Valve job for Tecumseh HM100 - Snowblower Forum : Snow Blower Forums
 
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post #1 of 9 Old 08-31-2015, 08:39 AM Thread Starter
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Valve job for Tecumseh HM100

How does one determine if a valve job is needed on an engine?

Every Tecumseh cold weather motor I've ever used has been cold blooded and this is no different. It starts on two pulls with adequate priming and takes a minute to warm up and runs fine. It's not smoking and has adequate power to move most of the snow types I encounter. It certainly got a good work out last winter!

I'm not going to tear into a motor that appears to be running fine, but if needed, how hard is to do a valve job on this type of motor? I have never done a valve job but I have a couple of motors I can practice on.
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post #2 of 9 Old 08-31-2015, 08:57 AM
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Best way is a leak down test. Compression test can give false results due to the compression release.

Also check valve clearance, simple enough to do, and if tight remove the valves. lap & set clearance.
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post #3 of 9 Old 08-31-2015, 09:58 AM
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If the engine restarts fine after getting the engine hot and there is no popping sound, usually from the muffler, the valves are PROBABLY ok. The exhaust valve is normally the one that looses clearance and stays open a few thousandths when really hot causing a slight loss of compression and power. As scrappy said, pulling the breather cover and checking valve clearance or a leak down test is a good indicator.

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post #4 of 9 Old 08-31-2015, 01:40 PM
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bogging, you will hear air rushing out the muffler when pulling over, not wanting to rev even after carb clean and adjustment
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post #5 of 9 Old 08-31-2015, 04:48 PM Thread Starter
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Yeah, it pops a little and it can require priming/choking to restart when it's warm. How hard is it to do a valve replacement? Are we talking removing seats or just popping in a new one?
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post #6 of 9 Old 08-31-2015, 04:59 PM
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basically you pull the head the intake assembly and muffler and remove the valve, then file down the stem until the valve doesnt spin in the seat at tdc
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post #7 of 9 Old 08-31-2015, 05:09 PM Thread Starter
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Thanks.
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post #8 of 9 Old 08-31-2015, 05:18 PM
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There are plenty of u-tube vids showing how to do this, and check the clearance with a feeler gauge. it's not rocket science, I was doing it when 12 yrs old on minibikes and go carts.
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post #9 of 9 Old 09-01-2015, 06:00 PM
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Smile

The advice I can give you is grind the valve stem just a little bit at a time and recheck the clearance, because if you end up with too much clearance you'll likely need a new valve.
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