White smoke on a Wright R1820-56 - Aircraft of World War II

lolo67 · 10-05-2009, 04:07 PM

Hello,

A friend (but not terribly keyboard/internet expert) operates a T28 with a Wright Cyclone R1820-56 and experiences white smoke coming from the exhaust pipe of the two lower cylinders.

The engine has the clean kit. He replaced the two cylinders with two overhauled (albeit some time ago) cylinders but the problem is still there. This is only happening at idle.

Any guru on Cyclone engines around here, to give us a few hints ?

Many thanks and by the way, great forum !

Henri.

FLYBOYJ · 10-05-2009, 05:21 PM

Quote:

Originally Posted by lolo67

Hello,

A friend (but not terribly keyboard/internet expert) operates a T28 with a Wright Cyclone R1820-56 and experiences white smoke coming from the exhaust pipe of the two lower cylinders.

The engine has the clean kit. He replaced the two cylinders with two overhauled (albeit some time ago) cylinders but the problem is still there. This is only happening at idle.

Any guru on Cyclone engines around here, to give us a few hints ?

Many thanks and by the way, great forum !

Henri.

Has he done a compression check on those 2 cylinders? What's his oil consumption? At landing does the engine backfire when the throttle is pulled back quickly? Dose this happen at idle when the engine is hot?

For the most part it sounds like he's got some problems with exhaust valves or valve guides.

lolo67 · 10-09-2009, 10:21 AM

Thankyou FlyboyJ !

Well the engine does it ONLY when hot and at idle. With power on, it doesn't smoke white any more. And when the engine is cold, it does not either. As for your other question, he never pulls back quickly the throttle so he can't say, but he will do so this afternoon during a flight test and will report.

One thing is, when he replaced the two cylinders, he kept one oil-scraper ring from the old cylinders because he did not have a replacement of the same type. I believe that the tightness of the rings is better when the engine is delivering power than at idle, is that correct ? That could be an explanation then. But why only when the engine is hot ?

This afternoon he will take momentarily the clean kit off, to see what happens.

Many thanks for your informed comments, FlyboyJ, and blue skies !

Kind regards,

Henri.

FLYBOYJ · 10-09-2009, 10:34 AM

My Pleasure Henri.

The oil scraper ring "may" be part of the problem. It does sound like valuve guides. After today's test flight I'd recommend a compression check.

lolo67 · 11-02-2009, 10:40 AM

Hello FlyBoyJ again !

Problem still not solved. He did a flight recently, did not notice any change in behavior when he pulls back quickly or not the throttle, the engine always rattles a bit but no different as before. Like said, this is only happening at idle, engine hot. He is now in the process of looking at the two scavenge pumps, the one in front is fine and he will be looking at the one on the back side of the engine, fact is when he activates the clean kit electric pump after a flight he pumps a lot of oil back in the oil tank, which would suggest that the mechanical pumps do not scavenge well the oil during or just after the flight.

Compressions are all OK. Also, the harness was changed after the problem appeared, to no avail.

I have also suggested to look at the surface of various cylinders after a flight, by taking the plugs off, the two down cylinders but also others, for comparison, if the surface is oily then that should indicate a worn scraper ring, shouldn't it ? (I'm no wizard in radial engines).

I've also heard, on a Franklin engine (flat-six), of a cracked boss in the cylinder where the valve guide is inserted, the crack was minor and only visible with a magnifying glass, but obviously oil could then flow by. But that required taking the jugs off, this is only for the next step of problem solving.

This problem is actually quite puzzling.

Many thanks for your help,

Henri.

FLYBOYJ · 11-02-2009, 12:14 PM

Quote:

Originally Posted by lolo67

Hello FlyBoyJ again !

Problem still not solved. He did a flight recently, did not notice any change in behavior when he pulls back quickly or not the throttle, the engine always rattles a bit but no different as before. Like said, this is only happening at idle, engine hot. He is now in the process of looking at the two scavenge pumps, the one in front is fine and he will be looking at the one on the back side of the engine, fact is when he activates the clean kit electric pump after a flight he pumps a lot of oil back in the oil tank, which would suggest that the mechanical pumps do not scavenge well the oil during or just after the flight.

