PULL CORD HARD TO PULL

jam0067

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I have a Craftman Briggs and Stratton lawn mower self propelled (i have only used it for a few seasons) I am having trouble pulling the cord. I never had a problem starting it. I went to start it this year and the cord was extremely hard to pull. I thought it might be the piston that got corroded on the cylinder since it's been a while since I have use the lawn mower( I keep the lawnmower in my garage). I took off the blade, disconnected the self propelled belt and the took off the cylinder head. I turned the engine by hand and the piston looks to be going up and down and valves are opening and closing with out a problem. I did note the piston seems like it was getting caught on something at times when I was turning it by hand (I was thinking a possible bent crank). I changed the oil, flushed the fuel system, change the blade but still having the same problem. I took off the recoil mechanism (pull cord) off the lawn mower and checked it and it is not getting caught on anything. I put everything back together. it is easier to pull the cord then at first but I am still getting a lot of resistance. I then thought it might be the brake for the self propel mechanism. I disconnected the belt for the self propel mechanism to see it the issue was there. that did not make a difference. At this point I am thinking I have a bent crank. I have hit a lot of rocks in the past and the blade was pretty chewed up so maybe the problem is there. When I put the lawn mower on it's side with the propelled belt off and the spark plug off the blade seem to have a lot of resistance when I turn it. I don't know if that is normal. also as I turn the blade it seems that sometimes it frees up for about 1/4 turn and then I get a lot of resistance again. I don't know if that is normal. I don't think it is. Anyways, if anyone has any input on my problem I would appreciated. I was thinking of replacing the crank ( I am pretty good with mechanical stuff) but I just don't think it's worth it. the Crank goes for about $100 w/ shipping. I probably will have to buy a lot of hardware and spent a lot of time doing it when I can just go buy another lawnmower for a little over $200.
 

Gsnod

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You should pull the spark plug and see whether that makes it easier to turnover. If so, then that will help identify this issue -- i.e. bent crank, versus a value sticking (such as the exhaust valve).

I have a Craftman Briggs and Stratton lawn mower self propelled (i have only used it for a few seasons) I am having trouble pulling the cord. I never had a problem starting it. I went to start it this year and the cord was extremely hard to pull. I thought it might be the piston that got corroded on the cylinder since it's been a while since I have use the lawn mower( I keep the lawnmower in my garage). I took off the blade, disconnected the self propelled belt and the took off the cylinder head. I turned the engine by hand and the piston looks to be going up and down and valves are opening and closing with out a problem. I did note the piston seems like it was getting caught on something at times when I was turning it by hand (I was thinking a possible bent crank). I changed the oil, flushed the fuel system, change the blade but still having the same problem. I took off the recoil mechanism (pull cord) off the lawn mower and checked it and it is not getting caught on anything. I put everything back together. it is easier to pull the cord then at first but I am still getting a lot of resistance. I then thought it might be the brake for the self propel mechanism. I disconnected the belt for the self propel mechanism to see it the issue was there. that did not make a difference. At this point I am thinking I have a bent crank. I have hit a lot of rocks in the past and the blade was pretty chewed up so maybe the problem is there. When I put the lawn mower on it's side with the propelled belt off and the spark plug off the blade seem to have a lot of resistance when I turn it. I don't know if that is normal. also as I turn the blade it seems that sometimes it frees up for about 1/4 turn and then I get a lot of resistance again. I don't know if that is normal. I don't think it is. Anyways, if anyone has any input on my problem I would appreciated. I was thinking of replacing the crank ( I am pretty good with mechanical stuff) but I just don't think it's worth it. the Crank goes for about $100 w/ shipping. I probably will have to buy a lot of hardware and spent a lot of time doing it when I can just go buy another lawnmower for a little over $200.
 

exotion

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He saw the piston and valves plug was definately off. Flip the mower on its side carb up spark plug off. Pull the cord observe the crank does it wobble? If so you have a bent crank. Do the valves seem loose are the rods connected properly?
 

MRCo.

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Worn cam = no decomp maybe?
 

jam0067

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You should pull the spark plug and see whether that makes it easier to turnover. If so, then that will help identify this issue -- i.e. bent crank, versus a value sticking (such as the exhaust valve).
===
thanks for the reply. I took off the spark plug and put the lawn mower on it's side and spun the propeller again... the propeller is now spinning a little easier and it doesn't get caught on anything as i am trying to spin the propeller. That makes sense to me. I guess i was feeling a non-uniform resistance before when spinning the prop (with the spark plug in but wire off) because i was getting some resistance when the piston was on it's compression stroke... i still feel like there is way too much tension on that cord. is it possible for a lawn mower to start with a bent crankshaft? it's hard to see if the blade is wobbling when i spin it. I will try taking some measurements from the propeller bolt to another reference point as i spin it.
 

jam0067

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He saw the piston and valves plug was definately off. Flip the mower on its side carb up spark plug off. Pull the cord observe the crank does it wobble? If so you have a bent crank. Do the valves seem loose are the rods connected properly?
---
thanks for the reply. i just disconnected the spark plug wire when i originally posted. i removed the spark plug before and that seem to help a little. it's really hard to see if the crank is wobbling. i am going to try and measure it out... I only took the cylinder head off. I didn't take the piston or valve out. When i took the cylinder head off i did not see anything out of the norm. the valves seem straight and closing and opening without a problem. the piston also looked ok. i did not see any scoring to the cylinder wall.. do you think is possible to start the lawn mower with a bent crank?
 

MRCo.

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If there was an amount of resistance with no plug then there's an issue...with no plug it should be free as a bird to pull. Maybe your crank bearings went bad?
 

pete fender

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It's a few years later, but for anyone with this problem, check your valve clearance.
I have been a mower and landscape mechanic for over 35 years, and if the clearance is too tight, the lifter is not riding the cam correctly, the compression relief bump on the cam is not opening the intake vale a tiny amount to release some compression when starting.
This is for overhead valve engines, they have adjustable rocker arms under a valve cover.
Older motors have this same tight clearance problem (too much compression) when starting.
They need to be removed and filed down a bit, increasing valve clearance.
This compression relief does not happen once the motor reaches running speed.
 
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