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Old 04-13-2017, 01:15 PM
Bubblehead's Avatar
Bubblehead Bubblehead is offline
Join Date: Jul 2007
Location: Keller, TX
Posts: 1,527
Default Sniffle valve for water too?

On the way back from Sun-N-Fun to Fort Worth Monday I landed for fuel at Mount Pleasant, Texas and could not get out before ceilings and visability lowered. I tied the plane down, signed up for the crew car and went to dinner and to find a hotel.

Overnight the town and surrounding area got 5 to 8" of rainfall and gusty winds. The next afternoon ceilings were improving so I went to the airport to load up and get on home. When I cranked the engine the prop moved about 20 degrees and stopped, which is definitely not normal. I tried it again but no go. After turning the ignition and Master off I got out of the plane and saw water coming out of the exhaust pipe.

I pulled the prop through about 20 blades and got more water out. Once I stopped getting any water out I tried starting the engine again but could not get it to fire. It did crank but more water was coming out!

Thanks to a good Samaritan mechanic we rolled the plane over to his hanger and put the batter on charge. I pulled the cowling off and removed the spark plugs. All were wet with water. I blew them out and fulled the prop through another 20 blades or so. More water came out!

I have a Superior cold air sump and there are two drain plugs for the air section. I removed the rear one and got about a cup of water out! I jostled the plane a lot to get all the water I could out before putting all the spark plugs back in and finally the bottom drain plug. The engine started and ran normally and a quick mag check told me things were back to normal. I replaced the cowling, loaded up the baggage, disconnected the charger, restarted the engine and flew the rest of the way back to T67 Hicks Airfield north of Fort Worth.

I did not install the sniffle valve when I installed the cold air sump. I'd never had much trouble starting the engine when hot so I did not think I needed the valve and left it off. KISS ruled. I think having the sniffle valve would have allowed the water to drain and perhaps helped me avoid a delayed departure and a lot of work.

My plane is an RV-8 with horizontal induction and the air filter on the baffle ramp on the left side. The driving rain Monday night must have been blowing right onto that filter and the water flowed down the duct through the FI unit into the air sump.

I am also ordering cowl plugs. Those would have helped this situation too. And yes, I realize what hydraulic lock would have done, which is one reason I am writing this! Perhaps someone else can avoid this problem by installing the sniffle valve, cowl plugs, or both, and if they see water coming out the exhaust pipe will reconsider trying to start the engine.
RV-8 180 hp IO-360 N247TD with 10" SkyView!

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Old 04-13-2017, 01:53 PM
Bill Dicus Bill Dicus is offline
Join Date: Jan 2005
Location: Shorewood, WI (Milwaukee area)
Posts: 1,066
Default Water

Thanks for the heads up! I certainly will be careful to ensure cowl plugs are in place when outside. Let me know if you do the snifflevalve install and how that works. Thanks again.
Bill Dicus
Shorewood (Milwaukee) Wisconsin
RV-8 N9669D Flying 12/4/14!
Flying Pitts S-2A, Piper Lance
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Old 04-13-2017, 02:07 PM
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AX-O AX-O is offline
Join Date: Jun 2005
Location: SoCal
Posts: 2,257

I also have a superior cold air sump and that sniffle valve has failed 2 times on me.
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Old 04-13-2017, 02:47 PM
BillL BillL is offline
Join Date: Sep 2007
Location: Central IL
Posts: 4,554

Yeah - if you ever get water out the exhaust on rotation DO NOT TRY TO START THE ENGINE. There is a good possibility of slugging once the airflow starts and having major damage. Possible: broken - piston, head/barrel, case, bent crank, bent rod, wrist pin - - - just to name a few.

Thanks for posting, I would not have thought that much water could get in there. I have a TG and will take note. Thanks, hopefully you have no damage, but should check (borescope) after a few hours in case a ring land was broken. A leak down test would not hurt asap.

1st Flight 1-27-18
Phase II 8-3-18
Repairman 11-15-18

Last edited by BillL : 04-13-2017 at 07:05 PM.
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Old 04-13-2017, 03:08 PM
rv8ch rv8ch is offline
Join Date: Feb 2005
Location: LSGG
Posts: 2,389
Default sniffle valve failure

Originally Posted by AX-O View Post
I also have a superior cold air sump and that sniffle valve has failed 2 times on me.
Axel, can you tell us more about this? Never heard of one failing.
Mickey Coggins
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Old 04-13-2017, 03:28 PM
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Tbone Tbone is offline
Join Date: Jan 2006
Location: South
Posts: 515
Default Oil

It would probably be a good idea to change the oil. If you had water on the top of the pistons it is a good possibility that some water "may" have found its way to the crankcase side.
XP IO360
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Old 04-13-2017, 03:30 PM
Larco Larco is offline
Join Date: Mar 2005
Location: DVT Phoenix
Posts: 1,075

Maybe I am completely misunderstanding the issue, but wouldn't a small hole drilled in the air filter intake right in front of the injection servo let any rain/water that entered through the filter drain out instead of filling the servo intake. IIRC the plans call for the hole? Correct me if I am mistaken. Larry

PS My Hanger neighbor had a compression lock due to water from an overnight storm. Had no hole in the intake. Now has a hole. :-)

Last edited by Larco : 04-13-2017 at 04:12 PM.
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Old 04-13-2017, 03:44 PM
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MikeyDale MikeyDale is offline
Join Date: Aug 2012
Location: Garden City Texas
Posts: 814

I remember the snorkel instructions saying to drill a small hole in the lowest point in the snorkel.
Mike Hillger
Garden City, Texas
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Old 04-13-2017, 04:32 PM
DSmith DSmith is offline
Join Date: Feb 2006
Location: Panama City Beach, FL
Posts: 123

The problem is a hard blowing rain will not drain out a small hole in the snorkel. I have a friend with an RV-8 with the 200 hp I/O 360 that experienced that exact problem. Tail-draggers with horizontal intake sumps need the sniffle valve for sure. I have one in my RV-7A with cold air sump just as a precaution.
Danny - PCB, FL
RV-7A, TMX IOF-360, WW 200RV
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Old 04-13-2017, 06:01 PM
Jordan1976 Jordan1976 is offline
Join Date: Apr 2007
Location: WA
Posts: 157

Originally Posted by Tbone View Post
It would probably be a good idea to change the oil. If you had water on the top of the pistons it is a good possibility that some water "may" have found its way to the crankcase side.
You get a bunch of water in your oil all the time due to condensation and blowby when you shut down. As long as your oil temps hit 180F or higher when flying, this will just boil off. So unless your dipstick reads 2 quarts high because you have so much water, it's not an issue.
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