I have an old John Deere 522 snow thrower that has a 5hp 4-stroke
engine. When I received it from my father-in-law, I noticed that it
occasionally had backfire (or afterfire) from the exhaust. But
lately, the problem seems to be more apparent -- either it happens
more often or I start paying more attention to this problem.

Seem like the backfire occurs as soon as I start the engine regardless
the engine is under load or not. Sometimes, I even see flame throwing
out from the exhaust. Consequently, the exhaust is blackened.

Online source says that the air/fuel mixture probably is too rich in
fuel and the incompletely burnt fuel ends up getting burnt in the
exhaust. According to the operator-manual, the problem must have
something to do with the carburetor not adjusted correctly or the
carburetor leaks air. Either case, the manual suggests me to bring it
to the dealer. But I really don't want to bring it to the dealer in
the middle of winter when I need to use the snow thrower. I would
much prefer to bring it in in late winter or spring when I don't need
to use it any more.

My questions a

o Can I continue using the snow thrower in this winter? Then I can
bring it to the dealer in the spring.

o Is this something that I can fix if I can find a service-manual and
a parts list? I am reasonably handy (home improvement...etc) despite
the fact that I have never opened up an engine before. Note that the
operator-manual doesn't say anything about fixing / checking /
adjusting the carburetor. I hope that the service manual may have the
necessary info.

Thanks in advance for any info.

Jay Chan

On 23 Feb 2007 10:28:59 -0800, "Jay Chan"
wrote:

I have an old John Deere 522 snow thrower that has a 5hp 4-stroke
engine. When I received it from my father-in-law, I noticed that it
occasionally had backfire (or afterfire) from the exhaust. But

I guess you mean afterfire, because backfire is firing through the
carburetor. A lot of people have been misusing the word lately.

lately, the problem seems to be more apparent -- either it happens
more often or I start paying more attention to this problem.

Seem like the backfire occurs as soon as I start the engine regardless

I don't really know the term afterfire, but I think that's the term
you want.

the engine is under load or not. Sometimes, I even see flame throwing
out from the exhaust. Consequently, the exhaust is blackened.

Online source says that the air/fuel mixture probably is too rich in
fuel and the incompletely burnt fuel ends up getting burnt in the
exhaust. According to the operator-manual, the problem must have
something to do with the carburetor not adjusted correctly or the
carburetor leaks air.

Leaking air would normally lean the mixture, not enrichen it. But
that still leaves "not adjusted correctly". Someone else who knows
more about small engines will have to help here, but I thought there
was generally only an idle mixture or speed adjustment, and you'r not
talking about when it is idling, or are you?

Another cause of afterfire would I think be a retarded spark, that
fires too late so the gas is still burning when the exhaust valve
opens. Does the thing still have the proper amount of power? I
would think that quite a bit of power would be lost if this is the
problem. I don't relaly think it is the spark timing because every
small engine I know, that can't be adjusted. (Although it could be
retarded if you hit something that stopped the shaft from turning and
partially sheared the key that holds the flywheel to the crankshaft.
(The flywheel usually causes the spark as it passes the coil) You
should be able to take off a cover or two and see the top of the
crankshaft and the flywheel, and you should be able to see the key
that way and be able to tell if it is still rectangular in cross
section. If it is shaped like a B or 8 but the bottom half is offset
from the top half, it is partially sheared. Ask again how to replace
it. Getting the flywheel off takes some instruction.

Either case, the manual suggests me to bring it
to the dealer. But I really don't want to bring it to the dealer in
the middle of winter when I need to use the snow thrower. I would
much prefer to bring it in in late winter or spring when I don't need
to use it any more.

My questions a

o Can I continue using the snow thrower in this winter? Then I can
bring it to the dealer in the spring.

Ask your fil how long it has been doing this. Maybe for years. Is it
getting worse?

How much more snow will you have, how many more hours does it have to
run?

o Is this something that I can fix if I can find a service-manual and
a parts list? I am reasonably handy (home improvement...etc) despite
the fact that I have never opened up an engine before. Note that the
operator-manual doesn't say anything about fixing / checking /
adjusting the carburetor. I hope that the service manual may have the
necessary info.

