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PAW .15 muffler leakage

Old 02-24-2013, 01:10 PM
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Max_Power
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Default PAW .15 muffler leakage

My PAW .15 leaks more oil around the muffler than through it. This is a just broken in engine and I have made sure the head bolts are tight. I've seen some glow engines spit out the Carb and accumulate around the cylinder, but I'm pretty sure this is not what is occurring. I can idle it down and clean the oil off and as soon as I throttle up it takes about 5 seconds for about 1 CC of "burnt" oil accumulated at the muffler area and on the leathery looking gaskets, then running back and dripping off the body of the muffler. As the fuel is darkened and not pink it makes me believe it is definitely through the muffler seals and not from the nose or Carb. Any ideas? Is this common on this engine? Todd
Old 02-24-2013, 02:13 PM
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Default RE: PAW .15 muffler leakage

Todd most likely old and dried out just call Eric Clutton or Carlson and replace them do not mess with permatex or the like coating them messy but will work martin

Just noticed new engine so old and dry not the issue make sure seated right and not damaged


\ Post note I have 3 or 4 PAWs I did put a thin coat of Koppercoat sealer wen installed with a small artist brush repeat just a tiny thin coat both sides of gasket no leaks
Old 02-24-2013, 02:13 PM
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Default RE: PAW .15 muffler leakage

ORIGINAL: Max_Power....... it makes me believe it is definitely through the muffler seals ........... Todd
Then change the seals?

If it is the modern collector ring plus side canister muffler and not the older and smaller plain collector ring then check if the cooling jacket fins have been relieved around the the contact area of the canister.

And obviously check that nothing is squashed or damaged.

Good luck, and photos may be good to push this one further.
Old 02-24-2013, 03:13 PM
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Default RE: PAW .15 muffler leakage

Yeah, changing seals would be a pretty obvious solution, but I wanted to make sure noone said " they all leak there" or "look at this spot right here and see if x-problem exists" etc first. I did just pop the top end off and found a little flake of aluminum swarf that looked like maybe fell down the bolt hole on assembly and landed next to the bolt hole and was keeping the cooling head from seating evenly. There was a obvious oil stain around this part of the gasket. It easily came out of the gasket, and seeing it looked like there was plenty of unaffected area at that radial on the gasket I have lightly flat-filed the muffler and reassembled and checked for fin clearance. Hopefully this will resolve the issue. I plan to run it again tomorrow and see?
Old 02-24-2013, 03:30 PM
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Default RE: PAW .15 muffler leakage

Just wondering if you could pressurize the muffler by placing some tubing over the outlet, dunking the engine in some kero with the piston at TDC and blowing into the tube.

It would quickly show you where any leaks may exist.
Old 02-24-2013, 03:49 PM
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Default RE: PAW .15 muffler leakage

Rather amazing that the area so small can dump out such exhaust oil. my irvine mufflers were covered at every seam, coated the whole muffler. I resolved by loosening the center screw and put koppercoat on the section surface joints then tightened no more weeps or leaks martin
Old 02-24-2013, 05:45 PM
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Default RE: PAW .15 muffler leakage

Thanks RF and AMB, I stock the engine in liquid and did the air test and honestly it still leaks pretty horrible, almost as if the bolts tighten down before the collector and gaskets are "crushed"...., as it leaks at several points around the ring and the number and size of bubbles is pretty directly dependent on how hard I blow. I haven't decided whether I want to try to use some sealant, or try to make a shim or something. I really dislike having to buy parts for a brand new engine to seal, but maybe I'll call Carlson and see if they are in stock? This is pretty thick gasket material, but perhaps the local parts store has something slightly thicker. I build transmissions for a living, and over the years have grown to hate using glue or sealant unless it is the factory method, and have come to believe that if you have clean, flat surfaces and assemble correctly things should stay dry as a bone. Maybe PAW can tell me whether they think I have a poor fit on something?
Old 02-24-2013, 05:53 PM
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Default RE: PAW .15 muffler leakage

Try the Koppercoat think it is made by permatex do NOT use the regular black stuff and let it sit for a day to cure martin
Old 02-24-2013, 06:06 PM
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Default RE: PAW .15 muffler leakage

Got a large diameter small thickness heat proof Viton 'O' ring in your workshop?

