IOWA'S 170

How to keep the Cessna 170 flying and airworthy.

Moderators: gahorn, Bruce Fenstermacher

Re: IOWA'S 170

Postby gfeher » Thu Sep 13, 2018 9:01 am

iowa wrote:could really smell the gas in the cabin as well
is this due to the vent as well?

Could be one or both of the short sections of rubber tubing connecting the gooseneck vent to the aluminum vent tubes from the tanks is beginning to fail or one of the clamps is loose. May have leaked or weeped slightly to create the smell when the fuel was transferring. When those hose sections on my plane failed a few years ago, i smelled fuel in the cabin, then fuel started dripping on me. Caught my attention pretty quickly. Changing those hose sections is kind of a pain, but do-able. There's at least one thread detailing how to do it.

iowa wrote:also, my exhaust gauge doesn't work
my radio man, Spencer Avionics in Spencer Iowa,
says its probably the sensor in the exhaust.

where is this located?
and where does one purchase a new one?

I have an Alcor dial-type EGT gauge and the sensor probe is on the exhaust pipe of the right rear cylinder (looking from the cockpit) right below where it attaches to cylinder. It looks like a standard hose clamp wrapped around the exhaust pipe with a wire coming from it. (When I open the top right cowl cover in my '52 B model similar to your A model, it's right there in front of me.) The probe extends from the hose clamp portion into the exhaust pipe through a hole in the pipe. The wire goes from the end of the probe at the clamp to the gauge in the cockpit. Replacements are readily available from Spruce. The clamp and probe are sold as a single sensor unit.
Gene Feher
Argyle (1C3), NY
'52 170B N2315D s/n 20467 C-145-2
User avatar
gfeher
 
Posts: 393
Joined: Fri Sep 26, 2014 9:19 pm
Location: Greenwich, NY based at 1C3

Re: IOWA'S 170

Postby n2582d » Thu Sep 13, 2018 2:08 pm

iowa wrote:could really smell the gas in the cabin as well
is this due to the vent as well? ... .
My guess is that the gas you smell is fuel that went out the tank with the cap off. Probably still a good idea to change the crossover vent tube connector hoses since they may be decades old but I doubt that is where you are getting the fuel vapors from if you didn’t notice the smell before flying without a fuel cap. Always a good idea to look at the inboard wing trailing edges after takeoff for fuel. Don’t ask how I know! :oops:
iowa wrote:... My exhaust gauge doesn't work
my radio man, Spencer Avionics in Spencer Iowa,
says its probably the sensor in the exhaust. ... .
Before you start replacing parts willy-nilly you might want to do some troubleshooting. Not sure if yours is an Alcor EGT but Alcor calls for 0.8 ohms resistance between your probe leads.
4F21B0C8-65A8-461F-A1C7-358626C52400.jpeg
Click to Enlarge
Gary
User avatar
n2582d
 
Posts: 1845
Joined: Mon Apr 29, 2002 4:58 am
Location: Mariposa, CA

Re: IOWA'S 170

Postby gfeher » Thu Sep 13, 2018 2:39 pm

I hate to admit it, but I left a fuel cap off once after filling the tanks and flew for about 1/2 hour and didn't notice a thing until after I landed and saw the open cap as I was walking away from the plane. No fuel smell in the cabin, no noise from the cap aganst the top of the wing, no excessive fuel drain (but it was only a 1/2 hr flight). (This occurred about a year after I changed the rubber vent lines at the gooseneck.) So I would check those rubber vent lines, just in case. They may not get enough cross flow to leak (or weep) during normal use but there may have been enough cross flow with the cap off to create enough of a leak to create the smell. I'm just guessing at this point, of course. But it's worth checking out.
Gene Feher
Argyle (1C3), NY
'52 170B N2315D s/n 20467 C-145-2
User avatar
gfeher
 
Posts: 393
Joined: Fri Sep 26, 2014 9:19 pm
Location: Greenwich, NY based at 1C3

Re: IOWA'S 170

Postby gahorn » Thu Sep 13, 2018 3:59 pm

Your EGT probe is most likely clamped to your exhaust riser about 1.5" below the cylinder flange.

The fuel smell could be a couple of sources.
1-If the tanks are full and you perform a wheel landing and heavy braking.... fuel may vomit out of the cabin overhead gooseneck onto the cabin roof/windshield.
2-If the tanks are full ...the vent line above the headliner may have old/rotten rubber hose connections which have shrunk and/or leaking.
3-The fuel selector valve may have a leaking O-ring where the selector-handle-shaft enters the fuel valve.
4- (rare)- The fuel lines in an A or B model which pass up the rear doorposts may have control cables, hardware, or upholstery hardware which has chafe'd thru the fuel lines which are inside the doorpost cover.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight.
An originality nut (mostly) for the right reasons. ;)
User avatar
gahorn
 
Posts: 17739
Joined: Fri Apr 12, 2002 8:45 pm
Location: Spicewood (Austin), Texas

Re: IOWA'S 170

Postby c170b53 » Thu Sep 13, 2018 4:15 pm

I did have occasionally the smell recently and to George’s post it was the fuel valve o'ring and the valve gasket
Last edited by c170b53 on Thu Sep 13, 2018 8:59 pm, edited 1 time in total.
Jim McIntosh..
1953 C170B S/N 25656
02 K1200RS
User avatar
c170b53
 
Posts: 1785
Joined: Mon Apr 22, 2002 8:01 pm
Location: Vancouver B.C.

Re: IOWA'S 170

Postby gahorn » Thu Sep 13, 2018 4:18 pm

I love the smell of aviation fuel in the morning.

Just not in the cabin.

:twisted:
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight.
An originality nut (mostly) for the right reasons. ;)
User avatar
gahorn
 
Posts: 17739
Joined: Fri Apr 12, 2002 8:45 pm
Location: Spicewood (Austin), Texas

Re: IOWA'S 170

Postby hilltop170 » Fri Sep 14, 2018 8:43 am

My C180 had an aluminum fuel line in the belly from the right tank chafe where it crossed a longitudinal stringer to the point it was almost worn thru. Had it failed, the entire contents of the fuel tanks would have emptied into the belly. It was found at annual.

Once removed, one slight bend by hand broke the tubing in half showing almost no wall thickness left in the chafed area. No telling how much longer it would have lasted before starting to leak.
Richard Pulley
2014-2016 TIC170A Past President
1951 170A, N1715D, s/n 20158, O-300D
Owned from 1973 to 1984.
Bought again in 2006 after 22 years.
It's not for sale!
User avatar
hilltop170
 
Posts: 2998
Joined: Sat May 06, 2006 6:05 pm
Location: Retired in Alaska and the Texas hill country

Previous

Return to The Hangar

Who is online

Users browsing this forum: epeter786, Majestic-12 [Bot] and 6 guests