If it is the carburetor, you don't have to open the engine. Two bolts
and maybe a hose or a couple wires and the carb is off. The lawnmower
guy wanted to see me about every replaceable part, for a total of
maybe 25 dollars. iirc. If he were around the corner, I would have
replaced the parts one at a time, in order to learn which one was the
problem, but I needed to mow the lawn and he was several miles away,
so I bought almost all of them. The jet(s) and the needle valve seemed
most important. A needle valve that doesn't shut will definitely
cause too rich a mixture, if it will start, because the height of the
gas in the bowl will be too much. Jets I guess don't get bigger, they
get smaller when gas hardens in them over the summer (in the case ofa
snow blower) but a lot of people would just replace everything.


Thanks in advance for any info.

Jay Chan

On Feb 23, 1:28 pm, "Jay Chan" wrote: brevity
snip

o Is this something that I can fix if I can find a service-manual and
a parts list? I am reasonably handy (home improvement...etc) despite
the fact that I have never opened up an engine before. Note that the
operator-manual doesn't say anything about fixing / checking /
adjusting the carburetor.

You could try adjusting the carb. Typically they have a needle valve
screw with a spring around it.

**First, turn the screw in, all the way, and note how many -full-
turns it takes to bottom out.** You can always use this reference to
return to the original setting, and no harm done.

Try backing it out 1 turn, then 1-1/2 turns, etc. and see what effects
that has.

I'd check the first reference first, return to the original setting,
start the motor and work the valve in from there.
-----

- gpsman

Another common problem is that the key between the crankshaft and flywheel has
partially sheared. The cure is to remove the flywheel, replace the key, and put
the flywheel back. It will be a lot easier if you have a flywheel puller.
--

Larry
Email to rapp at lmr dot com

On 23 Feb 2007 10:28:59 -0800, "Jay Chan" wrote (with
possible editing):

I have an old John Deere 522 snow thrower that has a 5hp 4-stroke
engine. When I received it from my father-in-law, I noticed that it
occasionally had backfire (or afterfire) from the exhaust. But
lately, the problem seems to be more apparent -- either it happens
more often or I start paying more attention to this problem.

Seem like the backfire occurs as soon as I start the engine regardless
the engine is under load or not. Sometimes, I even see flame throwing
out from the exhaust. Consequently, the exhaust is blackened.

Online source says that the air/fuel mixture probably is too rich in
fuel and the incompletely burnt fuel ends up getting burnt in the
exhaust. According to the operator-manual, the problem must have
something to do with the carburetor not adjusted correctly or the
carburetor leaks air. Either case, the manual suggests me to bring it
to the dealer. But I really don't want to bring it to the dealer in
the middle of winter when I need to use the snow thrower. I would
much prefer to bring it in in late winter or spring when I don't need
to use it any more.

My questions a

o Can I continue using the snow thrower in this winter? Then I can
bring it to the dealer in the spring.

o Is this something that I can fix if I can find a service-manual and
a parts list? I am reasonably handy (home improvement...etc) despite
the fact that I have never opened up an engine before. Note that the
operator-manual doesn't say anything about fixing / checking /
adjusting the carburetor. I hope that the service manual may have the
necessary info.

Thanks in advance for any info.

Jay Chan

I have an old John Deere 522 snow thrower that has a 5hp 4-stroke
engine. When I received it from my father-in-law, I noticed that it
occasionally had backfire (or afterfire) from the exhaust. But
lately, the problem seems to be more apparent -- either it happens
more often or I start paying more attention to this problem.
Seem like the backfire occurs as soon as I start the engine regardless
the engine is under load or not. Sometimes, I even see flame throwing
out from the exhaust. Consequently, the exhaust is blackened.
Online source says that the air/fuel mixture probably is too rich in
fuel and the incompletely burnt fuel ends up getting burnt in the
exhaust. According to the operator-manual, the problem must have
something to do with the carburetor not adjusted correctly or the
carburetor leaks air. Either case, the manual suggests me to bring it
to the dealer. But I really don\\\'t want to bring it to the dealer in
the middle of winter when I need to use the snow thrower. I would
much prefer to bring it in in late winter or spring when I don\\\'t need
to use it any more.
My questions a
o Can I continue using the snow thrower in this winter? Then I can
bring it to the dealer in the spring.
o Is this something that I can fix if I can find a service-manual and
a parts list? I am reasonably handy (home improvement...etc) despite
the fact that I have never opened up an engine before. Note that the
operator-manual doesn\\\'t say anything about fixing / checking /
adjusting the carburetor. I hope that the service manual may have the
necessary info.
Thanks in advance for any info.
Jay Chan


Test post

Sorry about the test post. I was having problems responding.

