# JD 790 w/Yanmar Diesel - black then white smoke



## mvortex1 (Oct 8, 2019)

I realize this issue has probably been reviewed more than once already but here goes...

I have a JD790 with a Yanmar 3 cyl diesel with 290 hours. I think the tractor is a 2008 model and although not always true the low hours match the condition which is excellent. Auction price was 10K. 

I don't run it often and when I do it's low and slow work like raking and pulling trees out of the woods as well as some bucket and fork work. 

I fuel it with gas-station grade diesel from the pump, standard low sulfur.

I have, or had two issues. The first was black smoke at startup - I fixed that with new air filters and an oil change (I hope). The second is now white smoke, which matches what I've been smelling for some time. Running the tractor, even outdoors feels like I'm about to get lung cancer. The smell from the exhaust will choke you out and leave your clothes reeking like smoke. The white smoke goes from start-up to warm up and gets worse, as expected with an increase in throttle.

The oil has no evidence of anti-freeze. The exhaust leaves my fingers with no soot, no sweet tasting moisture but definitely a smelly sulfur stench. I am losing no oil, no coolant and other than stinking up the place the tractor runs great with lots of power.

I figure I have a few scenarios...

1) Bad fuel
2) Bad injector(s)
3) clogged up fuel filter

The injectors run about $200 for all three so that's not a quick, easy or cheap replacement to see if the problem goes away.

I don't want to blow up the tractor, should I just take it up to the JD dealer (I can drive it there) and let them go over the machine? Or maybe first drain out and replace the fuel or run some cleaner through the existing tank full? I have run the same fuel in my bullet heater and that also smelled horrible, so maybe the fuel is no good?



Thank you!


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## marc_hanna (Apr 10, 2017)

When you say low and slow, does that mean that you’re not running your tractor at rates RPM? Usually, the throttle should be set around 2,250rpm. If your engine isn’t running at the correct rpm, it won’t get hot enough. That can cause white smoke, but it can also cause excessive wear. 

Otherwise 290 hours is very low for worn out injectors.


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## mvortex1 (Oct 8, 2019)

Good question marc_hanna - "low and slow" means I don't run the engine screaming in high gear for everything I use it for. Lower gears, normal RPM ranges keeping the stress factors down. I do run things like post hole diggers closer to idle, but everything else normal engine speed.

Thanks


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## Hoodoo Valley (Nov 14, 2006)

I've got the next size up, the 990, and a Kubota BX 2200. I run my throttle between 1,500 and 1,800 for almost every application, even mowing. I do like you when running my post hole auger and run at idle and go slow to prevent damage. To me, running wide open just seems excessive. In your car or truck, you'd never open the throttle wide open unless you're running from the cops...  To me, it just seems abusive to the engine unless you're of course working the tractor hard. That being said, I've never experienced the conditions you speak of. Myself, I'd drain the fuel and put new fuel in. You don't know if somethings been added to your fuel that doesn't belong there, and what do you have at the most....? 7 gallons on board? That would be a cheap way to see if it made a difference.


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## marc_hanna (Apr 10, 2017)

WOT on my Kioti is something like 3,500 or 4,000rpm, I’ve never ran it past 2,250. Rated RPM is the RPM the tractor is designed to be operated at under load. Road vehicles are designed for very different operating conditions: they need to wind through the power band to get up to the desired ground speed. 
Tractor engines, particularly diesels, run at a certain rpm so that the implements and hydraulics operate at the required speed and to maintain a constant ground speed. Diesels like to run at a steady state at proper operating temperature. With the throttle turned down too low, when it needs to make more power under load, you end up with really rich injections, which is not ideal. Unburned fuel, low temp burns, and as a lot of people on this forum talk about, wet-stacking. 
2,250rpm is my no means a high rpm and it is the recommended operating speed by the manufacturer. 
I’m not saying that this is the issue in this circumstance but it is a variable to be considered. 
I don’t know how many hours the OP started off with when he bought it, but with that low of hours, it’s still at the tail end of the break-in period, so it might not have properly seated rings from being run too low under load. 

interestingly enough, building power at low rpm can be harder on the engine than at higher rpm because of peak cylinder pressure from injection dose. Compared to gassers, diesels can build disproportionately more power without a change in RPM by increasing the injection volume because diesels don’t have to maintain a strict fuel:air ratio. Theoretically, they can produce the same amount of power and torque at different RPMs by changing the injection volume, the difference (besides rpm) is that you have less frequent but more powerful power strokes at lower rpm. 
I generally only idle down my tractor, between tasks and only after it’s warmed up. My oil, is sparkling clean even after a 100 hours of service, so I ran it an extra 50 hours this time and then I’m going to send it off for analysis. 

