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Rough Engine - sudden CHT/EGT loss on cylinder 4

vinodwahi

Member
Hi everybody,

I need to seek advise.....
Three days ago, I was out for a normal local flight and everything appeared to be normal. Then, from one moment to the other, the engine was starting to run rough. Oil pressure and oil temps were both fine. All temps were ok as well, except for EGT and CHT on cylinder 4. These haven fallen rapidly to 150?F / 117?F (EGT/CHT). I landed and returned to the airfield the next day. I checked the compression by turning the prop (w/o ignition of course, lean and fuel off) and it felt ok. I checked both sparking plugs and they seemed to be alright as well. I checked the vent springs and the vent movement from the outside, all good. When I again turned on the engine to check I was still facing the same issue...
Any idea what has happened? And how to solve this?
Thanks so much for your support,

Sunit & Vinod, D-ESVM Germany
 
Stuck Valve one of many possibilities

How many hours on the engine? If the engine has 500 hours or more did you do a "wobble test" on the exhaust valves?

I have had this problem and it cost me considerable time and some money to replace my bent pushrod and pushrod cover after the valve stuck.
 
I need to seek advise.....
Three days ago, I was out for a normal local flight and everything appeared to be normal. Then, from one moment to the other, the engine was starting to run rough. Any idea what has happened? And how to solve this?
Thanks so much for your support,

Sunit & Vinod, D-ESVM Germany

Put it this way. If you had a heart pacemaker and it suddenly malfunctioned causing your heart to beat erratically would you a) go back to your doctor immediately, or b) go to an internet forum for advice on how to fix it from a bunch of guys you don't know and who do not have access to the malfunctioning device.

When you are flying, your aircraft engine is no less important than a heart pacemaker. You need it to keep running to stay alive.

My advice. Get out your cheque book and call in a qualified aircraft maintenance engineer. He will probably determine your problem in 10 minutes.

Your engine is talking to you. It's saying: "Call the doctor". ;)
 
An IO engine will almost certainly have a partially blocked injector or injector line. Maybe the flow divider orifice.

If it is an O engine it could be a massive induction leak.
 
Mehr informationen bitte

Please give us all the information on your engine.
Lots of good "doctors" on this forum.
Your engine problem is not unheard of and someone will be able to
point you in the right direction to find the cause of your rough running engine.

You have already pinpointed the problem cylinder using your EGT/CHT monitor.
Your engine problem has a definitive cause and is very solvable but we need
more info.
 
rough engine

I had similar occurance. Check the 1/8 pipe plug used to block the hole in the head casting, where a primer nozzle may be installed. Usually on the bottom area, tricky to see. Mine went missing, causing a dead performing cylinder with normal compression and ignition.
Dale
 
thanks for all the feedback, guys!
I was taking your hints and was looking at all scenarios....

Disassembled the carb, nothing found. Disassembled the intake pipe, nothing there either. Checked compression, all good. Checked Magnetos, all ok.

Then I took one spark plug from cylinder four and put it into #2. Turns out that the failure was moving along. Eventually found the problem: Both spark plugs failed. What an unlikely scenario.... Replaced them and wow, what a significant push on performance.

Cheers
Sunit
 
Put it this way. If you had a heart pacemaker and it suddenly malfunctioned causing your heart to beat erratically would you a) go back to your doctor immediately, or b) go to an internet forum for advice on how to fix it from a bunch of guys you don't know and who do not have access to the malfunctioning device.

When you are flying, your aircraft engine is no less important than a heart pacemaker. You need it to keep running to stay alive.

My advice. Get out your cheque book and call in a qualified aircraft maintenance engineer. He will probably determine your problem in 10 minutes.

Your engine is talking to you. It's saying: "Call the doctor". ;)

Isn't getting advice from option b) above the whole basis for this forum? :confused: Actually you provided advice in your reply.
 
thanks for all the feedback, guys!
I was taking your hints and was looking at all scenarios....

Disassembled the carb, nothing found. Disassembled the intake pipe, nothing there either. Checked compression, all good. Checked Magnetos, all ok.

Then I took one spark plug from cylinder four and put it into #2. Turns out that the failure was moving along. Eventually found the problem: Both spark plugs failed. What an unlikely scenario.... Replaced them and wow, what a significant push on performance.

Cheers
Sunit

It is likely that one plug had already failed and the other eventually went - versus both failing at the same time.

Consider rotating plugs every 50 hours and doing the ohm chk at the same time.
 
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