Tecumseh HH60 Help

[bwillmoth]

I have a Troy Bilt Horse tiller that I believe has a Tecumseh hh60 engine. I am getting exhaust pressure back out through the carburetor (I would say 25-50% of exhaust). I have checked valve clearances at top dead center, inspected the valve seats, and made sure the valves are cycling properly. Everything looks fine. What do I check next? I'm stumped. Thank you.

 

[Steve@Advance]

Have you checked for clogged exhaust?

Also some small engines use a centrifugal compression release on the exhaust cam. Try setting the valves
while turning the engine through and finding the loosest point.

 

[UncleTom]

Try checking the clearance on the valves when the opposite valve is starting to open by quite a bit. I have done 4 Tehcumseh snow blowers in the last 2 months that ALL had no clearance on the valves. One of them was so bad it acts like you describe. I had to grind the bottom of the stem off .010 just to get 0 lash. Then i took another .005 off and lapped the valves. Then recheck to make sure there is a final .005. I checked the compression before and after and gave me an instant 60 psi more compresion. They started low at 75psi. Now they have 140 psi. All of them Runs like a top now.

 

[Bruce Dorsi]

Check & set Intake valve clearance while the Exhaust valve is fully raised.

Check & set Exhaust valve clearance while the Intake valve is fully raised.

This a fool-proof way to set valve clearances and bypass any compression release methods.

As previously suggested, check for a clogged exhaust.

Other possibilities are a broken camshaft or incorrect valve timing.

Are you sure it's exhaust back pressure and not crankcase pressure?

The Tecumseh HH60 is a cast-iron engine.

 

[bwillmoth]

(quoted from post at 17:56:54 02/09/23) Check & set Intake valve clearance while the Exhaust valve is fully raised.

Check & set Exhaust valve clearance while the Intake valve is fully raised.

This a fool-proof way to set valve clearances and bypass any compression release methods.

As previously suggested, check for a clogged exhaust.

Other possibilities are a broken camshaft or incorrect valve timing.

Are you sure it's exhaust back pressure and not crankcase pressure?

The Tecumseh HH60 is a cast-iron engine.

I'm not sure that it's not crankcase pressure. How would I know this? I will try the advice you all have given me tomorrow. Thanks!

 

[stevieb49829]

Did you rotate each valve to assure you don't have a bent valve stem?

 

[guido]

bwillmoth,

Simply rotate the engine untill one
valve is fully open, adjust the
other valve.

Repeat for the other valve... DONE!

GUIDO.

 

[Mule Meat]

While you are digging around in the engine.
Check for a sheared flywheel key that could be throwing it out of time.

 

[bwillmoth]

I got the chance to work on it today, and made some progress. Now I'm having a problem with fuel coming up through the crankcase vent after a few seconds at
higher revolutions. I think this might have been my problem to begin with, I just didn't notice it. It will sit and idle for a few minutes, no problem. But any
throttle and it dies after a few seconds. I put a cheap new carburetor on it last year. Would this be my problem? That the float is not seating. I'm thinking it
may be best to rebuild the old carburetor; I'm sure it was better quality, and I know this engine doesn't have a ton of use; It just sat in my grandmothers garage
for 45 years. Any feedback is greatly appreciated! It may be easier to take it to a repair shop but I'd rather figure it out myself. Thanks!

 

[used red MN]

Hello Mr. will welcome to YT! Am I correct or should I say are we talking about the same thing as far as the crankcase vent? Rubber hose coming off the rectangular valve tappet cover going to the carb? That in no way should have gas coming from it. It may have oil droplets, but not gas. Unhook it from the carb and run it to see what if anything comes out. It could have gassy oil coming out of it if the engine sat at a slant and the carb float leaked by and over filled the crankcase with gas through the intake and an open valve. Rare occurrence on a single cylinder motor. The float will not cause compression or exhaust pressure the come back through the carb. I will echo what Steve says about the exhaust, any mud dauber wasp around where you live? Also a little side note about your valve setting. Others were telling you to recheck your valve settings but none told you why. Just a reminder incase this slipped your mind or you are not aware. A 4 cycle engine has 2 top dead centers with in the 4 strokes of the piston or 2 turns of the crank. One is at the top of the exhaust stroke and one at the top of the compression stroke. To set the valves or time the spark the engine has to be on TDC of the compression stroke.

 

[Geo-TH,In]

Try removing the crankcase vent tube that goes to the carb.
That will tell you if the gas is coming from the crankcase.
I think you may have an intake valve not closing causing air to
go backwards through the carb on the compression stroke.

 

[VicS]

Check your oil. It's not full of gas is
it.

 

[dhermesc]

I messed with one of them on my tiller for about a year when I first bought it. When I finally got it running good I realized I had low compression - who knew after 30 years a small engine would wear
out. Did what I should have done in the first place - bought a 6.5 hp Predator engine from Harbor Freight for $90 (a few years ago) then installed their Heavy Duty aircleaner (original was just a
sponge like a lawn mower has). I was prepared for it to die after a year or two of use and 5 years later it still runs and starts like a champ.

 

[brooktre]

If you need it the service manual is freely available for download. Just search for tecumseh engine manual.

 

[thdrduck]

(quoted from post at 14:46:56 02/14/23) I messed with one of them on my tiller for about a year when I first bought it. When I finally got it running good I realized I had low compression - who knew after 30 years a small engine would wear
out. Did what I should have done in the first place - bought a 6.5 hp Predator engine from Harbor Freight for $90 (a few years ago) then installed their Heavy Duty aircleaner (original was just a
sponge like a lawn mower has). I was prepared for it to die after a year or two of use and 5 years later it still runs and starts like a champ.

Probably the best $100 you ever spent. I put one on an old Troy bilt and ran it for 5 or 6 years (big garden) then sold it to guy who tills up deer food plots with it. Only thing I did to that engine was replace the starter rope.