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Water Pump Failure?

RFSchaller

Well Known Member
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. I?m wondering if my alter pump died, any ideas on how to verify if that is the case?
 
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 EGT?s. 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 luck?
 
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 wasn?t 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.
 
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.
 
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. I?ll take it up for a longer flight this weekend and confirm it. Thanks for the suggestions!
 
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. I?ll 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.
 
Looks like the problem was that simple to fix. I flew it three hours yesterday with normal temperature indications.
 
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 ?EMF Low? alert, but main bus voltage was stable at 13,8 VDC.

Any ideas from the brain trust? Tomorrow I?m going to talk to Dynon.I suspect the D180 May have an issue.
 
Below is a quote from page 2-2 of the D-180 installation manual. I suggest that ALL electrical loads be turned on during this test. Make sure the airframe ground connection is tight and that there is no paint interfering with the connection.

Because of the current drawn by the FlightDEK-D180, even very small resistances between
battery ground and instrument ground can cause voltage differences which adversely affect
engine sensor readings. An easy way to test the quality of the instrument?s ground is to measure
voltage between the ground pin at the FlightDEK-D180 and the ground lead at your aircraft?s
battery. With the FlightDEK-D180 powered on, connect one lead of your voltmeter to a free
ground lead coming from the FlightDEK-D180. Connect the other lead of your voltmeter to the
ground terminal of your battery. The voltage between these two points should measure very
close to 0 mV (within 5 mV). If it does not, you must improve the ground connection between
the ground of your battery and that of your avionics bus.
 
Thanks,Joe.

After reading through the manuals I think what I heard in the middle of the cacophony was ?EMS Alert? as opposed to ?EMF Low?. I talked to Dynon today and will send the unit in tomorrow to get checked. I don?t think it is a grounding issue because only the temperature indications are affected. I?ll let you know whatDynon says.

Rich
 
I'm no expert like Joe Gores, but I think a failing voltage regulator has the potential to generate all kinds of strange electrical readings from sensors. I've also read that replacing the battery for some people has for whatever reason extinguished unexplained gremlins.
 
Just FYI.. sorta related.. these symptoms reminded me of a video I had watched recently..

skip to 5:30 where his electrical problem begins.. and 7:45 he shows you the weird sensor readings..

https://www.youtube.com/watch?v=qRvJ-5JgT_4

This guy's problem turned out to be that the B+ wire to the alternator was arcing. But, it goes to show you how an electrical issue may show up on sensors... not a way I would expect.
 
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