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Old 01-11-2018, 05:00 PM
447BB 447BB is offline
Join Date: Sep 2017
Location: Savannah, GA
Posts: 8
Default Gascolator or not

In process of installing O-320 in place of failed Subaru engine on our RV-7. The old set-up had low pressure and high pressure in-line fuel filters.
With the Lycoming, and the typical Vans fuel line arrangement a gascolator is supposed to provide some protection against fuel contamination.
The recommended mounting location is not the low point in the fuel system, for a resting tail dragger, so it probably doesn't work for water trapping. Also on the firewall at the bottom of the cowl seems like a really impossible place for access to drain the gascolator.
Any thoughts on the merits or requirement for a gascolator most appreciated.
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Old 01-12-2018, 01:03 PM
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caryr caryr is offline
Join Date: Jan 2005
Location: northwest georgia
Posts: 289

If I were to do it again, I would opt for the filter route.

I have a gascolator, but you are right its nearly inaccessible on the firewall.

A pair of filters in front of the spar in the tank fuel legs might be a possibility.

But maintenance is difficult there during annuals and is messy.

I think I would use a single filter under the cowl somewhere. Just make sure filter has a bypass option.

Cary Rhodes
Taylorsville, Georgia
Van's RV-7
First Flight April 2004
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Old 01-12-2018, 02:45 PM
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Sam Buchanan Sam Buchanan is offline
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Location: North Alabama
Posts: 3,798

Some builders have put a filter in each wing root. That provides redundancy (as long as you don't run a tank dry!!!! ) and won't leak fuel in the cabin during maintenance.
Sam Buchanan
1999 RV-6
1918 Fokker D.VII replica
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Old 01-12-2018, 03:59 PM
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rvator51 rvator51 is offline
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Location: Peoria, AZ
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If you put the filter on the firewall, it will be forward of the electric fuel pump and won’t provide any protection for it or the fuel valve for FOD in the tanks.

Thomas Velvick
Goodyear, AZ (KGYR)

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Old 01-12-2018, 04:09 PM
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DanH DanH is offline
Join Date: Oct 2005
Location: 08A
Posts: 7,858

Gascolator for carb, filter for fuel injection.

Water can stop flow through a carb jet, which operates on a low pressure delta. With FI it just blows on through.

The typical gascolator is both filter and water sump. It does not need to be at the system low point, and very often is not. A gascolator is its own low point.
Dan Horton
Barrett IO-390

Last edited by DanH : 01-12-2018 at 04:13 PM.
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Old 01-12-2018, 08:44 PM
Taltruda Taltruda is offline
Join Date: Oct 2017
Location: Las Vegas, NV
Posts: 100

I wouldn’t be happy about flying a plane without one.. I delivered a Cessna once that had water in the tanks, I rocked and rolled the wings, tail down, up and down, and sumped and sumped till it was gone. Every fuel stop still had water in the gascolator (less and less each time). I know that gascolator saved my bacon!
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Old 01-13-2018, 07:29 PM
BillSchlatterer BillSchlatterer is offline
Join Date: Jan 2005
Location: Arkansas
Posts: 498
Default Gascolator Access ??

Not sure why access is a problem. Add the longer drain connection fitting on the bottom of the gascolator. If you put a dime size hole in he bottom of the cowl directly underneath the fitting, you can stick a piece of 3/8 or 1/2 inch tubing up through it. Let the drain go inside the tube and push up and open the drain. Catch it in a glass if you want to. It's easy, clean, and no issue. Put a 6 inch piece of tubing in the plane if you drain it every fueling.

I guess I'm just lucky, 580 hours and I have never found a thing in the screens.

Just as a reference point, I have 800 hours in Barons burning 32-36 gallons an hour and check the drains religiously. Never found any water ... ever. Most FBOs today do a really good job on filtering fuel.

Last data point....fuel systems are the root cause of a significant number of RV accidents. Vans does a really good job of designing a KISS system that just works. Following the plans closely will provide a very safe reliable system.

Bill S
Got the Grin :-)
7a Ark KORK
Dues Paid 2/11/18 for 2018

Last edited by BillSchlatterer : 01-13-2018 at 07:32 PM.
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Old 01-14-2018, 09:14 PM
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vfrazier vfrazier is offline
Join Date: Jan 2007
Location: Mount Vernon, IN
Posts: 1,094

You might consider the Aerolab filter/gascolator which mounts in the belly.
Vince Frazier
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