What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Dip stick not staying seated - any one else have this issue?

Drippy

Well Known Member
Guys,

I threw this out on the traditional motor forum and got nothing so I though I would try it here.

The dip stick on my IO540 C4B5 is the friction fit style vs the screw on style.

I have recently noticed a little leaking around the stick and thought I must not have properly seated it, but coming home yesterday about 1.1 into a 1.2 hour flight I noticed oil streaming from the aft end of my oil access door. Upon landing I pulled the top cowling and saw oil around the top left side of the engine and the inside of the rear baffle.

I was also able to easily lift the dip stick ~.25" without using the lever. I didn't take an picture, but I am pretty sure this was the source of oil due to the mess.

I had made a concerted effort to ensure the dip stick top was down before I started the return leg and had seen no leaking when I check the level before starting the return leg, after looking closely due to previous mentioned leak

I was going to order a new washer and try that but really would rather swap to a screw in style if possible. Anyone else experience similar issues?
 
Yes, you could try replacing the o-ring on the stick, see if that does it.
Also check the gasket at the bottom of the dip stick tube, possibly leaking there.
Last thing, check for a restricted oil breather line, possible build up of crank case pressure?
 
I'm with Ralph---check for a restricted breather hose--sounds like too much crankcase pressure. Used to have it back in the racing days.
Tom
 
High Pressure

I will take a look it was a cold day ~20F at alt and I flew through some snow ect, could have frozen up???

Also I did install a slime fighter device last spring and while I haven't seen any issue up to now, but it could have become clogged up, maybe??

I take things apart and take a look.

Thanks
 
What if

It is actually possible for the crank case breather hose to freeze shut. If this happened, popping the dip stick could happen. It is common practice to drill three 1/8” holes in the side of the breather tube to provide alternate venting if the tube ever did plug up with ice. Your push in dip stick is actually a good safety feature, if ever there was a pressure build up in the crank case. Think what would happen to the other engine models that have screw caps on their dip sticks- if they had the vent tube freeze, there would a real possibility of popping out the front crank seal!
 
Drill some holes

Ralph

Thank you, I was thinking that and that is why I mentioned the temp and snow, though I haven't had the issue before it was a nasty combo of moister and cold that day.

I will look into adding a few safety holes. Though I wish I had thought to look at the breather post flight.

Mike
 
Flew today

So a little more info. I checked the oil today and may not have lost as much as I though during the previous 'oil streaming' flight. The oil level was right were I expected it so I don't believe I lost to much. I also checked the oil breather line didn't find any obstructions - If I had one it melted - though I didn't see any oil on the floor either.

I few it today and didn't have any issue. There was a very little bit of oil around the top left side of the engine but the cap remained down and the little oil might just have been stuff I missed cleaning up that got swirled round due to air flow.

One question - I ran into a guy today who mentioned he has had a similar issue when flying through light rain and he believed it was water flowing through the engine that picked up any oil around the engine and exiting a gap in the oil access door.

Anyone else heard of this before? I hadn't.

Thanks
 
I had a similar problem with my four cylinder Lycoming some time back.

I would tighten it and when I would land it would be completely unscrewed with oil streaming out of it.

It took me a bit to find the problem, which was....

Wait for it....

Behind the flywheel, where you couldn't see it were two mud dauber tubes, back-to-back. The imbalance was just enough to vibrate the dipstick loose.
 
almost spit out my coffee!

...

Behind the flywheel, where you couldn't see it were two mud dauber tubes, back-to-back. The imbalance was just enough to vibrate the dipstick loose.
That's one I have not heard! Wow! :D Those pests are quick - they can build those nests in just a couple of hours - a good thing to look for during a preflight.
 
Back
Top