RayS Posted April 24, 2011 Posted April 24, 2011 Just got back from a 180 mile round trip with my new toy!^ Move this to talking tractors because of questions. Should I use the newer 5W-40 synthetic or the Rottella 15W-40 conventional oil in this. My concern is whether to put in a synthetic or stay with the Rotella 15W-40 that is in it. I know the manual calls for a straight 40 weight in the summer, but I have never seen this weight in straight weight. What does adding a transmission fluid to the fuel do? Clean injectors, pump, ect? It is super clean but had a broken axle tube. I changed hydro rear ends yesterday when I got it home. It is the narrower rear end from a 7116H but that is fine with me. The axle tube from the diesel tractors appear to be about a 1-1/2" longer on each side. The axle tube has been broke at least 6 years that I am aware of another friend of mine owned it before Craig. Other than being ran periodically it has sat because of the tube.
MDB Posted April 24, 2011 Posted April 24, 2011 Looks pretty good, did you pick that up close to Delta Ohio?:D
RayS Posted April 24, 2011 Author Posted April 24, 2011 Sure did this morning. He has another. I have a new seat to put on it. Came with new battery and starter and a spare air cleaner and fuel filter
Brettw Posted April 24, 2011 Posted April 24, 2011 Nice. Now you can become one of those torque-a-haulics. :D
Burntime Posted April 24, 2011 Posted April 24, 2011 Ahhh, thats the next one on the list! I NEED a diesel! Ray will beat me to the diesel with power steering but I will suffer and learn to live with it...:D:D:D
Les Posted April 25, 2011 Posted April 25, 2011 If you use synthetic, check oil often, the thinner synthetic will find any gaps present and go right out the exhaust. Back in olden times(1970's), when they first came out with Mobil One, I knew of engines being ruined because they put synthetic in a new engine before the rings seated. Todays engines run tighter tolerances so that is no longer an issue but the same situation could take place on an older worn engine. Shell Rotella T1 straight 40W is available, it is a slow mover so you will probably not see it at the mass merchanisers, probably have to go to a Shell Oil jobber or a truck parts place. Rotella T 15W40 has been around so long and I have heard so many accolades about it and in over 30 years I have never heard of a problem with it so that is what I would recomend. Shell only uses 15W E85 base oil when they make Rotella T 15W40 so it is very similar to synthetic anyway. A synthetic would be E95 or better. I happen to use the Wolfshead/Amalie 15W40 which is the same product as the Shell at a much lower cost. Shell has farmed out virtually all of their blending/packaging to other firms.
MPH Posted April 25, 2011 Posted April 25, 2011 Nice score Ray. At least the previous owner cared enough to fire it up now and then, even with a broken axle tube. First I've heard of the 7790's being wider. Is the wheel base wider too or are the rims a different reverse?
RayS Posted April 25, 2011 Author Posted April 25, 2011 The axle tube is around a 1 1/2" longer on each side. Frame is the same length.
RedbarnRick Posted April 25, 2011 Posted April 25, 2011 Nice tractor how does the lombardini diesel run? Now what did I do with that can of RAID!
427435 Posted April 25, 2011 Posted April 25, 2011 Ignore the old wives tales about synthetic oils. My engine had worn out rings when I bought it due to the previous owner not keeping grass out of the cooling fins. I put in new rings, lightly horned the blocks and reused the old pistons. Never took the con rods off the crank. Filled it with conventional oil and blew some snow for about an hour and then drained that oil out (I wanted to flush whatever dirt had gotten into the engine while I the blocks were off). I then put Mobil 1 5w-40 diesel oil into it. It ran fine all last summer with the tiller and this winter with the snowblower. Zero oil consumption. Will change the oil again sometime this spring. The reason engine manufacturers used to recommend straight weight oils was that the dino multi-vis oils would shear down----sometimes pretty quickly. That is a 10w-30 oil would become a 10w-20 or even 10w-15 after some use. Air-cooled engines don't like low viscosity oils. The multi-vis synthetic oils don't shear down and provide quick lube on start-up without sacrificing the 40 weight oil characteristics at operating temps. For as little oil as goes into a 7790, don't cheap out. By the way, I think you will love your diesel (do get some ear protection). I doubt that I even used half the fuel running the tiller and the blower as I did when I used my 917.
