{"id":272,"date":"2010-07-08T21:28:26","date_gmt":"2010-07-09T01:28:26","guid":{"rendered":"http:\/\/freemansgarage.com\/blog\/?p=272"},"modified":"2022-11-07T20:23:26","modified_gmt":"2022-11-08T01:23:26","slug":"simplicity-7790-diesel","status":"publish","type":"post","link":"https:\/\/www.freemansgarage.com\/index.php\/2010\/07\/08\/simplicity-7790-diesel\/","title":{"rendered":"Simplicity 7790 Diesel"},"content":{"rendered":"

I acquired my dad’s 1984 Simplicity 7790 diesel about 5 years ago.\u00a0 My dad used this tractor for everything for 20yrs and originally bought it from my grandfather back in the 1986.\u00a0\u00a0 I have a ton of attachments for this thing including a cool front dump bucket.\u00a0 Sadly, when I received the tractor it was pretty worn out.\u00a0 The engine smoked really bad and leaked fuel everywhere.\u00a0 It was very hard to start and was unusable.\u00a0 The engine is a Lombardini 10LD400-2 two cylinder 18.5hp diesel engine.\u00a0 It’s air cooled and is a real work horse.\u00a0\u00a0\u00a0 The only bad things are that it is loud and smells.\u00a0 I however think it is a neat tractor and like driving it. This is identical to the Allis Chalmers 920 Diesel. All attachments from the Simplicity 7000 series frame tractors fit this tractor and many tractor parts (except engine parts) are interchangeable as well.
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\nI spent the next month rebuilding the engine and getting it back into good working condition.\u00a0 All the parts had to be imported from Italy which cost a lot and takes several weeks.
\nI bought all the engine parts from here:\u00a0 http:\/\/powersupplyequipment.net\/<\/a><\/del>
\nThey deal with Lombardini parts and were able to get me everything I needed.\u00a0 The total cost for the rebuild was $582 which included a gasket set, valves, bearings, and piston ring set.\u00a0 I did not need pistons or jugs since they were within factory specs.
\nUpdate 12-22-14<\/span><\/span>– I guess powersupplyequipment.net no longer supplies the Lombardi engine parts.
\nKholer now owns Lombardini. Parts might be available with them as well. There are also other parts that fit this engine perfectly. Rings are the same as a Mazda 626 Diesel, part # 2M4210.
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\nThe engine leaked everywhere and had grease and dirt all over it.\u00a0 Debris collects under the cowling and prevents air from cooling cylinder heads.\u00a0 This will cause the cylinders to overheat and destroy the rings.\u00a0 After every use you need to blow compressed air through the engine cowlings and blow all the grass and crap out of there.
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\nThe first thing I did was remove all the cowlings. Next unbolt the intake and exhaust manifolds and carefully unscrew the injector lines. The engine is a really simple one to work on and has nothing special to worry about other than its a diesel. I plugged the injector ports with a clean rag to prevent dirt from falling in there.
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\nExamining my valves revealed a bad sign.\u00a0 You can see oil everywhere which came from bad rings and leaky valves.\u00a0 I needed to order a complete gasket kit, valves, and rings for this engine so far.\u00a0 I also bought new con rod bearings as well.
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\nI bought this service manual by Clymer for this engine and I am not going to go into great detail on how perform every detail to an engine rebuild.
\nThis book completely covers the Lombardini 10LD400-2 engine and I highly recommend it if you want to get your engine running.\u00a0 I recommend that you have some mechanical experience before you attempt anything like this. \u00a0 I cleaned everything and installed new valves and had the valve seats ground.\u00a0 I also honed the cylinder jugs and installed new rings and bearings.\u00a0 I took apart the injectors and cleaned them very carefully.\u00a0 I had to replace all my fuel lines and a small copper gasket that was inside the fuel injector right under the nipple.
\nThe engine is all cleaned up and put back together.\u00a0 The manifolds are not on there yet but they will be shortly.
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\nThe injector pump is a very delicate device.\u00a0 Do not dismantle this unless you know what you are doing.
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\nThe compression on this engine was much higher after the rebuild and my starter could not turn it over.\u00a0 I took my starter to a local starter repair shop and it had it repaired.\u00a0\u00a0 $100 later I had a rebuilt starter.\u00a0\u00a0 The tractor now starts easily and even in the winter it has little difficulty starting.\u00a0\u00a0 The rebuild was completely worth it.\u00a0\u00a0 I was amazed at the power that this little garden tractor has.\u00a0 I mainly snow blow and rototiller my garden with it and have never had any problems so far.\u00a0\u00a0 I’ll try to post some video of it running soon and some pics of the attachments.
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\nShown above is the cool dump bucket.
\nUpdate 01-26-14
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\nHad some trouble with the trans-axle this week.\u00a0\u00a0 Winter is blasting us here in Michigan so I have been using the snow blower attachment every week.\u00a0\u00a0 The tractor started to have trouble moving and eventually stopped moving unless I held the hydraulic lift lever open. \u00a0 Honestly I have never touched the trans axle or changed fluid.\u00a0 Its probably original since my dad never remembers changing it either.\u00a0\u00a0 Anyway,\u00a0 I ended up changing the fluid and filter.\u00a0 The fluid was dark red and I only drained about 1.5 quarts out of it.\u00a0 I used Valvoline ATF type FA transmission oil to refill and added 2.5 quarts.\u00a0\u00a0 Wow this thing moves like new now.\u00a0 I must have slowly lost some response over time because its never been this responsive.\u00a0\u00a0 I’ll be changing the fluid every 400 hrs like the manual states now.\u00a0\u00a0\u00a0 I used the replacement simplicity filter which was expensive.\u00a0 Does anyone have a Napa cross reference for a non brand filter?\u00a0 Has to be 25 micron.\u00a0 I also checked the bevel gear box and ended up adding some 80-90 weight oil to that.\u00a0\u00a0 I’ll take the old filter up town and see if I can get a Napa replacement.\"Transaxle<\/a>
\n\"Transaxle<\/a>
\n\"Transaxle<\/a>
\n\"Bevel<\/a><\/p>\n

