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IH Forever

686 engine

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I'd like to add a 686 to my collection sometime in the future as I helped for a farmer when I was in high school that had one and I always really likeed it. I've been looking around tyring to see what's available and have noticed a coupe for sale that say they have the D312. I always thought they all had the D310. Where some made with the 312?

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I thought all the 86 series had the 312. I had a 666 and it had the 312. It's a good engine but noisy. I currently have that engine in an 86 Hydro. I know nothing about the 310. Is that the German engine?

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I thought all the 86 series had the 312. I had a 666 and it had the 312. It's a good engine but noisy. I currently have that engine in an 86 Hydro. I know nothing about the 310. Is that the German engine?

Yes, that is a German, same engine as in the 756.

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AFAIK, the 686 always had the American D312.

The 686 was only made during the first part of '86 series production.

IH discontinued the 686 in early 1980, replacing it with the 786, which uses the D358 German diesel engine.

IH used the German engines because they had a bunch of them stockpiled and they needed the manufacturing capacity to build DT466's for trucks.

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I think it was 1979 when the 312 was replaced with the 310 German.

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AFAIK, the 686 always had the American D312.

The 686 was only made during the first part of '86 series production.

IH discontinued the 686 in early 1980, replacing it with the 786, which uses the D358 German diesel engine.

IH used the German engines because they had a bunch of them stockpiled and they needed the manufacturing capacity to build DT466's for trucks.

They definately used the D310 in some. The one I drove as a kid had it and looking on tractor house many have it. Until I started looking recently I just assumed they all used that.

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tractor data covers this very nicely.

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MATT - I wouldn't say IH had the Nuess engines "Stockpiled", they (Nuess) shipped containers of engines every month to FARMALL. But I'd agree that Melrose needed capacity for the 400-series to meet demands of Ag & truck divisions. Both ag & medium duty trucks were having good sales about that time.

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our 686 has the D310. has 6500 hours, engine is tight, no leaks. its excellent on fuel. and never knows when to stop pulling. neighbor has one with the D312 and its a hard starting beast. typical german engine.

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1977 and 1978 model 686 had D312. 1979 and 1980 models had the D310 engine. Both were good engines. I have seen d312's with 8000 and 9000 hours on them and never been opened up.

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our 686 has the D310. has 6500 hours, engine is tight, no leaks. its excellent on fuel. and never knows when to stop pulling. neighbor has one with the D312 and its a hard starting beast. typical german engine.

the 310 is the german.

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My 666 diesel is the easiest starting diesel on the place. Never plugged it in yet, but it only arrived here a month ago :lol:

I am starting a registry of the 666, 686, hydro 70 tractors. Please help out and PM me if you have one!

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1977 and 1978 model 686 had D312. 1979 and 1980 models had the D310 engine. Both were good engines. I have seen d312's with 8000 and 9000 hours on them and never been opened up.

I bought my Hydro 86 with about 3800 hrs on it and it has an IH Reman tag on the engine and "1243" scratched in the paint beside the tach. I have no idea what went wrong.

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My 1979 Hydro 86 has a 310 german. I've only had it 3 months but have been satisfied so far. Eason

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My 687 is a 1977 model and I bought it in 1980 with 300 hours on the tach. It now has a little over 2000 hours on it. It has a 2250 loader on it and only use it for loader work. That is why the hours are so low. It has been a real good tractor.

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our 686 has the D310. has 6500 hours, engine is tight, no leaks. its excellent on fuel. and never knows when to stop pulling. neighbor has one with the D312 and its a hard starting beast. typical german engine.

the 310 is the german.

i always get em mixed up. :rolleyes::lol:

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Two of my neighbors have 310 powered 686's. There are not too many engines that sound better than they do. I have a pair of 358's in the shed and they both start great in the cold, sip fuel and sound good too. Sorry about the underline fellas......

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our 686 has the D310. has 6500 hours, engine is tight, no leaks. its excellent on fuel. and never knows when to stop pulling. neighbor has one with the D312 and its a hard starting beast. typical german engine.

I would think with either engine the rear end would be the weakest point, not the engine.

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Just don't go putting a 4x16 model 720 plow behind it. The tractor will pull it but I have seen about 4 of them (back 25 to 30 years ago) with the bolts broken on the carrier to crown gear bolting surface during the plowing season. It usually busts the carrier casting. I have even seen a D282 in a 656 do it when hooked to too large a plow and a a dual put on the land side. I would suggest if the 686 had been built in quantities like the 560 was and used for heavy tillage it would have been the 560 fiasco all over again. That is why my 686 has never been hooked to a plow.

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I have a Hydro 86 with the D310 engine-some had the 312. The german engine is very cold blooded- you learn to plug it in if it's much below freezing.IT is much cheaper to get parts for than the 312.

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Just don't go putting a 4x16 model 720 plow behind it. The tractor will pull it but I have seen about 4 of them (back 25 to 30 years ago) with the bolts broken on the carrier to crown gear bolting surface during the plowing season. It usually busts the carrier casting. I have even seen a D282 in a 656 do it when hooked to too large a plow and a a dual put on the land side. I would suggest if the 686 had been built in quantities like the 560 was and used for heavy tillage it would have been the 560 fiasco all over again. That is why my 686 has never been hooked to a plow.

We have pulled a 4X16 with both our 686s without any issues for years.

As far as the engine, the 312 is a much better engine than the 310, starts better, and the overhaul is much cheaper as the 310 needs the block line bored to install new cam bearings if the cam needs to be redone, all the germans are that way I am told. The internal components in a 312 are much larger than the 310, such as comparing the push rods. The 312 is much noiser, that is really the only complaint I have with it, the governor on the german engine seems to be a little snapier than that on the 312 american.

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isnt the 312 basically a miniature 414?

Sure looks like it from the outside. My little 666 D impresses me more everytime I use it :wub:

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isnt the 312 basically a miniature 414?

Sort of. It is a 360 with a shorter stroke, and the 360 is the smaller brother of the 414/436/466 line.

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I have a 360 crankshaft in my 686 with a mw turbo kit and I love it! it will pull 4- 16 in 2nd gear ta ahead! Would not trade that tractor for anything. Easy on fuel and starts when nothin else will when its cold. I als have 18.4 38 tires on it so it skips along pretty good on the road.

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