If so then roll it down the cylinder OUTSIDE of your head bolts as part of the packing on top of the collector - you never know, it just may work!
Old 02-26-2013, 02:11 AM
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Default RE: PAW .15 muffler leakage

This old vertical intake PAW 249 runs very well, but unfortunately leaks like a sieve between the top flange of the collector ring, and the adjacent surface of the lowest fin on the cooling jacket.

http://www.youtube.com/watch?v=YhqOwEvcOlg

This engine was given to me from a deceased estate (ref. my earlier thread "diamonds in the rough"). It is very well made with first class materials and exemplary working fits. Compression is excellent despite it's strip down and re-assembly. A real credit to Gig.

The let down is that the lowest fin on the cooling jacket has been crudely filed away. The bottom surface is not trued. I suspect the engine was originally sold without the exhaust collector, then added by the owner at a later date with his own cutting down of the lowest cooling fin.

I will either skim and true the bottom surface of the lowest cooling fin and make a thicker top gasket to take up the clearance, or enquire with David Owen about a new cooling jacket. That would be a pity. The current cooling jacket has an ideal "tight slip on" fit promoting efficient thermal transfer.
Old 02-26-2013, 02:47 AM
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Default RE: PAW .15 muffler leakage

This stuff, Perfect brand Gasket material is great for model engine gaskets. I've used it for ETA 29 head gaskets and it hasn't failed yet.

I got mine from this lot on ebay: http://www.ebay.co.uk/itm/1709245958...84.m1423.l2649

Yes the international postage is excessive but it's much cheaper if you're in the US. It's also available from a whole lot of other dealers.



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Old 02-26-2013, 05:57 AM
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Default RE: PAW .15 muffler leakage

This .60 pictured here leaked like a sieve when new but as the gasket got soaked with lube oil and swelled up it quit leaking.
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Old 02-26-2013, 12:49 PM
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Default RE: PAW .15 muffler leakage


ORIGINAL: qazimoto

This stuff, Perfect brand Gasket material is great for model engine gaskets. I've used it for ETA 29 head gaskets and it hasn't failed yet.

I got mine from this lot on ebay: http://www.ebay.co.uk/itm/1709245958...84.m1423.l2649

Yes the international postage is excessive but it's much cheaper if you're in the US. It's also available from a whole lot of other dealers.



Without contacting the seller Ray, I would imagine that you could get probably 3 or 4 lots of this Gasket Paper for the same postage.

Cheers

Fredo

Old 02-26-2013, 01:29 PM
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Default RE: PAW .15 muffler leakage


ORIGINAL: fiery

This old vertical intake PAW 249 runs very well, but unfortunately leaks like a sieve between the top flange of the collector ring, and the adjacent surface of the lowest fin on the cooling jacket.

http://www.youtube.com/watch?v=YhqOwEvcOlg

This engine was given to me from a deceased estate (ref. my earlier thread "diamonds in the rough"). It is very well made with first class materials and exemplary working fits. Compression is excellent despite it's strip down and re-assembly. A real credit to Gig.

The let down is that the lowest fin on the cooling jacket has been crudely filed away. The bottom surface is not trued. I suspect the engine was originally sold without the exhaust collector, then added by the owner at a later date with his own cutting down of the lowest cooling fin.

I will either skim and true the bottom surface of the lowest cooling fin and make a thicker top gasket to take up the clearance, or enquire with David Owen about a new cooling jacket. That would be a pity. The current cooling jacket has an ideal "tight slip on" fit promoting efficient thermal transfer.
Now this rings a bell, when Dave Owen turned down the bottom fin of my old PAW 19 DS in lathe it had what he termed a 'drunken thread' and needed further adjusting.

The fins were not perpendicular to the bore.

Good call Derek.

Old 02-26-2013, 01:45 PM
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Default RE: PAW .15 muffler leakage

THAT i SUSPECTED But did not post if bottom of fin not 90 degrees to bore it will leak, sounds like cylinder was not dead center on when mounted and turned in lathe martin
Old 02-26-2013, 01:48 PM
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Default RE: PAW .15 muffler leakage

Thanks guys....I guess I'll at least chuck it up and measure run out the next time I pull it apart. I have marked everything when I took it apart to minimize "reseat" wear. I did notice that the little end of the rod, although having no vertical slop rocks a lot as if the hole is bigger at the edges than the center. Also the sleeve looks like the od rusted and pitted horribly but was scotch brited or sandpaper polished but still is very pitted on the OD. Do they "green" these pieces before boring like some cast iron auto blocks or something?
Old 02-26-2013, 01:52 PM
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Default RE: PAW .15 muffler leakage

Yup center up rotate and use a dial indicator on the mating surface make sure " no list to port mate" martin

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