Anyway, in response to the OP:

Running it won't hurt it.

In older engines gunk builds up on the valve stem. When this happens,
the valve may either sticks open or close slower than normal,
therefore (in your case) allowing the engine to fire when the
"exhaust" valve is slightly open. If the valve were to stay open, it
wouldn't run. It could be a broken/weak spring, but unlikely. After it
warms up the stem gets a little oil and runs properly or at least
better. This is normal for gunk build up.

Using a lighter weight oil MAY help the problem. But to fix it, the
valves have to be removed and cleaned. "lapping" them in at this time
would be suggested also.

Hank ~~~~ having trouble posting

On Thu, 27 Jan 2011 07:46:06 -0800 (PST), Hank
wrote:

Sorry about the test post. I was having problems responding.

Anyway, in response to the OP:

Running it won't hurt it.

In older engines gunk builds up on the valve stem. When this happens,
the valve may either sticks open or close slower than normal,
therefore (in your case) allowing the engine to fire when the
"exhaust" valve is slightly open. If the valve were to stay open, it
wouldn't run. It could be a broken/weak spring, but unlikely. After it
warms up the stem gets a little oil and runs properly or at least
better. This is normal for gunk build up.

Using a lighter weight oil MAY help the problem. But to fix it, the
valves have to be removed and cleaned. "lapping" them in at this time
would be suggested also.

Hank ~~~~ having trouble posting
Run some "SeaFoam" in the gas - and some "marvel mystery oil" in the
oil - the valves will free up if they are the problem, and the jets in
the carb will too - often exhaust backfiring is due to running too
lean.
Lighter oil won't help in this case - you can almost guarantee that.

Removing the muffler and squirting a solvent like carb and choke
cleaner on the valve stem may help too. = When the crap softens,
scrape it off with a wooden stick.

On Thu, 27 Jan 2011 09:25:58 -0800 (PST), wrote:

On Jan 27, 10:46Â*am, Hank wrote:
Sorry about the test post. I was having problems responding.

Anyway, in response to the OP:

Running it won't hurt it.

In older engines gunk builds up on the valve stem. When this happens,
the valve may either sticks open or close slower than normal,
therefore (in your case) allowing the engine to fire when the
"exhaust" valve is slightly open. If the valve were to stay open, it
wouldn't run. It could be a broken/weak spring, but unlikely. After it
warms up the stem gets a little oil and runs properly or at least
better. This is normal for gunk build up.

Using a lighter weight oil MAY help the problem. But to fix it, the
valves have to be removed and cleaned. "lapping" them in at this time
would be suggested also.

Hank ~~~~ having trouble posting

My first thought is this is another troll post, using one from the
past,
looking to get hits for a website. But assuming it's real, I'd say
the
most likely culprit is a fouled carb. Snowblowers are prime for this.
Left with gas sitting in them, etc. Over time, the carb gets fouled
up.
I don't know why, but of all my eqpt, my Sears snowblower with a
Tecumseh engine is most susceptible to this. I've let it sit with gas
for just a few months and had it foul.

Solution is to get a shop manual and a carb rebuild kit, which should
cost $12 or so. That gives you everything you need to take it apart,
clean it out, and reassemble. In a pinch, you can try it without
the
kit.
Sea Foam costs about half that, and a bottle will treat that blower
carb 4 or 5 times, at least. And it's a whole lot less work.

Run some in the gas constantly and it won't go skunky, fouling the
carb.

wrote in message
...
..
Sea Foam costs about half that, and a bottle will treat that blower
carb 4 or 5 times, at least. And it's a whole lot less work.

