View Full Version : manifold preasure guage

04-07-2005, 12:58 PM
I put a MP guage in my 2+2 (0-320) about a year ago (150 hours ago) and it's starting to get oil in it. I can just see the oil at the bottom of the guage. When I put the guage in someone told me this might happen, but I thought I would see what happens. Is there a filter I can put in the 1/8th line going to the guage, or maybe I should put a petcock in the line and drain it once a year.


04-07-2005, 03:01 PM
I've got oil in my MP gage, too. It seems to drain out on its own, and hasn't caused any obvious problems. I'm going to live with it unless a problem develops.

04-07-2005, 03:26 PM
My 14 has a MP gage that it came with 57 years ago. It is mounted towards the top of the panel and I have never had an oil problem. Maybe if you use less than 17 qts when you change oil it will not flow up to the gage.

04-07-2005, 05:07 PM
17 qts.! I only put 15 in there when I change the oil. :D It holds 8 and when I change the oil and filter I put in 7qts..

Ron B.
04-07-2005, 06:46 PM
In my Rotorway helicopter, they advised to route the 1/8"line up as high as possible and then back down, to help keep fluid out of the guage. It's been working for me. I don't know if this would apply to a cub!

04-07-2005, 08:27 PM
What's a manifold pressure gauge? Crash

04-07-2005, 08:27 PM
That sounds like a good idea, I think I'll try it. Can't hurt


Steve Pierce
04-07-2005, 08:59 PM
Pacers and Tri Pacers have a loop in the MP line above the cylinder with a hole in it. Maybe that is why Piper did that.

Jerry Burr
04-08-2005, 09:11 AM
This was a regular problem for me as I used the smallest line possible for the gage. I put a one inch piece of tube two sizes larger in the line where it went vertical. Never been a problem since.
Crash. A MP and VSI are two instruments critical to accurate testing of flight parameters before and after any change to the airplane. A pair of 2" can either be velcroed in for testing or just istalled in the corner of the panel.
Tim. You can disassemble the gage and wash it out. Just be very careful with the glass. They break (real) easy.
Jerry. :)

04-08-2005, 02:10 PM
Thanks Jerry, I'am going up north next week after Sun&Fun. When I get up there I"ll take the guage out, clean it and put in a piece of larger tubeing :)


04-08-2005, 08:48 PM
Don't make fun of my friend Crash. He cannot help it.

Ron Babos
04-21-2005, 08:07 PM
One of the simplest ways to stop oil is to make a small can and mount it with the cap to the bottom. Add two tubes on the top of the can for the inline connection from engine to gage. Oil will now collect in the can and not the gauge. Remove the cap to drain excess oil out as required. Some thing the size of 2 ounces is more than enough to do the job, and should be thick enough so it won't cave in from vacuum. Ron

04-23-2005, 01:36 PM
Another easy fix is to simply install an automotive fuel line filter with replaceable element in the MP line. The filter will prevent any liquids from getting to the gauge. You aren't talking much liquid, either, so you can likely get away with changing the element once a year or so.