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mikev


Joined: Dec 21, 2007
Points: 9

Low Compression, some smoking and some oil coming from breather tube
Original Message   Feb 6, 2008 8:04 pm
I have an older John Deere 726 with a 7 hp Tecumseh engine. It has really been given a work out in the last month and I think the engine is getting a little tired. When I use it I usually run it for 1 - 2 hours. Lately I can only operate it a the slowest speed and have to release the drive in heavier loads to keep it from stalling. I checked the compression when it was cold and only got a reading of 35psi when I cranked it over by pulling hard a number of times. 

I also noticed that it smokes somewhat when it is heavily loaded and some oil is on the frame from the breather tube.

Any ideas on how I might get the rest of the winter out of the engine?

Would you rebuild an engine like this?

Would you put a new or used engine on an older machine?

Thanks for any feedback.

Mike

   

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borat


Joined: Nov 10, 2007
Points: 2692

Re: Low Compression, some smoking and some oil coming from breather tube
Reply #2   Feb 6, 2008 9:24 pm
With smoke and oil puking out of the machine plus low compression, I'd be leaning toward a prognosis of worn rings.  Your valves may also be going.  How old is the engine?   From your description, It does sound like it could be on it's last legs.

Would I rebuild it?  No.   Would I re-engine?  Being that it's an older JD and likely made by Ariens, that's the route I'd go.  You can get a nice, quiet, smooth and powerful Briggs and Stratton 11 h.p. for around $350.00 at Small Engine Warehouse.   Nowadays, it seems that engines are getting better while the machines themselves have become more technically involved but not as durable as the older units.  

 A couple of years ago, I just couldn't believe my eyes.  My mechanically inept neighbour blew the engine on his 1990s era Toro that was in excellent condition.  He had a truck come pick it up.  A couple weeks later, I saw him using an new Yardworks machine.  I asked him what he had done with the Toro?  He said he  blew the engine so he scrapped it!!   Now, I'm not a fan of the new Toros.  However, the old units were rock solid.  When he told me that, I couldn't believe it.  To me, that old Toro without an engine is worth more than the brand new Yardworks that he paid at least $1100.00 for.  If I had know he was going to scrap it, I would have readily taken it off of his hands.   An older Toro with a sweet 10 or 11 h.p. B&S would last a life time with proper maintenance.    

 

This message was modified Feb 6, 2008 by borat
mech12


Joined: Feb 20, 2006
Points: 273

Re: Low Compression, some smoking and some oil coming from breather tube
Reply #3   Feb 7, 2008 6:34 pm
rebuild.  new rings will usually take care of it. 
borat


Joined: Nov 10, 2007
Points: 2692

Re: Low Compression, some smoking and some oil coming from breather tube
Reply #4   Feb 7, 2008 7:48 pm
mech12 wrote:
rebuild.  new rings will usually take care of it. 

Rings alone will not get the job done.  If you put in new rings, at the very least, the cylinder will have to be honed.  Chances are that the cylinder will have to be bored to the next over size and a new piston required .  So, let's see, to bore & hone cylinder  = $50.00, new piston & rings = $50.00, gaskets = $25.00, labour probably around $150.00 depending on who's doing the gouging.   I'd buy a new and better over head valve engine. 
Moderator Denis


Location: Ville Lemoyne
Joined:
Points: 595

Re: Low Compression, some smoking and some oil coming from breather tube
Reply #5   Feb 7, 2008 8:03 pm
borat wrote:
Rings alone will not get the job done.  If you put in new rings, at the very least, the cylinder will have to be honed.  Chances are that the cylinder will have to be bored to the next over size and a new piston required .  So, let's see, to bore & hone cylinder  = $50.00, new piston & rings = $50.00, gaskets = $25.00, labour probably around $150.00 depending on who's doing the gouging.   I'd buy a new and better over head valve engine. 


Listen folks rebuilding small engines not worth these days, new engines are very cheap to buy, it's not like rebuilding a Ford 351M or GM 427 or 383 magnum hehehehe.

Regards

Denis

OPE MODERATOR

mikev


Joined: Dec 21, 2007
Points: 9

Re: Low Compression, some smoking and some oil coming from breather tube
Reply #6   Feb 7, 2008 8:22 pm
Some  info:

Purchased the unit 2 years ago, and according to John Deere it was manufactured in 1977.

