Leaking Racor 500FG filter on Universal Diesel M25.

[patrickkidd]

Hi there!

I am trying to troubleshoot a leaking Racor 500FG (user manual: http://www.westernturbo.com/images/stories/Filters/Racor/Turbine Series.pdf), which is leaking fuel out the drain plug until it is extremely tight, and then seeping fuel out the seal between the glass bowl and the metal casing. I recently replaced the old facet fuel pump on my Universal M25 with a Universal Electric Purolator Pro 87SV (same as Facet FEP87SV, http://www.facet-purolator.com/solid-state-fuel-pump.php), which operates at 4-5.5psi. The Racor apparently has a maximum working pressure of 25psi, and all the o-rings are brand new and I re-sealed the bowl o-ring with Vaseline, and the bolts are tightened to the point where the metal casing will allow. The o-rings and mating glass and metal all look clean and the Racor is overall in very good condition.

The fuel pump primes the filter well enough, but then never stops running even though the bowl is full. Maybe it's still priming the injectors?

The pump is set up before the filter, and the filter is between the pump and the engine. Maybe this is backwards?

What am I doing something wrong? should I get a new and/or different racer filter?

Help!! Thanks,
-Patrick

 

[PineyWoods]

The hydraulic pressure created by a small bore fuel line under only it's rated ~5 PSI into a large bore cylinder (filter) would create huge filter wall stresses, as the hydraulic force multiplier varies with the square of the relative in-line diameters . With, say, an 1/8" line ID into a 3" ID filter: 9"/0.0156" = 577 (hydraulic multiplier) X 5 PSI = 2885 PSI of filter housing wall stresses!! As it feeds back into the same ID line, line pressure reduces to the same 5 PSI.

So move the pump down-stream of the filter and all should be OK unless the filter is permanently deformed. A suction pressure gauge could be installed between the filter and pump to check fuel filter status: the higher the suction needed, the more the filter blockage present. This is how the big boats do it, and the cost should be minor...

Pete

 

[patrickkidd]

Ah ok I thought so. But do you mean move it up stream, meaning between the pump and the tank so the pump is pulling fuel through it instead of pushing?

 

[patrickkidd]

Ah never mind, you said move th PUMP downstream. I'll give it a shot!

 

[PineyWoods]

Right - move the pump downstream of the filter, or the filter upstream of the pump - the pump pulls from the filter in either case.
Pete

 

[Ron20324]

Doesn't you engine have an on-engine fuel pump? Maybe you don't really need the electric- or is it OM?

 

[patrickkidd]

I don't believe the M25 has a pump other than the injectors. I called Racor and they said the 500FG are designed to be upstream of the pump, but shouldn't leak in either case. We'll see...

 

[kloudie1]

Bummer, Patrick.. the filter should work with pump on either side, as you note.. The pump can't make enough pressure to exceed the working pressure limit for the filter.. Check for tiny cracks or scratches that go across the sealing face radially; same for the top sealing surface of the bowl. The drain may have a tiny bit of debris on its internal sealing surfaces.. when the bowl is off, pull the drain pug and rinse it through as best you can with a stream from a garden hose.. inspect it .. ya may have to get a replacement from Racor.. Happy leak hunting..
EDIT: sometimes the injectors stop in a place on their cam which allows fuel to flow through to the overflow line and back to the tank. This is most likely why the pump continues to run..

 

[patrickkidd]

Well it definitely stopped leaking. I also found pet of the source of the leak was the plastic plug just above the bowl. No idea what that's for, but it's very soft and difficult to screw in all the way.

However, I think there is air in the line somewhere because the engine keeps losing power. Maybe I'm not bleeding it very well....there is fuel coming out of both bleed plugs on the engine although with a bit of air at the same time, both very steady

 

[Stu Jackson]

but it's very soft and difficult to screw in all the way.

You still have a leak, only it's on the inlet side now, since you moved the pump.

Consider getting an O ring from a hardware store for that plastic plug.

 

[patrickkidd]

The plug itself almost seems like it should be replaced with a metal one. This one was incredibly difficult to remove, and then also to re-insert, and is so soft that I had to mangle the head to get it in there. It's hard to find a part number for it...

When you say "inlet side," do you mean somewhere between the racor filter and the tank?

