David78 6 #1 Posted August 8 Just bought my first Wheel Horse tractor. It's a 312-8 that's in great shape. Previous owner hadn't used it much in several years so I talked him in to partying with it. It runs and mows fantastic for an old tractor, but where it's sat for several years it needs some maintenance and tinkering and either the carburetor cleaned or rebuilt. It has the 42 inch deck and is in desperate need of new belts and blades. Was hoping someone could help me with correct belt and blade sizes. I'm going to change the drive belt, oil and filter, ait filter, fuel filter and transmission fluid all at the same time. Any help would be greatly appreciated. 1 2 Share this post Link to post Share on other sites
Cee245 846 #2 Posted August 8 Welcome to RS! Do you have the model numbers for the tractor and deck? Tractor model os under the seat. Mower model is on deck shell. I highly recommend replacing the shift boot. Water/debris can get in there. You'll know when you replace the tranny fluid, It comes out milky if contaminated. The 312-8 is a nice basic mower and very reliable. Nice pick up! -C 2 Share this post Link to post Share on other sites
Bill D 2,278 #3 Posted August 8 (edited) Welcome! Very nice tractor. Drive belt is 82"x5/8", PTO to deck belt is 103"x1/2", deck belt is 86"x1/2", all available at TSC. Some people prefer OEM drive belts. P/N for the blades is 106636. I like the XHT blades available on Amazon. Air filter kits are sold at TSC, sorry I can't remember the P/N. Spark plug is a Champion H10C. Engine oil is Rotella T1 30, no oil filter. 75-90W gear oil for the transmission. Plan to change the fuel lines, fuel tank grommet and shut off valve. Use the shut off valve with the built in screen. Ask lots of questions, someone here always knows the answer. Edited August 8 by Bill D 2 4 Share this post Link to post Share on other sites
953 nut 60,348 #6 Posted August 8 Very nice looking 312-8, glad to see you are going to show it a little love. @Bill D has you covered on most of your questions, Rotella T1 30 is the oil he was referring to. Your air filter part number is Kohler #45-083-02 and the foam pre-filter is 45-083-01. Tractor Supply or any outdoor sports dealer should stock aftermarket copies of them or go to for a better price. When you drain the old oil from the transaxle be sure to jack the front end up as high as you can, there is a hump in the bottom of the transaxle case which will prevent it from draining completely if not jacked up. 1 Share this post Link to post Share on other sites
peter lena 9,309 #7 Posted August 8 @David78 agree with others on recommended changes , replacing all fuel lines is a vital part of that , the ethanol in fuel , breaks down hose , and clogs all fuel related passage points . also a good opportunity , to give that paint a mineral oil / penetrating oil soak down , put it on paint and lightly rub it on , leave it for days , that sun would be perfect for lubrication soak / draw in to paint . then lightly rub it down with a clean cloth penetrating oil . not a one and done , but initial oil will recover paint . also like a hi mileage ATF fluid for a drive around , trans flush agent , put some time on it , use every gear , like cul de sac driving , for road testing and trans oil flushing effect , before draining and . 80-90 oil refill . always bring a small bag of tools / lubricant on my road rides . lots to learn , good for you ! pete 1 Share this post Link to post Share on other sites
David78 6 #8 Posted August 8 7 hours ago, Cee245 said: Welcome to RS! Do you have the model numbers for the tractor and deck? Tractor model os under the seat. Mower model is on deck shell. I highly recommend replacing the shift boot. Water/debris can get in there. You'll know when you replace the tranny fluid, It comes out milky if contaminated. The 312-8 is a nice basic mower and very reliable. Nice pick up! -C Any idea where to find the shifter boot? 1 Share this post Link to post Share on other sites
David78 6 #9 Posted August 8 Thank you guys for your help! I'm going to get the ol girl in tip top shape and try to keep er there. I really enjoy it so far. 1 Share this post Link to post Share on other sites
953 nut 60,348 #10 Posted August 8 42 minutes ago, David78 said: Any idea where to find the shifter boot? 1 Share this post Link to post Share on other sites
Andy N. 2,417 #11 Posted August 8 39 minutes ago, David78 said: Any idea where to find the shifter boot? https://wheelhorsepartsandmore.com/ should have most of what you need. If not, eBay and Amazon are always good as well. When you get the Model numbers from the deck and tractor, you need to visit the manuals section of this forum and download what you need. https://www.propartsdirect.net/ is also good for the parts manual and usually puts the alternate part numbers in their parts list. I just finished a full refresh of a '89 312-8 and also have a '86 312-8. They are great machines that do most of what I need them too. 3 1 Share this post Link to post Share on other sites