That turned into a long post. Sorry about that. Just some food for thought.


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## mvortex1 (Oct 8, 2019)

Thanks HooDoo, I just drained the pre-filter screen and housing - it wasn't too bad but had some gunk in it. I'm going to drain the fuel like you suggested (only like a gallon left) and then pull the fuel filter and replace. Before I replace, Seafoam recommends filling the fuel filter up with their product, install and run the engine for two minutes. Then shut off and sit for 30 minutes. Then restart and run for 30 under normal RPM's. 

I figure this will eliminate most of the original fuel, a contaminated filter and clean the injectors all at the same time.

Regardless, I started it again after that initial cleaning and oil change and it's still blowing white smoke and STINKS so bad I had to walk out the shop, two overheads and a man door open and I was choking on the fumes.

If this does not correct the problem I'm going to drive it to the JD dealer 4 miles away. We're under quarantine for Covid-19 and I'm wondering how busy they are right now. If the Covid-19 doesn't get me the fumes will! ; )


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## DK35vince (Jan 22, 2006)

marc_hanna said:


> WOT on my Kioti is something like 3,500 or 4,000rpm, I’ve never ran it past 2,250.


That sounds really high.
Full throttle (Max RPM) on my Kioti DK 35 is listed at 2700 in my service manual.
I know mine stops there at full throttle.
540 RPM PTO speed is at 2500 RPM. I generally run 2500-2600 when mowing.


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## marc_hanna (Apr 10, 2017)

DK35vince said:


> That sounds really high.
> Full throttle (Max RPM) on my Kioti DK 35 is listed at 2700 in my service manual.
> I know mine stops there at full throttle.
> 540 RPM PTO speed is at 2500 RPM. I generally run 2500-2600 when mowing.


That’s just what’s on the tach, I have no idea if it will go that high.


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## Hoodoo Valley (Nov 14, 2006)

I know that regular construction equipment, yeah, absolutely, you have to run full throttle otherwise you'll burn up hydrostatic drive pumps and so on .the rpm thing really is subjective and I guess from my perspective, I run about one third to half throttle, and take it slowly and easy on my equipment. More rpms means more hp and torque and so when augering post holes for instance, I run almost at idle because our ground is Rocky and I want to be sure I don't snap my auger, or break something else. So to my .I get the high rpms argument, it's just that I'd rather bring that power down, with the rpms, and preserve my tools, and my teeth!


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## Hoodoo Valley (Nov 14, 2006)

Put another way..... I select my rpms. Then work in that capacity, rather than hammering the throttle, while pushing a refuse pop can over to the burn pile. 
.


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## marc_hanna (Apr 10, 2017)

Understood. But you should have a sheet pin on your auger.


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## Hoodoo Valley (Nov 14, 2006)

Oh I do. I have s box of them. Frankly even at just above idle, when that auger hits a rock, it literally starts bouncing viololently. Couldn't imagine going full tilt. There'd be shat flying everywhere.


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## marc_hanna (Apr 10, 2017)

You must have some big rocks.


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## DK35vince (Jan 22, 2006)

Hoodoo Valley said:


> Oh I do. I have s box of them. Frankly even at just above idle, when that auger hits a rock, it literally starts bouncing viololently. Couldn't imagine going full tilt. There'd be shat flying everywhere.


Yes it would.
I run my auger at or just above idle so I can control it better.


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## Hoodoo Valley (Nov 14, 2006)

Not so big, just lots of them! Think river bed. There's more rock than dirt. I can bore holes just fine, I just need to be on the controls to lift the auger and pull the rocks out of the holes


marc_hanna said:


> You must have some big rocks.


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## Hoodoo Valley (Nov 14, 2006)

Even more than the rotating speed of the auger is the fact that idle speed provides adequate power. Full or even middle engine rpms would be rediculous.


