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3520 water separator / sediment bowl

11157 Views 3 Replies 3 Participants Last post by  Brian
The manual says to service the water separator / sediment bowl when the fuel is low. I assume they mean when the fuel tank is low in fuel. What's the reasoning behind this?

Is there an aftermarket water-separator (with indicator) that someone can recommend? The clear plastic OEM one seems adequate but the plastic housing itself and drain valve makes me wonder if it will crack or brake at sometime or another considering your' to use the drain valve daily "to prevent engine damage." I'm also considering inserting a 3-way/in-line fuel drain valve (between the tank and the water separator) so that the tank alone can be drained.

Any problems (or tips) when it comes to purging the air after servicing the fuel filter(s)? Even thought the system is "self-bleeding", is there a better way of manually doing this if it leads to a quicker / complete bleeding, other than by "cranking" the engine.
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Toolcrib, I just did the service on my 2005, 990 that I bought used. It has the water separator/sediment bowl/filter at the tank. It then has another filter at the engine. My 990 is about 7 years old. I don't know how to find the exact date that it was manufactured. Maybe there is a way to do that on JD's website. Getting back to the subject the filters have never been changed on my 990. You can see in 2 of the pictures that the fuel filter at the engine still had the green paint around the top of it. It had 174 hours on it when I bought it. I bought the filters and O-rings. So this past Saturday I did the change out. You can see the pictures below. Brian had noted in an earlier post that the bowl could get brittle. Mine was not brittle however I wish that I had purchased a new one of these also due to its discoloring. I cleaned it out as best I could. There are some little narrow slots in the bottom of it that proved to be too difficult to clean completely. The other thing is that there is a red float inside it which I am guessing is suppose to float on the water if there is any water in the bowl. That I could not see before. I can at least see it now but it is still a little murky because of the discoloration of the bowl. In one of the pictures you can see the color difference between the old filter and the new filter. My guess here is that rust is probably the biggest discoloring factor. I looked down in the tank with a flashlight and it looks very clean. However the nozzel for filling the tank at the top inside of it is where you see some rust pits and most probably due to condensation. Also in an earlier post Brian had suggested a fuel additive that one should use with your diesel fuel. I went and purchased it and added it so hopefully this will help with any water in the fuel and also benefit the whole diesel system all the way to the injectors. You can find that complete thread here


P.S. this thread that I put the link to was actually started by someone who had a 3720. My guess is that things are probably pretty similar on the 3520 as well.

Also there is one more post to finish up on the pictures.


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Here are the rest of the pictures. You can at least see the red ring now in the bowl.

Also if I remember correctly if you turn the key on my 990 it will start to pump the fuel. I did that for about 20 seconds and then started it and it started right off. It sounded like it was misfiring at first and then just started purring.


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Forgive me as I cannot use any punctuation other than a period.

It has a been a while since I have had a 3720. I had 2 of them and neither had any issues with the fuel bowl. I also never used the drain and I did change the filter per the instructions in the manual without any issue multiple times.

IMHO, the only reason you would need to drain water is if you get bad fuel or it sits for a long time. I would check the plastic bown to see if you see water. If you do not, go about using the tractor. Deere does not want the bowl to fill with water and it to get sucked into the injectors.

Use a good additive that suspends the water in the fuel and you will not have an issue. If you use the ones that dropt the water from the fuel it will end up in the bottom of your tank and in the fuel bowl.

I would not look for an aftermarket with a sensor as I do not beilive it is needed. I doubt it would ever be used. But, there are places on the market that have them. Check Raycors web site. I believe those are what the the GM factory diesel uses. Filters will be about 10 times the cost of what you have now.
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