Yesterday I added some Bardahl oil treatment and then had the opportunity to use it twice. First with heavy wet snow and then with about 5in. of dry powder. The heavy wet snow was very slow going but was able to get through it and do  4 neighbours.  Today it went through the dry powder much better, even though I could only use the lowest speed. I did notice that it was blowing further than it had before using the oil treatment. It even went through the EOD stuff reasonably well.

I checked the compression right after using it today and got a reading of 55psi after a number of good hard pulls.

So it looks like I should be able to get through this season alright and may look for a new engine.

I noticed that the higher HP engines have a larger diameter output shaft. Do you think it would  be wise to just go with a B&S 7.75 HP that has the same size shaft, rather than trying to compensate for a larger shaft. I see they have one at the site you mentioned Borat  for $250 plus $110 shipping to Canada.

Mike

borat


Joined: Nov 10, 2007
Points: 2692

Re: Low Compression, some smoking and some oil coming from breather tube
Reply #7   Feb 8, 2008 12:01 pm
Not sure where you live Mike but I get my stuff shipped to a handler on the U.S. side of the border.  Usually for free.  Then I take a 25 minute drive to pick it up.   Pay taxes on the Canadian side and that's about it.  Seldom do I ever have to pay duty.  There are plenty of 9 to 11 h.p. engines listed with 3/4" shafts.  I assume that's the size you need.  Peruse the "snow engine" list.  I'd go with at least a 9 h.p. 

If shipping the engine in from the U.S.  isn't worth the cost/effort, take the price to a local small engine dealer and see if they will drop their price to something reasonable.   I checked the price on a 10 h.p. B&S overhead valve, horizontal shaft engine at a local dealer last October.  They wanted $850.00!!!  Yeah.  Sure.  Where do I sign?   The very same engine from Small Engine Warehouse was $350.00 with free shipping.  Can't see how a dealer can charge more than double for the same product.  If they're paying that much to their suppliers, maybe they should start buying them from Small Engine Warehouse themselves???

mikev


Joined: Dec 21, 2007
Points: 9

Re: Low Compression, some smoking and some oil coming from breather tube
Reply #8   Feb 9, 2008 9:12 pm
Driving to state side would definetely be an option. I didn't know you could have it shipped to a handler. Thanks for the suggestion Borat.

Two more question.

Would you invest $350 or so on a 1977 John Deere 726?

Are the low priced snowplower engines available all year or just during the winter?

Mike

borat


Joined: Nov 10, 2007
Points: 2692

Re: Low Compression, some smoking and some oil coming from breather tube
Reply #9   Feb 9, 2008 11:06 pm
mikev wrote:
Driving to state side would definetely be an option. I didn't know you could have it shipped to a handler. Thanks for the suggestion Borat.

Two more question.

Would you invest $350 or so on a 1977 John Deere 726?

Are the low priced snowplower engines available all year or just during the winter?

Mike



If the unit is structurally sound and doesn't appear to need extensive and expensive repairs (gears, bearings etc.), it's certainly worth the price of a new engine.  Take a good look at how rugged the machine is then compare that with many of today's offerings demanding in excess of $1000.00.   If it is in good shape, I'd re-engine. 

I'm pretty sure they keep their engine stock consistent all year round.   

JohnnyBoyUpNorth


Location: New Brunswick Canada
Joined: Dec 30, 2007
Points: 72

Re: Low Compression, some smoking and some oil coming from breather tube
Reply #10   Feb 10, 2008 6:46 pm
I agree with Borat on this one. A new engine is a sound investment. I put a fairly new Honda on a Bolens machine made sometime in the early 70's, and I am very happy with it. You might be able to buy something as reliable today brand new, but you'll spend a lot more doing it than you have to.

Think about what you're going to do with a snowblower, and ask yourself how glamorous does it have to be? I've got a machine with 3 shades of rust, faded Honda colours, mismatched mittens and I am still the envy of every shoveller out there..

John

Contents under pressure....
borat


Joined: Nov 10, 2007
Points: 2692

Re: Low Compression, some smoking and some oil coming from breather tube
Reply #11   Feb 10, 2008 7:53 pm
JohnnyBoyUpNorth wrote:
I agree with Borat on this one. A new engine is a sound investment. I put a fairly new Honda on a Bolens machine made sometime in the early 70's, and I am very happy with it. You might be able to buy something as reliable today brand new, but you'll spend a lot more doing it than you have to.

Think about what you're going to do with a snowblower, and ask yourself how glamorous does it have to be? I've got a machine with 3 shades of rust, faded Honda colours, mismatched mittens and I am still the envy of every shoveller out there..

John


Very well put bud.  Got a laugh out of that one. 
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