# Tecumseh HS50 won't start



## tmiller (Dec 30, 2005)

Hi all,
I had a problem getting a spark on my snowblower engine, but a new coil, condenser and spark plug seem to have fixed that problem. I get a good strong spark now. However, even though I overhauled the carb and have both needles out 1 1/2 turns, it won't start. I have only got it to fire a couple of times out of a couple hundred pulls. I don't have the muffler on and gas is coming out the exaust and dripping out the choke side of the carb after I push the primer bulb 3-4 times. I am thinking that it may be getting flooded, but even if I let it sit and try pulling it without pushing the primer bulb, I get nothing. Any ideas how to get this bad boy running? This is a HS50-67209E that I think is from about 1970. I have gone through the entire machine, replaced several internal engine parts and spent about $100, so I'd really like to see some return on investment.
Thanks,
Todd


----------



## bugman (Aug 12, 2004)

make sure the plug isn't getting gas fouled, that is wet with gas..... the carb doesn't just keep flowing gas everywhere does it? how good of a overhaul was done, soaked wasn't it?


----------



## tmiller (Dec 30, 2005)

The plug is pretty wet, but the carb doesn't keep dripping gas out unless I press the primer bulb. I double checked the needles and they are 1 1/2 turns out. I did a full carb overhaul with all new O-rings and Welch plugs. It also soaked in carb cleaner for a long time. The float is sound. No gas inside.


----------



## bugman (Aug 12, 2004)

needles weren't damaged at the tips? bent, rounded off or scar'd ?


----------



## tmiller (Dec 30, 2005)

The old ones looked okay and they were both replaced with new needles.
Todd


----------



## bugman (Aug 12, 2004)

well it should run, either good or bad........ should atleast make a effort. it could be out of timing, either the flywheel key, or the cam and crank weren't lined back up if it was taken apart


----------



## tmiller (Dec 30, 2005)

I'm still having problems with this engine. I tried everything that anybody recommended and still could not get even a little indication that it was trying to start. I took it to my local small engine shop and they took a look at it. They were fairly certain that it must be something small because they sold me all the parts over the past month. The things I have done to it are: replaced broken governer gear and weights, overhauled carb, replaced coil, replaced condenser, replaced spark plug, carefully timed the ignition and generally inspected everything else. The shop found out that the exaust valve had stretched and needed reseated. I was hesitant to pay another $100 for that, but they reassured me that this is a great engine and that if the valve job didn't fix it, I wouldn't have to pay for it. They fixed the valve and it still wouldn't run, so they rechecked everything I did including opening the case to make sure the cam and crank were properly aligned. Anyway, I got a call yesterday saying they have put several extra hours into this, but can not figure out what is the problem. They are not charging me at all and suggest I get a new engine. Does anybody have any other ideas? I am having a hard time thinking about putting a new $350 engine on this old Ariens, but it may be worth it.
Thanks,
Todd


----------



## bugman (Aug 12, 2004)

spark plug gets wet? then it sure is getting gas, otherwise, compression was tested right?


----------



## scrench (Dec 8, 2004)

all it takes is fuel fire and compression , check the compression , tell us what it is 
i would think that the shop would have checked the compression , 

it might not be firing under a load condition , a spark checker that will check [email protected]


----------



## tmiller (Dec 30, 2005)

The shop told me that it has 60 psi of compression (almost double of what they expected or think is required) and they did test the coil under a load--which was supposedly fine. They questioned my carb rebuilding skills, but said they couldn't even get a fire with starting fluid. However, when I had it, there was definitely gas on the spark plug. Have you guys ever had an engine that you just couldn't start like this despite all this work? Also, is there a more affordable engine to replace this with (forward and reverse horizontal output shafts)? $350 sounds like a lot to me, but is it worth it on an old heavy Airens in great shape otherwise?
Thanks,
Todd


----------



## bugman (Aug 12, 2004)

well, $350 is more then likely worth it, on a in good shape ariens, i wouldn't get it from them, online source maybe. did they say thats "double what they expected or think its required" ? should be around 70 on the low side i beleive, 60, it still should start, was it a leak down tester? or a regular compression tester, one way to do it, test it dry with the compression tester, then test it after a little oil is squirted around the piston, it seals bad rings, so if it jumps.....rings. ok gas on the plug, its still getting spark right? new flywheel key and torqued down to spec? no, i've had one 11hp briggs vertical shaft on a murray one time, compression was low, it still started, but fouled plugs every 10 minutes.


