Rebuilding a Snowblower Engine (Tecumseh 5hp)

[JTK]

To each his own, but a 5hp flat-head on a heavy 24" like that will be an absolute turd plopping dog. I'd rather bench-build a donor 8hp than bother with that scrap 5hp.

Transplant an 8hp Snow King or put something OHV 7hp or larger on it if you want to make a decent snowblower out of it.

Joel

 

[steve20]

Shhhhhhh--my 20 year old 5 hp SnowKing doesn't know it's a dog yet---

 

[eljefino]

Yeah there's more to a snowblower than raw power. I had a "sno-cat" with mere 7 hp that was an absolute ringer/ snow flinger. Impeller design and execution is apparantly a black art.

Or one could install a "Clarence kit" (rubber flapper/ scrapers for 2nd stage.)

 

[Donald]

Its the wet snow that separates the men from the boys. But 5 HP does sound low for a decent width snow blower.

 

[JTK]

Originally Posted By: eljefino
Yeah there's more to a snowblower than raw power. I had a "sno-cat" with mere 7 hp that was an absolute ringer/ snow flinger. Impeller design and execution is apparantly a black art.

Or one could install a "Clarence kit" (rubber flapper/ scrapers for 2nd stage.)


Agreed, but even a 7hp is night/day compared to a 5. I've used a few old school machines like the OP's w/ ~5hp engines on them. They are underpowered. It's probably why this engine is in pieces anyway, from having to run with the governor pegged (throttle wide open) at all times.

Much newer, much lighter weight MTD type machines with 5hp engines are OK. They're typically sized accordingly and not 24", with heavy components.

Joel

 

[lars11]

Yeah, if you replace that engine it sound be smart to pick a slightly bigger one, maybe 6,5 OR 7 hp. Should be easy to retrofit if you find one with à 1inch axle. But, I must say that it is quite ok to use this little 5hp.

 

[meep]

i can't stop laughing. i mean i really can't. "turd-plopping dog..."

 

[lars11]

Mounted impeller flaps of my own design on two out of four blades to make sure that no "turd" is getting stuck in that housing. They now cover the 6-9 mm gap between the blades and blower housing. No good snow to test it on right now but it sure acts like a heavy duty fan running dry... waiting for some heavy wet snow to test it on.

 

[SHOZ]

I've got a low hour Snowking OHV 5hp that I can't get running again. It stretched the shear key for the flywheel and after putting a new one in no start. Plenty fuel and spark. I've read it's the valve timing or something.

 

[JTK]

Shoz, yes, that will throw your spark timing off if the flywheel moves in relation to the crankshaft. FWIW, that 5hp OHV Tecumseh has about the equiv power to a 7hp flathead. I love the OHV Tecumsehs. My 14yr/old one purrs like a kitten and starts on 1-2 pull every time.

LARS, that's an AWESOME paddle kit you built! That's exactly what most of the old-school girls need as well as the cheaper MTD impellers.

Joel

 

[SHOZ]

Quote:
Shoz, yes, that will throw your spark timing off if the flywheel moves in relation to the crankshaft. FWIW, that 5hp OHV Tecumseh has about the equiv power to a 7hp flathead. I love the OHV Tecumsehs. My 14yr/old one purrs like a kitten and starts on 1-2 pull every time.


The problem was making itself know as I had to eventually run with the choke on. When I took the flywheel off the shear key was almost sheared off and the flywheel was lagging behind because of it.

But after putting a new key in it has never started again. Like I said, good fuel and spark but there must be a compression problem of some sort. Took the head off and all looked good.

 

[JTK]

Originally Posted By: SHOZ

But after putting a new key in it has never started again. Like I said, good fuel and spark but there must be a compression problem of some sort. Took the head off and all looked good.

But it ran before you pulled the flywheel to replace the key?

If you're positive the fuel quality is perfect, the spark is strong and you got the push-rods, etc all in place after yanking the head, I'm at a loss!

Nothing else *should* have changed by just replacing the key, unless a keyway wallowed out, knocking the spark timing off?

Joel

 

[SHOZ]

I never took the push rods out. Just pulled the valve cover off to make sure the valves were working. It's got an electric start so when I pull the plug out, ground it and crank the motor over there's a good spark. The plug is wet with fuel. Somewhere I read about doing something to the valves/pushrods but I can't find it now..

Got tired of taking the motor cover off and on as it is a PITA and it's just been sitting for a couple years. Hardly any use on the motor. Maybe 10-15 hours.

 

[JTK]

Maybe try a new spark plug.

If the plug is wet with fuel, it could be as simple as a fouled plug that's not sparking strong enough. I've had this happen too many times to count.

 

[SHOZ]

I got a new plug.

 

[lars11]

what caused the key to shear?? Must have been violent...
Remove the flywheel again and see how all parts line up. Any damage to the ignition assy? Will the key lock in a single positive place? Put all back together, remove the plug and:
1. Try to spin the engine by hand and see if the spark appear to be at TDC of compression stroke.
2. Measure the compression, but if it feels like before when pulling the rope, it should run.

 

[andyd]

IIRC, There are differnt keys for differnt timing. I would pursue that line.

 

[bumpdraft]

I have the same engine and I just got done slightly wrecking it.
It's a YardMan Leaf Vac. It specifies 30 wt. HD oil.

What I did:
The bottom of the aluminum engine case has cooling / stiffening ribs I let them get completely clogged with debris.
I used Rotella 15W-40 and tipped the engine "back" too far while vacuuming up a pile of leaves. I'm guessing this led to oil starvation of the output side of the crank shaft bearing.
...and as soon as the big impeller started vibrating, I shut it off

So, I bought another engine cover (with the so-called "bushing") and a new crankshaft...and a new impeller (in case the old one wore out-of-balance after 14 years).

As a spare, I will polish the old crank and have a competent machinist put a sintered bronze bushing in the case.

Can't believe it lasted this long! It runs at the rev limiter (govenor) with this big ol' pos hanging way out there!

Cute little thing!