Gascolator or not

[447BB]

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.

[Kyle Boatright]

I have one on my carbureted O-320, and would not install one if I had it to do over. I find it hard to sump, never find anything in it anyway, and think it acts as a heat exchanger to warm the fuel (which is bad on a hot day).

If I ever remove it, I will install a filter to substitute for the screen in the gascolator.

[rvbuilder2002]

It depends largely on the storage environment and operating procedures......

A gascolator installation in an RV (per the plans installation anyway) is not intended to be a low point for draining water from the system.

The fuel pickups go up hill inside of the tank so water can never migrate from the tank into the rest of the system anyway. Removing water and other contaminants is what the drain valves on the bottom of each tank are for.

The gascolator is intended as a pre-flight cleanable filter and water separator... that filters the fuel on its path between the tank and the carburetor.

I have done maint. on RV's where I found a lot of water and debri in the gascolator.
This can generally be avoided with good operating procedures (sumping the tanks regularly, etc.) Having the gascolator will help with anything that might get missed..... whatever the reason.

Having a gascolator mounted fwd of the firewall does induce an additional level of fuel preheating, but fuel systems properly installed using fire sleeved hoses and heat shields where appropriate usually preform fine even in extreme temperatures using 100LL. If you plan to use mogas in very hot environments, a heat shield and cooling air hose might be a good idea.

Sumping the gascolator is not a problem if the appropriate hole has been made in the cowl below the drain valve, and you understand the need for having the electric boost pump on since it isn't a gravity feed system.
Having the pump on has a secondary safety benefit...... it will confirm that the drain valve fully closed and seal when the sample tube is removed.

[RV7 To Go]

Scott+1
In Canada it is a requirement to install a gascolator. I had an older Cessna style on the fw on my 4. A 1" hole in bottom cowl made sumping a non-issue. On my 7 I installed a Steves gascolator in the Vans location with a coupling to bring the Curtiss drain to bottom of the cowl. Again, no issues to sump the bowl. All fuel lines after the gascolator are sleeved. I run avgas in both and have not experienced vapour locking issues. I always turn the boost pump on before sumping.
I have never experienced water in the gascolator but know a number of people on the field who have....seems it is usually caused by leaking orings on the gas cap.
Al

[snopercod]

I have a fiberglass airplane and have never EVER found any water when draining the gascolator or the wing tanks. Every annual, when I pull the bowl and inspect, I never find any debris in the bowl or in the the internal screen. Immediately downstream of my gascolator is a Facet "Gold-Flo" boost pump which has it's own internal screen. The carburetor inlet also has a fine screen. So I'm not worried at all about water or debris making it to the carburetor.

What I do worry about, though, is that the spring holding the gascolator drain closed will get weak and all my gas would spill out the bottom of the cowling. I'm thinking about removing the gascolator at the next annual.

Disclaimer: With metal airplanes, condensation in your fuel could actually be a problem so you might want to keep your gascolator.

[rv7charlie]

I run E-free mogas in my -4. After a minor incident involving (stupidly) running winter gas on a 100+degree day, I removed my gascolator. I reached the same conclusion as others; its primary purpose for me was for heat input to the fuel. I've got sump drains and a fuel filter (that's more effective than a screen), so after several years gascolator-free, I'm calling it good.

YMMV, etc....

Charlie

[447BB]

Excellent comments all. Thanks for your collective wisdom.

[rv6ejguy]

One of my customers is planning to use this on his aircraft: https://www.flyboyaccessories.com/product-p/72rr02.htm

[bill v]

having ran old farm machinery and chemical equipment until the filter is plugged and the machine stops I want a large collection place and a large surface area for the filter element.

[Walt]

Originally Posted by bill v

having ran old farm machinery and chemical equipment until the filter is plugged and the machine stops I want a large collection place and a large surface area for the filter element.

The typical gascolator screen area is tiny compared to the average inline pleated filter area.