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replacing fuel level senders

martinair

Member
Hi, I am planning to replace the fuel level senders in my 1998 RV4, #2785. The old ISSPRO senders are useless, the gentleman who built my aircraft almost 20 years ago wrote: they failed after 2 weeks. I want to connect the new senders to my Dynon EMS D 10 digital engine instrument, so that I have accurate readings (fuel flow already working very well!). Vans doesn't sell capacitive senders anymore, Cies can't help, but Vans can: Mitch was very helpful with all his mails and suggested the parts I need to order IE F-385C & IE F-385B senders, antirotation brackets, fuel pick up tubes and sealer of course. I believe I only have to remove the tanks for my work, not the wings. So, the question I have for this forum: any difficulties I might face, any problems with conneting to the Dynon, anything else I might need to know in advance? Thank you very much!
 
No problem at all connecting new Vans resistive senders to the Dynon.

Follow the 2 gallon at a time calibration procedure and you will be fine. In the -6 they won't read past 16 gallons due to the dihedral, but with the Dynon fuel flow hooked up it's no problem.
 
Removing the tanks isn't difficult. Drain the tank completely into a properly grounded container. Disconnect the fuel lines and other connections inside the wing root. Best to cut and splice any wire to a resistive gauge rather than attempting to loosen the screw on the sender (which can seize and break a solder joint/wire and render the sender useless). However, since you are replacing the sender, that may not be a concern for you. A paint cutting tool for #8 screws is helpful, and consider using new screws for re-installation. I painted the new screw heads prior to reinstalling the tank.

Incidentally, Van's supplied two versions of the old Stewart Warner type senders over the years. The oldest had shorter arms and were identical to those used in Cessna and other production types. The newer ones had longer wires that required bending and proper orientation to fit and work properly inside the tank.

The most difficult part when pulling a tank is getting the skin dimples to pop out of the rib and spar (they nest quite tightly). If you use pieces of some thin, heavy plastic (I used plastic signs I purchased at a hardware store) to slide under the tank flange like a shoe horn, you will be able to slide the tank off. Slide the plastic under as much of the tank flange as you can.

The hardest part of the job is removing the old sender, which requires you to pull the access panel, likely pro sealed in place. A quick search will bring up lots of discussion on this topic. The important thing to note is to not use metal tools that could damage the structure.

Drop me a PM with your email address or email me directly at vacf15 at yahoo dot com and I'll be happy to share some pictures.

Good luck!

Vac
 
Removing senders

Don't use the cork gaskets. Instead, use pro seal. Replace the screws on the round sender plate with hex head screws so it will be easier next time.

On the new senders don't forget to make the small 90 degree bends in the very ends to keep the senders from rotating.
 
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flange sealant

I've posted this before. If you're willing to think outside the box, there are options other than using permanent sealant on a removable cover. I used this stuff when I re-sealed my -4's tanks about 2 years ago, and no leaks on the flange. Wish I could say the same for the various proseal joints....

https://www.permatex.com/products/gasketing/permatex-permashield-fuel-resistant-gasket-dressing-flange-sealant/

No gasket; the sealant does all the sealing.

A bead on the flange surface, going around the screw holes, with a match head sized drop in each screw hole, did the job.

Charlie
 
tanks are out!

yesterday we removed the tanks. Absolutly no problem at all, especially thanks to Mike's advise. I used wooden wedges. After 2,5 hours everything was done. Longest part was draining the remaining fuel. Now heading to the workshop!
 
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