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  #11  
Old 02-09-2018, 08:00 AM
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JPalese JPalese is offline
 
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Quote:
Originally Posted by Piper J3 View Post
How can you be sure it isnít leaking during flight? Perhaps it doesnít drip down until it sits for a while. Is there coolant on the belly of the airplane? This would be most plausible explanation, as the coolant would most likely leak with heat/expansion/pressure.

When the engine shuts off and begins to cool the opposite occurs and vacuum begins to form and withdraw coolant from the overflow tank.
There is no coolant on the belly.

After the engine was wiped clean and dried, the engine was run for .6 with the Rotax mechanic observing. No leaks were observed during or immediately after the engine run.

LEAF, the local Rotax distributor, then directed the mechanic to pressurize the cooling system to 15PSI. No leaks were found.

We observed the engine for another .5. It was then re-cowled. The next morning the 2 small spots were on the ground as I initially described.
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  #12  
Old 02-09-2018, 09:00 AM
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Piper J3 Piper J3 is offline
 
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The Dye / UV Black Light will find the source of your leak...
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  #13  
Old 02-09-2018, 10:39 AM
EXflyer EXflyer is offline
 
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Quote:
Originally Posted by Piper J3 View Post
The Dye / UV Black Light will find the source of your leak...
Also leave the cowl off, place white paper towels under the AC will help locate where its coming from same for oil leaks. Leaving the cowl on can cause problems as coolant will run off of it in a different place away from the leak.
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  #14  
Old 02-09-2018, 11:44 AM
bajapilot bajapilot is offline
 
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John, I had a similar experience on a 912 uls in my Rans S-7S. For over two years I chased a similar leak as yours. The leak never showed up when running or right after flying. The engine was completely dry after flying or during a static run up uncowled. But, I would return the next day and there would be from a few drops to maybe half an once of coolant on the hanger floor. Seem to show up more on cool nights. Tried all manner of testing and repositioning of clamps no no avail. The coolant lost was minimal maybe adding 6 oz. between annuals.

Finally traced the leak by shining a light in a darken hanger and noticing a slight reflective trail from the top of right front cylinder, down between the heads onto an exhaust pipe and then to the cowl. The leak was from the coolant return elbow on top of the head. Held on by two screws and sealed by a small red o-ring (which looked to be in good shape) the leak disappear when I replaced the o-rinng.

Just my experience , but you might want to check. My symptoms exactly matched yours.
Bill
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  #15  
Old 02-09-2018, 12:29 PM
JBPILOT JBPILOT is offline
 
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Default Same here - -

Right Front top of cyl, coolant elbow 'O' ring.
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  #16  
Old 02-11-2018, 09:18 AM
Jolly Jolly is offline
 
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From my understanding there are 3 places that are common coolant leaks, but for different reasons.

After the 5 year rubber change this seems to happen if the spring clamp on the 17mm coolant hoses are too far back and not up by the flared end in the aluminum tube underneath the hose. Place the clamp just behind the flared end, but not on top of it. This makes a far better tight seal. Keeping the clamp to far back towards the end of the rubber hose can allow some oozing on some engines. After 25 hours of flight time take a few minutes and tighten up any screw clamps. The rubber will settle.
p.s. All clamps on the coolant hoses are better sealing up next to the aluminum flared ends on the metal tubing.

If you live where it gets really cold then you can see a few tablespoons of coolant at times back behind the rear tire on the ground. I learned in class that this happens because of different materials in the coolant pump. The coolant shaft setup is make up of stainless, two ceramic halves and the aluminum housing. Due to different expansion and contraction rates for these materials they can drip at times during cold weather and heating and cooling cycles and drips out the weep holes. It should be no more than a few tablespoons and if it's a large puddle there is another problem.

The last place a leak may show up, but may not always be real visible is up on top of the engine where the 17mm hose 90 degree aluminum tubes are. They can ooze around where they are threaded in. The air flow through the cowl can make this one a little harder to find. The give away is some tiny wet or dried residue barely seen around the base of the aluminum tube where it screws into the flat base. This is very easy to fix. Drain the coolant down past that high point. Take the flange off and heat gun it and the tube will unscrew. You can use either Loctite 243 or better yet Loctite 648 on the threads when you screw it back in. Do not forget to use a black magic marker to mark the tube and flange orientation so it will be in the alignment you want when you re-install it. let it dry over night without coolant to get the best seal. You can see this on YouTube videos.
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  #17  
Old 02-11-2018, 11:23 AM
TLYNCH TLYNCH is offline
 
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Location: Mequon, WI
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Default Hose Springs missing?

John,
What do you recommend for our A&P to avoid this problem?
Something about leaving out two radiator hose springs?

Tim
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  #18  
Old 02-11-2018, 06:53 PM
RFSchaller RFSchaller is offline
 
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I had a tiny leak develop after hose change out - about 1/2Ē overflow bottle level in 50 Hours. The fluorescent dye didnít show anything except around the weep hole on the bottom of the water pump. After about 80 Hours and tightening hose clamps at oil change (I replaced most spring clamps) the leak seems to have disappeared. My engine has about 700 Hours on it. Changeout was at about 590 Hours.
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  #19  
Old 02-14-2018, 07:26 AM
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JPalese JPalese is offline
 
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Default Leak stopped (for now?)

Now that the ambient temperatures are no longer in the deep freeze, my mysterious leak just stopped.

Coolant level in the overflow tank is visually unchanged, and out of curiosity I topped off the expansion tank .... about 1/2 ounce of coolant was needed to top off the expansion tank.

IF I find the cause or have further info I will advise the group.
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1) AAL Captain & Check Airman (ret)
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Active:
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  #20  
Old 02-17-2018, 04:42 PM
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JPalese JPalese is offline
 
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Default Picture of hangar floor

https://johnpalese.smugmug.com/RV-12-Coolant-Leak/

Not exactly a lot of fluid when it does leak.
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John Palese
1) AAL Captain & Check Airman (ret)
2) USAF LtCol & Command Pilot (ret)

Active:
1) ATP / CFII ASME
2) Adjunct Professor-Aviation Science
3) MKE FSDO FAAST Lead Rep & Remedial Trainer.

RV-12 Transition Training, Rental & Instruction.
RV-6/6A, RV-7/7A, RV-9/9A transition training
RV-7 Transition Training LODA.
Drone Detection & Counter-measures
---..
...--
DE WB9JPH
<IXOYE><

www.facebook.com/rv12wi
www.facebook.com/rv7wi
http://www.terravigilis.com

Last edited by JPalese : 02-17-2018 at 04:46 PM.
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