atreff
Well Known Member
Sorry to take up the bandwidth with a non-RV question, but an EAA buddy who helped me on my glass work is having a terrible time getting his newly overhauled O-200 to run on his Q-200. I'll post his symptoms below, and below that will be a summary in red of all he's tried. Any help for my friend would be greatly appreciated.
Art in Asheville
I desperately need to tap into our brain trust on O-200's.
I want to detail as best I can what has gone on the last couple of days. What we tried and the results. In summary, everything we have tried has failed to change any of the symptoms of the engine, negatively or positively. On various runs the symptoms remain rather constant but occur at varying rpm.
First I will bring you to the starting point.
New, zero-time engine buildup. 9.0:1 ECI pistons, stock cam. 1.3 hours total run time on ground.
CHT never above 350 deg.
Dual Electroair ignitions, reconditioned and timed for the O-200 by Electroair
Overhauled and updated MA-3 Carb.
4 into 1 stainless, ceramic coated exhaust
standard fuel system, gravity feed, 3/8" line. Fuel monitoring controller in line between shutoff and engine.
Symptoms:
Engine idles fine. As low as 500 rpm
Initially, engine ran strong up to 2000 rpm where it would start to pull down and lose 100-150 rpm and run rough.
On occasion I leaned the engine beginning at 2000 rpm and it would increase to 2350 before the leaning killed the engine.
After the engine "stalls" it will not recover and when the throttle is pulled back it continues to run rough and will not idle. Eventually the engine stops. An immediate restart typically yielded a lower max rpm. Today it deteriorated from 2000 rpm successively down to 1250 rpm. Next to last run of day was back up to 2000 rpm without any changes attempted between the previous run.
Initially, at idle I would pull the mixture and it would rev up about 100 rpm and the engine would stop. Now when the mixture is pulled, it will continue to try and run "diesel" and sputter to a stop.
The engine reacts the same whether running on one ignition, the other, or both.
There doesn't seem to be a noticeable change in CHT/EGT when the roughness starts. Of course they drop off rapidly when the throttle is retarded. Usually it wasn't running well enough to let the CHT/EGT reading to stabilize, therefore don't have definitive readings.
Diagnostic efforts: All yielding NO change to symptoms.
My carb and intake elbow were successfully tested in flight on Earnest's (identical) plane with identical engine and ignition setup.
Earnest's carb was installed on my plane - no change.
Carb float level checked
Intake elbow removed from my carb - no change.
Spark plug wires inspected to insure that the tension spring on top of the plug made contact and that the wire spike was in contact with the spark plug lead conductor. Spark plug gap checked.
Spark plugs (top and bottom) removed and inspected. All 8 were gray in color. No indication of misfiring.
Timing checked with timing light (more on that below)
Electronic ignition timing adjusted to 16.5 deg advanced which yield a 20.9 deg advanced setting at 1500 rpm. (more on that below)
One ignition pickup sensor replaced with new one. Checked gap setting at .015 on each.
Fuel vent lines inspected.
Plumbed a 5 gallon gas can directly to the carb and held above head for pressure
Removed 4 into 1 exhaust system and installed 2 into 1. Noticed excessive carbon build up inside 4 into 1 pipes.
Both exhausts were ejecting "bursts" of black smoke at the higher rpm attempts
Removed 4 spark plugs from bottom cylinders. All carbon covered. (this wasn't the case when they were removed yesterday) Replaced with 4 new plugs - NO change. Next step is to replace the leads.
Performance data:
Timing light indicated start setting of -4 to 0 Deg on start
650-1000 rpm = +6-+8 deg. Max rpm of 1650 (the max obtainable on that run) = 16-18 deg.
Right Ignition Only (volt meter readings) 500 rpm 1000 rpm 1500 rpm
16.5 18.0 20.9
Left Ignition Only (volt meter readings) 15.5 17.0 20.?
Manifold pressure: Idle 700rpm - 16" 2000rpm = 28"
Fuel flow indicator hasn't been calibrated on this engine but was increasing from 3 gph at idle to 7+ at 2000 rpm.
8/28/07 Update:
What was done today
Replaced 4 month old gas with fresh 100LL - no change
Did differential leakdown compression check - all cylinders 80/80.
Reset the timing starting from scratch - no change
Checked electronic star gear on crankshaft for roundness. Found about .001-.002 differential among some teeth
Regapped electronic ignition sensors from 15 deg to 19 deg - no change
Upon noticing that the bottom sparkplugs on the two rear cylinders were covered with soot, replaced the ignition coil
that supported those two cylinders.- no change
Changed sparkplug leads on bottom sparkplugs of all four cylinders - no change
Checked entire induction system by spraying starting fluid on all flanges and joints - no rpm change
Checked voltage going to ignition system control boxes = 14 volts
Swapped ignition with another from working engine = no change.
Checked Cam timing = normal.
It appears that it doesn't matter what parameters are changed, the results remain the same - UGLY.
Continuing symptoms
Starts and idles up to 1000 rpm smoothly with no black smoke from exhausts.
When power is pushed up the exhausts begin to smoke and the engine begins running rough and resists rpm advancement. However it can be reluctantly pushed up to 2000 rpm and on occasion up to 2300 before it starts rolling back rpm and running extremely rough while billowing black smoke.
