The customer was afraid they were going to need a new engine. I hate going in behind someone else taking parts off. Especially when you get some parts in a box. So I didnt know what to expect so I was scoping the cam and cylinder walls before putting it back together for a test run.
couple comments: yes, engine should be hot first before doing a leak down test. (sometimes valves, head gaskets, or even small micro cracks do not develop until engine is hot...) while it IS true you want to perform a LDT while piston is at top dead center, you ALSO want to make sure you are one the correct stroke cycle at top dead center AND you want to make sure that if your engine has a compression release on the cam, then make sure that is not engaged. One way to check this is that if your LDT goes immediately to zero..then unhook it and rotate engine another 180 degrees at the "OTHER" top dead center...then check the leak down test again. If you are off the proper stroke cycle or in the compression release phase of rotation you will get faked out thinking you have leaky valves. just something to know before you do a leak down. also this: top dead center is how you determine valves problems (can be due to valves stuck or stepped out seats or too much soot in the seat), but it can also be due to a timing problem: improper valve lash! So always make sure you have the valve clearance set correctly at top dead center before you do the LDT test. If you do the valve clearance and the LDT still fails, then you probably have a stepped out valve seat or too much soot or out of plane valve to seat fitment. also this: sometimes the a compression issue is not related to valves...it can be the head gaskets..or it can be some problem with the cylinder walls and piston rings. One way to find out if you have a cylinder bore to piston ring issue is to put the piston at BOTTOM TOP CENTER...again making sure both valves are CLOSED and that you are NOT in the compression release phase. If the LDT is okay at top dead center, but fails at BOTTOM DEAD CENTER, then you either have cylinder to piston ring issue, or there can be a tiny crack somewhere down lower in the cylinder or the head gasket is failing. I like to put a heavier viscous oil in the spark plug and then move it to BOTTOM DEAD CENTER and do the LDT again. If it tests better, then it's probably some bad piston rings or a worn out cylinder or both. some folks have better luck using some old school tricks when doing the LDT...especially the old timers who don't have very good hearing anymore. You tie off some air balloons to the oil filler cap and the carb throttle body and the exhaust....leaks that happen when cause the balloons to expand. Especially helpful in a noisy shop where the compressor is running and you can't hear hissing. Also helpful is to use some soapy water on the head gasket area...look for bubbles forming for the external leaks. same thing on the intake gaskets to the cylinder.... another things to look for is missing or leaking welch plugs in the carb. this is one of those things that you always want to check if an engine is misfiring or running roughly or surging. (as well as a gas cap that is not venting!).. God Bless America
had a mate cook the kawasaki engine on his fairly new Toro a few weeks ago. Had never checked or changed the oil or taken it for dealer service ... my only comment to him was oil and filters are dirt cheap ...
I cant tell you how many times Ive seen customers decline oil changes, $5 fuel filters, and $15 air filters...then end up having to spend $3k on a new engine.
The fastest easiest way to find top dead center on the compression stroke is to use the leak down tester. Just put 5 to 8 PSI in the cylinder then turn the engine by hand. You will feel the compression. Just turn the engine back and forth over the hard spot then stop in the middle of the hard spot. BOOM DONE. There’s no need to clamp the engine in place. If it’s at TDC it will stay there. Now crank up the leak down tester and perform your test.
I got my otc leak down tester from zoro. There $89 and if you get their emails they almost always send me a 20% off something all the time. Plus free returns if your not happy. Only issue I found with my otc leak down tester was the glass on the right gauge was very loose so I had that exchanged the second one was better but still moved around. It always seemed to be the right gauge and not the left.
I have a kohler vtwin, it has the same symptoms, it has almost no power and tons of fuel coming from the intake tube. I did a leak down test, and it has no leaks on the intake or exhaust valves. What else could cause these symptoms?
@@Mechanical_Mind thank you for the fast reply I failed to mention that I did a ton of work to this engine as it had worn out rings and the flywheel key had sheared as the original owner probably hit something hard, Just recently installed a brand new carburetor on it, has new gaskets and seals, new piston rings, valves lapped, also bled the hydraulic lifters, i am going to pull the bottom of the case off just to make sure i did set the timing right on the cam and crankshaft. I doubt thats the problem but am out of ideas.
Wow, how can people leave stuff like that and not let the owner know .... ridiculous. Good job working through it all!
