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Discussion Starter · #1 ·
Were Case 446s offered with 20hp Onans? I'm looking at a 446, and it looks to have a 20hp Onan, but I understood they were equipped with 16hp Onans. The seller (not the original owner) believes it's original, and thinks it might have been a factory upgrade, along with the 3-point hitch. I haven't seen it in person, but it looks to be in good shape.
 

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All 446 models came with a 16 HP Onan engine. Case then offered the 448 model with an 18 HP engine. Later on, when the tractor line became Ingersoll, a 20 HP Onan powered model was introduced, as in the 4020. Three point hitches were always an option on the big wheel models. The 20 HP ONAN IN THE TRACTOR YOU ARE LOOKING AT IS a replacement, not original.
 

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Discussion Starter · #5 ·
All 446 models came with a 16 HP Onan engine. Case then offered the 448 model with an 18 HP engine. Later on, when the tractor line became Ingersoll, a 20 HP Onan powered model was introduced, as in the 4020. Three point hitches were always an option on the big wheel models. The 20 HP ONAN IN THE TRACTOR YOU ARE LOOKING AT IS a replacement, not original.
Thanks for this. As a collectible, I assume the replacement lessens the value, but functionally, assuming the 20hp isn't a lesser engine from an engineering/longevity standpoint, it's an upgrade.

With a 20hp Onan, rear PTO and 3-point hitch in very good original (well, mostly original) and rust-free condition, with everything working as it should, what would you think a fair price?
 

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VALUE is dependant upon what you intend to do with the tractor. If you are a collector, then you should want the correct engine under the hood. If you intend to work the tractor, then the 20 HP engine is a bonus. The hitch alone would likely bring 500 dollars and the rear PTO kit should be worth at least 200 dollars. A basic 446 with 48 inch mowing deck, in decent condition would go for around 5 or 6 hundred, Obviously, there are many factors that can increase or decrease those figures. If I were you, I would find out what he is asking and get as many photos as possible
 

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Discussion Starter · #9 ·
Finally got it home (long story). The serial number tells me it's a '74. As noted earlier, it looks like it was re-powered with a 20hp Onan Performer. Generally runs ok, but it sounds like the carb could use a bit of cleaning. As part of the engine swap, it look like the PTO was wired such that the mower deck belt doesn't just slide off, so sharp eyes will see just I wrapped it around the front after the deck was removed to get it out of the way.

Before digging in with any kind of serious work/repairs, I'll take some time to drive it and get to know it. I'm sure I'll have a bunch of questions.

Case 446 day 1.jpg
Case 446 day1 Onan Performer.jpg
 

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Hemlock Case Guy
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Finally got it home (long story). The serial number tells me it's a '74. As noted earlier, it looks like it was re-powered with a 20hp Onan Performer. Generally runs ok, but it sounds like the carb could use a bit of cleaning. As part of the engine swap, it look like the PTO was wired such that the mower deck belt doesn't just slide off, so sharp eyes will see just I wrapped it around the front after the deck was removed to get it out of the way.

Before digging in with any kind of serious work/repairs, I'll take some time to drive it and get to know it. I'm sure I'll have a bunch of questions.

View attachment 2487956 View attachment 2487957
The oil filter is too short. It needs to be at the very least flush with the cooling tins. The reason the oil filter must be flush with the cooling tins is that there is a vital to proper engine cooling rubber seal. It is a filter to shroud seal. Without the seal in place, the cooling air does not reach the head well enough on that side.

The Onan part number is 122-0502.
 

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Discussion Starter · #12 ·
The oil filter is too short. It needs to be at the very least flush with the cooling tins. The reason the oil filter must be flush with the cooling tins is that there is a vital to proper engine cooling rubber seal. It is a filter to shroud seal. Without the seal in place, the cooling air does not reach the head well enough on that side.

The Onan part number is 122-0502.
Thanks for this. Yes, the parts manual lists 122-0502 as the oil filter gasket, but I also see reference to an air seal grommet (#508–0273) that looks like it fits over the filter completely. Is the gasket used when using a longer (4.5") filter, whereas the grommet used when using a shorter (3.5") filter? If the longer filter fits, is there a reason to use the shorter one? Both lengths are referenced in the parts manual.
 

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Hemlock Case Guy
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Thanks for this. Yes, the parts manual lists 122-0502 as the oil filter gasket, but I also see reference to an air seal grommet (#508–0273) that looks like it fits over the filter completely. Is the gasket used when using a longer (4.5") filter, whereas the grommet used when using a shorter (3.5") filter? If the longer filter fits, is there a reason to use the shorter one? Both lengths are referenced in the parts manual.
Honestly, I had never seen that short of a filter on an Onan before yours. So, my experience is that the longer filter is used with the gasket I mentioned. Before now I had no idea there was a short filter with a proper gasket to cover it.

What I do know is not having the gasket can cost you a lot of money. I have seen the valve seat become loose, the 2 piece intake leak on that end from the heat cause seal separation, and then a lean condition that can cause engine failure.
 

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Discussion Starter · #14 ·
Ordered. I picked up the correct filter, too, so when the gasket comes in, I'll change the oil and install the correct filter & gasket. Thanks for the heads-up (y)
 
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