----------



## scrench (Dec 8, 2004)

not enough compression


----------



## bugman (Aug 12, 2004)

still should try and burp atleast. when the head was off, how did the wear ridge on the bore look? how did the bore look in general?


----------



## tmiller (Dec 30, 2005)

I don't know how much compression it had for sure because I don't have a compression tester. I thought he said it had about 60 psi and it only needed about 30 to fire. How much compression do you guys think it needs? How much is a new set of rings? The bore felt and looked totally smooth. I could not find any scars or defects at all. Do you think a new set of rings will make this run? With all I've done to this engine I can't believe it won't at least fire. I feel that I am very close to fixing everything on it. What do you all think?
If all else fails and I need a new engine, where can I find a good replacement? The shop told me they could not find any exact excanges anywhere until Tecumseh found 2 on a distributor's shelf for them. The shop told me that most new engines have a different output shaft heights than mine and I may run into problems with that.
Thanks,
Todd


----------



## bugman (Aug 12, 2004)

find another shop if you can, it won't fire on 30 psi. needs atleast over 80, but it should try on 60 as for rings, try a little oil down the cylinder, if it does indeed raise the compression, it is the rings for sure. check online sources, smallenginewarehouse, etc. for engines.


----------



## tmiller (Dec 30, 2005)

I will check with the shop tomorrow on the exact compression the engine had. How much is a set of rings? With a smooth bore, is that the only thing that will reduce compression? Do they still make these dual shaft engines?
Thanks,
Todd


----------



## bugman (Aug 12, 2004)

yeah, its about the only thing that will, for one, the head gasket was replaced, the valves done, so.....that should rule that out. rings vary, probablly about 10 bucks.


----------



## scrench (Dec 8, 2004)

tmiller said:


> I will check with the shop tomorrow on the exact compression the engine had. How much is a set of rings? With a smooth bore, is that the only thing that will reduce compression? Do they still make these dual shaft engines?
> Thanks,
> Todd


is that the only thing that will reduce compression?

like bug man said you can rule out the valves if the shop done a valve job and done it right ! two ways you can check , the easier of the two is to take off the head ( i would do first ) and turn the engine over by hand until one valve is fully open and try to turn the valve the one thats down just be sure its on the lowest part of the lobe on the cam ,, if you can turn it then the valve job was not done right ,, with the head off you can check out the cyl wall and see if its not waisted ,,


----------



## tmiller (Dec 30, 2005)

I got the engine back from the shop and took a close look at it. I noticed that when I rotated the crank, the exaust valve lifted slightly during the compression stroke momentarily. I took they valves out (which the shop told me was impossible without a special tool. The valves did not look like they had been ground at all. However, I don't know if they will show a fresh metal look on the ground edge or if they always stay black. Anyway, I noticed that the top of the exaust valve was bent, although it seemed to seat ok. I looked at the cam and found a ridge on the cam opposite the apex where the exaust lifter rod rides. This was causing the exaust valve to open inappropriatly. I think that means all the compression would leak out just before the spark plug fired. In this situation, what would a compression test show? When I saw the bent (and unground) valve and think this had no real compression at all, I lost all confidence in the shop that told me it had 60 psi and they did a valve job. They also broke most of the flywheel threads off the crankshaft and didn't tell me. Just to see what would happen, I ground the ridge off the cam, put the bent valve back in and put the piston back in with only 2 rings (broke one in the reassembly) . The crankshaft barely has enough threads to get the flywheel back on, but when I had it all back together, it fired a couple of times on starting fluid, until I sheared the flywheel key. 
So, I ordered a new set of rings and a new set of valves and some new flywheel keys from a different dealer.
What should I do about the old shop who couldn't fix this? I feel like the guy I talked to on the phone was honest, but the guy doing the work was lying so he didn't have to work more. Alternatively, they may have been just trying to sell me a new engine. They told me to grind the exaust valve was $140, but they didn't charge me because it didn't solve the problem. I ended up not being billed for any of their work. Also, what should I do about the broken crank?
Thanks,
Todd


----------



## bugman (Aug 12, 2004)

if they didn't charge you, about the only thing you can do is complain about the other work, nothing was in writing... just a verbal agreement, as for the crank, i'd try to get them to replace it


----------



## tmiller (Dec 30, 2005)

What would a compression test show if the exaust valve was opening during the compression stroke?
Todd


----------



## scrench (Dec 8, 2004)

tmiller said:


