M20K Rocket Breather Tube-Picture Wanted

[Piloto]

Just now, floridaflyer said:

Thanks Jose. I'm already using 100W oil and according to engine monitor oil temp stays below 200F during climb. I ordered an AIrwolf separator, unless and until leakdown + borescope says otherwise, oil won't have any other way to go but back in crankcase...

For best performance on the oil separator plug any side holes on the breather tube.

José

[Vlakvark]

You think 100W in summer unstead id 15/20?

 

[peevee]

15 minutes ago, Vlakvark said:

You think 100W in summer unstead id 15/20?

 

Ram recommends w100 in summer and i think most consider them the leading authority on big bore Continentals. W80 for winter.

http://www.ramaircraft.com/Maintenance-Tips/Oil-Recommendations.htm

[snowds]

Hi all.  FloridaFlyer reminded me via PM to get my butt on here, so thanks to FloridaFlyer for the reminder.

The oil loss through the breather hose continued sporadically until we did an overhaul last year.  Even with the new engine, the cowling gets a few drops of oil on each flight, but nothing like what it used to be.  The oil shows up on the outside of the right gear door; the only way that can happen is when the gear is up and the doors closed.  No oil shows up on the left door, which tells me this is happening in cruise, not during takeoff, climb, or landing, when the left door is right next to the breather. One thing the overhauler mentioned is the possibility that the cap locking lobes on the filler neck tend to wear down over time, leaving the dipstick less tight than it should be, thus allowing air flow into the crankcase, especially when the engine compartment is at high pressure during high speed ops.

 

When we talked to Continental about the issue, they said first replace the entire dipstick and o-ring (they said do not replace just the ring, and definitely do not double the ring).  Then, if the problem persists, change the prop seal.

 

My working hypothesis is that even a new prop shaft seal isn't enough to completely block air from entering the crank at the speed the Rocket goes, and a less than perfect shaft seal just causes that much more oil to blow.  Unfortunately, I have no practical way to test this hypothesis.  With a new engine, it's just a couple/few drops per flight now, which I can live with.

 

Hope that helps!

Stephen

[floridaflyer]

Stephen thanks for the details, this is very helpful. My filler cap/dipstick seems rather loose so I'll try to seal it better and go fly it to see if it makes a difference on amount of oil consumed and whatever pressure I'm reading on the airspeed indicator I'm in the process of hooking up to the filler.

[snowds]

Great, let us know how it goes.  At one point, we connected an airspeed indicator to the filler, and ran it at full power.  We saw no increase in pressure in the crankcase.  However, we did not try doing it in flight, which is a much better experiment.

[floridaflyer]

Just finished installing an Airwolf oil separator so I figured I'd post the pics for other Rocket owners. The airsep is big. 10 hour job, could have been 2 hours less if I had the proper spring compressor and crowsfoot 7/16" wrench for the #2 back intake bolt. The most time-consuming step was replacing the #2 cylinder pushrod tube with the Airwolf tube so it can be used to return the oil to the engine, it was a real tight fit to wedge the new tube past the cylinder cooling fins after removing the intake. Had to fabricate a simple L-shape aluminium bracket to secure the airsep using the three bolts holding the LH side of the oil cooler. It's a tight fit but there was no space on the RH side of the cowling, not enough space under the LH intercooler (which would have probably disrupted the air flow anyways), and the space next to the LH intercooler wouldn't have placed the airsep high enough for the oil return hose to continuously slope downward back to the pushrod tube. I'll report on performance soon. On a related note an A/S indicator hooked up to the oil filler cap read around 20 MPH at 2,200 RPM on the ground, so well below the TCM maximum of 90 MPH which would indicate blowby is not the issue.

[peevee]

That looks real nice, makes getting to and safety wiring the filter harder though.

[floridaflyer]

Peevee this engine is so tightly cowled I had to buy an oil extractor from Harbor Freight to suck the oil out of the filler cap because the oil "quick drain" is so difficult to access. Makes my old Lancair IV look roomy in comparison. The oil filter is a PITA to remove and requires intercooler removal. Good news is in the picture the rubber hose connecting the vacuum pump outlet to the airsep looks like it goes over the top of the oil filter, but it actually goes aft so it's not in the way and easy to disconnect anyways. 

[Jim F]

Hi Floridaflyier

Why is the pressure side of the dry vacuum pump plumbed into the oil separator?

jim

[floridaflyer]

Jim F I understand the Airwolf system uses the vac pump discharge to help push the oil separated by the airsep back into the crankcase. If there is no vacuum pump available it says to hook up the hose to a hole in the baffle to use ram air pressure instead. At $950 this better work!

[peevee]

2 hours ago, floridaflyer said:

Peevee this engine is so tightly cowled I had to buy an oil extractor from Harbor Freight to suck the oil out of the filler cap because the oil "quick drain" is so difficult to access. Makes my old Lancair IV look roomy in comparison. The oil filter is a PITA to remove and requires intercooler removal. Good news is in the picture the rubber hose connecting the vacuum pump outlet to the airsep looks like it goes over the top of the oil filter, but it actually goes aft so it's not in the way and easy to disconnect anyways. 

I have no trouble whatsoever with the quick drain. Do you have the rocket drain fitting?

I certainly have never removed the intercooler for a filter change.

[snowds]

2 hours ago, peevee said:

I have no trouble whatsoever with the quick drain. Do you have the rocket drain fitting?

I certainly have never removed the intercooler for a filter change.