JohnMBerst Posted April 26, 2011 Posted April 26, 2011 Great tractor! Some day when my two grow up, they want to be a 7790. Hope it works well, runs great and last long. ;)
427435 Posted April 26, 2011 Posted April 26, 2011 I forgot to ask-------any fuel leaks?? They will really aggravate grass clippings building up on the cooling fins.
hotrodtractor Posted April 26, 2011 Posted April 26, 2011 I almost added a 7790 to my collection a few months ago.. but was leary of the old design engine and issues when chafed up with grass. My neighbor had one he sold and he said it was a loud noisy stinky beast... but sure had some big power. Most members here seem to love them...especially for snow work. With the knowledge you have Ray I am sure you will not have any issues... nice machine and good buy enjoy it!
RayS Posted April 26, 2011 Author Posted April 26, 2011 I don`t see any fuel leaks yet. Just finished changing hydro fluid and filter. BGB next.
427435 Posted April 26, 2011 Posted April 26, 2011 quote:Originally posted by hotrodtractor I almost added a 7790 to my collection a few months ago.. but was leary of the old design engine and issues when chafed up with grass. My neighbor had one he sold and he said it was a loud noisy stinky beast... but sure had some big power. Most members here seem to love them...especially for snow work. With the knowledge you have Ray I am sure you will not have any issues... nice machine and good buy enjoy it! The easiest answer to the grass clipping issues is to use another tractor to mow lawn with!!! That provides a good reason to own more than one toy.
Burntime Posted April 26, 2011 Posted April 26, 2011 quote:Originally posted by 427435 quote:Originally posted by hotrodtractor I almost added a 7790 to my collection a few months ago.. but was leary of the old design engine and issues when chafed up with grass. My neighbor had one he sold and he said it was a loud noisy stinky beast... but sure had some big power. Most members here seem to love them...especially for snow work. With the knowledge you have Ray I am sure you will not have any issues... nice machine and good buy enjoy it! The easiest answer to the grass clipping issues is to use another tractor to mow lawn with!!! That provides a good reason to own more than one toy. Now that makes sense. Especially to tractor guys. The only way to make it better is to add power steering!
crahmes Posted April 26, 2011 Posted April 26, 2011 I've had my 7790 since 1997 and mowed 4 hilly, bumpy acres each summer. I run Rotella T1 SAE 30 in it and have never had any issues with the motor. I don't use it in the winter here in Virginia. It currently has 1370 hours (some just sitting in the garage with the key on). This winter, I took the motor out to weld the motor mount bracket and replace the rubber isolators. While it was out, I tore it down and replaced the seals, gaskets and rings. The rings, pistons and cylinder walls were all in great shape...I still replaced the rings and honed the cylinder walls. The only real problem that I saw was a pretty healthy carbon buildup on the tops of the pistons and around the valve seats on the bottom of the heads. It didn't smoke much before, but now it doesn't smoke at all. I've mowed twice this season and it hasn't used a drop of oil. Grass buildup around the cooling fins isn't really that big of an issue if you don't have any oil or fuel leaks. My 7790 is the first and only lawn tractor that I've ever owned. I've done so much work on it now that I feel like I know it like the back of my hand (with lots of help from this forum...I've been lurking around for years). My biggest tips for you are: - always use a funnel to add oil (so you don't drench the cooling fins with grass collecting oil) - run at high RPMs to prevent carbon buildup - clean fins of grass clippings (you already know that) - Lombardini parts are expensive and difficult to get. I use Blue Ridge Diesel because they are 20 minutes from me and they know what they are doing. (I use a NAPA fuel filter and I used rings for a 4 cylinder Mazda from RockAuto.com to save some cash) I hope you enjoy it. I'm sure happy with mine.
RayS Posted April 29, 2011 Author Posted April 29, 2011 Wix makes a fuel filter to replace the 0021750450 LOMBARDINI filter. The WIX number is 33961. Now to find a cheaper priced air filter. Lucky I got a new spare with the tractor.
RedbarnRick Posted April 29, 2011 Posted April 29, 2011 Ray, I was kidding about the RAID, you didn't have to delete the bug, I was looking for a fly swatter to add to my posts!
rfsmith1952 Posted April 29, 2011 Posted April 29, 2011 Good find, Ray. Have fun with it, and thanks for all your help.
RayS Posted April 29, 2011 Author Posted April 29, 2011 quote:Originally posted by RedbarnRick Ray, I was kidding about the RAID, you didn't have to delete the bug, I was looking for a fly swatter to add to my posts! It was annoying me too!
Recommended Posts