Been working on them for 25 years; The 318 is one of the better built tractors. If you were to ask me what is the week point on a 318. I would have to think long and hard, They are/were the Most durable GT made. Buy it you will feel proud, Well come to the forum.
Hello aphares
I agree with Tony here the John Deere 318 is one of the Toughest Lawn & Garden Tractor's that John Deere ever Built. Like any Piece of Equipment if it has had reasonable Care it will last a Very Long time, and that is why so many of them are still out there going strong. I have had my First Year 1983 John Deere 318 for almost Six year's now, and have not had any serious break down issues. The Transmission's in these 318's are very tough but they can develope leaks at the Hydro Valves, as well as seal's or Gasket area's, Mine hasn't Yet but I have heard of other's that have. The Onan engine is of Industrial quality. Even though they no Longer make the Onan Engine block's you can get all of the Needed Part's to re-build one, and they were made to be re-built Multiple time's unlike most other air cooled gas engine's, an Onan is a Long Term Investment engine. I Mow two full acre's of Grass per week during our Nine Month Mowing season here in East Tennessee so mine get's a solid work out in the summer and I also Till Our Vegetable Garden with mine as well as some Neighbor's with my model 30 Hydraulic tiller twice a season.
The Biggest annoying issue I have had with mine
is Fuel. This Pump Gas with Ethanol Kills small gas engine's as well as their Internal rubber gas lines. Many John Deere 318 owner's have had issues of
Plugged carburetor's from the break down of the Internal Gas line which turn's it into a Sticky Black looking Goo and Often send's it past a single gas line filter to Plug up
the Idle jet inside the Carburetor. I had this issue last spring and finally located it and replaced all of my fuel line's as well as Placed Two see through heavy duty gas filter's that are now mounted in Plain sight on the machine's firewall. I try to only Buy Pure Gasoline for mine, but if I have to run Ethanol blended fuel I always' use Lucas Brand Ethanol safe Guard Gasoline additive.
John Deere still offer's about every part that one would need to replace on the 318 Tractor which is nice as there is nothing worse than having a Tractor that you can not get part's for any more. The Early Model 318's made from 1983-1986 time span will have the Onan B-43-G engine's in them that have a Point's & Condenser Ignition system. One's made after 1986 should have the Onan P-218 engine in them that has Electronic Ignition system's. Mine came with a Point's-Condenser Ignition so when I replaced it's tired engine last year during my restoration of the Tractor I had a P-218 engine built for mine as they are Five Cubic inche's larger than the Original B-43-G engine's were and used my Existing Point's style Ignition system on the new engine. The Power of a Fresh P-218 engine is Awesome I have Pulled my front wheel's about Six Inches off the ground when I am Tilling hard with it and the engine show's no sign of Bogging down.
As Other's have told you here there may be some leak's of Oil or Hydraulic fluid that have to be addressed. I was lucky when I bought mine as it did not really have any leak's on it but mine was
Missing it's belly Screen which attaches to the bottom of the machine's frame area and filter's out Grass, dirt and debris so over the long haul with no filtration in that area of Incoming fresh air the dirt, grass and debris took it's Toal on my Piston ring's making the engine tired. I have since added the Much needed belly screen when I put my new engine in and I Now pay much closer attention to it's air breather Pre-foam filter as well as the Paper element, I clean them Bi-Weekly. I run my new engine on full synthetic engine oil being Pennzoil Platinum brand and drop it @ 50 Hours placing a new oil filter when I do so. I also change my Hydraulic Transmission filter Twice a season to Insure a Long trouble free life out of the Transmission.
When you check this 318 Out just go over it well to insure that you are getting a Good Tractor as there are still Ton's of them out there to be had and
Nothing Can be worse than Buying a money Pit. I have no Regret's on the Purchase of mine the new engine cost me $1475.00 for it, but given the level of care I give it, I feel it will last me the rest of my life. Keep us Posted if you buy this 318 we all love Picture's. Here are some Picture's of mine I paid $300.00 for it when I bought it six year's ago and it came to me with an almost new Replacement 48" Mowing deck which retailed for $1300.00 alone. I have added a Model 30 Hydraulic tiller to it as shown of which I paid $700.00 for and a 54" four way dirt dozer blade that I Picked up for $100.00 that I restored. All in and done I have a total $2600.00 in my entire Restored 318 package and I am very Plased with it. Regards, Hammerdown
isgus: (Jeep Wrangler). 
