My Lawnmower Forum banner
1 - 10 of 10 Posts

·
Registered
Joined
·
16 Posts
Discussion Starter · #1 ·
I have an old Snapper I picked up back in February. Replaced the blade, spark plug, and have a new air filter on the way.

When I am mowing my lawn and I stop the mower and turn it off. I can't get it to start back up. It cold starts on the first pull every time. Once the engine is warmed up it starts but it idles real low and rough and sometimes shuts off. If I let it sit for a while it starts right up again first pull.

My thoughts are this:

Old gas (michigan has alcohol in their gas)
gummed up carb
coil going bad
bad air gap on spark plug

I am not an expert in small engine repair, and any suggestions would great.

What weight oil do these engines take? I think an oil change is in order after I mow my lawn today.
 

·
Premium Member
Joined
·
5,898 Posts
If you can check for spark right when you are having your problem. If you still have a strong spark when the engine is still hot, I would think your coil is probably ok. Is the old air filter plugged up, or is it degrading? It could be starving for air. You could try (Just in a clean area on the concrete, DO NOT MOW) running it without the air cleaner for a bit to see if the engine does the same thing. You may consider rebuilding/cleaning the carb as you don't know how long it sat prior to you purchasing the mower. As far as the oil, I don't have the specifics but I would think you would be safe with 30W
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #3 ·
If you can check for spark right when you are having your problem. If you still have a strong spark when the engine is still hot, I would think your coil is probably ok. Is the old air filter plugged up, or is it degrading? It could be starving for air. You could try (Just in a clean area on the concrete, DO NOT MOW) running it without the air cleaner for a bit to see if the engine does the same thing. You may consider rebuilding/cleaning the carb as you don't know how long it sat prior to you purchasing the mower. As far as the oil, I don't have the specifics but I would think you would be safe with 30W
Thanks for getting back to me so fast.

How do I check for a strong spark?

I pulled the air filter to see if that helped (on the concrete of course) but that made no difference. The filter is just old and I thought a new one would be a good idea.

I'll try a rebuild kit if the spark turns out good. A coil is around $130 and a carb rebuild kit around $30. Either way I still got a good deal on this thing.
 

·
Premium Member
Joined
·
5,898 Posts
If you have a spare plug you could remove the plug wire and put it on the spare plug and ground the electrode of the plug to the block and have someone pull start it for you. You should see a bright clean whitish blueish spark.
Make sure you hold the plug/wire with an insulated tool so you don't get zapped!

I felt compelled to tell you that ;)
 

·
Registered
Joined
·
130 Posts
Although the four items you listed could be potential problems, the symptoms of each is not what you are describing. What you are describing is a lack of compression when hot. 99% of the time, it is the result of improperly set valves, ethanol gas causing the engine to run hot, ramming the intake and exhaust seats into the block more, and ultimately causing a lack of compression when the engine warms up. I have 8 snapper 21401 series mowers, like the one you have. They are excellent machines which require very little work in order to keep running in tip top shape! I am not the biggest fan of the Wisconsin Robin, aka FUJI heavy Industries engines, but the valves are definitely the culprit this time! Been there done that :)

6 of my 21401P/PS's have Briggs and Stratton engines, 3.5, 4, and 5hp, 1 has a Tecumseh TVS105, and the last has a Wisconsin Robin 2-cycle 4HP "extra tough" engine. I regard these mowers as the best mowers Snapper ever made. They are literally bulletproof. The only thing which usually breaks on them are the plastic discharge shoots and rear rock guard. Otherwise, they are a beast. They commanded that price too. They usually ran you anywhere from $625-750 new in the 1970's depending on engine and options (snapperizer, mulcherizer, thatcherizer, pac n sac, air lift blades, electric start, etc)

Chris
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #7 ·
Although the four items you listed could be potential problems, the symptoms of each is not what you are describing. What you are describing is a lack of compression when hot. 99% of the time, it is the result of improperly set valves, ethanol gas causing the engine to run hot, ramming the intake and exhaust seats into the block more, and ultimately causing a lack of compression when the engine warms up. I have 8 snapper 21401 series mowers, like the one you have. They are excellent machines which require very little work in order to keep running in tip top shape! I am not the biggest fan of the Wisconsin Robin, aka FUJI heavy Industries engines, but the valves are definitely the culprit this time! Been there done that :)

6 of my 21401P/PS's have Briggs and Stratton engines, 3.5, 4, and 5hp, 1 has a Tecumseh TVS105, and the last has a Wisconsin Robin 2-cycle 4HP "extra tough" engine. I regard these mowers as the best mowers Snapper ever made. They are literally bulletproof. The only thing which usually breaks on them are the plastic discharge shoots and rear rock guard. Otherwise, they are a beast. They commanded that price too. They usually ran you anywhere from $625-750 new in the 1970's depending on engine and options (snapperizer, mulcherizer, thatcherizer, pac n sac, air lift blades, electric start, etc)

Chris
Is there anything I can do to fix the issue? Run different gas, or add an additive of some type?
 

·
Registered
Joined
·
130 Posts
Adjusting the valves is time consuming, but not the most difficult thing in the world. Have you ever adjusted the valves on an engine before?

The W1-145V is an L head over head cam engine, without valve adjusters.
You will need to remove the starter shroud, cylinder head, carburetor, and valve cover. With a valve spring compressor, you will need to remove the valves. First turn the flywheel so that the intake valve is all of the way up. When the intake valve is up, the exhaust valve is down. With the exhaust valve down, position the valve spring compressor under the exhaust valve spring retainer. After cranking upwards, the spring will compress and the valve will slide upwards. When the valve is up, tap the valve down with a rubber mallet, and slide the retainer out of the way. Slide the valve out, and remove the spring compressor. Take the valve to the wire wheel and clean up any residue which has built up on the valve stem. With some Permatex valve lapping compound, and a valve rotator, apply some compound between the valve and seat. Spin back and forth for a few minutes, until the seat and valve touch completely. With the valve now lapped. Reinsert the valve. With a set of feeler gauges, measure the clearance between the end of the valve and the valve lifter. It should be around 0.006" or so. (Im not a FUJI guy, so check the manual for measurements) If the valve gap is larger than the allotted clearance, the camshaft is worn excessively and needs to be replaced. If the valve gap is less than normal, the valve seats have pressed into the block too far (caused by overheating) You must remove the valve and slowly take off a little bit of material from the end of the valve until the clearances are correct. When the clearances match the book, and you have double checked your measurements, insert the valve, compress the spring and slide the retainer back on. You must do this for both the intake and exhaust valves. Once properly set, and the engine re-assembled, your problem will go away and the engine will run properly.

If this is your first rodeo, I would bring the engine to a mechanic or mower shop and ask to watch what they are doing. You must check that the valves are straight and the valve guides are not sloppy. Someone with the tools and experience can do all of this in an hours time.

Chris
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #9 ·
I have not messed with valves before. There is a place in town that will probably do it and allow me to watch. I'll check it out.
 

·
Registered
Joined
·
130 Posts
I do not know the location of towns in Michigan, but I bought my truck from Denny Zeiss, who is the president of the Midland Antique Engine club. If you have any trouble finding a reputable shop, I am sure someone from the club knows where to point you!

Chris
 
1 - 10 of 10 Posts
Top