Oil Consumption and Breather Tube - Page 11

RV3bpilot · #**101** 06-30-2014, 11:13 AM

My engine was leaking oil and using it until I re-routed my breather tubes to another location which seems to have more negitive pressure. Since then my oil leak stopped and my engine is using less oil, about 15 hours per quart.
You may have problems with too much crank case pressure which I'm sure was my problem.

douglassmt · #**102** 07-02-2014, 01:55 PM

Saw this thread and wondered how my air/oil separator is doing with regard to plugging. Got out the borescope and looked up the exhaust. These are poor quality pix but I don't see any fouling or coke-like deposits. As I understand it, the deposits were accumulating on the outlet of the beveled tube? I have about 50 hours since installing the air/oil separator from Anti Splat. Not enough data to compare oil consumption, but the recently cleaned belly is still clean. Will remove drain tube from exhaust pipe fitting at next oil change to check entire area, might install the extra reed valve per Dan H.

Bill.Peyton · #**103** 07-02-2014, 02:49 PM

Bryan,
That is clean. I originally had mine protruding out 1". That could be some of the issue. I have corrected that and it looks just like yours now. BTW, what brand and type oil are you using?

douglassmt · #**104** 07-02-2014, 03:13 PM

Bill -

I'm using Phillips X/C 20/50.

Was I correct that the plugging you found was on the very end of the tube where it extends into the exhaust stream?

Bill.Peyton · #**105** 07-02-2014, 03:15 PM

Bryan,
I am using the same oil, and yes, the blockage occurred at the very end of the tube.

vic syracuse · #**106** 07-09-2014, 08:29 PM

I would encourage everyone to put the safety valve in the breather circuit. I reinstalled the valve on the exhaust hoping to keep the belly clean on the way to Alaska. I have now put about 30 hours on it and when we landed in Anchorage there was oil on the belly coming out from the safety valve. I took it apart today and it was coked completely shut again. I have now just put the breather tube directly overboard, and when I get home I am going to reinstall the airwolf oil separator, as I never had any oil on the belly when using it.
This is on my RV-10. In the 30 hours mentioned I added 3 qts of oil. I put in 9 qts at the oil change plus 1 can of camguard. So, I don't know if I should let it run lower than 6 qts. Kind of hesitant to go that low with all of the exposed flying up here in Alaska. We were actually solid IMC with approaches to minimums coming up the coast yesterday and the day before (Ketchikan and Yakutat).
I will add more later....

Vic

vic syracuse · #**107** 07-09-2014, 10:53 PM

Ok, sorry, had to go to dinner.

Here's the positive. I think we have proven that Dan Horton's recommendation for the safety valve in case of blockage actually does work. That's nice! The last time mine coked up I had oil blowing out from every seam on the engine and luckily didn't blow the nose seal.
The last time I had it installed with the Anti-Splat air/oil separator. This time it was the straight breather tube.
I think we need to figure out why it is coking up. I believe it might have to do with location, but don't know for sure. Mine is installed right in the bend of the tail pipe aft of the mufflers/heat muffs on the RV-10. IO-540 with Vetterman exhaust.
The compressions are all in the mid 70's or better. I measured crank case pressure and Dan and I agree that it seems normal, so I am not thinking I have excessive blow-by. The engine burns about a quart of oil every 7 hours or so, and the oil analysis from Blackstone says everything is great. Perhaps I am running the oil level too high, but it is interesting to me that it also coked up when running the separator.
Again, I would certainly recommend that anyone going on long trips should have a safety valve setup.

Vic

Toobuilder · #**108** 07-10-2014, 06:57 AM

Has anyone looked at putting the valve right at the engine? As long as the hose (or pipe) connecting it to the exhaust has a stiff enough wall, there still should be a strong vacuum pulse. That should solve the problem of valve coking.

I was considering adding my second (safety) valve right to a fitting on my vacant vacuum pump cover plate rather than routing it to a corner of the cowl somewhere.

douglassmt · #**109** 07-10-2014, 07:59 AM

After talking to Bart at Aerosport (now Titan), I add 9 qts at oil/filter change, which becomes a little less on the stick after the filter fills up. Then I add a quart at 7-7.5 qts. Before the ASA separator I was still getting oil on the belly but was adding about a quart every 12 hours. The oil on the belly wasn't bad but added up over time. After the ASA separator I have no oil on the belly but haven't had enough time to get a new oil use rate. I also don't have any coking in my exhaust pipe at the separator discharge, but it's only been 50 hours or so. I will monitor it but I suspect it may be due to the oil levels that I run.

Bill.Peyton · #**110** 07-10-2014, 12:35 PM

Mike,
It's not the valve that's coking up, it's the outlet of the spigot at the exhaust. I suspect that Dan is correct, for the rv10 we must have the outlet location placed where the exhaust temp is perfect for coking. I was burning around. A quart every 10 hours or so, so that's a little less than Vic. This could be the reason it took over 100 hours for mine to start to clog up. I suspect I am going to have to relocate the A/O sep outlet upstream to a hotter area, or just dump the outlet overboard directly.