Thorp Air Command - T18.net

So...as I think most of us know, Lycoming and the oil manufacturers are in cahoots..... with the engine oil producers paying Lycoming a royalty for each recommendation knowing that Lycoming engines (especially old narrow decks like mine) will find a way to release oil to all parts of the engine compartment in small enough amounts to make locating the actual source as successful as finding Bigfoot...

Yesterday evening, after punching 3 teeth out of the bendix of my 25 month old starter (sold to me by Spanky with a 2 year warranty) I replaced it with the spare starter I thought was bad, but wasn't(it was the battery)

This engine leaked like an incontinent moose for the first year before I replaced hose, most fittings and tightened it up to where it was really doing pretty well...although...There had always been a little oil around the front of the engine at the bottom and all over the front of the starter - a normal and regular gathering place for leaks as the bottom of the case at the front loves to leak with all the vibrations localized there, with alternator brackets and starters adding to issue - as well, the front main seal can leak, although it did not seem to be a culprit with my engine.

Anywayyyyy....I when I pulled the starter, there was oil all over the machined mounting face, and as I looked closer, shore nuff, one of the thru-bolts connecting the case halves was threaded/machined into the area/small void above the machined mounting face of the starter. I had put some thread sealant in all the thru bolts, but this one did not have a nut on the other side of the case, so the oil was leaking down into the bolt threads and into the starter mounting face and then around the face and down and out....For the past two years, I literally thought my starter was leaking, knowing it could not. (at least not as much as it was) There was no way of knowing about it until replacing the starter and seeing just a pinprick of a hole where the tap had just barelygone into the starter mount.

I wonder where I will find the next leak....

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Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)

Fascinating, Jim.

How is it you know so much about Mooses?

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http://www.dixiefriedfabrication.com/

Huh???

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John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

But seriously, I’m was just being a smart ass, finding the pinhole in the bottom of a bolt hole was a good find.
I hate those leaks to, messes up the chrome.

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http://www.dixiefriedfabrication.com/

So the way I'm reading this the thru bolt was not actually closed on the other side with a nut correct? Might not be lycomings fault ..

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Lee Walton
Houston, TX
N51863,N118LW
KEFD

It is difficult to detect ANY oil leak . Flying at 150 + mph the oil will flow/drip from just about any where and not from where you thought is was leaking from ? Although not an oil leak I had several old Volvos that began leaking Radiator coolant . Funny thing was the coolant spot on the garage floor was just about where the starter was ? Come to find out the "weep" hole in the water pump was leaking coolant onto the exterior of the water pump bypass tube to the back of the block and dripping onto the floor ! I happened to find the leak by accident when I ran my hand along the "tube" ! A clean engine compartment will certainly help find those pesky leaks . I use Jet A to degrease my engine compartment with a pneumatic solvent gun . The Jet A does a great job removing the grease/oil , leaves almost NO residue , will not harm the paint . At about $4-5 a gallon it is a bargain !

RB

I have had good luck using baby powder on the engine to locate leaks. I searched for months for an oil leak a while back. I finally wiped the engine down with a shop towel and applied baby powder where I thought the leak was coming from and then went flying. I repeated this process 5 or 6 times. Finally, on the 5th or 6th flight, I had applied the baby powder in the right spot and the leak appeared in the baby powder like a river through the powder. I was an oil line adapter screwed into the accessory case that needed a smidge of tightening. But man, did that little sucker leak all over the back of the motor and then spray onto the firewall. I couldn't believe the mess such a tiny leak was making.

Lee - You read it correctly - pardon my lack of brevity - perhaps it might not be Lycoming's issue - that hole may have been drilled and re-tapped deeper - I should have taken a photo, but still have trouble remembering my phone is also a camera. Being a narrow deck 1959 motor (co-inkadinkaly, my birth year), the alternator bracket is not bolted to a machined face, but has three holes through which the bottom case bolts go - this one is the middle hole, which ends up intersecting the starter face just a sniglet to the rear of the aft starter bolt, and is without a nut on the other side. There is no "failure" here per se.....no crack I can see - but if I had to guess, I would say that perhaps back in 1959, the drill press operator may have pushed through the stop just a hair, or if the case was re-worked, same scenario. If the silk was holding up, it would not leak.

Lou, I've not yet been intimate with a moose.....they're meaner than you think....

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Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)

That'll teach you to not turn down the 'extended' warranty.

Spanky

Tom Jones's Thorp in my hangar just went through those trials. Mid-60s O-320-E2D overhauled and upgraded with parts to beef it up to 180hp by a reputable So Cal shop. He and a local A&P assembled the engine. Long story short -- flies great, flies fast, makes lotsa oil. He replaced the Crankshaft Oil Seal but it still leaked up front onto the starter ring gear, etc. Finally discovered the 2 case through-bolts are supposed to have O-rings installed at assembly. They weren't there. They machined a dowel to insert them and -- problem solved. He's roaring around Rosamond breaking it in and it sounds great and looks fast. I'll try to get him to do a write-up for the web-news-letter.
Tony
PS: Pic is from when Brazell came to visit for the LA County Airshow. Tom's T-18 is in the back.

Now that's how hangars should look.

Tiger den

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http://www.dixiefriedfabrication.com/