# Tecumseh Hsmk 100 Valves



## bambamshere (Oct 22, 2016)

Today I tried to start my snowblower and notice it didn't start. The last time it did it ran like crap. It was back firing. So I had a new carburator I put it on and didn't make a difference. Then looked at ignition and that was fine. So I knew that this machine was at family farm since new and they usually used something till it was dead and bought new. 

Now I took it apart today and looked at the valves and noticed at Top Dead Center both valves were sticking up. I checked to see if they were stuck but both seemed to be fine except at tdc. I am going to take them off tomorrow but to grind the stems. Ok now I habe a feeler gauge and on the intake I was able to stick about .043 into top between the valve and head and for exhaust it was about .021. 

My question is how much is to much to grind off stems or should I buy new bit will I have the same problem. 

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## Yanmar Ronin (Jan 31, 2015)

Welcome to MTF. 

Well, you'll need to grind off the amount they're sticking up, plus the amount of the recommended valve clearance. For the HSMK100:

Intake and Exhaust Valve Clearances

min / max ( in. ) .008 / .012
min / max ( mm ) .203 / .305

You might want to lap those valves in first, if it's been running that way for a while.

New valves on their own won't solve the problem, what has happened is that the valve heads have worn down into the seats, and so decreased the valve clearances. You'd have to grind the stems on the new valves just the same to match what the engine has become.


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## bambamshere (Oct 22, 2016)

Yanmar Ronin said:


> Welcome to MTF.
> 
> Well, you'll need to grind off the amount they're sticking up, plus the amount of the recommended valve clearance. For the HSMK100:
> 
> ...


Oh ok I was just wondering about the stems and if it ok to grind that much down on them. Seems like a lot but I will see hoq it goes. The valves them selves look to be not to bad except for a thin layer of carbon on them. I took the head off tonight and looks like someone has been in there before. The reason I say that is there was a couple of bolt on the carburator sidw that had a bunch of washers on them. Guess someone lost the original bolt for it. Plus the were that tight. Couple had to be brook loose but yeah. Like I said see how things go tomorrow. Murphys law and all 

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## Yanmar Ronin (Jan 31, 2015)

Just remember it's a lot easier to take it off than it is to put it back on...

Go slowly and many measurements, first get it at zero and tight then open the clearances from there.


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## 351beno (Oct 12, 2017)

You may wanna check the clearance with one valve fully open. That way your not on the compression release or an over lap spot. If the intake is fully open ck the exhaust side. Once you have that side done spin it so the exhaust side is fully open and do the intake valve. You are checking the clearance from the valve stem to tappet right?


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## bambamshere (Oct 22, 2016)

351beno said:


> You may wanna check the clearance with one valve fully open. That way your not on the compression release or an over lap spot. If the intake is fully open ck the exhaust side. Once you have that side done spin it so the exhaust side is fully open and do the intake valve. You are checking the clearance from the valve stem to tappet right?


I was told to go to tdc and take it when both are supposed to be closed. Problem is at tdc neither of them is closed. 

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## 351beno (Oct 12, 2017)

bambamshere said:


> I was told to go to tdc and take it when both are supposed to be closed. Problem is at tdc neither of them is closed.
> 
> Sent from my LG-H831 using Tapatalk


Try spinning it a full turn and see if both are closed. You can do it with one valve fully open also because if one valve is fully open the other valve will be closed. It sound like your on an overlap to me or maybe a bent valve or someone really messed the valves up.


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## bambamshere (Oct 22, 2016)

351beno said:


> Try spinning it a full turn and see if both are closed.


Ok will do 

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## bambamshere (Oct 22, 2016)

bambamshere said:


> Ok will do
> 
> Sent from my LG-H831 using Tapatalk


Ok so I spinned it around once more and they are both down. I measured both of them and the intake is at .010 and the exhaust is at .008. Should the exhaust be alittle bit more then the intake. I going to take them out anyways to clean them off as both valves are black from carbon and reseat them. 

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## bambamshere (Oct 22, 2016)

bambamshere said:


> Ok so I spinned it around once more and they are both down. I measured both of them and the intake is at .010 and the exhaust is at .008. Should the exhaust be alittle bit more then the intake. I going to take them out anyways to clean them off as both valves are black from carbon and reseat them.
> 
> Sent from my LG-H831 using Tapatalk


Oh ya by the way neither of them are loose and turn. 

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## 351beno (Oct 12, 2017)

Good deal I would set both to .010 in. Just make sure your not on the compression release also. Its hard to see but one will open just a hair before tdc so its easy to have the tappet up just a hair to throw your reading off. That's why if your not sure I always say adjust one when the other one is fully open. It don't matter if the exhaust is more or less both just have to be in the range it call for.


