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At least I think it's a carburetor problem. First things first. Hello all. I'm new here. I don't know why I'm new here. I should have joined long ago as much as I find myself working on all of my equipment. I have perused this website before while searching for answers to my problems, but only joined now. I'm glad I did. I hope to learn some more in my time here and help out others as I can.

I have a Craftsman 2-stage snowblower with 5.5 HP Tecumseh engine. The engine model is LH195SP, Spec 67517D. This thing has never run right since I got it. Last year, at the beginning of the winter, during the first big snow, it died on me. I couldn't get it running and it got really cold outside, and we were getting a LOT of snow, and with all of the other things I had to do, I couldn't find enough time to try and fix it. So, I shoveled, and shoveled, and shoveled. All winter long. This year I swore I was going to try and get it running before the snow started falling. We've been lucky here, so far, as far as the snow is concerned, but I still haven't got it running right.

Before it died, I always had to run it with the choke partially on. This year I cleaned the tank out and cleaned and rebuilt the carburetor (non-adjustable, EPA compliant). The carb "looked" pretty clean before I cleaned it. Anyways, after messing with it for a couple weeks, taking the carb off and re-cleaning multiple times, I finally gave up on it. A couple times it gave a few "putters" where it attempted to start, but it never did. I used new gas and a new spark plug, even though the old plug was still fine. I checked for spark and it is good. It would just not start.

After all this I bought a new carburetor. I bought the "older" version of the EPA carb that came with the snowblower. The one I bought has the adjustable main jet and the adjustable idle mixture screw. I installed the new carb and after a few pulls, she started right up. To me, that makes it obvious that there was something wrong with the old carb, whether it was plugged-up passageways or whatnot.

After some adjusting, I got it to run "OK" at full throttle. It's not perfect. There's a little "popping" going on. The thing is I cannot get it to idle. When I move the throttle lever down, the RPMs drop and eventually it dies, even if I try and partially apply the choke. I preset the carb main at 1 1/2 turns out from lightly seated and the idle mixture screw at about 1 turn out from lightly seated.

I have good function from the main jet and the engine responds well to either leaning or enriching. HOWEVER, the idle mixture screw seems to do nothing. As a matter of fact, the engine will keep running even if I screw the mixture screw all the way in. I understand that the idle circuit doesn't even come into play until the RPMs reach a certain level.

The OEM EPA non-adjustable carb was a 640084B. The new carb is a 632107A, which is supposed to be the equivalent of the 640084B carb, but with adjustable main and idle mixture screws. As I said, it fired up fairly easily with the new carb and wouldn't even start with the old one.

I'm using new fresh gas, although it is E10. There is no E0 available in my area.

Th bad thing I did late this summer when I started working on this snowblower was mess with the governor. I don't know why I did, but I did. The thing about this governor is that the shaft barely turns. I checked it unhooked from the carb and the shaft will maybe rotate 5 degrees. I was watching a video on YouTube where a guy was showing about adjusting governors and he was showing the governor shaft movement on his Tecumseh motor (5 HP) and it was able to rotate WAY more than mine, more like 20 or 25 degrees I estimate. I don't know if this has anything to do with my non-idle condition or not. This snowblower has had very little use. I haven't ruled out any valve issues. When I did get it running with the new carb, I was able to rule out a bad gas cap, since it ran at high (not excessive) RPMs for at least 20 minutes until I shut it down.

Sorry for this long post but I'm out of ideas and would greatly appreciate any input. If any other info is needed please ask. Thanks

http://www.tecumsehpower.com/CustomerService/OperatorManuals/pdf/181-1275-14.pdf

Tecumseh Service Manuals Are you using correct weight oil? fuel stabilizer?

https://www.google.com/search?q=ser....51768j0j8&sourceid=chrome&es_sm=122&ie=UTF-8 click on" SERVICE DEALERS & TECHNICIANS TRAINING, K& T PARTS"

Hey Mark. Thanks for the links. The first link for the Tecumseh manual I already have. It's pretty much the same as the manual I got with the snowblower.

The "google" link you provided doesn't show "SERVICE DEALERS & TECHNICIANS TRAINING, K& T PARTS" when I click on it. I get a page of results but don't see anything like that anywhere on the page.