Compressions are all OK. Also, the harness was changed after the problem appeared, to no avail.

I have also suggested to look at the surface of various cylinders after a flight, by taking the plugs off, the two down cylinders but also others, for comparison, if the surface is oily then that should indicate a worn scraper ring, shouldn't it ? (I'm no wizard in radial engines).

I've also heard, on a Franklin engine (flat-six), of a cracked boss in the cylinder where the valve guide is inserted, the crack was minor and only visible with a magnifying glass, but obviously oil could then flow by. But that required taking the jugs off, this is only for the next step of problem solving.

This problem is actually quite puzzling.

Many thanks for your help,

Henri.

Hi Henri;

Sounds like you're right on track on what I would do and yes "if the surface is oily then that should indicate a worn scraper ring."

Pulling the lower jugs may be the last resort and aagin you could replace valve guides as a precaution.

What's his oil consumption like? Is he burning a lot of oil?

10-05-2009, 04:07 PM	#1
lolo67 Junior Member Join Date: Oct 2009 Posts: 3	White smoke on a Wright R1820-56 Hello, A friend (but not terribly keyboard/internet expert) operates a T28 with a Wright Cyclone R1820-56 and experiences white smoke coming from the exhaust pipe of the two lower cylinders. The engine has the clean kit. He replaced the two cylinders with two overhauled (albeit some time ago) cylinders but the problem is still there. This is only happening at idle. Any guru on Cyclone engines around here, to give us a few hints ? Many thanks and by the way, great forum ! Henri.

10-09-2009, 10:34 AM	#4
FLYBOYJ IP/Mech THE GREAT GAZOO Join Date: Apr 2005 Location: Colorado, USA Posts: 16,049	My Pleasure Henri. The oil scraper ring "may" be part of the problem. It does sound like valuve guides. After today's test flight I'd recommend a compression check. __________________ "IF ITS RED OR DUSTY, DON'T TOUCH IT"

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10-09-2009, 10:21 AM	#3
lolo67 Junior Member Join Date: Oct 2009 Posts: 3	Thankyou FlyboyJ ! Well the engine does it ONLY when hot and at idle. With power on, it doesn't smoke white any more. And when the engine is cold, it does not either. As for your other question, he never pulls back quickly the throttle so he can't say, but he will do so this afternoon during a flight test and will report. One thing is, when he replaced the two cylinders, he kept one oil-scraper ring from the old cylinders because he did not have a replacement of the same type. I believe that the tightness of the rings is better when the engine is delivering power than at idle, is that correct ? That could be an explanation then. But why only when the engine is hot ? This afternoon he will take momentarily the clean kit off, to see what happens. Many thanks for your informed comments, FlyboyJ, and blue skies ! Kind regards, Henri.

11-02-2009, 10:40 AM	#5
lolo67 Junior Member Join Date: Oct 2009 Posts: 3	Hello FlyBoyJ again ! Problem still not solved. He did a flight recently, did not notice any change in behavior when he pulls back quickly or not the throttle, the engine always rattles a bit but no different as before. Like said, this is only happening at idle, engine hot. He is now in the process of looking at the two scavenge pumps, the one in front is fine and he will be looking at the one on the back side of the engine, fact is when he activates the clean kit electric pump after a flight he pumps a lot of oil back in the oil tank, which would suggest that the mechanical pumps do not scavenge well the oil during or just after the flight. Compressions are all OK. Also, the harness was changed after the problem appeared, to no avail. I have also suggested to look at the surface of various cylinders after a flight, by taking the plugs off, the two down cylinders but also others, for comparison, if the surface is oily then that should indicate a worn scraper ring, shouldn't it ? (I'm no wizard in radial engines). I've also heard, on a Franklin engine (flat-six), of a cracked boss in the cylinder where the valve guide is inserted, the crack was minor and only visible with a magnifying glass, but obviously oil could then flow by. But that required taking the jugs off, this is only for the next step of problem solving. This problem is actually quite puzzling. Many thanks for your help, Henri.