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Breather tube mess


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Hey gang.
 
Have an M20K 231 with the -GB, Merlyn wastegate and Turboplus Intercooler. I had the intercooler installed last year. Ever since that install my breather tube is making one heck of a mess. We’ve washed the engine down several times. Used that special flashlight to detect oil leaks. Seals are all good. Bought an Airwolf Separator to hopefully take care of this, although I’ve been told it may not actually help despite their claims.
 
Found the install instructions on their website, seem to be much better then the generic book they sent us not mentioning actual instructions.
 
 
Doesn’t look like they accounted for an intercooler STC. Anyone have pictures of this install or opinion on my breather tube pukefest in general?
 
Mike
 
 
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Mike,

Some oil is always carried out the breather (that's why they quit putting them on cars). If you changed something and it causes more oil to come out the breather, then it might be best to figure out how the change precipitated this rather than put a bandaid on it. Excess oil out the breather generally comes from blowby past the piston rings that pressurizes the crankcase.

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I’m quite aware of the purpose of the breather tube. Compressions are all mid to high 70’s, its a 300hr engine. The only modification was the installation of the intercooler.

 

I’m wondering if anyone else has had this similar situation. 1 qt of oil out the tube every flight is getting annoying. And yes the dipstick is correct. We added oil 2 qt at a time to 6 to verify that a wrong one didn’t get put on when it was overhauled 4 years ago.

 

 

Again I’ll say that the only modification was to the induction system in the form of the intercooler install. We talked to Mooney about it initially and they had nothing. Said there’s a reason they all come with separators now. Their words not mine.

 

 

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How about we ask the intercooler guy..? :)

@Turboplus got a tech question for ya...  ^^^^ (regarding oil venting from a TC’d engine with a turbo plus IC...

 

Increased back pressure in the exhaust system may be accentuating the case pressure...

Putting a pressure gauge on the engine is a typical method for looking for case pressurization...

Typically exhaust getting past the rings, shows up as case pressure, and dark exhaust smelling oil in the case.

Best regards,

-a-

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The TSIO360MB in my K goes through less than a quart every 25 hours. 1400 hours on the engine.  

I keep it at 6 on the dipstick as any more than that gets spit out the breather. It took some time to find that sweet spot. Maybe yours is a little different?

 

 

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I installed a TurboPlus intercooler about 300 hours ago.  No change in anything except reduction in manifold pressure to obtain same level of performance.  I still use about 1 quart of oil every 25 hours.  Honestly, I can’t see why you’d puke out more oil just because of the intercooler installation.

Good idea on oil filler cap. I have to put 2 gaskets on mine for a tight seal.  Maybe you are pressurizing the crankcase that way?

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On 8/22/2019 at 6:17 PM, mooneyspeed said:


Have an M20K 231 with the -GB, Merlyn wastegate and Turboplus Intercooler. I had the intercooler installed last year. 
 

Don't wish to cause too much of a thread drift but how many AMU's to add the intercooler and wastegate?

I'm looking at a 231 @ all american and may be an option down the road.

Thanks!

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Merlyn was already on so I can't comment on its price, but the Turboplus Intercooler was about $5400 and then 12 hours of labor for install.

 

 

As a followup, we've done a few washes, ground runs,and seal changes.  Looks like the culprit is the vacuum pump garlock seal at this point.

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Is the engine talking to you?  If the consumption changed that much, I think so!  Do we have an idea on whether it’s blowing out or consuming the extra oil.  I mean if it’s using a quart in 3 hours, the whole belly would be coated (1 qt.) if we are just talking blowing by and not increased consumption.  If oil is all over belly, we kinda know the consumption rate may not have increased as much.  I believe your engine is talking to you and deserves at least a scope inspection.  

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Yes, we’ve scoped, done compressions. It’s dry inside. Compressions are good. Everything forward of the divider is clean. Through a process of elimination we’ve arrived at the Garlock seal at the vacuum pump. Also evidenced by a rotary spray pattern on the top cowling that gets distributed a bit by the intercooler flow.

Hopefully this fixes it and the pump lasts a bit afterwards too.




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If you need the pump, you might consider replacing it. If it gets any oil contamination, it won't last long. From Rapco's website:

Q: With my engine at idle, the vacuum gauge reads zero, but as the engine RPM is increased, the gauge will indicate vacuum. What causes this?

A: The cause for this symptom is most likely the carbon vanes sticking in the rotor slots due to an oil or solvent entering the pump. A leaking (Garlock) oil seal in the accessory drive case can cause this as well as the engine being washed with an oil based solvent without having the pump completely covered. Both of these fluids will work their way into the pump, mix with the carbon dust, and turn into a paste like substance.

