Technique for flushing hard lines?

[digidocs]

Hi VAF,

What is your preferred method for cleaning/flushing new aluminum hard lines prior to installation?

Compressed air seems to do a pretty good job, but I wonder how much crud is stuck in the middle of the line where I can't see it?

Thanks,
David

[rzbill]

Here is what I did.

Blow them out during fabrication/construction/and final assy. I may have sprayed some brake cleaner through the hard lines too. Don't remember.

Get the AN plastic screw plugs and keep them on the tubes religiously.

Don't permanently mount the tanks until later.

Pour fuel into a tank and do the shake shake shake dance with it in your hands. Pour into a white container or filter so you can see the crud.

Repeat until none comes out. Took 3 repeats for me, each tank. That was after meticulously cleanly building the tanks, thank you.

Image of crud from tank

Mount tank.

Connect hard lines and run fuel through lines, valve, boost pump and out firewall fitting to hose into a gas can. Run pump. I did 5 gallons. Be ready, the injection pump will shoot 60 GPH. Don't know what the Facet will do.

Afterwards, I repeated this as I incrementally added another hose to the fuel system, all the way to the spider. Note: the injection servo will not pass much fuel even with the controls firewalled. It needs airflow to open the floodgates.

[cajunwings]

I like to swab them out. Blow strong string thru the line with compressed air. Tie on a patch of cloth big enough for a snug fit, wet with solvent or contact cleaner and pull thru until the patches come out clean. A lot like cleaning a shotgun.

Don Broussard

RV 9. Rebuild in progress.

[BillL]

Originally Posted by cajunwings

I like to swab them out. Blow strong string thru the line with compressed air. Tie on a patch of cloth big enough for a snug fit, wet with solvent or contact cleaner and pull thru until the patches come out clean. A lot like cleaning a shotgun.

Don Broussard

RV 9. Rebuild in progress.

Good Idea, the spaghetti that are hydraulic hoses and lines on an excavator are cleaned with a foam plug. It only takes a couple of grams of fines to contaminate 50 gallons of hydraulic oil.

Personally, I use foam earplugs and blow them through the tubes. Using them dry dislodges the debris and blows it out. Three times and they are declared clean. It is what the pros do.

YMMV

[vfrazier]

I like the string idea.

I use a small wad of paper towel and just blow it through. 3X.

It's more fun if someone else is in the shop. Use them for a target.

[digidocs]

Lots of flushing, shotgun swabs, and ear plugs. I like it!

Would never have thought of using a "pig" to clean out the lines, but it makes perfect sense.

Thanks for the help!

David