Leaking Fuel Filter

[Noah]

I have a 3cyl Universal Diesel with a Racor 220 Spin on Fuel Filter. I can't get the filter to stop leaking. I have tightened down everything, and replaced all the seals between the head, filter and bowl. It's driving me nuts...Plus not great to have leaking diesel all over the place...

So the boat has an electric fuel pump on it between the filter and the engine. I don't think that it has been in the boat very long, and I wonder why it's there. The engine has about 450 hours on it, and runs great otherwise. Could a previous owner have installed it because the injectors or pump is bad and they needed more pressure? Could the pump also be creating back pressure that is pushing fuel out of the filter? Or could the diesel injectors be shot, and they are allowing back pressure that is going past the pump and into the fuel system?

Hopefully those are both worst case...

Are those older spin on Racor fuel filters know to be crap?

Thanks, I would love to get this solved...

Noah

[John B]

It'a clear bowl type filter, a bit like the old fuel bowl filter on my 48 Ford jailbar pickup(but bigger). I can tell you what happens to the old Ford ones. The strap that tightens them distorts the casting over time and they start to leak and suck air. I know you have a different type of attachment cos you said it's a spin on type,.... but I'd look at the mating surface of bowl to body and check that for distortion or damage.

[Bob Smalser]

I'm more a truck-tractor guy who runs 5 or so commercial diesels, but here goes:

Does the engine already have a mechanical fuel pump mounted on the engine and feeding the fuel filter?

See if you have a friend with a line-pressure test gage. There's no need for pressures any higher than needed to get fuel in sufficient quantity to the injector pump, where the high pressure begins. While multiple fuel pumps are common in some diesel systems, I've never seen one between the filters and the injector pump.

I doubt anything is wrong other than the placement of that pump. In the absence of testing those pressures you could bypass the electric pump if there's already a mechanical pump and try that. Or if the electric pump is the sole pump, you could try moving it to where they usually are mounted - before the filter and lower than it.

I've seen folks try all sorts of things to improve fuel flow when what was causing the poor flow was a clogged filter or screen that they never knew was there....like at the tank, a hidden inline filter or the screen at the input to the injector pump.

Check your shop manual and trace the line from the tank to the filter.

And I've had John's problem with warped/cracked filter housings, too - usually responsible for an air leak rather than a fuel leak - but replacing parts like filter housings and suspect line fittings is my usual next step.

[ 08-03-2003, 11:48 PM: Message edited by: Bob Smalser ]

[Mr. Know It All]

The part(filter) could be defective(leaking), even if new.

You could order a new one here......
http://www.go2marine.com/main.jsp

[ 08-03-2003, 11:49 PM: Message edited by: Mr. Know It All ]

[Mike Vogdes]

Is the spin on element also a racor? I would make certain you have the propper element for the housing it spins on.

[Noah]

Ok, some answers here:

I also replaced the filter element with a new Racor part. I believe that it is leaking between the element and the top of the unit which is aluminum so I wouldn't immediately think that something is distorted. I will disconnect the electric fuel pump and see what happens and how that effects either the performance of the engine or the leak.

The filter looks something like this (Though it's a different model)

http://boatdiesel.com/Store/images/Parts/Racor/460-175.jpg

The fuel system is pretty simple. It comes down from the tank gravity feed into the fuel filter. Next is the electric fuel pump (that is new) a few inches below the filter. Then it all goes down into the engine which I believe also has a fuel pump.

Thanks,

Noah

[Bob Smalser]

Posed your problem over coffee this morning to a couple guys who restore old machinery for a living.

They think there's too much pressure in the line, and allowed that electric pumps are often plumbed in north of the filter to overcome an airleak in the filter housing or elsewhere that allows bleedback of the fuel lines, resulting in hard starting.

I'd buy a new filter housing and try that - it could easily be warped or cracked by somebody trying to torque out an air leak. If a new housing/gasket still leaks, I'd then replumb the electric pump to a position on the fuel tank side of the filter and below it, so it has to lift the fuel at least 12 inches.

[Noah]

Ok, it sounds like it's time to replace the filter. (Though this ain't cheap) I still wonder if bad injectors or something else could be allowing engine compression to force air back out the system.

BTW, it only leaks when the engine is running. When it's stopped there are no problems.

Or could the electric pump be creating too much pre-engine pump pressure and reverse pressurizing the system (though this would be strange)

I guess I'm used to cars with Electric Fuel pumps having a fuel pressure regulator with the excess flow going back to the tank.

Noah

[Bob Smalser]

Worn injectors can allow bleedback of air when the engine is shut down - but I've never heard of of that air (or pressure) getting past the o-rings on the injector pump pistons.

No reason to get too spendy - any common NAPA filter housing and filter that will fit the mounting holes/space will work just fine. And I usually plumb in a second, larger filter with a water bleed screw and clear bowl earlier in the system - just for insurance - so when I do get that load of water-saturated fuel, I have a good chance of catching the problem before it hits and damages those injector o-rings.

[Del Lansing]

I took a look at the Racor website and the filters can handle 30 lbs of pressure so pressure is probably not the problem; if there was that much pressure pushing back to the tank, how would the engine get fuel? It looks like the fuel line connects with flare fittings; I wonder if one is stripped or cross-threaded or loose? Will it leak sitting at idle? with a couple of clean rags to wipe the area maybe you could isolate where it is weeping. Maybe the vibration of running is just enough to cause a drip at a marginally tight fitting. Perhaps a wee tweak with a wrench will get it? Don't want to overlook the obvious.

[Noah]

Yes Del, it could be one of the two hose fittings on the Filter, but I'm pretty sure it is at the junction of Filter and head. Of course the leak is in the back of the unit next to the bulkhead...

You are correct that if there was that much back pressure how would the engine get fuel...

It could just be a vibration thing...

I cleaned most of the spilled diesel up this morning before it got pumped out into the lake, and tonight I will go back and take a look at getting the other fittings tight.

Noah

[Bob Adams]

Hold on a minute!! I have seen many times on spin on type filters where the gasket attached to the element stays on the mount when the element is removed. You then install a new element which has a gasket on it, giving you two where only one should be. Take off the element and make sure there is no gasket stuck to the mount. Good luck!
Bob

[Gary E]

Bob is absolutly right..
and another thing or 3

...make sure the gasket surface is clean.. with your finger, not a rag...

... fill the filter before mounting it
... use a small amout of grease on the rubber seal..then screw it on the housing. d not over tighten, 1/4 turn past meeting is usually all you need.. remember this does not contail pressure, the pump is sucking oil from this filter..

... finally bleed the air from it.. diesels do not like air in the fuel

... check the return line.. should see good flow returning to the tank..