Run some in the gas constantly and it won't go skunky, fouling the
carb

I have seen the Seafoam but not used any.. I do put Stabil in the gas of
all the small engines now and that seems to help alot. I have had to tear
into the carb on a 5 kw generator several times in the past when I did not
run it for several months in the past. I think the added ethenol in the gas
is causing lots more problems also. Seems that they can add about 5 % or so
with out even stating that at the pumps.

I don't have a snowblower as I am in the South, but do have a tiller, mower,
pressure washer and chain saws that are only used in the warmer months.
Well maybe not the saws.

On Jan 27, 7:46*pm, "Ralph Mowery" wrote:
wrote in message

...
.

Sea Foam costs about half that, and a bottle will treat that blower
carb 4 or 5 times, at least. And it's a whole lot less work.

Having tried a variety of alleged "carb and fuel injector cleaners"
and
haven taken apart carbs to clean them, I'm very skeptical that any
carb cleaner that you just mix in with gas is gonna cure a fouled carb
in an engine. Upon taking them apart you find varnish and gunk that
is difficult enough to remove with carb cleaner sprayed on full
strength
and rubbed with a brush. Plus, especially with today's gas, and
cheaper
carb parts, you often find needle valves that are rusted, etc.

With the carb rebuild kit you get the new needle valves, gaskets,
o-rings, etc. And doing the work is maybe an hour and a half.






Run some in the gas constantly and it won't go skunky, fouling the
carb

I have seen the Seafoam but not used any.. *I do put Stabil in the gas of
all the small engines now and that seems to help alot. *I have had to tear
into the carb on a 5 kw generator several times in the past when I did not
run it for several months in the past. *I think the added ethenol in the gas
is causing lots more problems also. *Seems that they can add about 5 % or so
with out even stating that at the pumps.

I agree. But I think it also depends on the particular carb. I've
had no
problems with my mower, blower, trimmer, etc. But for some reason
the Tecumseh snowblower engine can foul within just a couple months.





I don't have a snowblower as I am in the South, but do have a tiller, mower,
pressure washer and chain saws that are only used in the warmer months.
Well maybe not the saws.

(PST), wrote:

On Jan 27, 7:46*pm, "Ralph Mowery" wrote:
wrote in message

...
.

Sea Foam costs about half that, and a bottle will treat that blower
carb 4 or 5 times, at least. And it's a whole lot less work.

Having tried a variety of alleged "carb and fuel injector cleaners"
and
haven taken apart carbs to clean them, I'm very skeptical that any
carb cleaner that you just mix in with gas is gonna cure a fouled carb
in an engine. Upon taking them apart you find varnish and gunk that
is difficult enough to remove with carb cleaner sprayed on full
strength
and rubbed with a brush. Plus, especially with today's gas, and
cheaper
carb parts, you often find needle valves that are rusted, etc.

With the carb rebuild kit you get the new needle valves, gaskets,
o-rings, etc. And doing the work is maybe an hour and a half.

Takes me at least 4hrs of work and an overnight soak to remove, tear
down, soak, re-assemble- re-attach-- but I'll better your 1 1/2 hours
anyway.g Once I've invested that time, effort & money- I don't
know what the outcome will be. did a tiny ball go missing? Did a
seal slip? Did I break a piece & now have to buy a new carb? Did a
Welch plug hide something important-- or did I remove it and not get
the new one in just so? [all things I have done in the past 40yrs of
carb-adventures]

I add a few tablespoons of K100G to a full tank - start the machine
and go do something else. This stuff goes wherever gas can go, and
it cleans all the crap without disturbing seals, seats, or plugs. I
rarely have to repeat it, but if I can get an engine to run for 5
minutes- it is well worth the effort to try.
http://shop.advanceautoparts.com/web...7CGRP2030C____

My neighbor is a small engine repair guy. He's been doing it for 40
years or so. He turned me on to the stuff.

This fall my snowblower didn't like last winter's gas. It was
running rough and searching for a speed. A tankful later, it was
running pretty good. I repeated the treatment- and now it runs as
good as it did in 1975.

Jim

On Fri, 28 Jan 2011 05:54:42 -0800 (PST), wrote:

On Jan 27, 7:46Â*pm, "Ralph Mowery" wrote:
wrote in message

...
.

