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#1
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Rough Engine, please help
The IO-520 in my Cessna 210 is running rough. It seems to run smooth
at 1000 rpm but the roughness appears above about 1400. One cylinder is “cold” and apparently not producing any power. I pulled the rocker cover and found that the intake valve spring was broken. My mechanic and I replaced it yesterday. But the cylinder is still not producing. The compression is good (74/80). The spark plugs are good. He’s going to check the flow through the fuel injector later today. Any more ideas? What should we do next? Thanks! John Clonts Temple, Texas N7NZ |
#2
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At the very least, borescope that cylinder, and especially its valves.
Compression may be terrific if a valve never opens! Rip John Clonts wrote: The IO-520 in my Cessna 210 is running rough. It seems to run smooth at 1000 rpm but the roughness appears above about 1400. One cylinder is “cold” and apparently not producing any power. I pulled the rocker cover and found that the intake valve spring was broken. My mechanic and I replaced it yesterday. But the cylinder is still not producing. The compression is good (74/80). The spark plugs are good. He’s going to check the flow through the fuel injector later today. Any more ideas? What should we do next? Thanks! John Clonts Temple, Texas N7NZ |
#3
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If anything has happened in the valve train, you should verify that the cam
lobe and lifter face are still good. The broken valve spring might be the result of cam wear or something entirely unrelated could have happened and the improper function of the valve train could have damaged the lifter. The valve train is very delicate and has some of the highest stresses in the engine. Any difficulty should result in a complete check from the cam through to the valve seat. I know of one case where a broken valve stem was simple replaced. The engine later lost power on take off and three people died. -- Roger Long John Clonts wrote in message om... The IO-520 in my Cessna 210 is running rough. It seems to run smooth at 1000 rpm but the roughness appears above about 1400. One cylinder is “cold” and apparently not producing any power. I pulled the rocker cover and found that the intake valve spring was broken. My mechanic and I replaced it yesterday. But the cylinder is still not producing. The compression is good (74/80). The spark plugs are good. He’s going to check the flow through the fuel injector later today. Any more ideas? What should we do next? Thanks! John Clonts Temple, Texas N7NZ |
#4
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I'd have that whole cylinder removed and sent off to be
checked/rebuilt by a good qualified repair station. Our 172 is in the shop right now due to one cylinder intermittantly running cold and not making power. We had the jug pulled and upon first examination, the intake valve had lead deposits on the face/seat and was only sealing sometimes, yielding zero compression during one check, and 74/80 the next time around. My A&P suspects the guide and or stem may have some slop too, so we're just going to have the valves in that one jug rebuilt since the other 3 are fine and the engine is only mid-time. |
#5
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"John Clonts" wrote in message om... The IO-520 in my Cessna 210 is running rough. It seems to run smooth at 1000 rpm but the roughness appears above about 1400. One cylinder is “cold” and apparently not producing any power. I pulled the rocker cover and found that the intake valve spring was broken. My mechanic and I replaced it yesterday. But the cylinder is still not producing. The compression is good (74/80). The spark plugs are good. He’s going to check the flow through the fuel injector later today. Any more ideas? What should we do next? Thanks for the replies. It WAS the fuel injector, which was blocked. Cheers, John Clonts Temple, Texas N7NZ |
#6
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A broken spring and a clogged injector... Murphy does not like you, does
he... denny "John Clonts" wrote in |
#7
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"Jay Honeck" wrote in message news:pygZb.224397$U%5.1418539@attbi_s03...
Thanks for the replies. It WAS the fuel injector, which was blocked. Good deal, John. Any idea what caused the clogged injector? Bad gas? Good question! My mechanic posited that the broken valve spring somehow facilitated the clogging of the injector. I'm not sure I can see that... Also, it's kinda hard to resolve the "intermittent" nature of the problem from flight to flight beginning a month or so ago, i.e. "When did the valve spring break?", and "When did the injector clog-- and was it suddenly, or gradually?". I will be pondering these things during my next few flights! Cheers, John Clonts Temple, Texas N7NZ |
#8
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I repeat. Make that next flight after the entire valve train has been
checked. Just the broken spring could have caused other damage that will come back to bite you. I've been talking to another guy who had the lifters in his 210 go bad just under 700 hours even without any broken valve springs. The cam shaft is driven directly by the engine and, when things go wrong in the rather delicate valve train, all that power can really screw things up. -- Roger Long John Clonts wrote in message m... "Jay Honeck" wrote in message news:pygZb.224397$U%5.1418539@attbi_s03... Thanks for the replies. It WAS the fuel injector, which was blocked. Good deal, John. Any idea what caused the clogged injector? Bad gas? Good question! My mechanic posited that the broken valve spring somehow facilitated the clogging of the injector. I'm not sure I can see that... Also, it's kinda hard to resolve the "intermittent" nature of the problem from flight to flight beginning a month or so ago, i.e. "When did the valve spring break?", and "When did the injector clog-- and was it suddenly, or gradually?". I will be pondering these things during my next few flights! Cheers, John Clonts Temple, Texas N7NZ |
#9
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Jay Honeck wrote:
: Thanks for the replies. It WAS the fuel injector, which was blocked. : Good deal, John. : Any idea what caused the clogged injector? Bad gas? : -- : Jay Honeck : Iowa City, IA : Pathfinder N56993 : www.AlexisParkInn.com : "Your Aviation Destination" Speaking of which, Jay... did you ever swap your Grape's fuel filter and cut open the old one? I ended up rigging a funky plumbing concoction with water-absorbing spin-on filter for refueling from 6 gallon cans. -Cory -- ************************************************** *********************** * The prime directive of Linux: * * - learn what you don't know, * * - teach what you do. * * (Just my 20 USm$) * ************************************************** *********************** |
#10
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