Max cooling during fuel stops

Especially on hot summer days, when stopping for fuel I like to park the plane into the wind, open the oil dipstick door, and pull the dipstick out a ways so that max heat/moisture is vented during refueling.
I fabricated the pictured gizmo out of 3/8" fuel tubing. It slips under the hinges and rotates into position to keep the dipstick from sliding back in. 5 minutes to fabricate, couple of seconds to insert and remove. Image visible at https://www.dpe.aero/pictures-and-videos

Personally, I think it’s a judgement call as to how much oil cooling this provides (and is it needed?) vs how much blowing dust might be ingested.

Even a few minutes with the dip stick out can vent a significant amount of blow-by moisture out. But I doubt you would lower the oil temp. The whole engine is heat soaked, some of it at higher temperature than the oil. So I don't think you are going to make a dent in that heat reservoir.

On the subject of fuel stops, for those of us with Bendix-type fuel injection:

Has anyone tried to make some kind of radiation shielding for the injector lines that might reduce the boil-off of fuel that floods the engine?

I would not want to hang any mass on the fuel lines themselves - one might change the natural frequency of the line in a way that would cause fatigue failure. But some kind of light-weight shield could be affixed to the pushrod tube that might significantly reduce the heat load into the injector lines.

I know many people have purge-valve systems that can put fresh cool fuel into the system, but that doesn't address the fuel that is already in the injector lines and sits there boiling as soon as you shut the engine down.

Anyone have any experience with something like this?

From the Aviation Department at the local Lowes...

https://www.lowes.com/pd/ADS-4-in-Dia-Corrugated-Adapter-Fitting/3136499

Sits inside the oil service door on parts of the engine mount/dipstick tube and keeps it propped open a few inches, even in the Texas wind...

4 bucks out the door...obviously, not as elegant a solution as a finely bent piece of aluminum tube, but effective.

scsmith said:

...

On the subject of fuel stops, for those of us with Bendix-type fuel injection:

Has anyone tried to make some kind of radiation shielding for the injector lines that might reduce the boil-off of fuel that floods the engine?

...

Anyone have any experience with something like this?

Click to expand...

Probably won't work, but what about using something like this hanging into both cowl intakes just after shutdown?

https://www.amazon.com/Hands-Free-Portable-Neck-Fan/dp/B07WSZ2TM8

My solution for ground cooling, can’t believe it’s been 2 1/2 years ago but it’s been the best mod I’ve done on the airplane.

https://vansairforce.net/community/showthread.php?t=171987

Prior I was boiling fuel in the carb bowl every fuel stop over 90 degrees, also setting off the temp alarm on the EarthX battery after takeoff. My prior Odyssey battery’s didn’t have a temp Alarm but also didn’t last in my airplane much over a year. The EarthX I installed prior to the cowl flap in 2019 is still working well, fingers crossed it handles the abuse for several more years!

With my cowling I found temps in the lower cowling went up below 120knts such as idle several miles out and entering the traffic pattern even though the CHT’s and Oil Temp were dropping. Temps climbed from there to low 200’s after a short taxi and shutdown. With the stock oil door removed lower cowl temps remained stable to slightly lower. I haven’t measure the temp differences on the larger actuated oil door but operationally it’s much better. I’ll open my oil door cowl flap several thousand feet prior to pattern altitude land, refuel and takeoff my fuel boiling and battery over temp alarm rarely happen.

rv8ch said:

Probably won't work, but what about using something like this hanging into both cowl intakes just after shutdown?

https://www.amazon.com/Hands-Free-Portable-Neck-Fan/dp/B07WSZ2TM8

View attachment 14509

Click to expand...

I like the principle of moving more air into the cowling during the stop. Not sure these would do enough to help, but they'd look cool!
It's very possible there is minimal/no gain with my procedure, but "hot air rises" so perhaps in addition to the two open ASA cowl flaps I'm helping my engine just a little bit...

scsmith said:

Even a few minutes with the dip stick out can vent a significant amount of blow-by moisture out. But I doubt you would lower the oil temp. The whole engine is heat soaked, some of it at higher temperature than the oil. So I don't think you are going to make a dent in that heat reservoir.

On the subject of fuel stops, for those of us with Bendix-type fuel injection:

Has anyone tried to make some kind of radiation shielding for the injector lines that might reduce the boil-off of fuel that floods the engine?

I would not want to hang any mass on the fuel lines themselves - one might change the natural frequency of the line in a way that would cause fatigue failure. But some kind of light-weight shield could be affixed to the pushrod tube that might significantly reduce the heat load into the injector lines.

I know many people have purge-valve systems that can put fresh cool fuel into the system, but that doesn't address the fuel that is already in the injector lines and sits there boiling as soon as you shut the engine down.

Anyone have any experience with something like this?

Click to expand...

I used the reflective foil wrapped around the SS lines on my 320. That engine has the injectors out in the primer ports, so struggled with fuel heating issues. Unfortunately I did it along with other mods, so hard to tell effect. I don't think it did much for shut down heat, but did help eliminate the issue on final and slow speed. I can still hear the fuel squirting out the injectors a minute after shut down. I believe that reflecting heat away only works for so long and eventually the part succumbs to the ambient temp and eventually matches it. It seems to be geared for reflecting localized heat that is above the ambient temps. Once the under cowl temp is 200, everything that is not insulated will quickly become 200 and even the insulated stuff will get there eventually.

Larry

And . . . .

lr172 said:

I used the reflective foil wrapped around the SS lines on my 320. That engine has the injectors out in the primer ports, so struggled with fuel heating issues. Unfortunately I did it along with other mods, so hard to tell effect. I don't think it did much for shut down heat, but did help eliminate the issue on final and slow speed. I can still hear the fuel squirting out the injectors a minute after shut down. I believe that reflecting heat away only works for so long and eventually the part succumbs to the ambient temp and eventually matches it. It seems to be geared for reflecting localized heat that is above the ambient temps. Once the under cowl temp is 200, everything that is not insulated will quickly become 200 and even the insulated stuff will get there eventually.

Larry

Click to expand...

The fuel is hot well before it gets to the spider.