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## bambamshere (Oct 22, 2016)

351beno said:


> Good deal I would set both to .010 in. Just make sure your not on the compression release also. Its hard to see but one will open just a hair before tdc so its easy to have the tappet up just a hair to throw your reading off. That's why if your not sure I always say adjust one when the other one is fully open. It don't matter if the exhaust is more or less both just have to be in the range it call for.


Ok sounds good deal. The reason I took this apart in the first place was because it was back firing and then stopped running altogether plus when you pulled the the handle ther was nothing there. Now that both of them are basically in range I guess it wasn't that. I have a new carb on it I bought last year and new muffler. Both are set up from last year. I guess the next is to see if rhw key is gone or broken on flywheel and or the air gap is right and if not change it. I had to take a bunch of rust off the ignition last year. Just used wire brush. 

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## RedOctobyr (Mar 2, 2014)

Yanmar Ronin said:


> Welcome to MTF.


Did you forget which forum you were reading?  Never call a forum by another forum's name! 

351beno, that's an interesting tip, to check one when the other is fully open. I don't recall reading that before, but it does make sense. And you don't have to worry about being exactly at TDC, or 1/4" beyond TDC, etc. Thanks! 

bambamshere, when you said it would shut down, then you pull the handle and there's nothing there, do you mean no compression, and no resistance when pulling the cord? The flywheel key wouldn't have anything to do with that. Now, a valve sticking open (not just a valve clearance problem) could cause zero compression, as just an example. But if the valve seats are OK, so they can make a good seal, and the valves are operating properly, then you should be getting compression.


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## sock-feet (Dec 14, 2017)

I have some issues with my HM100 Tec and I checked the valve clearance and the intake was 9 thousands and the exhaust is 12 thousands. I checked compression and it was around 170 full hot. I have major running issues when it completely warms up. I put new coil wire and plug. I rebuilt the carb cleaned the tank and ran new fuel lines. I gave up on it and put on a HF 13 hp honda clone and never looked back. It was $240.00 with my wife's discount and runs perfect with plenty of power and is quiet.


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## Yanmar Ronin (Jan 31, 2015)

RedOctobyr said:


> Did you forget which forum you were reading?  Never call a forum by another forum's name!


OOps... :icon_whistling:

Welcome to SBF!!!

ccasion14:


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## bambamshere (Oct 22, 2016)

So I cleaned the valves and set proper gap and machine still wasn't starting then I took flywheel off found broken key. Replaced key then machine still wouldn't start. Went on internet and looked at a bunch of sites and was like wth. Went back out to machine looked at it for about a hr and looked at wiring and ya no ground. Found ground and it started now to next problem. 

Why does the auger keep going even though the belt is backed off

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## RedOctobyr (Mar 2, 2014)

Awesome, I'm glad you got it running. At least your valve clearances are now correct, even if they weren't the root of the problem. 

Mine has a brake for the impeller pulley. So when I release the handle, the belt relaxes, and a brake also contacts the impeller pulley on the bucket. I assume this to make it stop more quickly, but also to keep it from moving slowly, due to the slight (loose) contact between the engine's pulley, and the impeller belt. 

Yours obviously shouldn't be turning at full-speed and power, with the belt relaxed. But maybe there's just enough belt contact, and no brake, to pass just a little torque to the impeller pulley? 

The belt could also be just a little bit too short, or the idler pulley might be set a little bit too tight. The manual might have instructions on how to set the tension on the impeller belt.


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## HCBPH (Mar 8, 2011)

On the question of the auger brake, there 'should' be some form of brake material that presses against the pulley when the auger is not engaged. I've seen more than my share of badly worn brakes. Luckily in my case I've had replacements off parts machines that worked.
In your case, assuming you don't have a replacement and it's worn - check out brake shops or places that do car restoration and see if any of them can rebond brake material. I have not done it but I've read about it. You 'glue' the material to the backing (using a special adhesive) and it's clamped tight then it's baked for about 20 minutes to solidify it. I've also read where people have riveted brake material to the brackets. If you try that be sure to use something in a soft rivet (like copper rivets) so they don't chew up your pulley if it ever comes in contact.

This also applies in some cases. Rust in the pulley grooves can cause a belt to grab when it's not engaged. Using a rotary wire brush should be able to clean that up if it applies.


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## guilateen02 (Nov 23, 2014)

My first time grinding down the valve stems I took too much of and the gap was out of spec. I forgot if it was the intake or exhaust. I could hear what sounded like valve tap/ smack noise. But the engine started extremely easy and felt like it performed very strong. Is there and advantages or disadvantage to a larger valve gap on these engines or any engines for that matter.


