Joeloliver Posted May 28, 2015 Share Posted May 28, 2015 My trophy truggy engine piston has stuck. Pull start jammed. Is this fixable? Thanks. Quote Link to comment Share on other sites More sharing options...
super sharp shooter Posted May 28, 2015 Share Posted May 28, 2015 Should be. Take the head off and have a look. Quote Link to comment Share on other sites More sharing options...
Joeloliver Posted May 28, 2015 Author Share Posted May 28, 2015 Will do. I like this hobby but its not cheap and my truggy always breaks. Maybe I should have bought a hyper 7 after all. Quote Link to comment Share on other sites More sharing options...
jea Posted May 28, 2015 Share Posted May 28, 2015 may just be stuck at tdc ? have you tried to free it buy turning the flywheel ? Quote Link to comment Share on other sites More sharing options...
Ben Willis Posted May 28, 2015 Share Posted May 28, 2015 (edited) If you can't turn the engine over, most likely it's stuck at top dead centre, where the liner "pinches" It mostly happens to new engines which are tight on pinch and compression. Best way to sort it is not to force it as this will damage it, but heat up the engine block then turn the flywheel as this will cause the liner to expand and the piston should the move freely. I also find it useful to make a mark on the flywheel and remember what point it's at when the engine's at bottom dead centre, in order to prevent it from seizing again Sent from my iPhone using Tapatalk Edited May 28, 2015 by Ben Willis 1 Quote Link to comment Share on other sites More sharing options...
Anthoop Posted May 28, 2015 Share Posted May 28, 2015 If you can't turn the engine over, most likely it's stuck at top dead centre, where the liner "pinches" It mostly happens to new engines which are tight on pinch and compression. Best way to sort it is not to force it as this will damage it, but heat up the engine block then turn the flywheel as this will cause the liner to expand and the piston should the move freely. I also find it useful to make a mark on the flywheel and remember what point it's at when the engine's at bottom dead centre, in order to prevent it from seizing again Exactly this... Whenever an engine is new then be prepared for hassle....heating and marking are a great help every time...never leave the piston near TDC...and when starting give the piston a little "run-up" before attempting to start Quote Link to comment Share on other sites More sharing options...
Joeloliver Posted May 30, 2015 Author Share Posted May 30, 2015 Thanks. Ill have a good look when I get chance early next week..Engine had approx one gallon through it. Quote Link to comment Share on other sites More sharing options...
Anthoop Posted May 30, 2015 Share Posted May 30, 2015 Unlikely that it is still tight enough to jam the piston at TDC after a gallon...but not impossible....try the advice given and if still no joy then pop the backplate and head off to see what is going on. Any problems just ask away...always someone to help round here. 1 Quote Link to comment Share on other sites More sharing options...
fatboyneil Posted May 30, 2015 Share Posted May 30, 2015 I'd take the head and backplate off first as if there is damage trying to force it even with heat could cause more damage Quote Link to comment Share on other sites More sharing options...
Joeloliver Posted June 3, 2015 Author Share Posted June 3, 2015 The flywheel does not move and the piston is not at the top. I will take the head and backplate off soon. Quote Link to comment Share on other sites More sharing options...
h4rri75 Posted June 3, 2015 Share Posted June 3, 2015 Jamie1987 had this on his MT 3.0 and it was the gudgeon pin had snapped causing the piston to jam in the liner. He ordered a new piston / liner set from the states and once fitted this resolved the issue. 1 Quote Link to comment Share on other sites More sharing options...
Tamiyacowboy Posted June 3, 2015 Share Posted June 3, 2015 Gonna say if that piston is not at TDC ( top dead center ) then it is more likely the conrod has a problem or more so a gudgeon pin thats shattered out. DO NOT try to move the engine by hand, any metal fragments can damage you internal bore - and crankshaft+brearings. remove the head , then undo the rear pullstarter and pop it off. you should see inside the crankshaft with a little pin and a rod fitted to it. top of that rod is a piston and a pin. and thats the area you need to look at. you may find the pin holding the conrod in place may have worn/snapped or jammed up and thats why the piston fails to turn the crank and vice a versa. it can happen to any engine new or old. Quote Link to comment Share on other sites More sharing options...
Anthoop Posted June 3, 2015 Share Posted June 3, 2015 Careful, if the piston is right at the bottom then you will damage the piston skirt when trying to remove the backplate. Quote Link to comment Share on other sites More sharing options...
Joeloliver Posted June 7, 2015 Author Share Posted June 7, 2015 Gonna say if that piston is not at TDC ( top dead center ) then it is more likely the conrod has a problem or more so a gudgeon pin thats shattered out. DO NOT try to move the engine by hand, any metal fragments can damage you internal bore - and crankshaft+brearings. remove the head , then undo the rear pullstarter and pop it off. you should see inside the crankshaft with a little pin and a rod fitted to it. top of that rod is a piston and a pin. and thats the area you need to look at. you may find the pin holding the conrod in place may have worn/snapped or jammed up and thats why the piston fails to turn the crank and vice a versa. it can happen to any engine new or old. Thanks . Your right, the pin that connects the piston and the connecting rod has snapped and metal bits were stuck in the engine preventing it moving. Quote Link to comment Share on other sites More sharing options...
h4rri75 Posted June 7, 2015 Share Posted June 7, 2015 Depending on damage to the rest of the engine you could get away with replacing the liner, piston and rod as a kit. Failing that it's new engine time Quote Link to comment Share on other sites More sharing options...
Joeloliver Posted June 8, 2015 Author Share Posted June 8, 2015 I'll try and see if I can get it under warranty. Quote Link to comment Share on other sites More sharing options...
Joew Posted December 31, 2020 Share Posted December 31, 2020 Hi i have the same issuse with the dynamite 28 mack 2 motor piston is s jammed an ive got back plate off but still cant get the pisston to move Quote Link to comment Share on other sites More sharing options...
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