Exhaust popping ECI IO 360

[donaziza]

Busted my hip--can't fly, so was out today just running the ECI IO 360 for about 20 minutes just to oil up the bearings. During this time, I got maybe 3 or 4 loud exhaust pops. About 1100 RPM and I always have mixture as lean as possible when I taxi.)

Then I remembered getting maybe 3 of these pops some 3 weeks ago while taxing out to fly. During takeoff, flying and taxing back in, everything was fine.

Would appreciate any thoughts out there if anyone knows why.

Thanks much

[lr172]

I find that sometimes you can get popping when too lean in auto engines. Next time it happens, richen it up a bit and see if it goes away.

Also, if I were to just "oil the bearings," I would run it for a minute or two, not 20 minutes. While I agree that oil dripping off the cylinder walls helps to kill cylinders, equally as damaging is building up moisture in the oil. This moisture comes from the H2O in the combustion gases and will build up over time. This moisture also comes from condensation when a hot engine cools down with more than moderate relative humidity. This water mixes with other combustion byproducts and becomes corrosive. This is what causes corrosion on steel thing like cranks, cams, etc. It usually takes 30 minutes at an oil temp near 200* to burn this out.

Larry

[grubbat]

Double check to make sure you don't have a possible intake or exhaust leak.
cj

[walkman]

Someone correct me if I'm wrong, but I was always told it was better to just leave then engine alone than to start it up for a little while and shut it down. For two reasons. First that a lot of wear happens during start when there is no oil pressure, and second that if you are just running it for a few minutes there is H2O byproduct of combustion that never gets properly boiled off increasing your chances of creating corrosion.

[lr172]

From my research, it takes a good month for the oil to run off the cylinder walls (depends upon specific oil additive package). Starts within that month (or whatever time it really is) do no significant damage. It's the starts that happen after the wall is dry that cause the real wear. Similar situation in the bearings and journals, but to a lesser degree. So, if you start it every two weeks, you prevent the wear. I am not advocating this approach.

The moisture problem, as I mentioned above, is a real issue. I don't know much about lycomings, but I am familiar with Porsche horizontally opposed, air cooled engines, and I see a good 20 minutes before the oil is north of 200*. You also need some time at the hotter temps to burn the moisture out, hence the general recommendation of an hour.

I suggested a 2 minute run, as it would only take a few seconds to recoat the cylinder walls and the less time running, the less moisture to accumulate. Also no condensation from cool down.

Qoute: First that a lot of wear happens during start when there is no oil pressure,

If that were true, each start would be damaging. We know from experience this is not the case. Some of the best looking engines at TBO are those coming from the flight school and they typically only run an hour for every start, however, they don't sit for extended periods of time and each run gets to operating temp. One of the key properties of engine oil is it's ability to "Cling" to surfaces for a good period of time and this clinging oil protects the engine on the next start, assuming gravity hasn't finally overcome the clinging, see above. Granted, there are negative attributes of short runs, but this is not a key one. Most are related to the engine not spending measurable time at designed operating temperature.


As an aside, my Porsche engine runs oil temps between 235-250* and that is considered normal. Somewhat different additive package in auto oil I suspect, but hopefully makes some feel better that they are not doing damage when oil temps get into the 200's.

Larry

[Smilin' Jack]

I also get popping in the exhaust especially if I am just starting and taxing out after a flight for another while the engine is still hot. I have a 4 pipe exhaust system on an IO-360

I talked to Stein at Stein Air and also Carlos Gann who built the engine and Larry Vetterman who built the exhaust system.

They have all said it is on my aircraft because I have hardly no back pressure in the exhaust system. I have the throttle body adjusted so I get a nice 70rpm rise just before shut down and I taxi the plane at approximately the 60 rpm rise the engine gets real smooth at this point.

They all stated it is a sign of a good engine... and the popping will not hurt anything. In flight if you quickly retard the throttle I will occasionally get the popping too. So I have learned to slowly retard the throttle in flight and that has eliminated the popping.

Hope this helps...
I should say this in retrospect. When I first fired up the plane with zero hours on it. I had an flow divider that was not even. One cylinder was indicating way leanon the EGT with the temperature climbing to 1300 degrees at only 1400 rpm. and that cylinder was not getting enough fuel. The engine felt like it was coming out of the aircraft. popping and sputtering.. I could hardly make 1400 rpm the vibration was so bad.
Called precision and got another fuel flow divider and it solved all the problems. That was 100 hours ago.

If your EGT temps and CHT temps are all grouped together... you should be fine.


Jack

[donaziza]

Originally Posted by Smilin' Jack

I also get popping in the exhaust especially if I am just starting and taxing out after a flight for another while the engine is still hot. I have a 4 pipe exhaust system on an IO-360

I talked to Stein at Stein Air and also Carlos Gann who built the engine and Larry Vetterman who built the exhaust system.

They have all said it is on my aircraft because I have hardly no back pressure in the exhaust system. I have the throttle body adjusted so I get a nice 70rpm rise just before shut down and I taxi the plane at approximately the 60 rpm rise the engine gets real smooth at this point.

They all stated it is a sign of a good engine... and the popping will not hurt anything. In flight if you quickly retard the throttle I will occasionally get the popping too. So I have learned to slowly retard the throttle in flight and that has eliminated the popping.

Hope this helps...
I should say this in retrospect. When I first fired up the plane with zero hours on it. I had an flow divider that was not even. One cylinder was indicating way leanon the EGT with the temperature climbing to 1300 degrees at only 1400 rpm. and that cylinder was not getting enough fuel. The engine felt like it was coming out of the aircraft. popping and sputtering.. I could hardly make 1400 rpm the vibration was so bad.
Called precision and got another fuel flow divider and it solved all the problems. That was 100 hours ago.

If your EGT temps and CHT temps are all grouped together... you should be fine.


Jack

This sounds good except for one thing. My engine didn't do this before. This is something new.

[AlexPeterson]

Originally Posted by donaziza

This sounds good except for one thing. My engine didn't do this before. This is something new.

How long is "before"? OAT higher?

[RV10inOz]

Intake gasket leak? You can use your EMS to find this by flying WOT full rich then pull back on the throttle like you would on downwind to slow up to land. The EMS will show which ones are at fault if this is the case.

[donaziza]

Originally Posted by AlexPeterson

How long is "before"? OAT higher?

Have had the airplane for just under a year.