Tecumseh Hsmk 100 Valves - Snowblower Forum : Snow Blower Forums
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post #1 of 34 Old 01-30-2018, 12:37 AM Thread Starter
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Tecumseh Hsmk 100 Valves

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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post #2 of 34 Old 01-30-2018, 01:47 AM
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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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post #3 of 34 Old 01-30-2018, 04:39 AM Thread Starter
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Quote:
Originally Posted by Yanmar Ronin View Post
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.
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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post #4 of 34 Old 01-30-2018, 05:13 AM
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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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post #5 of 34 Old 01-30-2018, 06:43 AM
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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?

Last edited by 351beno; 01-30-2018 at 08:30 AM.
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post #6 of 34 Old 01-30-2018, 01:28 PM Thread Starter
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Originally Posted by 351beno View Post
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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post #7 of 34 Old 01-30-2018, 02:20 PM
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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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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.

Last edited by 351beno; 01-30-2018 at 02:25 PM.
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post #8 of 34 Old 01-30-2018, 02:25 PM Thread Starter
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Try spinning it a full turn and see if both are closed.
Ok will do

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post #9 of 34 Old 01-30-2018, 03:14 PM Thread Starter
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Ok will do

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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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post #10 of 34 Old 01-30-2018, 03:15 PM Thread Starter
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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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Oh ya by the way neither of them are loose and turn.

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