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F.I. injector cleaning

randylervold

randylervold

moderator
In anticipation of my first condition inspection next year (I like to think ahead), what are most of you with F.I. using to clean your nozzles? I've heard the technique about soaking them in Hoppe's #9 gun cleaner but also heard the idea of using an ultrasonic cleaner. There is an Aircraft Maintenance Technology (AMT) article from 1997 that indicates the ultrasonic method is best but doesn't mention what sort of solution is used. One can buy a small jewelry cleaner like this one...
http://www.amazon.com/Haier-HU335W-Ultrasonic-Cleaner/dp/B0000BVGNJ
...do they work, what sort of solution should be used, and how long should one leave them in there?

Inquiringly,
 
I use my wife's ultrasonic jewelry cleaner (shhhh). It has a stainless steel reservoir. I use the Hoppes #9. I let them sit for 30 minutes or so. The ultrasound heats up the fluid, seems good to me.

Who has heard of the old wives' tale that you shouldn't blow them out with an air hose afterward? :confused:
 
Randy, carburetor cleaner works to remove visible stuff (isn't that an irony!).

I have not found anything visible on the bores yet. The only grime I've found so far is on the screens surrounding the injectors (AFP). Some of it is bug guts.
 
Injector Cleaning

Don?t sweat this too much. As much as been written on this subject by the ?experts? we find that cleaning the nozzles on a time basis is sometimes unnecessary and can lead to premature wear on the restrictor caused by cleaning with caustic solutions (Hoppe?s #9). Some of this stuff will etch the brass and change the flow characteristic of the restrictor if left in too long. Sonic cleaning works great (that?s what we use). First clean with carb cleaner or ?Choke Cleaner? to get the oil and grease off then put in a sonic cleaner with soap and water works well.

We have found that if the engine is running OK leave the nozzles alone. You can spray off the exterior of the nozzle with ?Brake Kleen? or equivalent to get the dirt and bug stuff off the shield and screen, then just blow off with compressed air. You don?t even have to take the nozzle out of the head of disconnect the nozzle line to do this.

More importantly during your condition inspection clean the fuel filter screen on the inlet side of the boost pump, clean and inspect the inlet screen in the inlet of the fuel control unit, inspect the nozzle lines for security of the clamps and inspect the braze joints where the nozzle line goes into the cone at each end of the nozzle line. Also don?t forget to check all the cable connections and the lever connection at the appropriate shaft. Make the teeth on the levers are engaged properly and the lock nuts are secure, and cotter pins are installed where required. Make sure that all screws are re-lock wired if screws were removed for maintenance or cleaning of components. Check flow divider hoses/ fittings, purge valve fittings, lock wire etc.

If you do decide to remove the injector nozzle for cleaning, make sure your ?? deep socket is broached deep enough so that the nozzle shield doesn?t get messed up. And be sure that if you had done nozzle tuning that you make record of where each nozzle is installed. Serious damage to your engine can result if you mismatch tuned restrictors in the wrong cylinder.

Don
 
Excellent info Don, just what I was looking for, and thanks for condition inspection advice also. Thanks for taking the time to post!
 
Last edited:
randylervold said:
In anticipation of my first condition inspection next year (I like to think ahead), what are most of you with F.I. using to clean your nozzles? I've heard the technique about soaking them in Hoppe's #9 gun cleaner but also heard the idea of using an ultrasonic cleaner. There is an Aircraft Maintenance Technology (AMT) article from 1997 that indicates the ultrasonic method is best but doesn't mention what sort of solution is used. One can buy a small jewelry cleaner like this one...
http://www.amazon.com/Haier-HU335W-Ultrasonic-Cleaner/dp/B0000BVGNJ
...do they work, what sort of solution should be used, and how long should one leave them in there?

Inquiringly,
Click to expand...

Hi Randy,
I have no experience with the ultrasonic cleaner you listed. Ultrasonic cleaners do work very well. I would suggest a methal chloride based carburetor cleaning solution as the best cleaning agent. Lycoming has a Service Instruction (SI 1275B) which details cleaning of fuel injectors. I can provide you with a copy off list. Obtain my email address by left clicking on my user name above. Send me an email and I'll send you a copy of SI 1275B
Charlie Kuss
 
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