David78 6 #12 Posted August 8 3 minutes ago, Andy N. said: https://wheelhorsepartsandmore.com/ should have most of what you need. If not, eBay and Amazon are always good as well. When you get the Model numbers from the deck and tractor, you need to visit the manuals section of this forum and download what you need. https://www.propartsdirect.net/ is also good for the parts manual and usually puts the alternate part numbers in their parts list. I just finished a full refresh of a '89 312-8 and also have a '86 312-8. They are great machines that do most of what I need them too. I have my tractor serial numbers but as for the deck, they have been removed when the deck was repainted several years ago. I'm going to start a note pad with all part numbers as I get them figured out for future reference. 1 Share this post Link to post Share on other sites
Andy N. 2,417 #13 Posted August 8 27 minutes ago, David78 said: I have my tractor serial numbers but as for the deck, they have been removed when the deck was repainted several years ago. I'm going to start a note pad with all part numbers as I get them figured out for future reference. The deck on yours is a 42" Side Discharge. I would assume from the 80's, but they were pretty much all the same in the 80's and 90's even though the model numbers changed, mostly to denote the manufacture year. A lot of the parts (minus belts, blades, and a few other parts) were the same between the 42" SD and 48" SD. A quick way to tell the difference is the 42" height adjust is on the right and the 48" height adjust is on the left. 2 Share this post Link to post Share on other sites
Lee1977 7,224 #14 Posted August 8 (edited) If the nut on top of the pulley of the deck spindle is 5/8" you have metric spindles. The bearings are 6203 2rs 17 mm ID 40 mm OD and 12mm thick. That's what deck should be on you tractor. Wheel Horses garden tractors were sold with out the deck, deck were extra and you could chose the size deck you wanted. Wheel Horse changed to the Tac-A-Matic in 1973 and all later Wheel Horses used the same system. Edited August 8 by Lee1977 1 Share this post Link to post Share on other sites
David78 6 #15 Posted August 8 9 hours ago, Bill D said: Welcome! Very nice tractor. Drive belt is 82"x5/8", PTO to deck belt is 103"x1/2", deck belt is 86"x1/2", all available at TSC. Some people prefer OEM drive belts. P/N for the blades is 106636. I like the XHT blades available on Amazon. Air filter kits are sold at TSC, sorry I can't remember the P/N. Spark plug is a Champion H10C. Engine oil is Rotella T1, no oil filter. 75-90W gear oil for the transmission. Plan to change the fuel lines, fuel tank grommet and shut off valve. Use the shut off valve with the built in screen. Ask lots of questions, someone here always knows the answer. What's a good substitute if the Rotella T1 isn't readily available? Share this post Link to post Share on other sites
johnnymag3 2,570 #16 Posted August 8 17 minutes ago, David78 said: What's a good substitute if the Rotella T1 isn't readily available? It can be found everywhere...I get mine from Amazon 1 Share this post Link to post Share on other sites
David78 6 #17 Posted August 8 5 minutes ago, johnnymag3 said: It can be found everywhere...I get mine from Amazon Was trying to source local. TSC doesn't have it. Share this post Link to post Share on other sites
Bill D 2,278 #18 Posted August 8 25 minutes ago, David78 said: Was trying to source local. TSC doesn't have it. A local auto parts store may have it, or be able to get it. I personally use Mobil 1 10W-30 in all my machines. I have hydros so one oil covers all. 1 Share this post Link to post Share on other sites
clueless 3,263 #19 Posted August 8 (edited) 34 minutes ago, David78 said: Was trying to source local. TSC doesn't have it. Are you sure are they just out of it? That is where I buy my Rotella, also is the engine the Magnum12, if so yours is a 1987/88/89. scroll down to the manual section click on it then over to tractor I open up the 1985 - then find your tractors owner manual, also parts list, your good to go. Also your deck is a 42 side discharge anywhere between 1985 to 1989 it doesn't realy matter their pretty much the same, you will find the owners manual and the parts list there also Edited August 8 by clueless 1 Share this post Link to post Share on other sites
Bill D 2,278 #20 Posted August 8 BTW, these tractors are addictive. I currently have 5. 1 Share this post Link to post Share on other sites
David78 6 #21 Posted August 8 11 minutes ago, clueless said: Are you sure are they just out of it? That is where I buy my Rotella, also is the engine the Magnum 12? Yes Magnum 12 Share this post Link to post Share on other sites
953 nut 60,348 #22 Posted August 8 We tend to us a little shorthand around here, Rotella is in fact SHELL Rotella, the T1 contains Zinc which is best for the flat tappet cams used in our engines. It is listed for diesel engines but is superior to regular automotive engine oil. Tractor supply probably has i but we threw them (and you) a curve ball by saying Rotella. 2 Share this post Link to post Share on other sites
Retired Wrencher 5,837 #23 Posted August 9 I usually find that oil meaning of the Rotella at Walmart. But like said above, that will work also enjoy your tractor. Share this post Link to post Share on other sites
Lagersolut 743 #24 Posted August 9 19 hours ago, David78 said: What's a good substitute if the Rotella T1 isn't readily available? I get mine at Auto zone - it's over with the diesel oil - Tractor supply also carries it but I've found finding in stock at mine is a lottery Share this post Link to post Share on other sites