Jump to content

OVERHAULING A 756?


Recommended Posts

Hello there, well our faithful 756 that i have had since 1983 looks like it needs a engine overhaul, there had been a small vibration the last year or 2 but couldnt really figure out where it was coming from, always felt like the clutch area, might of been a fore warning of a problem coming, well now there is a knock so shut it off in the middle of corn planting and narrowed up the 1066, So i have always heard high price to overhaul, pumps hard to fix and so on, the tractor is really nice, almost new set of firestones on , i figure a person probably will never have to deal with clutch, rear end and torque problems because of the lower power output, So id the 310 worth the overhaul or switch it to a 312 or 360, i know guys have put cummins in also, We have cows so it gets a lot of smaller tractor use, The only reason i mentioned the 312 0r 360 is parts and pumps, is there a newer version of the german diesel that was put in the 86 series where pumps are more available? thanks

Link to comment
Share on other sites

You're looking at a certain level of "unobtainium" no matter which option you choose. None of these engines are getting any newer, all are long out of production, and that date has been getting farther and farther away as time goes on. As time goes on fewer and fewer of them are in use, so the incentive to keep parts support is waning.

The 312 is only found in 666's and some early 686's. The tractor 360 is only found in 766's and early 886's, though there are more of these out there than 666's. Truck/Bus 360's are a hit and miss thing. Some areas they're difficult to find, in other areas they're impossible to find. You also have to contend with the truck/bus 360 being different internally from the tractor engines.

Cummins has its own set of challenges. You're fighting with all the Billy Big Riggers over the engines so it's going to cost more. Fitting the engine is all custom parts which you can get, but you're not paying "junk tractor" price for the parts.

In my opinion, there's no real clear cut answer. Probably the way I'd approach it would be to price out overhauling the D310 best case scenario the pump doesn't need what you can't get. Then you have a baseline to work from.

Another option to consider is a 400 series engine. With enough work they can be fit between the factory frame rails as I understand it.

Link to comment
Share on other sites

Seems like there's always a good used D310 that comes available from a combine or cotton picker.  Of course, that all depends on location, but I see them listed ever so often on various Facebook pages, and every now & then on BigIron.  The D310 was a rather popular engine for IH, so there are parts around there for them.

  • Like 1
Link to comment
Share on other sites

Figure out the knock, then go from there. If it's a catastrophic failure, another used engine like Matt said above would be my choice, 715 combine. Yours is a runner, so the pump should not have major problems. I've rebuilt a few VA pumps and they normally just need cleaned up, resealed and recalibrated. The failures to the pumps are typically caused by neglecting the injectors or fuel cleanliness. If you rebuild the existing engine, I suggest getting the pump and injectors done at a competent shop, then the 310 will run another couple of decades lol! Then we'll be discussing electric motor swaps lmfao!

  • Like 2
Link to comment
Share on other sites

I just watched a nice clean 806 diesel with a GB loader and bale spear sell for $6500 at auction Saturday.  For prices like that just buy another tractor and be going tomorrow.  You'll have $4000 just into a rebuild, plus down time.

Link to comment
Share on other sites

43 minutes ago, brahamfireman said:

I just watched a nice clean 806 diesel with a GB loader and bale spear sell for $6500 at auction Saturday.  For prices like that just buy another tractor and be going tomorrow.  You'll have $4000 just into a rebuild, plus down time.

Was that the Heidelberger auction by North Branch??

Link to comment
Share on other sites

8 hours ago, Matt Kirsch said:

You're looking at a certain level of "unobtainium" no matter which option you choose. None of these engines are getting any newer, all are long out of production, and that date has been getting farther and farther away as time goes on. As time goes on fewer and fewer of them are in use, so the incentive to keep parts support is waning.

The 312 is only found in 666's and some early 686's. The tractor 360 is only found in 766's and early 886's, though there are more of these out there than 666's. Truck/Bus 360's are a hit and miss thing. Some areas they're difficult to find, in other areas they're impossible to find. You also have to contend with the truck/bus 360 being different internally from the tractor engines.

Cummins has its own set of challenges. You're fighting with all the Billy Big Riggers over the engines so it's going to cost more. Fitting the engine is all custom parts which you can get, but you're not paying "junk tractor" price for the parts.

In my opinion, there's no real clear cut answer. Probably the way I'd approach it would be to price out overhauling the D310 best case scenario the pump doesn't need what you can't get. Then you have a baseline to work from.

Another option to consider is a 400 series engine. With enough work they can be fit between the factory frame rails as I understand it.

Hydro 70's have the 312.

Link to comment
Share on other sites

1 hour ago, brahamfireman said:

I just watched a nice clean 806 diesel with a GB loader and bale spear sell for $6500 at auction Saturday.  For prices like that just buy another tractor and be going tomorrow.  You'll have $4000 just into a rebuild, plus down time.

Yes but if you rebuild you know what you have.  Buy a 40 or 50 year old used tractor and expect issues to come.  One could make an argument either direction.

 

  • Like 3
Link to comment
Share on other sites

Hello everybody, thanks for the input, was thinking today, everybody is busy now, our normal guy has overhauled the german diesels but only the 4 cylinder models, going to try and get another guy to at least take oil pan off and maybe head and see how much damage, the rest of the tractor in really good shape, front end, shifting, park update, lot of work done to the PTO,it actually doesnt run too bad except it has hardly any power and a lot of blow by, sounds noisy on the top near the front.and again thanks for help.

Link to comment
Share on other sites

We had a vibration problem in our 1586 we could figure out. The engine had blowby, needing an overhaul, found an injector not opening properly and ended up ruining one wrist pin and connecting rod. Good luck with your, I would overhaul and know what you have when you are done. 

