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Discussion Starter #1
Hi everyone, I just started with the forum but I've been doing a lot of research on here the last few weeks. I just want to clear things up on a few questions I have.


So, a couple weeks ago I bought an early 1970's JD 726 with the Tecumseh H70-130158 engine. This thing is a beast. But it has been very temperamental for me. First thing I did was adjust the carburetor and that was a big help. Second, I changed the oil to 5w-30 from 10w-30 but it seemed to be a lot more temperamental. So i went back to 10-w30. It was still running weird so I ended up replacing the gas cap and now it runs great.



But anyways, this motor has always used 10w-30, so I was wondering if I should try switching to a semi-synthetic 5w-30 or just keep using conventional 10w-30?


Secondly, I am thinking about doing some other maintenance on it. Possibly replacing the head gasket, breather assembly, and the belts. So, one of the questions is, how do you know if you need to replace the head gasket? Also, is there a way to replace the belts without removing the auger from the body of the snowblower?


I am sure I have other questions but these are the main ones.


Thanks!
 

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Welcome to the forum!

I run synthetic Mobil 1 5W-30 in my Tecumsehs (more recent than yours). Personally, I think going to synthetic is fine.

If the head gasket and breather assemblies are working OK, why replace them? A failed head gasket can cause lower compression, possibly some visible smoke or oil around the head.

Belts, on the other hand, can weaken/stretch, and be worth replacing proactively. I'd keep the old ones around as spares, in case a replacement belt fails in the future.

For auger gearbox lube, what does your manual say? It's being discussed here presently:

https://www.snowblowerforum.com/forum/snowblower-repairs-maintenance-forum/147983-best-lubrication-auger-worm-drives.html

I don't think there's a single correct answer. It depends at least in part on what kind of gears you have, and their materials.
 

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Don't replace the head gasket if it's working. You have a chance of snapping a head bolt.

Use synthetic oil, any weight.

I have a JD1032, my manual calls for 5w-20 for the gear case. The level should be 1"-1 1/2" from the top.

I don't replace belts unless they are ripped, torn, ready to snap, slipping, or stretched too much where they are slapping.

To replace the belts on my 1032, you need two people, one to hold the handlebar as when you remove 2 bolts, the handle will fall. There is a rod on the bottom and the handle tilts on this bar when you remove the 2 bolts.
 
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Discussion Starter #5
Well I just used it a few minutes ago. Would hardly run on full choke with half speed, so I adjusted the high speed on the carburetor and it ran great. When I shut it down, I heard a knock and now it won't turn on at all. String is very hard to pull and even the electric start won't do it. Any suggestions?
 

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Check your oil level. Hope it's full or at least has enough. Make sure you're in neutral, clutch not engaged etc when pulling on the rope too.
 
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Discussion Starter #7
Oil is full. Changed it a few days ago. Took the plug off and pulled the string a couple times and could feel aircoming out the hole. Spark plug was a little gummed up so I cleaned it and engine still won't start. Seems the engine is flooding after 2 or 3 pulls
 

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String is very hard to pull and even the electric start won't do it. Any suggestions?
Oil is full. Changed it a few days ago. Took the plug off and pulled the string a couple times and could feel aircoming out the hole. Spark plug was a little gummed up so I cleaned it and engine still won't start. Seems the engine is flooding after 2 or 3 pulls
The fact that it got difficult to turn the engine seems interesting.

Is it possible the carb's needle valve is not closing properly, and is allowing gas to overflow, into the engine?

How are you trying to start it? As in, prime X times, full-choke, then pull cord, etc.
 

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Welcome to SBF!!!
You say you got the blower and adjusted the carb, By the sounds of it you need to pull the carb and clean it then re adjust. If you adjust a dirty or fouled carb to make it run better most times it will not be good for the next running as in your case.


If that is flooding over by the needle and seat then it complicates things as well.
Certainly keep track of your oil as not to fill the crankcase with flooding gas if this would apply to your style intake on your tec.
 

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Discussion Starter #11
I never have to prime it. But since this problem started, I've been trying multiple different ways to start it. Pulling can be difficult but that seemed to go back to normal. When trying to use electric start, it just keeps turning over. The gas is brand new but maybe the previous owner used bad gas and the damage was then passed to me?

Every time I try to start it with the electric start, smoke comes out of the muffler and it smells like gas. Once I let go of the button, a bunch of smoke comes from the carb.
 

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Discussion Starter #12
So I did some troubleshooting kn the engine. I think it is the spark plug wire. I have a tachometer that turns on when I pull the string. Didnt turn on from pulling the string or from the electric start... Leads me to believe that's the problem.
 

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It's a plate that covers the carb air inlet . . . the idea being that when it is closed, a soft pull of the starter cord will draw fuel in to prime. I had this on my 1974 H70, but tended to use the electric since the plastic starters were fragile. Throttle to full, choke *open*, hit the starter, close the choke just until it fires, and then right back to half or so. No matter what the conditions or temp, that has never failed to start an L head Tec for me almost instantly, and never used the primer either . . . (and never had one with the bulb of that vintage had I even wanted to). Seems like the spring loaded primer and the choke are pretty redundant, although the primer does not have a hole in it as I recall . . .
 

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It doesn't use a primer bulb. I don't know what it's called, but the engine uses a button with a spring around it for priming. It isn't required to start the engine though

:biggrin: I think tadawson nailed it. Primers are somewhat overrated cuz I've had plenty of small engines with no primer whatsoever. Most of which were B&S engines powering grass whackers. It's the danged carburetors they been bolting to small engines over the last couple of decades that complicate things and necessitate primers to keep the average Joe happy.
 

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Me personally, I use that spring choke primer...and I believe it helps. Push it closed and while closed I perform two slight "half pulls". Then with the regular choke lever on full, give the rope a good pull (or electric starter).

I own 3 machines with that setup. Starts 1st pull every time - or saves cranking time with the electric. Either way, they start up fast using it the way they describe to in the owner's manuals.
 

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I used it when manually starting, but with the electric, my way was typically running in about 1 to 2 seconds with the electric, so not sure home much crank time you can save on that . . .
 
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