Dry Air Pumps MUST remain DRY or their life expectancy will be cut extremely short. Inside each pump is a carbon rotor with vanes inside its slots. Centrifugal force slings these vanes out and against the Mil-Spec coated cavity walls moving air and creating vacuum or pressure. During this process, graphite dust is created as the vanes wear and helps keep everything in the pump moving freely. That is until the graphite dust is introduced to a fluid or moisture that creates the paste like substance, sticks the vanes in the slots and does not allow them to move freely and push or pull air until higher RPMS puts greater force on them to do so.

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  • 1 month later...
On 9/25/2019 at 10:26 AM, GEE-BEE said:

If the engine breather is in the slip stream, than you will have a siphon of oil

 

Had a early  m20 come in , I trimmed the hose length to lower tube, problem solved

Can you take a look at my pics and tell me if you trimmed it shorter than mine? I’m having an issue with an excessive amount of oil exiting my vent tube... the augmentor creates a low pressure area, but it is technically not in the slipstream.. I’m trying to rule out my vent tube arrangement.

I haven’t had the chance to see many other M20C’s

 

3212A6CE-FD9C-4CA6-864E-A9454ABE9746.jpeg

F88495EA-E0D9-4676-AC45-C34527073F03.jpeg

36642F08-3586-4CA4-A3EB-A10F1F827CD1.jpeg

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2 hours ago, philiplane said:

The breather exit must not be in the slipstream, or siphoning will occur. You can read more on this at the Airwolf website, they have good instructions on how to place breather tube exits so as to prevent siphoning.

Thank you. But I found no guidance regarding vent tube placement at the Airwolf site. The instructions for their oil/air separator for the Mooney use a duct hose as a vent outlet, so no tube is used With the oil/air sep installed

Edited by PilotCoyote
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The information is in their AFC-W300 installation manual, and they elaborate on what works and what doesn't. Basically you want the breather exit inside the lower cowl with no direct exposure to suction effects of the slipstream.The scat hose shown in the photos would be the worst possible placement and orientation for that hose.

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5 hours ago, philiplane said:

The information is in their AFC-W300 installation manual, and they elaborate on what works and what doesn't. Basically you want the breather exit inside the lower cowl with no direct exposure to suction effects of the slipstream.The scat hose shown in the photos would be the worst possible placement and orientation for that hose.

Interesting... That is contrary to the Mooney factory design. But the RV builders have done extensive testing regarding this, and their data supports your conclusion. My scat tube is part of the carb heat bypass plumbing on my plane, so I don't think there is an issue with that.... Are Mooney owners actually re-routing the it crankcase vent tubes? 

I had read the 311A instructions at Airwolf, as those are for my model Mooney...

I'll have to read the one you mentioned above. Thanks!

 

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Although I don't have an Airwolf separator I was interested in breather tube  management as mine seems to drip post flight.  Although I'm not surprised by the comment highlighting that suction that is formed when the breather tube is in the air stream it certainly makes sense.  Since there was a reference to the Airwolf installation manual I was curious what it said.  Here's is the most salient remark form the AFC-W300 install manual:

NOTE: The overboard duct should not extend into the airstream or below the lower engine cowl former.

That's it, nothing more or less.  Looks like I will be trimming my breather tube a bit to get it out of the slip stream this weekend.Thanks for the SA...

 

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Walk by another M20C for guidance...

The vent tube will drip after flights... usually some dirty water condensate.

The cowl flap usually gives the vent tube ends some shelter.

If you are getting oil out of the Case vent... be familiar with how much oil stays in the case, how much wants to leave... and other things like climb angle...

If your case vent isn’t original... look to make sure it has a leak hole in it... to prevent icing up...

It looks like somebody got inventive with your case vent...   its length looks like a good idea to prevent having oil get sprayed along the fuselage... but, the new invention has caused a little unintended side effect...

+1 on duplicating the original design of the tube with its leak hole to prevent ice blockage.

PP thoughts only, not a mechanic...

Best regards,

-a-

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12 hours ago, carusoam said:

Walk by another M20C for guidance...

The vent tube will drip after flights... usually some dirty water condensate.

The cowl flap usually gives the vent tube ends some shelter.

If you are getting oil out of the Case vent... be familiar with how much oil stays in the case, how much wants to leave... and other things like climb angle...

If your case vent isn’t original... look to make sure it has a leak hole in it... to prevent icing up...

It looks like somebody got inventive with your case vent...   its length looks like a good idea to prevent having oil get sprayed along the fuselage... but, the new invention has caused a little unintended side effect...

+1 on duplicating the original design of the tube with its leak hole to prevent ice blockage.

PP thoughts only, not a mechanic...

Best regards,

-a-

Yeah, I had a feeling that it wasn’t the factory piece....and it has no whistle hole. It must have been put there prior to the last engine overhaul, perhaps to do exactly as you suggest... I will need to fix this!

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