+1.  The quick drain on mine is a piece of cake with the Rocket-supplied drain tube, and removing the oil filter is trivial in mine, certainly not requiring removal of an intercooler.  Hardest part of doing an oil change is putting the bottom cowling back on.  I can definitely see the oil change process hindered by the separator, but maybe worth it for a clean belly.

[floridaflyer]

8 hours ago, snowds said:

+1.  The quick drain on mine is a piece of cake with the Rocket-supplied drain tube, and removing the oil filter is trivial in mine, certainly not requiring removal of an intercooler.  Hardest part of doing an oil change is putting the bottom cowling back on.  I can definitely see the oil change process hindered by the separator, but maybe worth it for a clean belly.

Can anybody post a picture or link to this Rocket drain tube we're talking about? My quick drain can be activated with a rather fat Bogert-style probe (see pic below), and the turbo housing is too close to reach the valve. I'm not a big fan of quick drains and I don't like removing the bottom cowling, but it would be nice to change the oil the old fashioned way once in a while. BTW I misspoke, removing the I/C is not a requirement, it's a 5-minute job well worth the improved access to the oil filter and minor considering the oil extractor avoids having to remove the bottom cowling.

[peevee]

I don't have a photo at hand. It's about a 3/4 inch alum tube with two fingers at the top to hold it on the drain fitting.

They cost 250 from rocket and probably ten bucks to make.

 

I might try the extractor route every other change just to save wear and tear on the cowl.

[floridaflyer]

1 hour ago, peevee said:

I don't have a photo at hand. It's about a 3/4 inch alum tube with two fingers at the top to hold it on the drain fitting.

They cost 250 from rocket and probably ten bucks to make.

 

I might try the extractor route every other change just to save wear and tear on the cowl.

Thanks for the info. I'm quite happy with the extractor I bought: https://www.harborfreight.com/6-1-4-quarter-gallon-oil-extractor-46149.html

[carusoam]

Great photos, ff!

thanks for sharing them.  It is really tight back there.

Is that a spare alternator in there as well?

Best regards,

-a-

[floridaflyer]

Just now, carusoam said:

Great photos, ff!

thanks for sharing them.  It is really tight back there.

Is that a spare alternator in there as well?

Best regards,

-a-

No the prior owner took the spare alternator out to try to improve the CG.

[Marcopolo]

  The prior owner may have removed the wiring for the spare alternator, but he left the spare alternator mounted to the engine.  Its the orange B&C unit next to the vacuum pump, unless you've got field approval to run that as the primary, which I doubt, as they are maybe 20amp units.

 

R

[floridaflyer]

On 6/28/2017 at 1:45 PM, Marcopolo said:

  The prior owner may have removed the wiring for the spare alternator, but he left the spare alternator mounted to the engine.  Its the orange B&C unit next to the vacuum pump, unless you've got field approval to run that as the primary, which I doubt, as they are maybe 20amp units.

 

R

I was wrong, the orange is a small 28V 4A backup alternator.

[peevee]

1 hour ago, floridaflyer said:

Thanks for the info. I'm quite happy with the extractor I bought: https://www.harborfreight.com/6-1-4-quarter-gallon-oil-extractor-46149.html

next time I'm at the hangar I'll try and get a shot of it. I was happy rocket had one, but less than happy to pay $250 for it... plus shipping.

 

I've had this guy for years

https://www.amazon.com/Mityvac-7201-Fluid-Evacuator-Plus/dp/B0002SR7TC

I had just never thought to use it on the airplane. I have mixed feelings about it, but every other change it might be a nice time saver and save wear on my cowl, removing the lower cowl on the rocket (and K) is a 2 man hassle as I'm sure you're aware. I'm thinking I can remove the lower every other change for a full drain and to clean/rotate the plugs, then the interim changes just use the extractor.

[peevee]

33 minutes ago, floridaflyer said:

I was wrong, the orange is a small backup alternator.

I'd like to have one of those. Need to get an electric backup AI and we can.

[Yooper Rocketman]

23 hours ago, peevee said:

 removing the lower cowl on the rocket (and K) is a 2 man hassle as I'm sure you're aware. 

I've been doing mine by myself for over 10 years.  Will have to You-Tube it the next time.  Clearly easier with two, but I rarely have the luxury of an extra set of hands.  I like to really inspect the engine compartment every oil change, which full cowl removal allows.  I've found a few issues over the years before they became serious with that procedure.  

I removed the intercooler once after purchase in 2000 (because the IA doing the pre-purchase did the same) and have done every filter change since with no issue with it on.

I have a much smaller oil separator which gives a lot more room to work in that area.  I'll get a picture of that the next time the cowl is off.

Tom

[milotron]

I remove and replace both upper and lower cowls solo on the ramp without too much issue. I use a large rubbermaid plastic box with foam on it to support the lower cowl going in and coming off. Takes a bit of patience but not really that big of a deal.

 

The worst part is getting the upper cowling on without hooking the TKS nozzle or the air breather.

 

iain

 

 

[peevee]

1 hour ago, milotron said:

I remove and replace both upper and lower cowls solo on the ramp without too much issue. I use a large rubbermaid plastic box with foam on it to support the lower cowl going in and coming off. Takes a bit of patience but not really that big of a deal.

 

The worst part is getting the upper cowling on without hooking the TKS nozzle or the air breather.

 

iain

 

 

Psh, I have a fix for that just take it off and send it to me. I'll put it all on ours

 

I find that even with support the action of sliding the cowl under while tilting the back but clearing the prop hub is difficult and easier with two.

It's always a lot easier if you remember to DC the cowl flaps also