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  #1  
Old 10-29-2018, 11:11 PM
RFSchaller RFSchaller is offline
 
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Location: Phoenix, AZ
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Default Water Pump Failure?

Yesterday I took off with an OAT of 77F and experienced both CHTs and an Oil Temp Hi alarms on climb so I returned to the field and did some ground run ups with a repeat of Hi Temp alarms. Iím wondering if my alter pump died, any ideas on how to verify if that is the case?
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  #2  
Old 10-30-2018, 12:37 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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I did a quick search and it seems the 912 water pump is pretty infallible. One guy described a problem like you are having and problem was traced to a vacuum leak causing lean operation and high EGTís. I also read about a suggestion to remove the radiator-style pressure cap on the expansion tank, run the engine, and look for evidence of coolant flow in the neck of the open tank to verify water pump working.

Good luckÖ
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Jim Stricker
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PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC
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RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 406

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Special Thanks to EJ Trucks
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  #3  
Old 10-30-2018, 07:32 AM
Dave12 Dave12 is offline
 
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I had a similar situation with my 1st 12 back in 2011. It was the D180. Run the engine until you see the temp going wild then check the coolant temperature with another source. I too suspected the pump, the sensors, etc. I sent the the display to Dynon 3 times before it was fixed. They were completely unable to re-create the scenario on the bench. Each time the unit passed the bench test. It wasnít until I borrowed a unit from another 12 and verified it that Dynon sent me a new display. Not ragging on Dynon here, they were loosing a little hair over it too.
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  #4  
Old 10-30-2018, 06:37 PM
hook hook is offline
 
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Have you replenished coolant and done a leak-check engine run with the cowl off?

I had an overheat issue, and this procedure quickly found a leak on one of the 1" coolant hoses where the hose clamp ate into the hose.
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  #5  
Old 10-30-2018, 09:08 PM
RFSchaller RFSchaller is offline
 
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Thanks for the suggestions. I will start troubleshooting tomorrow and post results.
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  #6  
Old 10-31-2018, 11:06 PM
RFSchaller RFSchaller is offline
 
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Today I pulled my D180 and sprayed the connector pins and sockets with cleaner. That seems to have done the trick. A trip around the patch showed normal CHTs and Oil Temp, so I am cautiously calling this a dodged bullet. Iíll take it up for a longer flight this weekend and confirm it. Thanks for the suggestions!
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  #7  
Old 11-01-2018, 11:19 AM
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DaleB DaleB is offline
 
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Quote:
Originally Posted by RFSchaller View Post
Today I pulled my D180 and sprayed the connector pins and sockets with cleaner. That seems to have done the trick. A trip around the patch showed normal CHTs and Oil Temp, so I am cautiously calling this a dodged bullet. Iíll take it up for a longer flight this weekend and confirm it. Thanks for the suggestions!
I have had some considerable experience maintaining computer equipment over the years -- everything from large, water-cooled IBM mainframes all the way down to PCs and smaller. It's not at all unusual to find problems that go away simply by re-seating connectors.

Based on that experience, part of my condition inspection includes unplugging, blowing out and re-installing every connector I can get to. The gold plated connector pins are typically not much of a problem, but any of them can accumulate oils, dust, etc. Just the wiping action of re-seating the contacts is usually enough to head off problems. Yes, connectors have a limited life span ; they're only good for so many cycles. If I have this thing long enough to wear any of the connectors out, I'll be a very, very old man indeed.
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  #8  
Old 11-01-2018, 12:06 PM
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Piper J3 Piper J3 is offline
 
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To corroborate what Dale says above, see recent RV-12 comm radio problem that was resolved by re-seating the radio in its tray.

http://www.vansairforce.com/communit...d.php?t=164899
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Jim Stricker
Hinckley, Ohio
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 406

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #9  
Old 11-04-2018, 11:05 AM
RFSchaller RFSchaller is offline
 
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Looks like the problem was that simple to fix. I flew it three hours yesterday with normal temperature indications.
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  #10  
Old 11-12-2018, 08:50 PM
RFSchaller RFSchaller is offline
 
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Well, my gremlin is back after three trouble free hours. Here are the symptoms:

1. CHT, EGT and OIL temps spike high. Left EGT spikes more than others at about every 2-3 seconds.
2. Spikes are not synchronized.
3. At low temperature the indications are reasonable. That is before start, they reflect ambient temperature and respond normally (I sprayed Freon on them and observed a drop in temperature below ambient.
4. Disconnecting the CHT leads drives the indication low leading me to believe this is not a connector issue.
5. Oil pressure, fuel pressure, tachometer and fuel flow are stable and unaffected.
6. Today during ground runs I got an voice alert ďEMF LowĒ alert, but main bus voltage was stable at 13,8 VDC.

Any ideas from the brain trust? Tomorrow Iím going to talk to Dynon.I suspect the D180 May have an issue.
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