# Tecumseh H70 problem



## curt4774 (Dec 22, 2009)

Hi to all. I just last night ran into a problem while using my Ariens Snowblower with an electric start Tecumseh H70 to attempt to clear some of the 17" of snow we just received the night before last and into yesterday morning. I had thought it would be ready to run, after changing points, condenser, plug, oil, and rebuilding the carb. After I got done last summer it started right up and ran well after I fine-tuned the carb screws. I started it this Fall and ran it fir a while with the same results. When I went to use it for the snow the other day, the same thing - started right up and ran well. I used it far about an hour blowing snow with no difficulties, and then suddenly I started hearing a ticking sound (valve?) near the top of the engine. the engine began to skip and would hardly stay running without me playing with the carb linkage with my finger, and would eventually stop. It would restart immediately every time it quit, but with the same result. It chugs, skips, won't accelerate at all, and emits some black smoke from the muffler-along with this regularly-occurring clicking/ticking sound up top. I think it's a problem with either or both valves, but not sure what happened. And it was running so well just before. I haven't touched it yet,, because I want to be sure where the problem is before i start a fishing expedition. It's not the carb, not the state of tune or spark, not the fuel nor compression, and not the crank and rod. Oil is full; no lower end noises or knocking.- Waht do you all think? thanks very much. Curt


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## 30yearTech (Sep 14, 2006)

Black smoke indicates a "Rich" condition. Too much fuel, this could be caused by a sticking intake valve, or the carburetor. On an "L" head engine, valve noise like what you describe is generally caused by excessive valve lash, but could also be caused by carbon build up in the cylinder head around the valve area.

Does it now make the noise all the time, or does it go away and run good when the engine is cold and first started?


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## curt4774 (Dec 22, 2009)

HI, and thanks for your response; I am hoping that i can get this straightened out - I really need to use this with all this snow! The problem happened all of a sudden and does not go away. The only way I can keep this going is by constantly fiddling with the throttle right on the carb. Using the throttle cable will not work because it doesn't move fast enough to keep it going, and I am only able to "BARELY" keep it going for a while, and then it quits eventually. The engine will always restart immediately (electric starter probably turns engine over once or even less and it fires) but will not clear out. I know black smoke is a sign of rich mixture, but I only get an occasional little puff of it through the muffler, because I cannot now get any steady RPMs from the engine, or there might be more of it. It just barely runs enough off and on to keep the engine rotating. I cannot figure out what happened-it was running so well. I spent so much time on this carb and also of course figuring out the throttle/governor linkage and spring confusion all over again (obviously forgot to take a pic or draw a diagram) that I don't know how it could be carb-related (but I'm not saying no either). I mentioned the valve-ticking noise - without any appreciable exhaust noise to drown it out, perhaps that is why I notice it, but as I said in the other email I can't say no to valve trouble either-I just don't know what it is. Whatever it is happened all of a sudden without any big noise or bang. Having no Parts List for this engine and no repair Manual doesn't help me either, if the valves need to be adjusted or replaced. Curt


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## 30yearTech (Sep 14, 2006)

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

Above is a link to the service manual that should cover your engine.

http://www.partstree.net/parts.asp

You should be able to find an illustrated parts list for your engine at this link, you will need your engine numbers.

The valves on this engine are only adjustable by grinding some of the valve stem off, but a ticking generally indicated excessive valve lash. You may want to pull the head and have a look at the valves, valve seats and general operation and appearance of the valves.


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## curt4774 (Dec 22, 2009)

Hi, and thanks for your response. I will go to the sites you gave me and see what I can find in the AM, after i get the Serial # from the engine. I don't think I'd want to take a chance on taking some material off the valve stem(s).; I've never done it because I've never had to, and so I would be afraid to mess something up. If i can narrow it down to valve trouble I probably would be better to just get 2 new valves, although this engine does not have a lot of hours on it;it was tucked away in the corner of the shed literally for 20-odd years, and this was a replacement long block from the dealer way back when. I might as well pull the bowl off the carb too and have a look, since I noticed earlier today that when I put the new fuel line on I forgot to add the fuel filter. If I see anything in the bowl-which I really shouldn't- I will pull the adjustment screws and spray the carb out again....oh, joy. I'll have a look and post a new message. Curt


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## kshansen (Dec 20, 2009)

One possible source of a ticking like sound can be a bad head gasket.

My first check would be the carb bowl and the main jet. Drain out old
fuel and install filter if you have one and refill with fresh clean fuel.

Also check inside fuel tank to see if something is plugging the fuel outlet.
Sometimes crap gets in tank and will restrict the flow of gas. While you
are checking things make sure the fuel cap vet hols are open.


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