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Procedure for draining water separator petcock?

Yahoo Message Number: 65845
I have some water in my sight bowl on my water separator. When I open the petcock on the bowl with the cat C-13 shut off and the outlet fuel line shut off there must still be a vacuum as it sucks air in through the drain hose on the bottom. I am worried it will suck too much air and airlock when I start up again. do I have to crack one of the inlet plugs on top to get it to drain?Or crack the filter loose?

Marc 05 affinity Cat c-13 Coach #6429

Re: Procedure for draining water separator petcock?

Reply #1 –
Yahoo Message Number: 65922
Ken here Retired Cat Tech. On your water seperator filter have a drain pan under it. You will get some air bubbles but by tapping the filter element water should drain then just close the valve. Start the Cat and give a little high Idle like 1000 rpm and if you hear the engine stumble and return to a fixed speed the air is out of the lines and you then Idle down the shut off the engine. Remember when the filter is changed air will enter the lines. Alway use clean fuel! to fill a new element as you dont want to run the fuel system dry. Yes factory says you can fill the filter again with CLEAN FUEL! and since you have a newer Cat no air is allowed!. Ken 99 Allure 30356

Re: Procedure for draining water separator petcock?

Reply #2 –
Yahoo Message Number: 65927
If uo do the 30 second prime with the key on does that pressurize the primary filter and allow fuel to drain without allowing air to enter?

Re: Procedure for draining water separator petcock?

Reply #3 –
Yahoo Message Number: 65937
Ken, I am with Bev on this. Whether you have all diesel or diesel with a bit of water in the bottom of the bowl, almost always, when you crack the drain, air will bubble up and in, due I assume to higher pressure outside than inside the fuel line. I doubt that tapping will reverse the process. So, again, how do we get the pressure higher in the line so fuel or water will drain out?

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Lee Zaborowski

07 Intrigue 12153, Cat C-13

Re: Procedure for draining water separator petcock?

Reply #4 –
Yahoo Message Number: 65949
I have the same problem with my Cummins 400 ISL. If I drain all the water I have to let a lot of air in the system. When I crank it up it will die and is sometimes hard to restart. I'll try draining it while running next time, the positive pressure makes sense but, I've never understood why it would have negative pressure to start with. Tapping it helps but only after the pressure is neutralized and then the air is already in the system.

Greg Jones

'03 Intrigue 11571

Re: Procedure for draining water separator petcock?

Reply #5 –
Yahoo Message Number: 65950
Do not open the petcock while the engine is running!! It will suck air in so fast you will not make it to the ignition to shut it off before it dies. Try it with the key on and engine off . This may create fuel pressure from the tank. I see racor has a filter seperator with a prime pump built in (model 490), I think I may try it. For now I think I will crack the filter off a tad, drain the water/fuel out and then refill the filter with a turkey baster from the outside holes which are the inlet side of the filter before screwing it back on.
I airlocked the cat last year and it was a 2 day ordeal to get it going and now I am super paranoid.

Re: Procedure for draining water separator petcock?

Reply #6 –
Yahoo Message Number: 65968
I am not sure about the Cummins 400 ISL but with the ISC the lift pump will purge the air in the - lines, and filters when the key is turned to run and left there for about 90 seconds. If You do this three or four times prior to starting, the lift pump will purge all the air. The lift pump only runs prior to start and then shuts down, you can hear it shut off. This is also is the way to purge a new filter NO NEED TO PREFUEL THE FILTER. It's in the book.

Marvin Swenson
01 Intrigue 11314

Re: Procedure for draining water separator petcock?

Reply #7 –
Yahoo Message Number: 65970
It's in the ISL book also. It works. When I change fuel filters or drain the bowl I have no need to pre-fill the filters. Two or three 60 second cycles of the ignition key and all air is purged.

George in Birmingham
'04 Allure 31038
George in Birmingham
2003 Magna 6298

Re: Procedure for draining water separator petcock?

Reply #8 –
Yahoo Message Number: 65971
George,

The Onan Generator is also self priming. It is done by holding the start switch on the Onan front panel the opposite way from start for a similiar amount of time.

Don Seager

2004 Allure 31046

Re: priming genset fuel system

Reply #9 –
Yahoo Message Number: 65972
Very useful tidbit. Do you mean the Onan on/off switch mounted on the control panel inside the front of the coach or the one mounted on the genset itself?

Jim M, '02 Intrigue #11410, ISL 400

Re: priming genset fuel system

Reply #10 –
Yahoo Message Number: 65974
Jim,

The one mounted on the genset itself. The in-coach start switches do not provide this capability. It is described in the Onan User's Manual.

Don Seager

2004 Allure 31046.

Re: Procedure for draining water separator petcock?

Reply #11 –
Yahoo Message Number: 65976
Hi Lee, Dont be afraid to open the drain on the filter, By Tapping I always do as sometimes debree will clog the small drain outlet. I have draind thousands of filters in my other life. Racor Filters, Cat, Cummins etc. I got rid of my service Man. as there was good info to share on this, when I retired three years ago. Again dont be afraid to drain out the water. Engine fuel systems have check valves built in gear driven fuel transfer pumps on the engine. Trust me if this was an issue there would not be water drain drain valves on fuel water seperators. On our older diesels we had a hand prime pump as you could hand pump the air out of the filter and send it to the return line back to the tank, But alas newer engines dont have this feature anymore from the factory. CC could of orderd one with their order build from Cat, Cummins etc. this costs money. Hope I was able to help. I always enjoy sharing my knowedge on Diesels. Ken 99 Allure 30356

Re: priming genset fuel system

Reply #13 –
Yahoo Message Number: 65980
My switch over the door provides the same function Don. I replaced the Onan fuel filter just a month ago and primed the air out of the system from inside.

George in Birmingham
'04 Allure 31038
George in Birmingham
2003 Magna 6298

Re: Procedure for draining water separator petcock?

Reply #14 –
Yahoo Message Number: 65982
Ken here, Again thanks for bringing this to the Table, I use to train fellow techs. Correct never run engine. Again on newer Cats never run the engine out of fuel. We had a newbie when I worked a few years ago on a C-15, He put on new fuel filters on a rental and put them in dry, Started the engine and it shutdown. After connecting the laptop I saw the problem! Myself and another tech. spent almost a Day getting air out of the fuel system and even using a vacum pump! The newbie was warned if you ever do this again you will be sent home for several days! Lucky for us there was no Injector faiure at several hundred dollars a pop! We always had our newbies work on our rentals not your Coachs! My 2 cents anyho putting this to bed!, Ken 99 Allure 30356

Re: priming genset fuel system

Reply #15 –
Yahoo Message Number: 65983
Hi George,

Well it is a night for learning. I just tried mine inside and it seemed to take longer than the one on the generator panel but after about 10 seconds I did hear the lift pump start. Sorry guys, George is right. I guess that since the only time I needed to prime the generator was when I changed the fuel filter and I was standing right in front of the panel when I finished I used it. Since the manual is an Onan manual they have no idea of how it will be installed in various coaches.

Good catch George.

Don Seager

2004 Allure 31046
 

Re: Procedure for draining water separator petcock?

Reply #16 –
Yahoo Message Number: 66001
And I, for one, enjoy hearing from you and appreciate your sharing your professional knowledge with us on the forum.

George Harper
04 Allure
31093