dripping turbo

[juergenklicker]

I just had both turbo check valves replaced at my M20K-262, together with an oil- and oil filter change. Ameliorated a dripping-oil-from-the-exhaust problem, but did not completely resolve it.

When I found another (smaller, I admit) paddle the next day, I was ready to puke.. My understanding is that every drop of oil going into the turbocharger must go through one of the two check valves to get there. Now I am looking at the "unlikely" issues:

1) new check valve bad on arrival

2) If these check valves would have been mounted incorrectly all along, chances are my mechanic would have done the same with the replacements. I am not talking things like "attached to the wrong oil line", I am thinking about a possible required mounting angle, geometrical distance from the turbocharger etc. 

Anybody had a similar experience?

Anybody can provide a picture of correctly mounted (working) check valves in a 262?

Thanks much for your help!!!

[N201MKTurbo]

I once installed the return check valve backwards. upon engine startup there was about a quart of oil on the ground and a huge cloud of smoke in about 30 seconds.

So I don't think they are backwards. Just make sure the arrows are pointed the right way. Follow the hoses from the scavenger pump to the turbo and then back to the oil supply. You should meet the pointy end of all the arrows.

 

Funny story,

The only time I have ever had an FAA inspector come to my hangar while working on my plane was right when this happened. I got out of the plane he walked over and flashed his badge and asked what was wrong. I told him I just finished working on the turbo and I was doing a run-up to see if everything was OK. I said I think the check valve is backwards. He asked to see my mechanics license. I showed it to him, he handed it back, said "you should fix that" and walked away.

Edited September 16, 2015 by N201MKTurbo

[N201MKTurbo]

FWIW

It is real easy to take those check valves apart and inspect the seals, clean them, replace the O-rings and inspect the springs on the flappers. After they are all clean and dry you can check them by blowing through them.

[kortopates]

Orientation of the check valves in listed in the TSIO-360 maintenance manual or overhaul manual or both. But the issue is exactly as N201MKTurbo says. I have never seen the leakage myself. Another pilot friend got it after maintenance from one being installed backward. However, if you have oil dripping from the exhaust the issue could be the turbine shaft is leaking and the turbo needs overhauling. Check the turbine shaft foreplay for excessive side to side movement. Oil out the exhaust or into the induction manifold are the common ways they wear out short of  a broken turbine blade causing a more catastrophic failure. One very clear sign of turbine leakage from being worn out if you see much higher oil consumption above 12K and higher versus below 10K where it remains pretty normal. Oil is always pumping through the same, but the wastegate is bypassing the turbo for the most part till you get up in altitude. 

[Guest]

The body of the check valve also has the word "hinge" on one of the flats.  It is meant to be installed upward.

Clarence

[juergenklicker]

Dear all,

thanks for all your help. The Issue is fixed.

Looks like my bird has been sitting in the hangar for too long at the time I bought it. It appears some gunk in the oil kept at least one of the valves from closing properly even after cleaning it. Now, a couple of grand for new valves AND a couple of oil changes later, the problem is gone. It turns out airplanes are made to fly, and sometimes flying is the best repair. 

Juergen

[carusoam]

It may be a good idea to have your mechanic flush the oil lines for some things like the turbo system...

the oil cooler and the prop would be less interesting but worthy of the cleaning thought.

These are ideas that I have learned on MS in general.  Not specific to any one particular plane.  But things I would want to know prior to taking ownership.

Blocked oil lines can get expensive...

Best regards,

-a-

[juergenklicker]

done.