> I got the engine back from the shop and took a close look at it. I noticed that when I rotated the crank, the exaust valve lifted slightly during the compression stroke momentarily. I took they valves out (which the shop told me was impossible without a special tool. The valves did not look like they had been ground at all. However, I don't know if they will show a fresh metal look on the ground edge or if they always stay black. Anyway, I noticed that the top of the exaust valve was bent, although it seemed to seat ok. I looked at the cam and found a ridge on the cam opposite the apex where the exaust lifter rod rides. This was causing the exaust valve to open inappropriatly. I think that means all the compression would leak out just before the spark plug fired. In this situation, what would a compression test show? When I saw the bent (and unground) valve and think this had no real compression at all, I lost all confidence in the shop that told me it had 60 psi and they did a valve job. They also broke most of the flywheel threads off the crankshaft and didn't tell me. Just to see what would happen, I ground the ridge off the cam, put the bent valve back in and put the piston back in with only 2 rings (broke one in the reassembly) . The crankshaft barely has enough threads to get the flywheel back on, but when I had it all back together, it fired a couple of times on starting fluid, until I sheared the flywheel key.
> So, I ordered a new set of rings and a new set of valves and some new flywheel keys from a different dealer.
> What should I do about the old shop who couldn't fix this? I feel like the guy I talked to on the phone was honest, but the guy doing the work was lying so he didn't have to work more. Alternatively, they may have been just trying to sell me a new engine. They told me to grind the exaust valve was $140, but they didn't charge me because it didn't solve the problem. I ended up not being billed for any of their work. Also, what should I do about the broken crank?
> Thanks,
> Todd


man i would try to score another engine 

exaust valve lifted slightly if it has a compression relief on the cam it will do that 

you might try some lapping compound on the flywheel and crank shaft 

but sounds pretty far gone


----------



## TurskRO (Aug 22, 2006)

*results*

So how did you make out on this engin?


----------



## oldstuff (Aug 12, 2006)

At least you got it to fire a couple of times. If flywheel key sheared, timing problem?
-Chuck


----------



## engine man (Mar 25, 2006)

hi i have about 50 lawnmower engines and tecumsehs and they all lift there exuast valve on compression stroke but still have lots of compression. i thought there was something wrong until i looked at the valves on our brand new tecumseh lawnmower we bought. before we tested the motor i had the head off and the exaust valve opened like all the older ones so i do not think its a problem it still had lots of compression.


----------



## tmiller (Dec 30, 2005)

*What to do with a rebuilt HS 50*

I never let you all know how this worked out. I got the engine back from the repair shop and played with it for a while while I waited for the new replacement to come in. They gave me a good deal on a new Tecumseh that was an exact fit. The shop told me the old one was unrepairable, but I couldn't bring myself to throw it away. After I noticed that the exaust valve was opening quite a bit, I decided to grind off the relief on the cam shaft and put it back together. I put the old rings back on the piston, but broke one of them in the process. I kept going with just the other one because I wanted to see if I could get it to fire. I sheared off a flywheel key and had to replace that, but on the next pull, it fired up and has been working great. I tore it back apart and replaced the valves and rings. The shop also gave me a new crank to replace the one they broke the threads off of. The only think I can figure is that I was not getting enough compression with the slight opening of the exaust valve (even if this is normal on a new engine) due to wear and a gradual decrease in compression over time. When I went in to pick up my new engine (that they made me prepay for), I took the old one in and showed them the "unrepairable" one fire up and run like a champ. They were embarrased to say the least. I still took the new one home and put it on my Airens. Now I have a different problem. I have a great running 30 year old Tecumseh that I don't know what to do with. Anybody have any suggestions? I am thinking of making a go-cart, but with only 5.5 hp, I don't know that it is the best motor for that job.


----------



## Fortune50 (Aug 28, 2006)

Wow, I'm glad you got that old engine to work. I too have an HS50 on a snowblower, but mine's a Sears Craftsman, lol. Mine's a 5hp, I started it today to see if that gas in the tank would still burn from last winter, lol. It would only fire up & run after spraying in carb cleaner in the spark plug hole. I'm guessing the carb is gummed up...
On a note about that cam lobe design, it's there to lift the exhaust valve a bit in order to vent compression so it's easier to pull start the engine. This also helps to prevent breaking the starter rope (or your hand) if it should kickback. Briggs engines have that design, too. Even my Polaris ATV's cam has a design to vent compression to help with pull starting.


----------



## 30yearTech (Sep 14, 2006)

I have had engines start and run with 50 psi. Sounds like a timing issue. What is the spec number of your HS50 engine?


----------

