out. This normally involves opening "vent" or "bleeder" screw on top of the secondary (on engine) fuel filter or injector pump and then pushing the fuel through until all of the air comes out that bleeder. You'll get nothing or fuel, then air, then foamy fuel, then pure fuel. Then you tighten Then you tighten bleeder and you are good to go. Obviously you want tohave rags around that screw to keep the mess under control.

The pumping can be done with the lever on the mechanicifter (on engine), if sonewuippee; an electric lifter or bleeder oumo, if sobewuioped; or by using the starter intermittently (so it doesn't overheat).

If using the starter and the engine starts, one normally just closes the bleeder and let's it take care of itself from there. If using a mechanical lifter it can take a /lot/ of pumps. Like hundreds. In your case you can keep an eye on the air level for a while. If after a couple hundred oumosbthe lever isn't at least firm and nothing is moving, youcoften want to tap the starter to reposition the engine w.r.t. pump to make sure you didn't roll snake eyes and end up in a position where it can't actually move fluid.

You really want to fill that filter as much as you can. Getting airbout is a pain. If your fueln level is higher or you've got a pusher bleeder pump between the tank and that filter, you canntry opening the fuel valve and loosening the top of that filter just until the fuel fills it and starts to overflow, and then tightening up and cleaning up.

No matter how much you fill things, some air will get in the lines, so some bleeding will be necessary. If it is just a little thenengine may sputter and smoke a bit for a few seconds while clearing it, but beyond that you've got to bleed it.

The details can vary, a lot, by engine. What engine are we talking about?

Thank you. Meant to specify cat 3126s.

That's a relatively easy one...check these out..

3116 and 3126 Truck Engines Fuel Priming Procedure | Caterpillar Engines Troubleshooting


Watch "How to Prime a Caterpillar 3126 Marine Diesel" on YouTube
https://youtu.be/9fCPGWXXSOg

I would adjust the racor's mounting so the top is level. I can't tell how it is mounted but either shims or redrilling you mounting points may save effort in the long run. Or host a party on your bow and run below and top off the racor with 15 people up there.

Great video. Interesting the cat operation manuel never mentions the 11/16 bleed nut to the right.
I like the party idea better than redrilling....when can you all make it?

Brief update. ...a dock neighbor said the racors on his prior boat were also out of level and he never had to bleed them. So I tried it andit worked! Ran engines about five minutes without any problems. However remounting the racors is on my fix it list.

Racors, what a pain and often messy and sometimes introduces air downstream. I threw mine away and installed a Tony Athens sequential setup. Close the fuel supply, spin off old filters, spin on new, open fuel supply, open bleeder on the filter head. In my case residual air bleeds out in a few seconds with no further bleeding required anywhere. Very little fuel gets through the bleeder.And, no need to prefill the filters before spinning on the new. Sure, I don't have the see-through bowl but an occasional bottom bleed tells me if I have a problem. The vaccum gauges tell me when to change filters. I don't miss those damn Racors one bit. Also, those spin-on filters you see are quite large and will last a lot longer than many Racors. Even if you have the 1000 model Racor you would need two to equal this setup.

Nice setup.

I have found that the Racors are very easy for me to change. I think a lot depends on the layout of your boat. I do have trouble getting my Racor filters to fill with diesel. To be honest, I really don’t worry about it. I always have some air at the top of the filter chamber. It is never a problem. The only reason I want them full is that provides more filter area to work.

I don’t like carrying a container of diesel on the boat to fill them. I have considered installing a bulb pump to handle that, but so far have been too lazy to do it.

If your fuel filters are below the fuel tank level then the filters will gravity fill if you leave the lids loose. Tighten when fuel runs out. No need to carry a separate tank of diesel to fill the filters. You might still get enough air to need to bleed. So if it’s a change based on hours, make sure you fill your tanks first.

High Wire said:

If your fuel filters are below the fuel tank level then the filters will gravity fill if you leave the lids loose. Tighten when fuel runs out. No need to carry a separate tank of diesel to fill the filters. You might still get enough air to need to bleed. So if it’s a change based on hours, make sure you fill your tanks first.

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I have tried that with not great success. Even when the fuel level in the tanks is higher than the filter housing , they don't want to fill all the way. Maybe I am just impatient?

dhays said:

I have tried that with not great success. Even when the fuel level in the tanks is higher than the filter housing , they don't want to fill all the way. Maybe I am just impatient?

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Interesting.

Are you vents clean?

Is there a pusher pump or anything like that between the tank and the filter?

Does a fuel lone between the tank and the filter rise above the tank level, such that it can't gravity drain and could have "lost its prime"?

dhays said:

I have tried that with not great success. Even when the fuel level in the tanks is higher than the filter housing , they don't want to fill all the way. Maybe I am just impatient?

