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917 Hydro done for good?


Austin

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Picked up this 917 Hydro maybe a month ago, and its been mowing well since I bought it. I knew it burned oil but not terribly bad. Well today the following happened:

 

Went to mow with the 917 Hydro tonight. Did the normal oil and gas check. Oil was oddly low, but it was known to burn oil so I didn't think much of it. But I did top it off. It was real hard to get going and then when it did, the whole shed filled with white smoke to where I couldn't breath even with the door wide open... Well on the way with it moving out the shed it died. And it wouldn't start again, without smoking everyone out and barely running unless at high throttle. My conclusion along with my dad's is that it's toast. Looks like it's time for a 16hp briggs swap? Sad to say I'm, out of a weekly mower for now. Guess its back to dad's Husqvarna. 

 

I did try and mount the deck on my T-10, but found the later decks sit too high up. Along with the pto belt makes contact with the axle steering rod. Which also happened to be too short to wrap around the center deck pulley. Maybe I should get on finally finishing the restoration on the Homelite 42" deck...

917.jpg

917before.jpg

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I also noticed a head gasket looks to have blown out in a spot. The grill was wet with oil directly in line with the gasket. And after it sat for a while it had a tiny oil puddle underneath where the grill was. Could that be part of my problem? Not 100% sure on what to do first other than take the engine out?

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Just now, Chris727 said:

Pull the head and check it out. Was it knocking? 

I don't recall any knocking. It ran fine last time I used it, but I'll check it out next time I get a chance. Before the white smoke today, it heavily exhaled black smoke every other time of use. I thought it just might need new rings. But I'm not sure now.

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Do you have a gas shut off valve?

I have had it leak gas into cylinder and act that way.

but usually it fills up crankcase as well

and yours did not

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43 minutes ago, Ronald Hribar said:

Do you have a gas shut off valve?

I have had it leak gas into cylinder and act that way.

but usually it fills up crankcase as well

and yours did not

I do not think it has a valve. I have not had a chance to go down and inspect the problems yet.

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If the tractor was using oil it probably had significant blowby which can pressurize the crankcase.  Many of the KT and Magnums will blow out the front seal (PTO) with high internal pressure.   This is easy to put a new seal in.  Unless something catastrophic happened the KTs are easy to fix.  Most only need new rings, they usually have very little cylinder wear, and it the bearings are OK, just deglaze the cylinders and put in new rings.  Complete gasket set with std. rings are under $150.

As for the smoke, as stated the crankcase could have filled with gas, blown head gasket, maybe a stuck valve.

Good Luck!

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2 hours ago, MikeES said:

If the tractor was using oil it probably had significant blowby which can pressurize the crankcase.  Many of the KT and Magnums will blow out the front seal (PTO) with high internal pressure.   This is easy to put a new seal in.  Unless something catastrophic happened the KTs are easy to fix.  Most only need new rings, they usually have very little cylinder wear, and it the bearings are OK, just deglaze the cylinders and put in new rings.  Complete gasket set with std. rings are under $150.

As for the smoke, as stated the crankcase could have filled with gas, blown head gasket, maybe a stuck valve.

Good Luck!

Thanks for the input Mike! As both you and Chris stated I should pull the head off soon, and then I can get to the bottom of the actual issue. Hoping you're right and just the rings and seals should be my only two problems.

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 As said above, blue = oil smoke, black is excess gasoline.  But white is diesel/kerosene (un-burned / flooding) or automatic transmission fluid. Water as well. May be others that I'm not recalling at the moment.

 Unless diesel or kerosene was put in it by mistake, I can't figure out what would cause that amount of white smoke. Please post when you find out !

 

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I had a 1970's snowblower - 8 HP Briggs - that did exactly the same thing. When started it filled up the shed with white smoke, then smoothed out and ran great. I tracked the problem (I think) to worn valve guides that would carry oil into the combustion chamber, then run down on the piston and sit there until started again. It always started on the first or second pull - likely because of the great oil-sealed compression. My solution was to start it up, run for cover, and have a few sips of coffee until the smoke cleared. I sold it before I fixed the problem.

I don't know if this is your problem, but cold oil will smoke white when burning off. 

I suspect over-filled crankcase.

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