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IH 656 only runs on full choke when warmed up

K

kevmar87

New User
Hi there is own a IH 656 1968 gas the tractor starts and runs great until it warms up then it will only run full choke eventually dieing I've wired everything new coil and resistor tested good I have rebuilt the carb cleaned the gas tank and no change now I am just scratching my head any experience would be much appreciated thank you
Ps the heat riser is working as it should
 
Lack of gas,something is blocking the flow. Sediment bowl,gas line,screen in the carb fuel inlet line,one or more of those little holes in the main jet plugged. Mine will run fine for a long time, and then the sediment bowl will plug with rust and its time to clean it again.
 
Thank you for your help and response this would make sense as the tank had rust in the bottom and there is some still stuck in the bottom is there anything that you guys have done as far as making some sort of stand in the tank that way if any more breaks loose it will stay in the bottom?
 
You can buy a stand up screen for the sediment boul. I've stuck a 1/2" or 3/4" 'standpipe' made of 1/4" copper tubing before. Worked!!
 
I think this tractor also has a screen that sticks in the carb off the back of the fitting where the fuel line connects to the carb. Are you sure it is clean? I'm not 100% sure if this tractor used one of these. I know they were used in the H's through 450s.
 
That's what common sense would tell me but I'm hanging up on the fact that it only does it after it warms up thank you guys for all your help
 
Warms up as in runs for a couple minutes? The tractor can do that on the fuel in the float bowl of the carburetor. If there's "almost enough" fuel getting in, that time can be extended quite a while.

Probably if you stopped, let it sit for 5-10 minutes, and tried again it would run fine for a short while.
 
the tractor will run for about 20 minutes before
it starts acting up usually as soon as you start
to put a load on it.
 
Well lets starft with checking your ING. timing and set it for full advance and full throttle , now as to the exact timing spec.'s on your tractor that one is not burnt into my computer and is in the books out in the truck . and i am NOT going out to the truck since it is cold out thar. You say you rebuilt the carb , fine but did you reall rebuild the carb . next did you check fuel flow from the tank to the carb ???? should be a full line flow . What plugs are you running ??? as for myself i will use a C86 AC - or the autolite ones , NO champions and NO HOT PLUGS . Next up the grade of gas your using they do not like cheap gas . We are starting to have problems with our gasser now because they have cut back on the octane again . Our fuel supplier told us this summer that he was no longer able to get us the 93 as now the best they are sending is now 90 and to get the 93 they would BLEND it , Well now we have two 706's down with burnt pistons and i am done trying to make them work . So either we are going to scrap them or they will get a transplant to either a Cummins or a DT 360 . Now if the housing market was booming maybe plant houses and forget about the farming and fixen old junk.
 
thank for the reply tractor vet yes i really rebuilt the carb went through it totally. it has full flow when its cold it has full flow when it runs like full choke. i have been running regular unleaded in it and are currently using champion spark plugs .
 
Change plugs , next change your gas and check the total advance of the timing as i stated The newer gassers requier higher grade fuel then what is at the pump today and i know some know it all will tell ya ya don't need it . But the gas back when these tractors were made reg. gas was 95 octane and 93 is the minimum . and back then yea ya bought reg. gas . Yes they will run on the low grade BUT you can NOT WORK them . between the cheap pistons and the low octane the added heat that this new gas burns at at peak combustion the pistons will swell a hug amount above the top ring and they can swell enough to seize to the sleeves . Then each time that head was off and trued up the compression ratio went up a little . You may have internal engine damage already , sometimes you can see the scoring by just looking into the spark plug hole . You will never hear predetionation (sp) what you will see is it starting to miss and die and if you pull the choke sometimes they will stay running somewhat and sometimes they die and literally seize up and will not turn over till everything cools down , sometimes they will seem to run sorta ok sometimes they have a light miss that will not go away and sometimes they have a knock mid way up on the block , NOW you have a huge problem . I have a ton of years behind me working on the gassers and spent a ton of money on them . Your dist. maybe a problem as the curve maybe plum wore out . Now on this one ya need to find someone that can run the dist. on a machine and have the curve chart to check it against. I can not see hear or do any of the checks myself so here your on your own .I am just telling you what all COULD be .
 
well its not knocking or anything when it starts to run poorly so do you think that i could jack up the octane in the gas thats already in it and possibly see results? after i change the plugs of course?
 