As far as the oil and stabilizer, yes the oil has been changed recently and I'm using SAE 5W30. When I bought the fresh gas, I put some stabilizer in it.

If the google link you provided is for the service manual, I already have that. I've been through it but am still unable to solve my idle issue.

Here's some new information. I went out today and messed with it some more. I couldn't get it to start. I found on the Internet some instructions for setting the governor. The instructions said to loosen the bolt holding the governor arm to the governor "clip" (not sure of proper terminology) and rotate the governor shaft all the way clockwise, hold the throttle arm wide open, and then tighten the bolt back down. This is supposed to statically set the governor. I did that and I could not get it to start. I repeated this procedure multiple times, each time moving the governor shaft a small amount counter-clockwise while still holding the throttle wide open and then securing the bolt. When I got nearly all of the way counter-clockwise on the shaft, I got it to fire up, although it ran only for about 15 seconds and died. I tried to restart it and could not. I again loosened up the governor arm and moved it more counter-clockwise, while holding the throttle open all the way and tightened the bolt. Again, it started, but only ran for a short bit.

Then, just for giggles, I removed the flywheel and checked the key for shearing. It looks fine to me. However, before I removed the flywheel, I checked the air gap between the magnets and the CDI. A .002 gap gauge was TIGHT. I checked my service manual and it says the gap should be .0125. Does that sound correct? If .0125 is correct, the air gap is WAY off. Also, on the flywheel, next to the groove, I can see evidence of a prior flywheel shearing. The edge is "chipped" slightly, about the thickness of a key, like what would happen if the flywheel spun slightly after the key sheared.

Does/can any of this have the effect of keeping this engine from running properly?

What would make this engine have to have the governor set all the way counter-clockwise (as opposed to static set clockwise) in order to get it to even fire a little?

FourtyCaliber said:

Hey Mark. Thanks for the links. The first link for the Tecumseh manual I already have. It's pretty much the same as the manual I got with the snowblower.

The "google" link you provided doesn't show "SERVICE DEALERS & TECHNICIANS TRAINING, K& T PARTS" when I click on it. I get a page of results but don't see anything like that anywhere on the page.

As far as the oil and stabilizer, yes the oil has been changed recently and I'm using SAE 5W30. When I bought the fresh gas, I put some stabilizer in it.

If the google link you provided is for the service manual, I already have that. I've been through it but am still unable to solve my idle issue.

Click to expand...

Click & download at bottom left of screen.

I have another question that I hope someone won't mind indulging.

I was looking at the flywheel key. It has a "notch" at one end. For the life of me I can't figure out what this notch is for. I remember when I worked on older motors that there was points cover and a notched key would slide under the points cover. But, my motor has a CDI ignition and therefore no points. There is a nylon bushing on the shaft, but it has it's own integral key that sits on the crankshaft groove and keeps it from spinning. There is no need for this notch in this key, as far as I can tell.

I, also, read on another forum where Sears/Craftsman would use an "offset" key. The information I gathered is that the width of the groove in the crankshaft is different slightly from that in the flywheel. From what I understand this "offset" key somehow alters the timing for some reason.

I guess what I'm getting at is if I have the right key for my engine? It was apparent to me that someone has worked on this before because of the indentations on the edge of the flywheel from a previous key shearing. I just wonder if the right replacement key was installed?

mechanic mark said:

Click & download at bottom left of screen.

Click to expand...

There's nothing at the bottom left of my screen.

Mark, I was able to download the manual you suggested. I just did a search for "SERVICE DEALERS & TECHNICIANS TRAINING, K&T PARTS". It's pretty much the same as the manual I have, but thanks for the additional information.

I'm back.Sorry about the delay. I have some family issues going on.

