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Scott Dorsey 05-06-2009 06:41 PM

Hard starting Briggs & Stratton 3.0 hp lawnmower engine
 
Ralph Mowery wrote:

I don't know what the part cost, but it should not have been more than a few
dollars. Chances are if the new part was put in it would be good for life.
If I had gone that far I would not worry about an inexpensive part. Even if
it had been an expensive part I would use the new one and maybe save the old
one.


Rubber parts fail. If you have the carb apart anyway, replace every damn
rubber part in it... seals and washers, diaphragm and everything. B&S
will sell you a "rebuild kit" that has everything in it. If there are any
rubber parts in the thing that haven't failed yet, they are on their way
to failing anyway so just change it beforehand.

Reminds me of what hapened at work. We had a large varitable speed moror
drive to go out. Called in a factory man to work on it. He found two bad
diodes. There was a third diode (three phase circuit) and I asked him to
replace it also. He said it was $ 200. I told him to go ahead. If it went
out that $ 200 was nothing to what it would cost to get him back in and the
ammount of downtime on the equipment.


And keep the old diode as a spare!
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Ralph Mowery 05-06-2009 07:30 PM

Hard starting Briggs & Stratton 3.0 hp lawnmower engine
 

"HLS" wrote in message
...

"Steve" wrote in message
...
muzician21 wrote:


I don't like tossing out perfectly good parts and if I can get more
lifespan out of a part I'm all for it.



A diaphragm that has been in service for some considerable time, then
is taken out and allowed to dry, might work a while longer, but....
if you want to mow the yard or till the garden, it is foolish to go in and
clean the carburetor and not install new elastomer parts, IMHO


I don't know what the part cost, but it should not have been more than a few
dollars. Chances are if the new part was put in it would be good for life.
If I had gone that far I would not worry about an inexpensive part. Even if
it had been an expensive part I would use the new one and maybe save the old
one.

Reminds me of what hapened at work. We had a large varitable speed moror
drive to go out. Called in a factory man to work on it. He found two bad
diodes. There was a third diode (three phase circuit) and I asked him to
replace it also. He said it was $ 200. I told him to go ahead. If it went
out that $ 200 was nothing to what it would cost to get him back in and the
ammount of downtime on the equipment.



Buzzie75 15-08-2009 03:38 AM

Quote:

Originally Posted by muzician21 (Post 846693)
Have a B&S on a 70's era Snapper 21" pusher with an aluminum deck. I
believe the engine is probably 10 years newer than the rest of the
mower.

Maybe 10 years ago I took it to a repair shop who installed a solid
state unit to replace the points. Even with the solid state ignition
it was never one-pull start, but as I recall it usually started with
probably 3 - 5 pulls. Now it takes probably 20 pulls or more and
monkeying with the throttle. Once it fires it runs like a clock, runs
up and down the speed range fine. It's also easier to re-start once
it's been running - though still not one pull. Doesn't seem to use an
inordinate amount of oil, no discernible smoke out the exhaust. It
gets what I'd call moderate use. I'm in central Florida so it gets run
bi-weekly or so during the rainy months, not at all during the months
of what passes for a winter down here.

I'm mechanically inclined but not well-versed on the theory of this
kind of engine. I've had it broken down far enough to remove and flush
the gas tank, change the points when it had points, replace the pull
rope. I've change the spark plug of course. I know it should start
much easier than it does. Any suggestions where to look, what to
tweak? There isn't that much to it from what I can see, so it
shouldn't be that difficult. I believe this mower has a lot of life
left in it.

Thanks for all input.

If you haven't got the problem fixed pull the head, turn the crankshaft to top dead center on the compression stroke, not the exhaust stroke, and then drop the piston 1/4 inchdown past top dead center. This will take all the tension off the lifters and there should be a gap between the lifters and valves. Then take a .002 or .003 feeler gage or just a regular piece of paper .004 thick not cardboard are such and go around the exhaust valve. Eventually you will find a gap, between the valve and the valve seat about one quarter of the way around the exhaust valve. The motor will go on starting for a while, and eventually it will take 40 pulls to start it. It best to go ahead and do a professional valve job or you can lap the valves but in this case it going to take 3-4 hours. At 40 pulls you will be pulling and stretching tendons in your elbow and then you going to have something else to repair. The engine still has a lot of life, the fuel economy will be great when you get the valve lapped and shouldn't have a problem for 2-3 more years but you will have to watch this valve seat. not much fun sleeping on a sore elbow for weeks on end. The little motor will purr when you get it back

Take care


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