Brainsparks30 Posted November 25, 2012 Share Posted November 25, 2012 I recently bought a used PAW 100 (no throttle) thinking it was all wonderfull but now its looking like trouble. I found the cold start setting and it flick started easy enough but barely had any power. Tacho showed 4800rpm with MT D1000 on a kavan 7x4. Then I noticed it spitting out from under the exhaust pipe ring. No gasket under silencer and the top one was split! Finally noticed the head screws were loose! Reluctantly took it all apart to remove the silencer (not willing to come off easily) and noticed scoring/scratches all round the cyclinder and piston, not up and down but radially. None of this is good. I have been having visions of the cylinder being so loose that its rotating. Is that possible? Is it trashed? How do I get the exhaust off the liner sympathetically (must be a burr)? I dont want to start spending a fortune on this when better things await along with a potential ebay dispute. Is there anywhere I can get silmilar gasket material and cut my own? As I am an enthusiast but not an expert with small diesels, I need a better opinion if anyone would like to share it. Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted November 26, 2012 Share Posted November 26, 2012 Hello. Did/does the engine have good compression ? Are the scratches deep and fresh or faint? the marks could be machining marks from manufacture although these would be very fine . The loss of power would probably be due to the leak at the bottom of the cylinder of crank case compression . new gasket are readily available from PAW and should only cost pence . Why not just fit some new gaskets and try running it . You say it flick started easily so it must have fair compression. Did yo mark the cylinder in relation to the crankcase prior to removing it? If not you will have to turn the cylinder to find the sweet spot where it was last fitted;fit cylinder and turn over checking for any tight spots. If its tight or slightly stiff turn cyl slightly . keep doing this until it will turn over without binding. if your lucky then it will turn ok first time .Cyliders on these engines should not be removed or disturbed too often as they wear into one another and every time you move them they have to bed in again almost like running in again. This will cause unescessary wear .The exhaust ring should slide away easily so sounds as though its been fitted wrong or damaged You shouldn't damage the cylinder by forcing it off or better still just cut it off. Should you have just contacted the seller before stripping it down ? once stripped and messed with they can refuse a return .Hope you get it running ok. Quote Link to comment Share on other sites More sharing options...
Brainsparks30 Posted December 3, 2012 Author Share Posted December 3, 2012 Really excellent tips, thankyou! I realised that I should have marked the cyclinder after the very nano second it rotated when the fins came off! The way you describe reassembly makes good sense, I wish I had known that sooner. The whole lot nearly ended up in the box labeled ''Things I never should have bought of ebay' whis is, err... not at all empty. I got a new set set of gaskets and they are a real fiddle not to ruin. Look a lot like cardboard to me. Managed to remove the silencer by gently using a socket as a drift over the cylinder (I was quite smug about that) and advoided butchering it. Replacements are not cheap anymore. Reformed the silencer ring gently with screwdriver. Really need a comp lock lever as its undoing itself. Compression seems good, noise is much lower than I could have hoped for. Oh and balancing the propellor is a good idea too. Your right about ebay returns, but I was keen to know if I had a quantifiable proplem I could argue the case with. Small oversights... Quote Link to comment Share on other sites More sharing options...
IanN Posted December 4, 2012 Share Posted December 4, 2012 PAW exhaust gaskets always leak, to some extent. The trick is to accept that, and not fall into the trap of overtightening - which will eventually distort the collector ring and make things worse Quote Link to comment Share on other sites More sharing options...
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