Oil Gauge (dipstick) thread size?

[terry.mortimore]

Hi gang:

I have a very old O-320 narrow deck engine that I've been slowly rebuilding. The oil dipstick threads measure 1 1/8" and 12 threads per inch.

For clearance reasons (long story) I needed a extension tube installed for the dipstick. I had a oil tube extension Part # 75761 which had a 1 1/4" thread. I turned down the extension tube to 1 1/8" in my lathe and cut threads into it. This modified tube now screws down into the hole in the crankcase and now I need to find a suitable dipstick.

The top end of this extension tube looks to have 1 1/4" threads in it and my original 1 1/8" dipstick will not screw into it.

Can someone tell me if the newer versions of the dipsticks are 1 1/4" threads? or will I have to find a way to modify my original stick?

I spotted a long dipstick on Ebay which I could cut to the length required if the threads on the cap will thread into my 1 1/4" sized extension tube.

http://www.ebay.com/itm/120963319405...84.m1438.l2649


Thanks in advance for the help, Terry.

[jrs14855]

I have a collection of dipstick housings and dipsticks. It is relatively easy to change the portion of the dipstick where the markings are. I may also have a dipstick you can remark and use if you will describe exactly what you need, thread size and dipstick length.
One of the issues here is that the dipstick housings and the short dipstick extensions are two different thread sizes.

[terry.mortimore]

Originally Posted by jrs14855

One of the issues here is that the dipstick housings and the short dipstick extensions are two different thread sizes.

Hi Jim, thanks for the response.

Are you telling me that the regular dipstick housings would be the 1 1/8" thread?

If so, perhaps all I need is a dipstick housing and it's matching dipstick. My situation does not require a very long tube, can you tell me if they make one in the 4 to 6" range?

My head hurts after a while of trying to sort through all the lycoming superceded numbers, I appreciate the help.

Terry.

[blueflyer]

I just went through this same issue. It is my understanding that lycoming used to make 1-1/8" diameter dipsticks/dipstick tubes and now have gone to 1-1/4". Since you have a new tube with 1-1/4" diameter, just call ECI http://www.eci.aero/ and order a new dipstick gauge to match. All you have to do is tell them the part # of the tube you bought so they can send you the gauge of the appropriate length. The Ebay price is $75. That's what a new one from ECI will cost you.

I believe the dipstick tube (or housing) comes in 11.5", 10.5" or 6." If you will use the search function, there are many posts with part #'s, etc. Here is a link to a few I found helpful:

http://www.vansairforce.com/communit...+dipstick+tube

http://www.vansairforce.com/communit...+dipstick+tube

http://www.vansairforce.com/communit...ad.php?t=99155

[terry.mortimore]

Thanks JR, that made my day.

I assumed I was the first to run into this, I should have known better.


Cheers, Terry

[David Paule]

Look up Lycoming's tech support number on Monday and give them a call. They'll give you the appropriate part numbers.

Dave
P.S. There's a thread in the RV-3 section about this.

[tgmillso]

Hi All,

I'm struggling to find a bung to fit where the dipstick goes. I have a homebrewed crankcase air drier (desiccant/aquarium pump/air filter/moisture sensor etc) that I have been using for the past few months. This has been circulating air from a plug at where the dipstick tube enters the crankcase (with a small air fitting mounted to the plug that came with the engine), and back in via the breather tube, however I now have to install the dipstick tube permanently as the aircraft is nearing completion. Thus I will have to find a bung that matches the dipstick thread. The engine is an IO-360 M1B from Van's, and has a dipstick thread that measures 1.091" OD and 12 TPI. I purchased some 12AN bungs thinking these would fit, however they were too small. When I look at sizing charts, the 16AN bungs look too large. Does anyone know where I can find a bung (preferably aluminium) that will fit? or does anyone have an old dipstick that they would like to dispose of at a reasonable price I can butcher to make an air drier breather port out of (new ones are crazy expensive)? I figure there must be a few around given the AD/SB that had people change the dipsticks in the past.
On a side note, the crankcase air dryer has been wickedly good. It uses only 2 Watts of electricity and keeps the engine around 10% humidity.
Cheers,
Tom.
RV-7

[lr172]

If you have a lathe and obviously comfortable with precision work, cut the dip stick and thread both ends. Then make a coupler sized to extend the dip stick the exact amount of the extension addition. Just cut a taper on both ends of the coupler to keep it from catching. You could also skip the threads and use set screws or a press fit with loctite.

Larry