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MTD Snowblower question.


0101010101's Avatar
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01-06-15, 09:40 AM   #1  
MTD Snowblower question.

Hi,
I have older snowblower MTD 5HP production date : 1996 with Tecumseh engine.
I got it from my neighbor, he moved to a different state and I do not know any service history.
It has the following issue: it does not restart when its hot.
It has manual and electric starter, when the engine is cold, I can start it with starting rope without any problems. If it runs for 2-3 min (engine is warm but not hot) I can restart it without any problems.
If I let it run for 10 min (engine is hot), I cannot restart it even with the electric starter. Ones it cools within an hour I can restart it without any problems.
I replaced sparkplug and I am using fresh gas with seafoam.
I did not clean or rebuild the carburetor but I removed the bolt head from the bottom of the carburetor and removed main adjustment screw.
Adjustment screw looks fine, no debris and fuel varnish it is not gummed up.
I checked all tiny holes with carb cleaner and they are fine.
I put back to the main preset: turn until finger tight and turn back to 1 and turn.
I did not check the idle screw, but the engine starts fine when its cold.

what is wrong with it?
thanks

 
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Nedly's Avatar
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01-09-15, 12:54 PM   #2  
It is most certainly over heating dangerously bad, and it is possibly a good thing it is not restarting for you. If it would you would have no issues cooking the engine rather quickly.

My first guess was oil, if there is none or it is low this could happen, especially when it is more hot. If there has not been an oil change it may be a good time for one. Oil should be checked and topped off at every tank of gas for things like snow blowers and generators.

Another option is some issue in the carb. If fuel was being restricted slightly the fuel to oxygen mixture will become lean causing it to run hot and over heat.

One of the other options that should be considered (if it is used with an unknown history) is the idea that someone ruined the timing. If the timing is set in an advanced mode it will run extremely hot, and some engines can over heat in seconds. Usually this issue could be indicated by an engine that not only runs hot, but also runs at a screaming rpm, or runs at a higher and louder rpm than it should.

Even an engine with 0 compression does not over heat if the gas to oxygen mixture is right, and the proper amount of oil is available. Even when an oil seal is gone an engine will smoke and spit out oil, but it does not over heat until the oil supply is gone or too low.

 
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01-09-15, 05:28 PM   #3  
You say you cannot re-start the engine when it's good and hot. Do you turn it off when it's hot or does it die and you cannot re-start it?

 
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01-12-15, 11:26 AM   #4  
Thanks for suggestions.
It dies by it self and I cannot restarts when it is hot.
On another forum, I got advice to replace coil.
The oil level is fine.
I ordered carburetor kit and new coil, I am going to rebuild carburetor, put new coil and change oil with 5-30 full synthetic oil. anything else?

 
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01-12-15, 11:52 AM   #5  
The coil was going to be my guess so it looks like you're on the right track already. Coils, when dying, can stop working when they get good and hot but will work again after they've cooled. Eventually it will stop altogether.

If you hadn't already ordered the coil I would suggest run it until it gets hot and dies on it's own then pull the spark plug wire and check for spark. I use an extra spark plug so as soon as it dies you can pull the wire off the engine's spark plug and put it on the tester plug. Make sure the tip or threads of the plug are touching bare metal on the engine and try starting. Look for the tester plug to spark. If there is no spark it's possibly a bad coil. If it sparks the problem might be elsewhere.

 
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01-15-15, 06:48 AM   #6  
MTD snowblower

Hi I have a MTD snowblower that had the same issue everything under the sun was done and the final solution the engine needed to be replaced because of piston wear it was tilting slightly at top dead centre. It would run for 5 to 8 mins then start slowing down and then stop. Had a small engine mechanic do everything to it but it needed a new Tecumseh 10.5hp short block. He said in his 34yrs in small engines he never seen this issue. Hope this helps

 
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01-15-15, 06:48 PM   #7  
Check your exhaust valve clearance, which if too tight could be causing compression loss, especially when hot. This can be caused by valve recession , a known problem with the Tec 5 and 5.5 hp motors.

 
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01-16-15, 12:02 PM   #8  
Field report.
In order to replace coil, I had to remove shroud.
In order to remove shroud, I had to remove 5 head bolts and exhaust muffler.
Since this model uses only 8 head bolts, I had to change head gasket.
I noticed that at least 4 bolts were not within torque specifications, more like tie down.
Exhaust gasket was leaking some exhaust on the intake manifold.
Maybe the coil was fine and I had a problem with compression and hot intake.
In any case, new coil, rebuild carburetor, new fuel line and new gaskets.
I put shell premium gas (no alcohol) witn seafoam .
I am using the following mix : 1 oz of seafoam for two gallons of gas.
Ran for 20 minutes, after that changed oil, I used 5-30 full synthetic oil and ran for an hour on throttle.
Ran fine, I was able to kill it and restart it ~ 10 times without any problems.
Now I have some questions about carb adjustments.
I have the following :
MDT 5HP TECUMSEH Model #316E610E382 Engine# HSSK50-67368.
Initially idle screw (IS) was set to ~ 5/6 – 7/8
main screw (MS) was set to ~ 2.
From my understanding, as per manual: IS – 1 ; MS 1
My first question about idle.
Do snow blowers have true idle?
I can get a stable idle wit turn, with 5/6 or 1 turn I got higher RPMs not idle RPMs.
I am not sure if is too lean for it.
I left MS at 1. With IS set it runs fine on high, if I set IS to 5/6 or 1 I am may get some misfire.
I made some short videos ~ 20 seconds each and I can post them on youtube if it helps.
Also on high RMP should governor stay in one position or constantly move back and forth?


Last edited by 0101010101; 01-16-15 at 12:21 PM.
 
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01-16-15, 06:33 PM   #9  
On this carb turning the idle screw in will richen the mixture out will lean it. It meters air not fuel.

 
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01-19-15, 11:50 AM   #10  
Just to confirm my understating, in this model TECUMSEH series 1 carburetor,
The Idle Screw and Main screw are controlling air not fuel.
By turning in, I am making rich, by turning out I am making it lean?
As per the manual, turning in leaner , turning out rich

I attached page from the manual

Attached Images
     
 
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01-19-15, 06:20 PM   #11  
Only the idle screw is metering air series 1 only in to richen out to lean. Main adjusting screw meters fuel out to richen in to lean.



Last edited by aj-allen; 01-19-15 at 07:12 PM.
 
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01-22-15, 06:11 PM   #12  
thanks for the info

I found another manual.
You are correct about idle screw.
I attached page from that manual.

I posted couple youtube videos with current adjustments.
Could you please, let me know if need to tune it more.
https://www.youtube.com/watch?v=s6eu...JSUkeq9h2CO05v

This is default settings for Tecumseh 5 HP.
Idle 1 turn
Main 1 turn

My final settings for now : 1 1/8 and 1 3/4
I used the following method:
Turn the idle mixture screw slowly clockwise until the engine begins to slow.
Turn the screw in the opposite direction until the engine again begins to slow.

For Idle, I got the following numbers : and 1
For Main, I 1 and 2

For some reason it is difficult to find drop point for the Main.

p.s I also ordered small engine tachometer, I think that RMPs are bit high.

Attached Images
     
 
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01-23-15, 07:39 AM   #13  
the engine is surging at full throttle so it is still lean or you have an air leak.

 
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