DK35vince said:


> Yes it would.
> I run my auger at or just above idle so I can control it better.


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## marc_hanna (Apr 10, 2017)

I haven’t run an auger on mine yet, but might be this summer. I live in a pretty rocky place, so I’ll post my out come. 

Anyways, back to the original discussion. Mvortex1, try getting your tractor good and warmed up, and run it at it’s rated rpm - should be marked on the tach with a red arrow or PTO marker. Hopefully it will run without white smoke, then under load, if the rings are bad, I would expect some white smoke.


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## mvortex1 (Oct 8, 2019)

Thanks for the replies. I just noticed a very scary thing - RUST on the bottom of my fuel cap and looking inside the tank is showing rust damage. This is very bad, hopefully I'm at the very beginning stages of it. I do have a pre-filter / water collector and a final stage inline fuel filter which I just picked up a replacement.

There was no rust sediment or anything like that in the water separator, or really any water from what I could tell but there was this brown slimy stuff.

I'm now at a decision point - don't risk anything and pull the tank, drain and blow the fuel lines and replace with a plastic tank or just drain the fuel, throw some Seafoam in the replacement filter and run it for a bit until all the old crap is out of it.

I've had this tractor for less than a year and have always kept it stored a concrete, attached garage. I suspect the rust occurred before I got it, or just got worse after I got it and now the water-laden fuel is making the tractor stink because it's not burning correctly.

I am reading horror stories of people having to replace entire engines due to this, what should I do?


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## marc_hanna (Apr 10, 2017)

Rust is a problem. The particles are abrasive and can cause serious damage to your engine and fuel system. Are you sure you don’t have a bunch of water sitting in the bottom of your fuel tank?


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## mvortex1 (Oct 8, 2019)

Oh wow, thank God everything seems to be cleared up. I drained "most" of the fuel tank into a milk jug and the fuel looks okay. There is rust on the fuel cap and what appears to be discoloration but no free rusting on the interior tank surface. Cleaned out the water separator bulb, replaced the fuel filter and primed it with Seafoam before installation. I just ran the tractor for 20 minutes and the white smoke has all but disappeared.

I will fill the tank to the top and make sure it stays that way. I installed a piranha tooth bar on the 61.75" bucket, bought a 6' box blade used and got the 3' quick attach forks from Titan so this machine is about to get a lot more use once it dries out.

81 trees and counting, too bad they're mostly PINE.....thanks everyone!!!


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## Hoodoo Valley (Nov 14, 2006)

Make sure you have the correct cap on your filler, that it's sealing properly and not allowing moisture in.


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## Hoodoo Valley (Nov 14, 2006)

Good to hear the situation has improved by the way!


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## ck3510hb (Sep 12, 2016)

Ok, I read a couple things here that make me want to ask if you considered contacting JD for sale history? Reason to do this is to find out if it was shipped and sold to a flood area. A friend bought a nearly new car that had problems and found it had been in fresh water (not salt) flood. It had been shipped or at least titled in a state without flood wrecked disclaimer.


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## mvortex1 (Oct 8, 2019)

ck3510hb said:


> Ok, I read a couple things here that make me want to ask if you considered contacting JD for sale history? Reason to do this is to find out if it was shipped and sold to a flood area. A friend bought a nearly new car that had problems and found it had been in fresh water (not salt) flood. It had been shipped or at least titled in a state without flood wrecked disclaimer.


I saw other forums mention this and it's a genuine consideration. I can verify however that the tractor was bought new from a local dealer not far from my home and was used almost exclusively to run a field mower on a small, private farm at the top of a hill overlooking a huge valley near Nockamixon state park. When I bought the tractor it did not blow white smoke. I think the reason I started having problems is because I didn't keep the fuel tank full, I failed to keep a close eye on the fuel separator and drain it frequently. Finally, I never replaced all of the filters (not hydraulics, not ready yet) - this is something that should always be done so you start with a fresh maintenance history.

Regardless, the issue appears to be resolved after I replaced the fuel, the fuel filter, drained and cleaned the in-line separator and primed the initial start with a can of striaght Seafoam. I'm going to buy some quality diesel treatment and keep that tank full from now on. Might even buy a finish mower and run the tractor back in the woods more to keep the fuel flowing more often and save my X570 mower deck.

Best regards,


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