Anyway, I tried some more and I still couldn't get it to start. I removed the head and the breather assembly. The exhaust valve is not fully seating. I don't think its from something stuck in the guide. There is no clearance between the valve stem and the pushrod. I think I read where there is supposed to be .004 - .008 lash? How are the springs and "keepers" removed? Once removed, I can remove the valve and grind a small amount off the end? How do I l know how much to grind off since there is NO clearance (lash) now? How do you control the grinding so as not to remove too much material from the stem? I just measure the lash between the valve stem and pushrod? Where should the piston be located when I measure lash? I checked 4 times around and the exhaust valve does not seat fully during any of the revolutions. It is definitely not seating. And how does the compression release figure into it? The manual doesn't cover this at all. I thought I read somewhere that the piston should be 1/4" down after the compression stroke and that is where the lash should be measured to account for the compression release. Is that right?

What's the best tool to compress the spring?

If I'm not right in my thinking please correct me. And please share any thing else that I may be missing or need to know.

Thanks

There is a lot to read through on the post above, but I will try to answer a couple of quick things. The gap being .125 is correct, and the .002 can cause it to be hard to start, no start, or not running correctly. Has minor effect on timing, as well as voltage flux.

The valve stems are pretty hard, and if you are working slow, you can just remove a small amount and keep rechecking the valve gap until you get it correctly. Valve stems are pretty tough, especially the exhaust stem, so hard to mess up.

Alright, I'm back. Still have some family issues going on, so not a lot of time to work on the engine. Anyway, I did the valves. I had to grind about .015 off the exhaust valve stem. That produced a lash of about .010. After that, I bought some lapping compound and lapped the lash back down to about .007. The intake was completely the opposite. The lash was about .011. I lapped the valve down until I got the lash down to a tight .004. That was a LOT of work. I made a tool for my drill to "spin" the valve for the lapping. I bought some industrial strength VELCRO and put mating sections on the top of the valve and on the tool I made and then applied the lapping compound on the valve angle. It worked pretty well. I had to use the screwdriver and zip-tie method to remove the valve springs since I couldn't find a spring compressor in 5 stores I went to. Napa would have ordered me one, but it was $50 and I couldn't see that for possibly a one time use. If I ever do this again, I'll buy one. I put a coat of oil on the stems and between the pushrods and ends so it won't run dry when I first start it up. That's where I am now.

I went and got my gaskets today and will put the rest back together tomorrow. I also bought a new fuel line since every time I run gas through the old one, I get little black specs out of it. I cleaned the breather element too. It wasn't bad. I checked the head for warpage on a flat piece of glass. It was OK, so I cleaned the mating surface by running it on some fine sandpaper on the piece of glass. I cleaned the head mating surface of the cylinder with a fine wire wheel.

I'm not sure which torque sequence to use in the service manual for the head, since there isn't one listed for the LH195SP specifically. Is the 200 in-lb spec for the head bolts correct? What is the right torque sequence? Anything else I should know?

Thanks

Couple of things.
For the head, the manual reads something like " all models except..." right? "K&T Parts House Lawn Mower Parts and Chain Saw & Trimmer Parts"

The motor ain't got no pushrods, it has tappets.

The motor also has an ACR that lifts one of the valves ( usually exh.) on the compression stroke so as to make starting easier. You may have been checking the exh. valve while it was on the ACR bump.

I just wanted to take a second and thank everyone who provided input and suggestions on my snowblower problem and provide and update on where things are right now.

I used the snowblower a few times since the last time I was here, including after the big dump several weeks ago. It starts up easy, not even needing a full pull of the recoil. I had to mess with the governor a lot to get it to that point. It's still not running perfect, though. I don't know how perfect a Tecumseh can run. I still have some "popping" while it is running at slow or full throttle. Also, I still don't have a lot of differential between the idle RPMs and full throttle RPMs, but after messing with the governor, I do have some now. If I lean out the main jet to achieve higher full throttle RPMs, the idle throttle RPMs comes up correspondingly. I think it's still in the governor adjustment, but its just too cold to mess with it right now. When it warms up I'll try adjusting the governor some more.

BTW, setting the "static" governor using the method that was mentioned in a previous post, did not work for me. Actually, I had to set it exactly the opposite of that. I don't know why. I had to hold the throttle plate closed while I rotated and held the governor shaft clockwise and then tightened the screw securing the arm. That's what got it running half-way decent.

