Small Engines (Lawn Mowers, etc.): tecumseh engine, bolens snow blower, garden tiller

Question
QUESTION: Hi Eric, I have an old Bolens Snow blower that I think has a broken rod ( motor turns freely without resistance from piston) it is an 8HP HM80 155022F Ser 9107D
In order to get into the case I need to remove the bottom pulley and I have tried everything I know tho get the 2 allen set screws loose.(soaking with WD40, heat, & tapping it.)
One of the set screws is holding a key, the other one just the shaft.
Do you know any tricks to get them out? they should be hardened so I thing that drilling them out may not work but who knows. I tied several different allen wrenches and non of them worked,  Once they set screws are out I suppose a good puller would get the pulley off. Any help will be appreciated.  Jurgen

ANSWER: Did you pull the head off the engine to make sure a valve is not stuck?

As far as the set screws, they are pretty hard but they can be drilled.  To put your situation in perspective, I once had a large garden tiller that took me about 3 months, off and on, to get the set screws out; finally was able to drill them out.

There are several things you can try to remove them.  First, WD-40 is not a penatrating oil.  Kroil is some of the best pentrating oil I've used but PB-Blaster and Zep-45 also work well.

Before drilling, I would get some good penatrating oil, soak the set screw well, let it sit for several days while contining to apply pentrating oil daily.  You can heat them with a torch but you risk damaging the rear engine bearing/bushing.  Map gas will work but oxy acetlyne will get much hotter.  

As a last resort you can cut the pulley in half with a grinder.  I would check to make sure a new pulley is avaiable before cutting the pulley in half.

Bottom line, get some good penatrating oil, soad and try to remove the set screws.

Let me know if this helps.
Eric

---------- FOLLOW-UP ----------

QUESTION: Eric, here is the feed back, No luck with the PB-Blaster yet but it's well. While I was waiting for it to soak in, I pulled the head as you suggested and found the exhaust valve stuck open. The lower valve spring cap broke. A new cap and head gasket are on the way. That's a cheap repair ($9.15) and I will be ready for the snow. Thanks, Jurgen!

Answer
You may need to set the valve gap.  Refer to this link:

http://www.cpdonline.com/692509.pdf

The manual will tell you to use special tools to grind the valve stem and cut the valve seats.  You can usually do a good job using a flat file to file the valve stem is you need to adjust the valve clearance.  As for the seat cutter, I have the tools but they are crazy expensive.  You can get by much cheaper by just lapping the valves.  This takes more time and you will need course and fine lapping compound but this method is much cheaper and very effective.

You may get lucky and the valve clearance may be fine and if the valve seat and valve face do not have any pitting you can skip the lapping.  

If you don't have the tools to do the valve work you can always take to a shop, with the head removed, and let a shop service the valves.  They should not charge you more than 45 minutes to do the work.

Eric