Here's an odd one

Cfrisella · #1 02-08-2012, 06:26 PM

I was checking over the engine today and I'm trying to figure something out. The short rubber hoses that connect the intake tubes to my cold sump all have what appeared to be oil droplets accumulating around the centers inside of the hose clamps. More so on the lower portions of each orange hose. Trying to figure out what the residue was, I wiped one down with white paper and it turned up "blue". Is fuel sweating through the hose? Why is fuel even getting there. Maybe one of you can explain this for me.

Ant CB · #2 02-08-2012, 08:17 PM

I had exactly the same thing.

On mine the gaskets on the intake tube to cylinder head join were perished so when you prime or shutdown fuel seeps past the gastket and runs outside the tube and down until it soaks onto the rubber flange.

Also oil can get around intake guides and also seep past the gaskets and run down the outside of the intake tubes and pool under the rubber flanges.

Normally it would run down inside the intake tubes and then discharge via the intake manifold drain under the air intake.

Vlad · #3 02-08-2012, 08:29 PM

I am currently changing them. Easy. Cheap also. SkyRanch sells them.

I am using TiteSeal on new ones.

Cfrisella · #4 02-08-2012, 08:43 PM

I only have 24 hours on the engine. It's weird though because it's only appearing in the middle sections. There's no sign of fuel running down the outside of the pipes.

Ant CB · #5 02-09-2012, 01:21 AM

Quote: "The short rubber hoses that connect the intake tubes to my cold sump"

Worth noting that these don't connect the intake to the intake tubes, the intake (on the ones I've seen at least) is a slip joint and the rubber flange goes around to give it an airtight seal.

I guess if the hose clamps were loose then fluid could seep through the slip joints and soak onto the rubber flanges.

I would check the intake bolts are snug onto the cylinder head and that the hose clamps are tight. Other than that, it's easy to take the intakes off and check the condition of the gasket.

How does it idle? If there is a leak it usually screws up the idle.

Also check the cylinder base where it is bolted onto the crank case for leaks, they could end up dripping onto the intake tubes.

If it's a new engine contact the builder and ask them about it.

terrykohler · #6 02-09-2012, 04:50 AM

Fix was as described above - new gaskets. Make sure the flanges are clean and smooth. Whether you use a gasket compound or not, be careful when you tighten down during install. Apparently these are very susceptible to pinching. Once the flange started to seat, I tightened from side to side only about a 1/4 turn at a time. Zero problems in the last 600 hours. Cheap fix.
Terry, CFI
RV9A N323TP

RV10inOz · #7 02-09-2012, 05:15 AM

I have had some interesting experiences here.

When I get back home tomorrow I will post more, but the Lycoming black gaskets seem to be a common thread here.

Anecdotal evidence suggest the Superior (Red) or ECI (green) gaskets are far better.

Do tell us more about your install.

WARNING
As for the guy with the photo and a gasket compound in view.....No Way...Naughty Naughty

Ask the engine builders, I think they will frown as well.

Cfrisella · #8 02-09-2012, 06:08 AM

I'll check those gaskets. I haven't been completely happy with the idle. Maybe an induction leak.

MS19087 · #9 02-09-2012, 02:46 PM

I am assuming that one would experience a higher MP at idle if these were leaking/bad? Since new I have had what I believe to be high MP at idle - something like 14" . . . maybe this is the source of my high MP?

Cfrisella · #10 02-09-2012, 03:27 PM

Well, if gas can seep out then air can seep in. Enough to make a difference? here's a picture of one of my hoses. This was after I wiped it down, but there were fuel droplets present.