9hp craftsmen snowblower-Tecumseh help!

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Old 03-09-07, 02:54 PM
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Question 9hp craftsmen snowblower-Tecumseh help!

I am totally baffled and thought I might get some insight from this forum.
I have a 9 hp Craftsmen snowblower with a Tecumseh engine # 143.029003.
The snowblower has less than 10 hours total running. It started running rough - no power - stalls. I tested the compression and it was 45-50 lbs. I removed the head- looked ok although 2 head bolts seemed loose- I tightened and reassembled. Tested compression again and was 125 lbs. I assumed the head gasket was leaking. Started up and sounded great, tried to blow some of this WI snow and went back to the same problem of running rough and no power. Compression tested again at 45-50 lbs. I took head off again, watching the piston valves while slowly rotating engine. When piston comes up on compression stroke, the exhaust valve "bumps up" slightly and then reseats. Obviously this is where the compression is lost. Assuming that there is a problem in the cam or lifters?? I haven't had the breather cover off yet. Am ready to junk this P.O.S soooooo any suggestions on what to check next??
Thanks!
Steve in WI
 

Last edited by stewi; 03-09-07 at 10:06 PM. Reason: misspelled a few words
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Old 03-10-07, 08:43 AM
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The exhaust valve lifting is normal and purposeful. It is the MCR (mechanical compression release) in action. The MCR allows for easy startup at low (starting) RPM's wherein it reduces the necessary force to spin the engine over at startup. A flyweight and pin mechanism on the camshaft then disengages the MCR by way of increased (running) RPM's. Your problem is likely a blown head gasket but don't rule out insufficient valve clearance(s). You didn't mention that you replaced the head gasket upon inspection and you should definitely do so. I recommend checking the valve clearances while you have the cylinder head off and be sure you have proper clearances on each valve stem. You will need to remove the crankcase breather to check such and have the piston postioned 1/4" down the bore past the compression stroke (on the power stroke) to be certain the MCR does not affect your measurements on the clearances. The valve clearance will be .008-.012 on both valves and the cylinder head torque is 200 inch pounds. The head gasket is Tecumseh part number 36448 and the breather gaskets are part number 27896A (two required).
 
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Old 03-10-07, 12:50 PM
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I have not replaced the head gasket yet. My gaskets are on order and I will be doing that soon. I appreciate your response. I was not familiar with the whole MCR concept, especially that it is not named in the craftsmen manual.
What is the ideal compression I should get once I replace the gaskets?
Thanks again for your help!
 
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Old 03-12-07, 10:21 AM
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With a new gasket and properly torqued cylinder head AND proper valve clearances, you should get in the neighborhood of 110 lbs. compression. By the way, you wouldn't find the MCR referenced in the Craftsman manual since this is an engine issue and would therefore be referenced in the Tecumseh literature which would be a seperate piece of paperwork. However, you will not find anything in an owners manual regarding the MCR as this is not a owner serviced item. You would find such information in a Tecumseh service manual.
 
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Old 12-06-07, 03:53 PM
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Question a new season---a new question

Earlier this year, I replaced gaskets and dealt with carb problems. All was running fine, although I didn't have a chance to actually use it due to the lack of snow.
I stored it, and now have brought it out.
Had no problems with the starting or warming up... even performed great in our first heavy, wet snow this year. BUT--as the engine got hot, it started to "pop" and seemed to lose power and run rough again. I noticed that the muffler was glowing, and it really starting sounding like it was running lean. My gut says it may be the timing. I am not sure if it is adjustable and I do not have a service manual. Any suggestions on how to proceed?? You came thru for me earlier this year and I seek your advice once again!!
Steve in WI
 
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