Great that you found out the air leak on this engine 👌👍
The customer was afraid they were going to need a new engine. I hate going in behind someone else taking parts off. Especially when you get some parts in a box. So I didnt know what to expect so I was scoping the cam and cylinder walls before putting it back together for a test run.
@@Mechanical_Mind that is a great idea to do that for the customer because of the price of a new one is going up in price for sure
couple comments:
yes, engine should be hot first before doing a leak down test. (sometimes valves, head gaskets, or even small micro cracks do not develop until engine is hot...)
while it IS true you want to perform a LDT while piston is at top dead center, you ALSO want to make sure you are one the correct stroke cycle at top dead center AND you want to make sure that if your engine has a compression release on the cam, then make sure that is not engaged. One way to check this is that if your LDT goes immediately to zero..then unhook it and rotate engine another 180 degrees at the "OTHER" top dead center...then check the leak down test again. If you are off the proper stroke cycle or in the compression release phase of rotation you will get faked out thinking you have leaky valves. just something to know before you do a leak down.
also this: top dead center is how you determine valves problems (can be due to valves stuck or stepped out seats or too much soot in the seat), but it can also be due to a timing problem: improper valve lash! So always make sure you have the valve clearance set correctly at top dead center before you do the LDT test. If you do the valve clearance and the LDT still fails, then you probably have a stepped out valve seat or too much soot or out of plane valve to seat fitment.
also this: sometimes the a compression issue is not related to valves...it can be the head gaskets..or it can be some problem with the cylinder walls and piston rings. One way to find out if you have a cylinder bore to piston ring issue is to put the piston at BOTTOM TOP CENTER...again making sure both valves are CLOSED and that you are NOT in the compression release phase. If the LDT is okay at top dead center, but fails at BOTTOM DEAD CENTER, then you either have cylinder to piston ring issue, or there can be a tiny crack somewhere down lower in the cylinder or the head gasket is failing. I like to put a heavier viscous oil in the spark plug and then move it to BOTTOM DEAD CENTER and do the LDT again. If it tests better, then it's probably some bad piston rings or a worn out cylinder or both.
some folks have better luck using some old school tricks when doing the LDT...especially the old timers who don't have very good hearing anymore. You tie off some air balloons to the oil filler cap and the carb throttle body and the exhaust....leaks that happen when cause the balloons to expand. Especially helpful in a noisy shop where the compressor is running and you can't hear hissing. Also helpful is to use some soapy water on the head gasket area...look for bubbles forming for the external leaks. same thing on the intake gaskets to the cylinder....
another things to look for is missing or leaking welch plugs in the carb. this is one of those things that you always want to check if an engine is misfiring or running roughly or surging. (as well as a gas cap that is not venting!)..
God Bless America
had a mate cook the kawasaki engine on his fairly new Toro a few weeks ago. Had never checked or changed the oil or taken it for dealer service ... my only comment to him was oil and filters are dirt cheap ...
I cant tell you how many times Ive seen customers decline oil changes, $5 fuel filters, and $15 air filters...then end up having to spend $3k on a new engine.
The fastest easiest way to find top dead center on the compression stroke is to use the leak down tester. Just put 5 to 8 PSI in the cylinder then turn the engine by hand. You will feel the compression. Just turn the engine back and forth over the hard spot then stop in the middle of the hard spot. BOOM DONE. There’s no need to clamp the engine in place. If it’s at TDC it will stay there. Now crank up the leak down tester and perform your test.
I got my otc leak down tester from zoro. There $89 and if you get their emails they almost always send me a 20% off something all the time. Plus free returns if your not happy. Only issue I found with my otc leak down tester was the glass on the right gauge was very loose so I had that exchanged the second one was better but still moved around. It always seemed to be the right gauge and not the left.
I have a kohler vtwin, it has the same symptoms, it has almost no power and tons of fuel coming from the intake tube. I did a leak down test, and it has no leaks on the intake or exhaust valves. What else could cause these symptoms?
Faulty carburetor, most likely.
@@Mechanical_Mind thank you for the fast reply I failed to mention that I did a ton of work to this engine as it had worn out rings and the flywheel key had sheared as the original owner probably hit something hard, Just recently installed a brand new carburetor on it, has new gaskets and seals, new piston rings, valves lapped, also bled the hydraulic lifters, i am going to pull the bottom of the case off just to make sure i did set the timing right on the cam and crankshaft. I doubt thats the problem but am out of ideas.