Chapter 23 – Oil dipstick tube

Over the last few days I’ve been involved in trying to figure out a solution for my oil dipstick/filler tube.  As you can see, the wide area at the top of the oil filler tube is uncomfortably close to the engine motor mount tube.  In fact, it’s so close that since the engine has been installed to the motor mount, I have NEVER had the dipstick in place… it just won’t thread in with the wider dipstick handle preventing it from being installed.

I know in the past builders have manipulated the length of this oil tube (usually shorter) with cutting it and then wrapping it with fiberglass.  Due to the position of the top cowling oil dipstick access door —to check the oil level pre-flight— I certainly don’t want this oil tube shorter… I want it readily available just inside the cowling access door to avoid any mandatory crazy gymnastics (on my part) to simply check the oil (e.g. such as having to climb into the back seat, etc.).

In lieu of my previous post on this subject, I modeled up an extension in Fusion 360 CAD and after too many attempts was finally able to get my 3D printer (AKA “Bob”) to print it out.  Note in the pic below the lower right was the bottom of the print, the upper left was the top and final portion to be printed out.  I point this out since in Fusion 360 when creating threads, there’s a little tick box that is used when you want to physically model threads vs simply have them show up on screen.  I (apparently!) forget to tick that block and was unpleasantly surprised to find that my part printed out sans threads (male) on one side.

The inside threads, for the dipstick, did print out.  Although the tolerance is a bit too tight and I had to really use some force to get the dipstick threaded in to the point it is in the pic.

This 3D printed extension is still just part of the info and data collection phase, R&D if you will, and I’m still looking at all available options.  That being said, the primary downside of this adding-an-extension method to fix this issue is that the widest part of the oil tube is still very close to engine mount tube.  Should I leave the small gap or simply pad it and secure the oil tube to the engine mount tube somehow that avoids vibratory chaffing but still allows movement betwixt motor and mount?  Moreover, if I did make the extension would it be some type of heat resistant plastic or machined out of aluminum?

Clearly one of the best options would to simply get a taller oil dipstick/filler tube where the actual tube part is narrowest as it crosses the area of the engine mount tube.  I’ve done a very initial look at those, but am hesitant to plop down nearly $200 for a new tube just yet!  Clearly I’ll flush out all available options first.

Finally, I will note that I did buy a length of solid 3/16″ 6061 aluminum rod that I will replace the current dipstick rod with once & however the oil dipstick tube has been increased in height.

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