Really hot cowl after shutdown

[TheTurtle]

Flew from sna to cno to get gas and then came home.  After parking while pushing back into the hangar I noticed the cowl was really hot to the touch and there was some gurgleing noises I havent heard before.

cht/egt temps during the flight were fine and I was running rich if anything as we only went to 3k and didnt lean much since its such a short trip.

Oil temp wasnt running high but I dont know how much I trust that 6pack gauge and I wasnt watching it all that well because the light on it doesnt work and it was anight flight so it just got hit with the flashlight during my scan a few times.

I pulled the cowl off and saw a drop of oil on one of the exhaust bolts.  I also noticed a loose exhaust nut on the other side.

I've put about 30 or 40 hours on this oil change and have added probably 6qts in that time.  The oil is noticeably darker than fresh oil and kind of smells.  I think ill change it this weekend but I thought 50-100 hours per change is pretty standard.

Engine does have 1700 hours.  Was hoping to get to TBO on her since my wife will kill me if I need a new one lol!!

any thoughts or ideas?

I have a GEMIII and will pull the SD card and look at the numbers tomorrow.

 

[Browncbr1]

The oil is on an intake riser.  Replace the intake gasket.  The gurgling is fuel expanding and bubbling in the lines as it is heating up after shut down because there is no air flow.   Hot cowl is normal after shut down in summer.  

I would be changing oil more often, ~25 hours ...  Retorque nuts and bolts since you see the loose one. 

Edited September 27, 2016 by Browncbr1

[XXX]

30 minutes ago, Browncbr1 said:

The oil is on an intake riser.  Replace the intake gasket.  The gurgling is fuel expanding and bubbling in the lines as it is heating up after shut down because there is no air flow.   Hot cowl is normal after shut down in summer.  

I would be changing oil more often, ~25 hours ...  Retorque nuts and bolts since you see the loose one. 

Ditto the above. I would also send an oil sample out to Blackstone for analysis and get a baseline established so you can keep track of any changes. 

[carusoam]

Some things that can be read around here...

 

1) Read up on hot starts for the explanation of the boiling gurgling sounds...

If your CHTs were in the 300s, the air above them is going to be hot.  The cowling doesn't have an insulation blanket under it.

Typical defense for this situation is to park into the wind and open the oil door on top of the cowling.

 

2) Oil burned vs oil leaking vs. ejected overboard...  

an IO360 typically uses a quart every ten hours.  

If you fill the oil over the 6qt line(?) the extra quart that you put in gets exhausted over board out the engine vent line.  The case vent tube is the source for oil on the plane's belly.  See how much is running down the bottom of the plane.

 

3) Oil color and aroma...

New engines with tight tolerances between Pistons and cylinders don't have as much blow-by of exhaust gas into the oil sump. Worn rings and rough cylinder walls allows a lot of exhaust to pressurize the case.  If your oil turns black quickly it may be collecting a lot of exhaust by-products. Colors can range from golden brown, to dark brown, to really black...  if it turns really black in ten hours and smells like exhaust, that's a hint!

 

4) Oil drips...

There are a lot of sources for potential oil leakage.  Most of them are easily correctable.  None of them are normal. Oil return lines on each cylinder, seals at the front or back of the engine, or under the governor.  

Oil spreads and can make it difficult to find the source. 

Problem leaks are uncommon but can occur.  The silk thread seal between case halves is a challenge to replace. Cracked engine cases can be expensive to get welded.

 

This is PP type knowledge.  I am not a mechanic.

Best regards,

-a-