Hi,
I have a Super Tigre G61 It has not run from last year . The engine was removed from the plane over the winter and refitted this year after some repairs to the plane.The engine appeared stiff to turn over . After fueling up ,priming and using the starter to start the engine the stiffness disapeared and now the piston apears to be too free!And the engine has yet to fire up.. It simply has no compression. it does not even pressurise the fuel tank. Between the bottom of the stroke and nearly reaching the top of the stroke the prop freewheels as if there is no contact between the piston and the liner. I.e. the piston ring is not contacting the liner wall.The glow plug is OK. The fuel if a little oily is OK.I have tried an exterior tank in case the tubes were blocked.The Needle valve assembly is clean.I feel positive that it is the ring glued up over the winter months, has anyone any idea how to free it off.
Many thanks
Richard.

Thread moved to GLOW engines.

This was originally posted in the GAS engines forum.

The ST .61 is a GLOW engine and runs on methanol. It is NOT a GAS engine.

You need to undo the 4 head screws, pull the liner and have a look. Hopefully nothing is broken []

I usually take the piston out and cook it in antifreeze and hope the ring frees up. If the ring does not free up it will need replacing.

Bill

Don't worry. It is probably just dried castor stuck in the ring groove. Soak the engine like he said in anti freeze in a crock pot (be careful) or just soak it in low nitro fuel for a day or two. At best ringed pistons have little cyclinder seal until under pressure of combustion anyway.

Most stuck rings will free themselves once an engine starts up and gets warm.

Otherwise you can try throwing the whole damned thing (except the plastic throttle arm) in the oven at about 220 deg F and then flushing it out with fuel.

Even with a stuck ring, it should still start if you're using an electric starter and that'll provide enough heat to melt the gunk that's causing the ring to stick.

Hi,
Thanks for all the advice, I can’t get the engine to run, one reason is with the lack of compression/ suction, the engine won't draw the fuel through! I think what you are all basically saying is "no big deal" which is a relief. I will go with the crock pot idea and soak the engine for a few days in antifreeze. Wish me luck.
Regards,
Richard.

I recently loosened a stuck ring with liberal use of some WD-40. Have used charcoal lighter fluid too. The glycol antifreeze method works well for engine cleaning but to get the internals really clean the engine must be disassembled before hand.

Terry in LP

Have you tried to blow thru the carb, maybe it is gummed up as well. If so the engine will not run at all. Also the muffler pressure tap may be plugged. If it is plugged it will be a bear to start and keep running.

Try putting a little fuel into the engine thru the carb, then apply glow heat and then electric starter, If there is no glimmer of a start, check the glow plug and make sure it is glowing bright orange. Even with a stuck ring, it should still start and run if it has fuel ect.

Good Luck

Richard

Hi Terry & Yukonflyr,
The carb & the exhaust nipple are both clear. I had a brainwave and Phoned the importers who after wrapping my knuckles for using the wrong fuel (Apparently this is most important when you have a piston ring) offered me their free repair service as long as I had not tampered with the engine. You pay for the post and packaging and for any new parts fitted. I think even then they are at a discount!
It seem a more than fair service and they gave me the impression that they repair the engine the day they receive it what more could you ask. So if you live in the UK try Tigre Engines. 01923 270129

Again thanks for all the advise (Which is never wasted)
Richard.

What fuel were you using?

I have a ST G75 with a ring and it was stored for 7 years with only a squirt of afterrun oil. I use 10% nitro and 50/50 castor mix at 20% oil content.

My engine was tight, but after a shot of Break Free CLP and rotating it by hand and then with the electric, it started up just fine. I thought that the ring might be stuck after that abuse as I did not intend to store it, just happened when I moved from California to the Yukon.

Glad to hear you can get it fixed

Richard

Hi Yukonflyr,
I have the engine back and repaired. I sent it off Monday afternoon and it was on my doorstep today Wednesday! I have a fair bill to pay but it has been ;
 Rehoned sleeve.
 New piston
 New ring
 New rear race.

No labour has been charged. But of course I have had to pay postage and VAT (TAX). So the total bill came to about half the price of a new engine. I bought the engine on the internet so I don’t know what original condition it was in. The guy has returned all the old parts so I know it is not a con, the old ball race is in a terrible state. He has sent me a do’s and don’ts list about half of it in highlight pen!

So I have learnt my lesson the hard way.
I should use Straight fuel. One recommended has 9% EDL 6% Castor 85% Methanol.

My old pal who taught me to fly passed away last year and bequeathed ( Well I don’t think it was actually in his Will but you know what I mean!) all his old fuel.
I used it regardless of what it contained and some of it was really smokey. One bottle I have left is Straight 20% castor 80 Methanol. I think it is the high castor oil that has done the damage.
Also “do not leave the model in a horizontal position after use always store it in the vertical position tail down. This is to prevent acid which is formed after combustion attacking steel parts and causing the rear ball race failure”.Point two I ignored.
From now on I will use after run oil. Any Ideas what is the best oil to use Yukonflyr?

Sorry for the long reply.
Regards
Richard.

Kairos - OK, Fai fuel got it. Even using castor at 50/50 with Klotz, I have never had a problem. Striaght Castor requires some engine maintance yearly, or at least I would do it yearly.

Afterrun oil - I like Marvel air tool oil, Can't get it here in Canada, I use a close relative called Kleen Flo and it seems to be the same stuff. I use a lot of afterrun oil, in the tablespoons. Lately I have been using 1/2 air tool with 1/2 ATF trans oil. Seems to be good also, a tad drier than straight air tool oil.

I don't think that the brand or type of oil is most important, using lots of oil is however of whatever you use. Whatever you do, do not get the afterrun in the tiny bottles for lots of $$$$. People tend to scrimp on the oil which does not help your engine. I use the foam ear plugs in the intake and muffler so when you hang your plane in the vertical the oil does not run out all over the floor.

Richard

I'd be interested to know what the list of dos ond dont's says. Any chance of posting it here?

Right hopefully this link should work.
http://farm4.static.flickr.com/3066/...dac16a87_o.jpg



The soft earplug is an inspiration Richard .I stuff paper towel up the exhaust but your idea is much better. (And I have some earplugs).
Today I bought some fuel but couldn't get hold of any straight fuel so settled for 5%nitro. People just do not use straight fuel. Oh and guess what the guy in the model shop said, "I have after run oil and it is not expensive" .. So I bought it! It cost me ÂŁ2.99 for .44 of a pint. (250Ml) But next time I will take your advice and use air drill oil.

Richard.

It won't be the castor. I'm using 25% all castor in my ST G51 (there's a reason for that though) but all my other engines use 20% all castor. You're in England so most likely your castor is Castrol M which is what I use.