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I'm about to change the fuel filter on my Cub Cadet mower with a Kohler XT 725 engine. I'm finding fuel filters with micron ratings from 15 to 75. What micron rating should I look for?

The Briggs and Stratton 695666 is a very good one rated at 30 Micron.

If the engine manufacturer does not specify, I would suggest a filter micron anywhere from 50-120. My feeling would be one more towards the 100

Reasons:

• The engines fuel delivery system will be able to handle a certain particle size without damage or blocking. No point in filtering out these particles.
• Too small a micron leads to more rapid blocking of the filter = more frequent changes = more cost for no discernible benefit.

Personally I preferer the "plastic' transparent body/casing, gauze media filters. These are almost indestructible, allow for inspection without removal, the gauze media will not breakdown/deteriorate, can be cleaned using compressed air but better to replace . Good examples are made by Baldwin & Hengst (be careful to select original manufacturer);

Is this a single cylinder Kohler engine? If so, it's a gravity fed unit. If you put too small of a micron rated filter on it, it will not run.

It's a V-twin

Auto Doc's said:

It's a V-twin

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The OP isn't giving us a full description. He said XT725 and not KT725.

XT 725? or XT 775?

if its a XT775, there is a filter in the tank

MParr said:

The OP isn't giving us a full description. He said XT725 and not KT725.

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and an XT725 doesn't exist. So its either KT725 Vtwin or XT775 push mower engine

MParr said:

The OP isn't giving us a full description. He said XT725 and not KT725.

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Not surprising.

Many people on this site ask for help and automatically think we are standing right there looking at their machine.

There's a couple of good YouTube videos explaining filter applications. One is from Taryl.

Thanks to all who assisted. I appreciate it. And I'm sorry for misstating the model as XT725. I conflated the Cub Cadet model XT1 with the Kohler KT725. It's not as difficult to do as you may think.

25 050 22 s1

Scrubcadet10 said:

25 050 22 s1

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That's the OE filter for the KT725.
It's also a good choice.
I was hoping that he would watch the video and get a better understanding of the various filter applications.

The video, posted by MParr, is not very helpful.
Pleated filter media can do a good job , however it is hard to judge the degree of material caught/blockage and there is the ever present risk of the media breaking down and entering the carburettor. Use a gauze filter medium.
Opaque filter casing do not allow inspection at all. Need to be replaced at regular intervals ($) as the operator has no idea when they may be about to block. Use a clear/transparent filter.
The in- tank "filter" is known as a "Finger Strainer" - its main job is to catch large contaminates, before they enter the supply system. More appropriate filtration can/usually takes place down stream before the carburettor.

"Need to be replaced at regular intervals" That is correct. It's best to change them yearly or ever 100 hours. They are relatively cheap. Also, the super cheap stuff sold on Amazon or Ebay are not the best. OEM, Stens, or Rotary are fine for that time period.

No matter what size filter, make sure it's properly installed. Some are directional.

MParr said:

"Need to be replaced at regular intervals" That is correct. It's best to change them yearly or ever 100 hours. They are relatively cheap. Also, the super cheap stuff sold on Amazon or Ebay are not the best. OEM, Stens, or Rotary are fine for that time period.

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My point is: Replacing an opaque filter at regular intervals, does not allow the maintainer to exercise judgement ie does it really need to be changed.

If the maintainer/operator exercises good refuelling "hygiene" the inline filter may not need replacing for many years. Saving $ You will only have confidence in doing this IF you can see the filter media (gauze)

I recently changed the filter on my ZTR. It had been on my mower for around a year. Inside was a very fine light colored sludge. The filter was a 10 micron Kohler filter. Any filter with a higher micron rating would not have captured that junk.

Hello MParr,

All fuel is inherently "dirty", and the fuel filter needs to be replaced to minimize this fine sediment "sludge" from reaching the carburetor and clogging up passages. A fuel filter is cheap insurance to prevent more serious problems. The more hours a machine is used, the more often the fuel filter should be changed.

In a nutshell, filters that are too fine will tend to clog up faster, ones that are not fine enough will allow this stuff to reach the carburetor and collect inside it.

Auto Doc's said:

Hello MParr,

All fuel is inherently "dirty", and the fuel filter needs to be replaced to minimize this fine sediment "sludge" from reaching the carburetor and clogging up passages. A fuel filter is cheap insurance to prevent more serious problems. The more hours a machine is used, the more often the fuel filter should be changed.

In a nutshell, filters that are too fine will tend to clog up faster, ones that are not fine enough will allow this stuff to reach the carburetor and collect inside it.

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Correct. That's why the engine manufacturers specify a certain timetable for replacement.
If you are running an EFI engine, the specifications of the timetable for changing then needs to followed.
This is my usual filter choice.

EFI engines need "cleaner" fuel than carburetted engines.
When it comes to talking filters its almost a chalk & cheese scenario - ie don't mix them

FI systems usually require significantly finer (smaller micron) filters. Most often metal casing. Higher cost. Often quite a large filter to allow for sort of standard service intervals, with les risk of blocking.

Carburettor systems - as we have been discussing. If able to see gauze filter medium - no need to follow service intervals - replace/clean as needed= save dollars.

Both filter systems will benefit from refuelling hygiene (filter funnel). Unfortunatly the FI system, being opaque, can not realy take advantage of the as needed extended service interval.

Auto Doc's said:

Hello MParr,

All fuel is inherently "dirty", and the fuel filter needs to be replaced to minimize this fine sediment "sludge" from reaching the carburetor and clogging up passages. A fuel filter is cheap insurance to prevent more serious problems. The more hours a machine is used, the more often the fuel filter should be changed.

In a nutshell, filters that are too fine will tend to clog up faster, ones that are not fine enough will allow this stuff to reach the carburetor and collect inside it.

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I agree that all fuel is potentially contaminated ("dirty" is a bit of an over statement).
Carburetted systems are able to tolerate significant particle size ie as long as particles are smaller than smallest jet aperture, they will pass through. This is why you should take advise from manufacturer as to filter micron - no point at all in having greater/finer filtration than needed.

The more hours a machine is used, the more often the fuel filter should be change

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Doesn't make sense - A filter that you cant visually check for adequate flow, should be changed according to the engine/mower manufactures recommendation ie after so many hours. Simple - the engine processes fuel at a near set rate ie so many litres /hr. After X number of hours the filter has allowed X amount of fuel to pass. On the basis of real life testing, may be approaching the point where flow will start to drop below that required to mainatine full operating rpm.

"..............stuff to reach the carburetor and collect inside it.

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What really matter is the "stuff" that wont readily pass through the jets. Float bowls that may collect a little stuff/water are doing their job - not a problem if servicing appropriate.