Link to comment
Share on other sites

2 hours ago, Farmall1066 said:

Was that the Heidelberger auction by North Branch??

No Bostrom on Saturday.  I did watch 2 806 gassers sell at the north branch sale for 2500 in pieces, and 3700 with water in the oil. I passed on both.

706 went for 3500 or 3700.

Link to comment
Share on other sites

1 hour ago, pt756 said:

Hello everybody, thanks for the input, was thinking today, everybody is busy now, our normal guy has overhauled the german diesels but only the 4 cylinder models, going to try and get another guy to at least take oil pan off and maybe head and see how much damage, the rest of the tractor in really good shape, front end, shifting, park update, lot of work done to the PTO,it actually doesnt run too bad except it has hardly any power and a lot of blow by, sounds noisy on the top near the front.and again thanks for help.

Probably worth rebuilding then.

  • Like 1
Link to comment
Share on other sites

7 hours ago, brahamfireman said:

No Bostrom on Saturday.  I did watch 2 806 gassers sell at the north branch sale for 2500 in pieces, and 3700 with water in the oil. I passed on both.

706 went for 3500 or 3700.

Dang it!! I knew I was going to forget about that sale! I was planning on looking at the 806 in pieces, to try bring home for some parts.  Guess that isn’t happening now! 🤣

Link to comment
Share on other sites

10 hours ago, Jacka said:

Hydro 70's have the 312.

True, but that only adds about 6 more tractors to the pool.

All this advice is dated, though. We have to keep forcing ourselves to remember it's not 1985 anymore.

How many 715 diesel combines are left out there to harvest engines from, for example? They're all gone around here. We have to be getting to the point where people have to start shaking their heads and saying "What a shame," when the few that are left get knocked in the head for an engine. Folks want to make parting out a tractor a capital offense, but nobody cares about the other machinery. Think about all that history that's going to be lost... Don't be an anticombineite! Don't be machinist against combines! :) 

  • Haha 2
Link to comment
Share on other sites

1 hour ago, Farmall1066 said:

Dang it!! I knew I was going to forget about that sale! I was planning on looking at the 806 in pieces, to try bring home for some parts.  Guess that isn’t happening now! 🤣

Guy painted the block, the head surface, and top of pistons red.... Looked like all original rotating assembly. 

1966 Set of flat top fenders with only the left side hand hold sold for $1050.

Link to comment
Share on other sites

Stay with the 756 and the 310.

You then know what you have.

It sounds like yours is better than 90% of them out there.

Just do it!

With the garbage fuel we are now forced to use, nozzles are a must to keep adjusted and clean.

The nozzles can have an effect on the engine hard parts too.

Use a good fuel conditioner and have them tested every 10 years or so.

Have them run the nozzles now with the overhaul.

Link to comment
Share on other sites

well guys we did pull it to the local repair guy today, started it up for second, he said i think you have a spun bearing, so we plan to take crankshaft out or i mean he will, i have very little experience when it comes to engines and he is great with these older tractors, so i did call the salvage yard that has a lot of locations thru out the midwest and at least a few in wis. no complete motors, and doesnt look like they have a crankshaft either in case ours is bad, guy will send it out to be magnafluxed ???  and reground if it isnt already cracked. so first time in my 55 years of driving tractors that we have lost a motor this way, it has always been the sleeves leaking, he also said another choice might be his 360 dt that he had planned on using in a 656, but has given up on that idea, it was in a school bus and has a turbo on plus the inline pump, he has a non turbo manifold and can get a tractor pump , i know its not the right way to go but if the 310 is bad shape it would be an option, so has anybody done one , at least of parts are needed the american 360 would be easier to get parts for maybe?  and the vibration i mentioned before was usually at a lower idle,  thanks for the replies so far,

Link to comment
Share on other sites

The bus/truck 360 is different from the tractor 360 internally. Different bore and stroke or something like that.

My 756 has a truck 360 in it (I have laid claim, if I get nothing else out of the estate I am getting THAT tractor). We went for functional, not correct, so a lot of compromises were made in installing the engine. Kept the inline pump. Used the gas frame rails. Used the gas radiator even though the outlet was on the wrong side.

Your 310 frame rails are already the 1.5" shorter that they need to be, which is good. Your 310 radiator will have the outlet on the correct side, which is good. Your hood might actually fit. Dad had to make bolt-on extensions for this one.

Front cover and rear plate are the same as 400 series so you've got good parts availability for that. You can try and find a D312 front cover but they're even rarer than a good D310 crank that isn't in an engine somewhere. The 400 series front cover will need to have its ears machined down to fit the 56 series frame rails, and you will be reduced to one bolt on each side in front. You will have 7/8" cheeks sticking out on each side of the bell housing from the 400 series rear adapter plate, unless you have those machined off.

As far as internal parts, no idea if Navistar still supports these engines.

Boy, I'm getting good at breaking down that D360 conversion... Seems like I've been doing it a lot lately :) 

Link to comment
Share on other sites

On 5/18/2022 at 6:57 AM, brahamfireman said:

1966 Set of flat top fenders with only the left side hand hold sold for $1050.

That was my other reason for going.  Were they nice straight, solid fenders?

Link to comment
Share on other sites

1 hour ago, pt756 said:

thanks Matt, guy thought a cover from a 886 would work, he recently junked one out, 

It will work, it just needs to be machined to fit inside the 56 series frame rails, and it will still cut you down to 1 bolt per side up front.

As long as it's an early 886 of course... Later ones had the D358, which you already have a front cover for.

Link to comment
Share on other sites

i am aware of the 358 in the 886, also what is the actual difference between the truck motor and the tractor motor? this truck motor does have a turbo on which if we go that route i probably wont use, and will the 360 fit underneath the fuel tank? thanks

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...