• To ALL forum users - As of late I have been getting quite a few private messages with questions about build ups here on the forum, or tech questions about your personal project. While I appreciate the interest, sending me a private message about these topics distracts from, and undermines the purpose of having a forum here. During the day I wear many hats as a small business owner-operator and I work tirelessly to provide the absolute best service possible to you, our valued customer. When I created this forum I rounded up some of the best minds I knew so that any tech question you might have could be asked and answered by either myself or one of my highly experienced moderators, this way the next time this same question is asked the answer can be easily found and utilized by the next IH enthusiast having the same question. This allows me the freedom to run the day to day operations of the business and minimize the impact to shipments and shop activities that these distractions can cause. It is of the up most importance for me to complete the daily tasks in order to best take care of you our customer, all the while providing you a forum to get the level advice and input you have come to expect and deserve from the premier IH shop in the country.

    So with that I ask that anyone with a question about one of our build ups or a general tech question to please use the forum as it was intended. I am absolutely available by telephone to answer your questions as well but at times may direct you back to our website to better field your question or questions. Most other private messages I will be glad to answer for you.

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    Jeff Ismail
    Owner/Operator

robert shaw thermostat

int77345

Member
does the Robert Shaw thermostat have some sort of bypass that allows a small amount of coolant to flow the the radiator even below the 180 degree set temperature. it is taking my scout greater then 45 min to reach 180 degrees when the out side air temp is below 30 degrees

from a clold start i reach 130 degrees quickly then 130 to 180 takes forever. costing down a long hill temperature will go decline from 180 and rest on 130 never going below 130.

seems some coolant is flowing to the radiator below the 180 temp???
 

ihpartsjeff

Administrator & Owner
Staff member
You may have to pull the thermostat and make sure it is not stuck open. When it is closed the thermostat is in bypass mode and the coolant circulates only thru the engine so it should not get any colder .But yes I have seen the engine temp drop on a long decline on a cold day.
 

int77345

Member
thank you for the reply !! i will take it out and have a look some time in the next few weeks.

out of curiosity do thermostats ever fail half open ?
 

Hondo

Member
Pot of water on the stove is a good test, put it in the pot and verify where it opens with a meat thermometer or similar device.
 

Robert Kenney

Super Moderator
does the Robert Shaw thermostat have some sort of bypass that allows a small amount of coolant to flow the the radiator even below the 180 degree set temperature. it is taking my scout greater then 45 min to reach 180 degrees when the out side air temp is below 30 degrees

from a clold start i reach 130 degrees quickly then 130 to 180 takes forever. costing down a long hill temperature will go decline from 180 and rest on 130 never going below 130.

seems some coolant is flowing to the radiator below the 180 temp???
To elaborate further, the RS thermostat has a cup that moves as it opens and closes, the inner surface of the cup is sealed against a ring that is in the center of the thermostat. That seal can leak and impede the engine reaching running temperature. This symptom can occur even it the stat opens and closes perfectly. Had 2 cheapo stats in a row do this, installed the old RS and it was fine. This is in the frigged South of California. :winky:
 
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