Suggestions that have not been pursued as yet:
Check valve overlap/timing
Call Continental
Check for broken/weak valve springs
Bleed down lifters and check clearance
Art in Asheville
I desperately need to tap into our brain trust on O-200's.
I want to detail as best I can what has gone on the last couple of days. What we tried and the results. In summary, everything we have tried has failed to change any of the symptoms of the engine, negatively or positively. On various runs the symptoms remain rather constant but occur at varying rpm.
First I will bring you to the starting point.
New, zero-time engine buildup. 9.0:1 ECI pistons, stock cam. 1.3 hours total run time on ground.
CHT never above 350 deg.
Dual Electroair ignitions, reconditioned and timed for the O-200 by Electroair
Overhauled and updated MA-3 Carb.
4 into 1 stainless, ceramic coated exhaust
standard fuel system, gravity feed, 3/8" line. Fuel monitoring controller in line between shutoff and engine.
Symptoms:
Engine idles fine. As low as 500 rpm
Initially, engine ran strong up to 2000 rpm where it would start to pull down and lose 100-150 rpm and run rough.
On occasion I leaned the engine beginning at 2000 rpm and it would increase to 2350 before the leaning killed the engine.
After the engine "stalls" it will not recover and when the throttle is pulled back it continues to run rough and will not idle. Eventually the engine stops. An immediate restart typically yielded a lower max rpm. Today it deteriorated from 2000 rpm successively down to 1250 rpm. Next to last run of day was back up to 2000 rpm without any changes attempted between the previous run.
Initially, at idle I would pull the mixture and it would rev up about 100 rpm and the engine would stop. Now when the mixture is pulled, it will continue to try and run "diesel" and sputter to a stop.
The engine reacts the same whether running on one ignition, the other, or both.
There doesn't seem to be a noticeable change in CHT/EGT when the roughness starts. Of course they drop off rapidly when the throttle is retarded. Usually it wasn't running well enough to let the CHT/EGT reading to stabilize, therefore don't have definitive readings.
Diagnostic efforts: All yielding NO change to symptoms.
My carb and intake elbow were successfully tested in flight on Earnest's (identical) plane with identical engine and ignition setup.
Earnest's carb was installed on my plane - no change.
Carb float level checked
Intake elbow removed from my carb - no change.
Spark plug wires inspected to insure that the tension spring on top of the plug made contact and that the wire spike was in contact with the spark plug lead conductor. Spark plug gap checked.
Spark plugs (top and bottom) removed and inspected. All 8 were gray in color. No indication of misfiring.
Timing checked with timing light (more on that below)
Electronic ignition timing adjusted to 16.5 deg advanced which yield a 20.9 deg advanced setting at 1500 rpm. (more on that below)
One ignition pickup sensor replaced with new one. Checked gap setting at .015 on each.
Fuel vent lines inspected.
Plumbed a 5 gallon gas can directly to the carb and held above head for pressure
Removed 4 into 1 exhaust system and installed 2 into 1. Noticed excessive carbon build up inside 4 into 1 pipes.
Both exhausts were ejecting "bursts" of black smoke at the higher rpm attempts
Removed 4 spark plugs from bottom cylinders. All carbon covered. (this wasn't the case when they were removed yesterday) Replaced with 4 new plugs - NO change. Next step is to replace the leads.
Performance data:
Timing light indicated start setting of -4 to 0 Deg on start
650-1000 rpm = +6-+8 deg. Max rpm of 1650 (the max obtainable on that run) = 16-18 deg.
Right Ignition Only (volt meter readings) 500 rpm 1000 rpm 1500 rpm
16.5 18.0 20.9
Left Ignition Only (volt meter readings) 15.5 17.0 20.?
Manifold pressure: Idle 700rpm - 16" 2000rpm = 28"
Fuel flow indicator hasn't been calibrated on this engine but was increasing from 3 gph at idle to 7+ at 2000 rpm.
8/28/07 Update:
What was done today
Replaced 4 month old gas with fresh 100LL - no change
Did differential leakdown compression check - all cylinders 80/80.
Reset the timing starting from scratch - no change
Checked electronic star gear on crankshaft for roundness. Found about .001-.002 differential among some teeth
Regapped electronic ignition sensors from 15 deg to 19 deg - no change
Upon noticing that the bottom sparkplugs on the two rear cylinders were covered with soot, replaced the ignition coil
that supported those two cylinders.- no change
Changed sparkplug leads on bottom sparkplugs of all four cylinders - no change
Checked entire induction system by spraying starting fluid on all flanges and joints - no rpm change
Checked voltage going to ignition system control boxes = 14 volts
Swapped ignition with another from working engine = no change.
Checked Cam timing = normal.
It appears that it doesn't matter what parameters are changed, the results remain the same - UGLY.
Continuing symptoms
Starts and idles up to 1000 rpm smoothly with no black smoke from exhausts.
When power is pushed up the exhausts begin to smoke and the engine begins running rough and resists rpm advancement. However it can be reluctantly pushed up to 2000 rpm and on occasion up to 2300 before it starts rolling back rpm and running extremely rough while billowing black smoke.
Suggestions that have not been pursued as yet:
Check valve overlap/timing
Call Continental
Check for broken/weak valve springs
Bleed down lifters and check clearance