One other thing here on your carb does it have the factory electric solenoid or did someone remove it and put a stupid adjusting screw in it ?? If it has the adjusting screw then back it off five turns and leave it there if it has the solenoid then it shold be opening all the way off the seatwhen it is powered . As far a sweeting up the gas by adding that ain't ah going to happen so that leaves draining it ALL out and filling with the best ya can find and today the best ya can find maynot be good enough .
Get a timing light on it and check the timing and like i said make sure it is to the BOOK wright . Eash I H modle has it's own setting and off the top of my head i can not remember what the 656 sets at . &06 with a C263 sets a 23 degree a 706 with a C291 sets at 18 degrees a 806 with a C301 sets at 23 degrees so one set does not cover all and doing by ear your going to be so far off you will not believe . THIS MUST BE DONE AT WIDE OPEN throttle at max RPM.
And like i said you will never hear it start to PING OR KNOCK till it is to late.
 

A possibility:

The expansion of the hot engine, may be opening up a vacuum
leak. The carb winds up getting way more air than fuel, so when you choke it you add that extra fuel to balance the excessive air.

Carb mount flange, or intake manifold. (?)
 
Humm, 20 minutes? What if you put a load on it right away? I guess I'd be wanting to know if it's the load or the heat that is causing the trouble. Or just the elapsed time. What does it do if you shut it off warm and then restart after 5 minutes? Three possibilities here and you need to eliminate two of them.
 
Run Champ. plugs in the machines with out a problem. The main problem is fuel quality. Had similar problem with 706 changed fuel no problem after. The damage was done however by the time the barrel full was gone (kept using to get rid of). It went a good while with different fuel. till it started badly burning oil (badly burnt/broken valves).My guess (just that guess) to the cause of that from running bad fuel (ran engine to hot) that long before changing then the full (power) work knocked the now heat stressed valves apart(one had almost 1/4" chip). Full overhaul resulted.
 
(quoted from post at 23:40:48 01/05/15) The tractor will not act up until it is at running temp
Click to expand...

Start with the simple things first. Two other posters suggested that you should check for leaks in the intake manifold. after the engine warms up spray some carb cleaner around the mating surfaces of the intake manifold. Do this with the engine at idle. When the carb cleaner gets in where the air leak is the rpms will increase a little. Give that a try if you don't find a leak, we'll move onto the next thing.
 
Burnt valves come from not running low ash oil , took me a long time to figure this out but after talking to and OLDER IH dealer mechanic machinist and looking at a TSbon the matter we switched to thew low ash and have not had a problem with valves , Pistons on the other hand that is a differant amimule .
 
That could be. Don't recall what the pistons looked like, they were so covered in oil burn gunk(replaced because they came with OH kit). Something was out of wack with fuel and changing helped (the main problem: same as original post), but the oil burning started not to long after the fuel switch back, to what we were using, that's why I assumed the fuel did it. Used it for to long burning oil and not filling soon enough that put it over the edge of valve job to complete overhaul. Runs good now.
 

If everything is open and free in the fuel system a full choke should flood the engine. Is it sucking air somewhere?
 
Internal cracks in the joint between the exhaust and intake manifold, or a leaking intake manifold will do what you are experiencing. An internal crack will open up gradually. Jim
 
The octane of fuel is inverse to its flamibility Regular 87 octane burns hotter and easier than higher octane. No point in going there. Jim
 

Octane level for any given engine is ten times the compression ratio. For example ;my IHC 340 has a compression ratio of 7.6 : 1, 7.6x10=76. This is the octane level this tractor was designed to run on. Keep in mind that these tractors were designed to run on low cost fuel. But the gas companies don't sell low cost tractor fuel anymore so 85-86 octane is what we have to use.
 
That's a good one !!
The only electrical things I can think of that would cause these type of symptoms are the coil ( too hot to touch when it dies) or the condenser, shorting out when it gets hot.

It sounds more to me to be fuel related, I would first try a 2 gallon separate "lawn mower" gas tank hooked directly to the carb, that would by pass any sediment bowl, tank, or fuel line issues. Care is to be taken not to spill or drop this temporary set up while it's running.
If that doesn't do it, then it has to be the carb float chamber level is too low, or the needle & seat are getting restricted or plugged somehow. You got me on this one.

I added a 1 in piece of copper tubing and soldered it to the inlet of the new sediment bowl making a stand pipe to keep the loose "stuff" in the tank. Kept it from having trash "cover" the inlet. They make a sediment bowl that has a stand pipe sort of screen already attached, but I haven't used one, as mine has been ok so far.
Have you tried it with the air cleaner hose off ??
Grabbing at straws here.
 
What number Champion plug are you using. If you are using a D21 or D23 it will act up under load from pre-ignition due to too hot a plug heat range.
 
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