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It always worked for me.

Comodave said:

It always worked for me.

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gkesden said:

Interesting.

Are you vents clean?

Is there a pusher pump or anything like that between the tank and the filter?

Does a fuel lone between the tank and the filter rise above the tank level, such that it can't gravity drain and could have "lost its prime"?

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Vents are clear. No pump between the tanks and the filters. No loop that rises higher either. I may need to just get the fuel in the tanks a couple inches higher.

It is one of those things that I do once a year and I’ve only owned the boat for 5. So limited number of trials so far.

dhays said:

I have tried that with not great success. Even when the fuel level in the tanks is higher than the filter housing , they don't want to fill all the way. Maybe I am just impatient?

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This applies to bottom tank fuel outlets only. If your fuel is pulled up and out through the top of the tank, or you have anti-siphon valves installed, sorry probably won’t work.
If the valve is open, the cap is loose to let air out, and no other obstruction then it has to seek its own level eventually.
Simple physics. The level in the filter will rise to the level of the fuel in the tank. If your secondary filters are also below the level of the fuel tank, they will fill too as long as the fuel line does not rise above fuel tank surface level.

Our last boat would siphon fill the Racors and it had the fuel fittings on the top of the tank not the bottom. It will still siphon up and out of the tank as long as there are no air leaks and the fuel hoses are full.

High Wire said:

This applies to bottom tank fuel outlets only.

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Well, if the tank has a top feed, it has a fuel line above the fuel level, which was one of the potential hazards mentioned. In this configuration, or any other with a fuel line above the fuel level, it should still siphon out, unless that prime has been lost by running out of fuel, or air in the line, or disconnecting the end of thenkine and lifting it above the fuel level, etc. Just shutting a service valve won't hurt the siphoned prime, nor will letting it run.

If there is an air leak, it could, but it would have to be a big enough leak to lose the prime quickly and let thebair in without suction driving it.

High Wire said:

or you have anti-siphon valves installed, sorry probably won’t work.

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Good point on anti-siphon valves...I know plenty of diesels have them...but somehow I think of them as a gas thing. Bad assumption on my part.


Also, a dirty a strainer/screen in the tank pickup could cause this problem.

I did what catalinajack did, went with spin on filter system from Tony Athens; installed the primer bulb with cleat tubing. Filters hold way more than racor filters and easier to maintain. Vacuum gauges with drag needles let me monitor filters. Great setup. Sold old racers and filters that allowed me to recoup 2/3rd the cost of the new system.

Captain Doug/catalinajack-
A question: Looks like a great system but, when you change the filters, do you need to then dispose of the entire filter's worth of diesel?

The amount of diesel in the filter is less than a pint and while it may be clean, the whole filter goes into a zip-lock bag and a plastic pail and disposed of at the marina.

Captain Doug said:

The amount of diesel in the filter is less than a pint and while it may be clean, the whole filter goes into a zip-lock bag and a plastic pail and disposed of at the marina.

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Absolutely agree... the amount and $ of the fuel is not worth risking any contamination... same with a spin on just toss it and any fuel involved. I know there are secondaries but come on a pint or so of fuel!

Mike GB32 said:

Captain Doug/catalinajack-
A question: Looks like a great system but, when you change the filters, do you need to then dispose of the entire filter's worth of diesel?

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I drain the filters into a 5-gallon used oil can. If you really think it is waste, you could drain them into your fuel filler port. Hardly worth the bother. Or, drain them into a container and use the fuel as a parts cleaner.

Oh, I wasn't actually thinking about waste. What I was wondering about is the ease of changing out the filters. It looked to me like there would be a lot of fuel to deal with as opposed to a Racor where one would only have to remove the filter itself, not a can full of fuel. But a pint of diesel is not a big deal.
Anyway, my apologies to the OP for the message creep

Mike GB32 said:

Oh, I wasn't actually thinking about waste. What I was wondering about is the ease of changing out the filters. It looked to me like there would be a lot of fuel to deal with as opposed to a Racor where one would only have to remove the filter itself, not a can full of fuel. But a pint of diesel is not a big deal.

Anyway, my apologies to the OP for the message creep

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Not really a problem. I jst place #10 can under the filter, unscrew it, and drain the fuel into a 5-gallon pail through a large funnel. Actually, I find it less messy overall than changing the filters in the Racor housings I retired. Yes, there is a bit of fuel remaining in the filters but they drop straight vertically down into the #10 can with any spillage (minimal) being captured in the can. Filters can be changed in five minutes and filled by gravity and bled right at the head through a bleeder fitting.