 

[kloudie1]

I agree with Stu: Inlet side would be between the bottom of the pick up tube and the suction side of the pump. Could even be the packing in the shut-off valve.. but usually is around the last place worked on if it wasn't behaving that way before the pump change..
Patrick, it sounds like the plastic plug may have been cross threaded .. you can take it to someplace that has fittings and get a plastic or stainless one (or brass if you isolate it with TefGel) Home Depot or Lowes or Ace, etc would have the part .. (West Marine may )

 

[patrickkidd]

klaude1, thank for the encouragement about eating a plug. I did indeed cross thread it a bit to start with, but then was able to repair and get it threaded in all the way as revealed by taking it out again in front of the west Marine engine guy. I'll et a good metal one next time I drain the bowl, unless I can't find a leak or obstruction anywhere else.

I was told yesterday by my dad about how it took him two years to figure out that the screen in the tank pickup tube was crystallized with diesel and fungus, which caused enough suction in the line to pull air in from wherever the weakest link was. The section from the filter to the pickup tube is the only thing I haven't replace so far, so I'll check that next as soon as I get a chance, and then that plastic Racor plug.

 

[Jim 5757]

Just to chime in this discussion... the racor instruction says it's better to have the filter before the pump cuz the pump tends to emusify the fuel. If your getting air it has to be from the suction side. After the pump you have pressure and fuel leaks out not air in.

 

[jssailem]

If I understand correctly, the plug is to the side of the fuel inlet. This is identified as the Heater Feed Through plug PT# RK 11-1679. There is an "O" ring on that plastic plug. Tightening recommended at 15-20 inch lbs. (For me - a bit over finger tight with glove on - if more needed get new O ring.)
I too like the filter suction side installed. Makes the vacuum gauge on the filter a simple measure of filter status.

 

[Stu Jackson]

Given your comment, you may be interested in our Critical Upgrades topic, we, too, like your dad, can now say: "Told ya so!" Only meaning we've been saving and posting these items for many, many years, and readers and contributors here on this site have seen this link many, many times. Perhaps you haven't. That's why a friend is trying to start up a Catalina 30 wiki, since you C30 skippers have soooo much in common with our boats but your information sources are pretty much spread out across the web. Also, IIRC, the C30 Association website has a prominent link to ours right on their own main page.

Critical Upgrades http://c34.org/bbs/index.php/topic,5078.0.html

This material is applicable to any boat with a diesel engine, more for Universals, though.

I was told yesterday by my dad about how it took him two years to figure out that the screen in the tank pickup tube was crystallized with diesel and fungus, which caused enough suction in the line to pull air in from wherever the weakest link was.

 

[Stu Jackson]

klaude1, thank for the encouragement about eating a plug. I did indeed cross thread it a bit to start with

Just a question: Why did you remove it in the first place? Do I understand correctly that it was the drain plug?

 

[patrickkidd]

jssailem: Thank you SO much for the part number. I was having a really hard time finding it. It was extremely difficult to remove the first time and it had clearly never been removed before, so I'm not sure that finger tight will do it. At any rate, I should get another one so thank you.

Stu: Thanks for the link to the critical upgrade section on c34! I've never seen it before. Yeah, the C30 info is all over the place although it seems like the data is there should someone have the motivation to consolidate it. I can't remember the exact reasoning I used to remove the plug in the first place, but it was during the initial troubleshooting marathon I did before realizing the pump was shot. In retrospect, that thing should never again come out.

This has been a very informative discussion so far.

 

[Stu Jackson]

Patrick, you might be interested in this too (noodle around the C34 site, lots of stuff there)

Engines 101 - The BIGGEST & BEST collection of M25 Series Universal Engine Information on the Internet, plus some M35, too

http://www.c34.org/wiki/index.php?title=Diesel_Engine

 

[patrickkidd]

Well thanks for all of your help, it really made a difference for me here. The engine is running solid under load, I think it just needed to get bled well. The screen was already removed from the pickup tube but man my tank needs a flush! Goop and grime all over that tube, and some water and gel in the Racor just before that fuel pump died.

I also informed my Dad that several of those forum posts emphasize removing the screen in the pickup tube altogether so he can do the same on his yanmar in the J/35.

What a great forum