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mtoney

Smokey 920 diesel

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mtoney

I got a solid 920 Diesel that starts super easy but is very smokey(white smoke), which is unburnt diesel. With it being easy starting, I dont think there is a compression issue. I suspect fouled out or worn out injectors. Just want to make sure I am not missing anything else. I will be fogging it up over at the Portland swap meet this friday, hoping to find a snowthrower for it. The PO said when he ran the mower for 10min, the smoke cleared up quite a bit. Since getting the injectors rebuilt isnt in the budget till next spring, I am running a healthy dose of Power Services injector cleaner/cetane booster thru with this tank of fuel. Here is a pic of the old girl. Mike

920d001_zpsb376f8d9.jpg

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mtoney

Yes, wet stacking is the term for what its doing. I have a bad exhaust manifold to muffler gasget, the muff got hit at some time in the past and bent its flange(warped it). I got it straightened but the gasget is shot. So when I pull it, I will look up into the manifold and see if both cylinders are wet stacking or just one of them. If I can find a snowthrower for it, with the predicted winter, she will get run hard over the coming months. Mike

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BLT

Wet stacking is caused by not working your engine hard enough. Another "achilles heel' is the engine has no regulated cooling system and many times your engine doesn't warm up enough to effectively burn off the injected fuel. You then get black slime sneaking out off areas what were thought air tight. In our industry this is a common problem, and the quickest cure is to work the he[[ out of it. The best way for you to get your cure, is to tow a heavy load like a car in neutral, engine running and the driver of that, ride the brake, it don't take much, force the engine to work hard and heat up. The person driving the tractor will think that the tractor is going to fall apart with all the smoke generated and in time should clear up to just black exhaust. Your black slime will disappear also. It will take some coordination between both drivers as you want to get the tractor to work so hard that driving on and up 2 X 4 will almost kill the engine. Good luck. Diesel engines were my way of life.

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mtoney

Nice engine there Bob! My thought is the owner that actualy ran it last didnt work it much. The non working meter shows 5500 hours but with how easy it starts, I do not think its accurate that or the engine was refreshed at some point(but possibly not the injectors). If we get the winter they are calling for, the snowthrower work will give her a good battle. The city rarely clears our long cul de sac. So myself and the neighbor clear it along with several of our neighbors drives. I am just thrilled to finaly have the Allis GT that I have wanted all along..The 920D

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mtoney

I will see what I can do once I get a new drive belt for the hydro, the one on it is stretched and slipping. I was basing the idea of running the thrower off doing the same with a 330 JD diesel GT. I could pull that Yanmar tripple down to almost stalling if I really kept the thrower loaded up. She would really lay down the coal smoke when I would do that. I have several heavy loads at the shop I could tow around while fogging the parking lot! What is the actual issue on wet stacking? Fouled injectors from light use? I understand what the effect is, poor/incomplete burn with raw fuel being dumped into the exhaust. Going to take her into work tomorrow to change that belt, degrease things, try to fix the muffler flange leak and if tiem permits, tow around something heavy hopefully. I forgot what a beast these are. I used to have the green DA version of this tractor.

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BLT

Wet stacking is the result of light loading by not getting the combustion area hot enough to completely burn off the fuel injected and then leaving a black gooey substance along with carbon deposits on the exhaust side. Too long of a period will cause the cylinder walls to glaze and eventually loose compression. So the quicker you address the problem the better off you'll be. Being that your engine has no thermostat to regulate block temperature, running your test on hot summer days will produce better results. 5500 engine hours equates to about 193,000 highway miles and that's a lot.

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Talntedmrgreen

...that's over 3 1/2 hours of use, per week, for 30 years. I would have to think she's either been meticulously maintained, or there has to be some wear in areas other than the engine. Impressive though! Looks hardly used...the PO must have taken his shoes off to run it ;)

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victorsnc
quote:Originally posted by mtoney

Nice engine there Bob! My thought is the owner that actualy ran it last didnt work it much. The non working meter shows 5500 hours but with how easy it starts, I do not think its accurate that or the engine was refreshed at some point(but possibly not the injectors). If we get the winter they are calling for, the snowthrower work will give her a good battle. The city rarely clears our long cul de sac. So myself and the neighbor clear it along with several of our neighbors drives. I am just thrilled to finaly have the Allis GT that I have wanted all along..The 920D


id="quote">
id="quote">I seriously doubt this good looking 920D has 5500 hours. Assuming this is a mechanical hour meter, are all the digits black except for the far right hand number? If the far right hand number is white - then you have 550.0 hours. If I am remembering my farm days correctly, any 1980's vintage diesel farm tractor (like an AC 190XT) would be ready for a serious overhaul at 5500 hours.

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mtoney

The paint isn't all original, the top of the hood and the fenders have been repainted (poorly) sometime in the past. The rest of the paint does look original. Here is a shot of the hour meter taken today. The meter can run if the key is left on. On this model, if the key is left on and no lights ect are left on, then the meter could get run up without killing the battery since the diesel is a mechanical shut down(only needs 12vt to crank over). But you are right, the hours do not match the overall condition of the tractor. Mike

DSC07416_zps442ec079.jpg

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mtoney

Did some work on the 920, checked the blow by. With a hot engine there is very little blow by if any, very little by feel an nothing visable. So if I am missing something, I am leaning toward injector issues or miss adjusted valve lash. Forgot my feeler gauges at work, so no valve adjustment today. Gonna fix a couple bad bearings in the mower deck, then go find some real tall grass to work it. Mike

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427435

To shut off the tractor, you pull out the big red knob. The manual says to leave the switch on until the engine is off. More than once, I have forgotten to turn the switch off. Eventually the oil pressure light does come on if you do that, but not immediately. I usually see the light before I leave the area.

It is quite possible that the previous owner forgot to turn the switch off, didn't notice the light, and the hour meter would have ran for days before the battery was dead (big battery).

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