 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
greenough
Joined: 10 Sep 2011
Posts: 3
Location: United States
|
 Posted: Thu Sep 29, 2011 7:35 pm Post subject: 912 Cooling Problem |
 |
|
Last time it was an "exhaust leak" that turned out to be the cowl vibrating against the coolant radiator. That was an easy one. This time my 100 hp 912 is overheating evidenced by EGT temperatures rising above 1600*F. Temps cooled immediately with reduced RPM but I had to return to the airport keeping RPM below 5000. CHTs and oil tempratures remained in usual range. On inspection the coolant overflow tank is full. It normally runs half full. So I suspect an air lock in the system. Is this reasonable? What could cause it? (it is the first time it has happened in 80 hours of flight time.) And is there a process for bleeding what i thought was a self bleeding system?
I did read that if the line from the filler neck to the overflow can collapse this may result in failure to suck coolant back in when the coolant cools. Could this be an issue?
I would appreciate any help on this subject.
Thanks,
Jim Greenough
| | - The Matronics Zenith701801-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Zenith701801-List |
|
_________________
Jim Greenough |
|
| Back to top |
|
 |
ruruny(at)aol.com
Guest
|
| Posted: Fri Sep 30, 2011 4:16 am Post subject: 912 Cooling Problem |
|
|
Jim,
If your EGTs are high, your probably running lean at the higher RPMs.
Possible leak or cracks in carb flanges. Due to lower Fall OAT, repositioning of the needles in the carbs
might help. I have CHT and Coolant temp monitored on my 912 UL and they are almost the same temps.
I would not suspect coolant to be an issue, since the CHT is within spec, but the sudden increase of coolant in the
bottle is a concern. Have you opened up or serviced the coolant system before this happened
or do you have a thermostat installed. Check the seal in the coolant cap. If that hose is collapsing or is obstructed and keeping
fluid in the bottle, the fluid in the reservoir would be low when the engine cools.
Brian
www.701builder.com
50 hrs
[quote][b]
| | - The Matronics Zenith701801-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Zenith701801-List |
|
|
|
| Back to top |
|
|
tlongo
Joined: 17 Jul 2007
Posts: 14
|
| Posted: Fri Sep 30, 2011 2:35 pm Post subject: Re: 912 Cooling Problem |
|
|
If your EGT's are high on both sides I doubt if you have an air leak on both sides. If EGT's were ok last flight and just changed I would suspect cooler air and/or fuel. If the ethanol content is very high your mixture will go leaner. Wide open throttle is your main jet and from 1/4 to 3/4 throttle open is your needles and idle to 1/4 throttle is low speed jet circuit. My EGT's run a little higher when I pull back from wide open and lower at wide open. The higher the octane the leaner the mixture will get. My EGT's with pump 93 run 1400 to 1450 and in the winter will run about 50 deg hotter than summer. Always go back to when things were ok and try to think if anything has been changed, there is usually a reason that caused it. Also if you checked your coolent overflow when the motor was hot the level will be high until motor cools and coolant gets sucked back in. Good luck!
Tom
| | - The Matronics Zenith701801-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Zenith701801-List |
|
|
|
| Back to top |
|
|
greenough
Joined: 10 Sep 2011
Posts: 3
Location: United States
|
| Posted: Sat Oct 01, 2011 8:38 pm Post subject: Re: 912 Cooling Problem |
|
|
Thank you to the several people who responded to my cooling problem question. I am convinced that mixture must be the issue, but I don't know why yet. I have four EGTs so I should know which cylinders were involved, but I guess I was not thinking completely clearly while this was going on. Back on the ground it did not happen. I will go out and try to isolate which cylinders are overheating.
I am perplexed because it is a pretty new engine (80 hours) and I was thinking I have not changed anything that could change mixture. Then someone mentioned fuel. Over the last few flights I have begun using non-ethanol premium (92) from one of the few suppliers in this part of Oregon. The sell a lot a gas and seem reliable. Still, I checked that it was ethanol free. Could the fuel change somehow make a difference?
Thanks again,
Jim
| | - The Matronics Zenith701801-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Zenith701801-List |
|
_________________
Jim Greenough |
|
| Back to top |
|
|
dashwood
Joined: 24 Jan 2009
Posts: 73
Location: sw ontario canada
|
| Posted: Tue Dec 27, 2011 7:57 am Post subject: Re: 912 Cooling Problem |
|
|
i used to get hi egt warnings when i pulled back the power in the landings. turned out to be some dirt in the lower end fuel setup. confirm that the rad cap is good and hoses are good. re tighten all hose clamp connections at heads . i find these tend to loosen in time.
try pulling the choke/ enricher cable when at full throttle and hold it . see what the egt does.. if it goes down you are running too lean. also sounds like you may have sucked up some debrise into the full throttle settings. just running at highest altitude possible and pulling the choke on may open needles enough to flush out some Smalll stuff. check float needles and carb bowls for evidence of dirt. at 80 hrs the fuel system is starting to clean itself out from the build and you have proly for the first time run the tanks a little lower then when you first started flying. make sure gasolator is flowing properly and any fuel filter is not pluged and flowing at full capacity.
i always run prem auto fuel
| | - The Matronics Zenith701801-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Zenith701801-List |
|
_________________
Ross Alexander: CH701 driver 912ul 788tt
It only takes two things to fly, airspeed and money |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
