756 international cooling problems

Kkendall

New User
I have a 1968 756 international and having cooling problems I have replaced radiator belt hoses new thermostat flushed block
The tractor starts great and runs great but it warms up and gets hot I have replaced gage and sensor checked to see that thermostat opens at correct heat it does it will stay at half on gage when idling but when it rev it up to 1000 rpm it starts getting hot if I shut it down the thermostat will click open and close does anybody have any suggestions

Kkendall
 
We do not know if you live in MN, or TX it makes some difference. We also do not know history (with you or a former
owner. If it is not loosing any coolant (into the oil, or out on the ground) the issue is probably one of four
things. A plugged up radiator core that will not allow enough coolant flow. A plugged up radiator fins not
allowing air flow. a collapsed radiator hose (internal to the hose, not visible, works like a heart valve). or a
failed water pump (loose impeller) Jim
 
Gas or Diesel? Is the coolant oily on top when stopped? Have you looked in radiator to see if there are bubbles in radiator? If so possible head gasket or cracked head.
Have you looked in radiator to see if coolant is circulating when up to temp? I personally have had a water pump impeller come loose on a car causing over heating and
have heard of the metal vanes being corroded off of impellers. That should give you some things to think about checking. Hope this helps.
 
first thong I do is check the rad cores for being corroded and plugged, as a plugged radiator is usually the first on the list , a diesel engine produces little heat at idle so you don't notice till under load. those rad's are old and don't know when it was hot tanked.
 
"if I shut it down the thermostat will click open and close"

I think, rather, you are hearing a pocket of the HOTTEST water BOILING.

Could be a plugged passage somewhere, an incorrect gasket, or even a waterpump with a failed impeller. (I ASSUME the t-stat is the correct one, and not installed upsidedown?)

Also, a combustion pressure leak into the cooling system will make "air pockets" that interfere with coolant flow and create hot spots.
 
Are you sure the thermostat is installed correctly?

I put a new thermostat in our pickup [345 V-8] during
fall work, & got it in backwards. Mind gets kind of
fuzzy when you're tired.
Might be worth checking.
Jim
 
Ok so you have a 756 WHAT , gas or diesel ?? this would really help here . If it is a gasser i will start with INg. timing first as you need 18 degrees full advance at wide open throttle , you have to have spark plugs no hotter then a 3116Autolite, a C 86 A/C oor if ya can get it to run on a D 15Y Champion. Next ya need the correct gas if it is a gasser , you can NOT work them on todays pump gas , yea someone will come on and say i don't know what i am talking about . i only work on them for a living . Next you maybe getting compression into the cooling system due to a leaking head gskt, cracked head and or block . Maybe to lean of fuel mixture . And maybe the water pump . Diesel it could be a leaking injector cup , cracked head and or block, again pump timing and fuel set , blowen head gskt . I am not there to look for myself.
 
kKendall, Welcome to YT! Sorry if it seems like
some of the replies you get come on a little strong, it
just some folks style. Okay, please don?t think I am
insulting you by any of the questions or read in any
implications I?m just trying to sort out you knowledge
level and experience with equipment. I would really
like to hear some feedback from you on some of the
questions others have posed in their replies. If you
aren?t familiar with forum layout just poke one of the
...reply... buttons in your post box or any of the other
replies to respond. My question would be how are
you checking it is getting hot? If you can get a hand
held laser point thermometer this would be very
helpful in proper diagnosis of your issue. These can
be purchased for a reasonable price at many home
improvement stores. Does the radiator ever boil
over with hot water and steam? I?m suspicious of
the comments you made about the thermostat
...clicks open... there is generally no detectable
noise associated with its operation. It would be very
helpful to know the ambient...outdoor... in building
etc. ... temperature the tractor is operating in? Gas
or diesel, was it operating fine at one point or is it
new to you and you have very little history with it?
An electrically operated temp gauge can act very
strange and give false readings with a loose
connection. Something as simple as the fan blowing
on the sender wire connection as it speeds up could
be your issue. I understand not every goof spends
his holiday poking around on a tractor forum so you
might not seen the replies yet, but oh well. You may
have even found another forum and got your
problems solved there, if so let us know so our head
scratching can move on to other issues. As many
on here say ...TIA...Thanks in advance... Sorry this was so long. PS
Welcome again!
Rick
 
(quoted from post at 11:43:29 12/31/18) I have a 1968 756 international and having cooling problems I have replaced radiator belt hoses new thermostat flushed block
The tractor starts great and runs great but it warms up and gets hot I have replaced gage and sensor checked to see that thermostat opens at correct heat it does it will stay at half on gage when idling but when it rev it up to 1000 rpm it starts getting hot if I shut it down the thermostat will click open and close does anybody have any suggestions

Kkendall
Thanks for all the great information looks like thermostat was not opening had a nother set of eyes look st the problems that I was having and after testing cooling system the water was not passing through the thermostat he tested it and at 180 it was barley opening hard to find exterior thermostat so I have an old one and we are going to take interior parts out of it and we hope this will solive problem all of your comments we verry helpful thank you all again if any one has a comment on not running thermostat please advise. Thanks Kkendall
 

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