Sea Foam costs about half that, and a bottle will treat that blower
carb 4 or 5 times, at least. And it's a whole lot less work.

Having tried a variety of alleged "carb and fuel injector cleaners"
and
haven taken apart carbs to clean them, I'm very skeptical that any
carb cleaner that you just mix in with gas is gonna cure a fouled carb
in an engine.
You can be sceptical untill you try it. The darn stuff works, and it
works well. If you have one that is TOTALLY mucked up, you may still
need to take it apart and rebuild it, but in MOST cases the greenies
dissapear and the jets open up, making a balky engine run like new.

One that won't run, period, is a different story.

Upon taking them apart you find varnish and gunk that
is difficult enough to remove with carb cleaner sprayed on full
strength
and rubbed with a brush. Plus, especially with today's gas, and
cheaper
carb parts, you often find needle valves that are rusted, etc.

With the carb rebuild kit you get the new needle valves, gaskets,
o-rings, etc. And doing the work is maybe an hour and a half.






Run some in the gas constantly and it won't go skunky, fouling the
carb

I have seen the Seafoam but not used any.. Â*I do put Stabil in the gas of
all the small engines now and that seems to help alot. Â*I have had to tear
into the carb on a 5 kw generator several times in the past when I did not
run it for several months in the past. Â*I think the added ethenol in the gas
is causing lots more problems also. Â*Seems that they can add about 5 % or so
with out even stating that at the pumps.

I agree. But I think it also depends on the particular carb. I've
had no
problems with my mower, blower, trimmer, etc. But for some reason
the Tecumseh snowblower engine can foul within just a couple months.

That's where I found the SeaFoam to be terribly effective - 35 year
old (or older) Tecumseh SnoKing. I replaced it with a little Briggs
powered blower and the SeaFoam got it running like new within minutes
this fall.





I don't have a snowblower as I am in the South, but do have a tiller, mower,
pressure washer and chain saws that are only used in the warmer months.
Well maybe not the saws.

On Fri, 28 Jan 2011 10:35:40 -0500, Jim Elbrecht
wrote:

(PST), wrote:

On Jan 27, 7:46Â*pm, "Ralph Mowery" wrote:
wrote in message

...
.

Sea Foam costs about half that, and a bottle will treat that blower
carb 4 or 5 times, at least. And it's a whole lot less work.

Having tried a variety of alleged "carb and fuel injector cleaners"
and
haven taken apart carbs to clean them, I'm very skeptical that any
carb cleaner that you just mix in with gas is gonna cure a fouled carb
in an engine. Upon taking them apart you find varnish and gunk that
is difficult enough to remove with carb cleaner sprayed on full
strength
and rubbed with a brush. Plus, especially with today's gas, and
cheaper
carb parts, you often find needle valves that are rusted, etc.

With the carb rebuild kit you get the new needle valves, gaskets,
o-rings, etc. And doing the work is maybe an hour and a half.

Takes me at least 4hrs of work and an overnight soak to remove, tear
down, soak, re-assemble- re-attach-- but I'll better your 1 1/2 hours
anyway.g Once I've invested that time, effort & money- I don't
know what the outcome will be. did a tiny ball go missing? Did a
seal slip? Did I break a piece & now have to buy a new carb? Did a
Welch plug hide something important-- or did I remove it and not get
the new one in just so? [all things I have done in the past 40yrs of
carb-adventures]

I add a few tablespoons of K100G to a full tank - start the machine
and go do something else. This stuff goes wherever gas can go, and
it cleans all the crap without disturbing seals, seats, or plugs. I
rarely have to repeat it, but if I can get an engine to run for 5
minutes- it is well worth the effort to try.
http://shop.advanceautoparts.com/web...7CGRP2030C____

My neighbor is a small engine repair guy. He's been doing it for 40
years or so. He turned me on to the stuff.

Another similar product is BG 100K - we used to say it was strong
enough to eat the backside out of a dead skunk from 100 yards.

This fall my snowblower didn't like last winter's gas. It was
running rough and searching for a speed. A tankful later, it was
running pretty good. I repeated the treatment- and now it runs as
good as it did in 1975.

Jim