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## RedOctobyr (Mar 2, 2014)

A valve clearance that's too large will: 
- Make the compression release not work as well, if on the exhaust valve. The extra compression while starting makes the engine harder to turn, with the pull start, and possibly too much for the electric starter to turn. 
- Reduce the airflow through the valve, since it isn't opening quite as far as it should. This will reduce your power somewhat. 

But this at least a "safe" condition. Valve clearances that are too small can let a valve fail to seat fully while running. You'll lose power (due to leaking compression), and you can also damage the valve and its seat. In addition to backfiring.


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## bambamshere (Oct 22, 2016)

Heres a question I have to snowblower apart again. There is a **** of a noise when you turn it over using the electric start thats not there when you pull start it. I have checked the starter and it is fine. Check flywheel and there no teeth missing anything else I should check. It turns over and all. It just load when you turn it over

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## RedOctobyr (Mar 2, 2014)

A video of the bad noise could be helpful, if that's feasible. 

Might be a bad bearing in the electric starter? I guess you could do 2 tests somewhat easily: 

- Really easy: remove the spark plug, to reduce the load on the electric starter. See if the noise changes, with the starter motor not having to push as hard. 
- Less easy: remove the starter motor, so it doesn't engage with the flywheel. Holding it safely/securely, run the starter, and see if the noise still happens. If you still get the noise, you know it's internal to the starter itself, and not due to meshing with the flywheel. So you can rule out gear-mesh problems, etc.


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## bambamshere (Oct 22, 2016)

Oh I know it's not the starter. I took it off and checked it and it engages and makes no noise. Might be flywheel. I will check in couple of days. 

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## bambamshere (Oct 22, 2016)

Ok so new problem. I took the flywheel of last week and put it back on and started it up for a minute or 2. Now it has no spark. I took it off again an checked everything on it from the key to the solid state ignition and to the magnets on back of flywheel. Everything look fine. Could it be that I need to torque the flywheel down. Don't have 1/2 inch torque wrench yet. 

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## RedOctobyr (Mar 2, 2014)

Torquing the flywheel shouldn't affect having spark. If you sheared a flywheel key due to not having the flywheel nut tight enough, you'd get spark, just at the wrong time. But you'd still see a spark when checking. 

Maybe disconnect the ground wire that kills the ignition, and see if anything changes?


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## bambamshere (Oct 22, 2016)

Ok thank you will do. But do have another quick question on this machine the. Ignition the key and the shut off are all grounded at the same place could this be a problem 

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## tadawson (Jan 3, 2018)

Should not be . . . typically the ignition key works by grounding out the ignition, the same as any other cutoff. The ignition switch is for safety, more than security, and trivial to bypass . . . If anything, it's considered good practice to tie all grounds to a common point.


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## bambamshere (Oct 22, 2016)

Oh ok well I took the ignition line off the key and shut off. I will put it back on the key and shut off. I grounded the ignition and it has good spark now. But there is only 1 wire coming off the ignition off the key and one coming from the shut off. I have a shop manual for this machine but it doesn't give anything in it for the 3 wires that it has and how they should be wired up. Does anyone have a picture to show where the 3 wires go or how they are supposed to go. Right now I have spark and gas and good compression. I think what is stopping this snowblower from starting is the wiring. 

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## bambamshere (Oct 22, 2016)

I was thinking last night about this snowblower and what I haven't done to it yet. The first thing I thought of was the sparkplug. So today I went outside and looked at it and it was wet. So I have a 1956 Dodge Truck and funny thing is it takes the same sparkplug so I will see if that works. 

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## RIT333 (Feb 6, 2014)

bambamshere said:


> I was thinking last night about this snowblower and what I haven't done to it yet. The first thing I thought of was the sparkplug. So today I went outside and looked at it and it was wet. So I have a 1956 Dodge Truck and funny thing is it takes the same sparkplug so I will see if that works.
> 
> Sent from my LG-H831 using Tapatalk


Maybe it has the same model engine ! LOL


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## bambamshere (Oct 22, 2016)

RIT333 said:


> Maybe it has the same model engine ! LOL


Funny lol well the engine in the truck did came out of 1953 Combine 

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## bambamshere (Oct 22, 2016)

Ok got my snowblower going today. It was the sparkplug. I used thw machine 3 times last year. Sparkplug was brand new. Any ideas why it might have went bad. Could it just be crappy sparkplug.

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## tadawson (Jan 3, 2018)

Any visible damage, or ? ? ? I suspect that even spark plugs are subject to the spotty quality from China these days . . . Not, of course, that you could not have always gotten a bad one. Not much to fail, though . . .


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## bambamshere (Oct 22, 2016)

Ya well we have gotten really no snow this year. Can't even try it out. What ever we have had has Ice under snow and I really don't want to break a shear pin on the auger so next year it will have to be. 

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