Update 01-27-15
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\nI upgraded the snow blower skids to a new heavy duty “Armor Skid” set from Home Depot.\u00a0 Welded from 1\/8 inch and 1\/4 inch steel.\u00a0 My old ones were getting worn away (see below).\u00a0 One of my skids was less than 50% and my snow blower was getting hard to push because it was dragging on the ground.
\n\"IMG_0762\"<\/a>
\nThe new ones work great and I painted them “Chevy Orange” which is incredibly close to simplicity orange.
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\nUpdate 03-03-16
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\nI broke the drive shaft today while I was snow blowing.\u00a0\u00a0 I knew the couplings were getting old and I hit a small seam in the concrete driveway that jolted the tractor enough to break the coupling.\u00a0\u00a0 What a disaster.\u00a0\u00a0 The shaft banged all around and twisted itself into a pretzel.\u00a0 I had to cut it out with a torch.
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\nI also busted a screw off in the engine mount.\u00a0 Gotta get that out.
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\nBusted up couplings.\u00a0 The 2nd coupling exploded into a million pieces.\u00a0 These are kind of expensive and I did not want to buy them.\u00a0 I made a set myself out of G10 (same material circuit boards are made of).
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\nGetting the new shaft into the tractor is not too bad.\u00a0 I had to lower one end of the hydraulic cylinder and remove one bracket that was in they way.\u00a0 It took about 2 hrs to make this repair.
\nDrive shafts are expensive\u00a0 ($150+).\u00a0\u00a0 I made mine easily with 1″ bar stock.\u00a0\u00a0 I ground the original ends off and welded them onto the new shaft.\u00a0 Total cost for the new shaft was about $5 for the 3ft piece of cold rolled steel from the local steel supplier.\u00a0\u00a0\u00a0 The new drive shaft measures 20 1\/4 inch exactly if you want to make one.
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\nNew drive shaft shown below.
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\nThe couplings can be made or purchased.\u00a0 Here is the drawing I made for the couplings:
\nDrawing of Drive Shaft Coupling<\/a>
\nI made mine on my CNC mill but you can make them with a drill press and a band saw easily.\u00a0 Just print the drawing to scale and tape it on your sheet of G10.\u00a0 Drill the holes and trace the circle on with a pencil.\u00a0 Cut it out with a band saw or jig saw.
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Now I need to get that broken screw out of the engine drive shaft hub.\u00a0\u00a0 I drilled it out from the back with a end mill.
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\nGot it out.\u00a0 I ran a 3\/8-16 tap in the hole to clean it out.
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\nHere is the new shaft and the new coupling.\u00a0 No problems now.
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\nMade some spare drive shafts for later….
\n\"Drive<\/a><\/p>\n

Update 12-04-16
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\nGetting ready for winter and I found one of my PTO pulleys had a failed bearing.\u00a0\u00a0 Stupid thing cost $45 from Simplicity dealer and is an odd size.\u00a0 I will be looking at Grainger or some other online store to find an equivalent for any other pulleys that fail.
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Don’t forget to press out the center bushing on the old pulley.\u00a0 It is needed for the new pulley.\u00a0 I just used a socket and small hammer to tap it out.
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All done installed.\u00a0 Good for winter.
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\nUpdate 07-30-17
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\nHere are some pics of the Rototiller attachment.\u00a0\u00a0 I use it all summer on my garden.
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