You seem to know more about this stuff than I though I have a few things to check regarding the not reducing revs when you drop the throttle. Does the governor arm that's attached to the throttle retract the way it should? I've read that the springs sometimes go bad, and/or their oil/grease just stick and don't allow the arm to retract smoothly. The other common problem apparently for this is if the throttle on the carb is either sticking or has a bad spring itself. OR if the same part is loose between the throttle shaft and the linkage plate.

As for the not running right, I'm having similar problems with my 10HP HMSK100 though have a cheap chinese junk carb that I need to replace first to start with.

Hey Ski. I don't know that I know all that much, really. I've always messed with engines some, but this is the first time I had to go in and mess with the valves. Well, maybe not the first time I "needed" to, but the first time I did.

Anyways. I think the governor arm is moving and retracting OK. As I said, I'm going to wait until it warms up some (-12 temp here tonight and windchills at -25) and then I'll check it out better. It might be something as simple as adjusting the spring. I made the mistake of messing with the governor when I was first trying to get it to run. I have also read where the governor innards do sometimes go bad or stick. It does seem to be doing something, though, so maybe it's just adjustment. I know the throttle on the carb is OK as the carb is brand new and I did check all the mechanisms before I installed it.

I'm pretty sure that the new adjustable carb I bought is also a cheap Chinese carb. How else could they sell it for $21.00? The engine wouldn't even run with the original EPA carb, though, so even running with some popping is an improvement. I installed the new carb and it started right away, although it ran like crap. That's when the advice I received on this forum led me to a valve issue. I also had to adjust the magneto gap.

From what I have read on many, MANY forums around the Internet, "most" Tecumseh engines never run 100% perfect, even when new. They're finicky and have their own personality, so to speak.

Does your engine have the straight valves like mine? I heard that they need periodic adjustment every 2 years or so. Not sure about the OHV engines. That exhaust valve not seating makes them run like crap until they won't run at all. You lose a lot of the compression on the compression stroke out the slightly "unsealed" exhaust valve. And if it isn't so bad and the motor does run, you get uncombusted fuel and air mixture forced into the exhaust port and into the hot muffler and it shoots out flames.


edit: I wanted to add that I can get the idle to go down to what would be considered an "idle level" if I open up (enrichen) the main jet, but then I lose full throttle RPMs at the same time. If I do that, then the slow speed circuit air screw does become active and I can further adjust the idle speed that way, too. Where I have the main jet set now, the idle RPMs are too fast for the slow circuit to be active. That's what leads me to believe that it may still be governor adjustment that's needed. I don't know if my conclusions are correct. I haven't heard anything back from any of the resident experts to comment on my latest reports.

fourtycaliber, great post. I have an HMSK80 that is behaving the same as yours first did. I should have left it alone, but I wanted it to run as smooth as the 5.5 MTD snowblower I had that started very easily and ran great. I now have a 27 inch snowking. I'm at the point it only runs with the gas from the prime. I'm also on the third carb! Since carb two and three run the same I'm getting ready to do the same checks as you did. Would you attribute your initial problem to the valves being the problem? I did a compression check on mine and only got 60 lbs., but read on-line you can't do a compression check because of the exhaust valve "release" that allows you to pull the cord easier. Luckily we have only had one big snow where I'm at. It will be ready to go next year....:confused2:

My kingdom for one big snow...

riseandrun said:

Would you attribute your initial problem to the valves being the problem? I did a compression check on mine and only got 60 lbs., but read on-line you can't do a compression check because of the exhaust valve "release" that allows you to pull the cord easier. ...:confused2:

Click to expand...

Yes. For the most part. Before doing the valves, I installed the new carburetor and I got it to run somewhat, although not very well. I definitely had something plugged up in my original carb. Still, it was the exhaust valve not seating completely that was causing 99% of the problems. I believe you're right on not being able to do a compression test because of the compression release. I'd go ahead and check the valve(s). I was able to do it without buying any special tools. I used zip ties to compress the valve springs. It worked just fine. And I lapped the valves in with lapping compound and repeatedly checked the gap between the valve stem and the lifters until I got the gap right.

From all of the reading I've done online about Tecumseh engines, it seems that 9 times out of 10 it IS the valves that are the problem.