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  1. #1

    Default Perkins 4107 coolant system problems

    My coolant pump started leaking badly I ordered a new one believe it or not they're still available for a 1974 I drain the coolant got about 2 and 1/2 gallons fitted the new pump everything seemed to be fine went to refill the system can't get any more than about 1 and 3/4 gallon into the system and it seems to be full I ran the engine watch the temperature gauge when it was finally seem to be full I'm not reading any more than about a hundred and forty degrees ran the engine for an hour no reduction in the amount of coolant in the system but I still have almost three-quarters of a gallon of coolant that came out of the engine what happened

  2. #2
    Join Date
    May 2015
    Location
    Oregon
    Posts
    122

    Default Re: Perkins 4107 coolant system problems

    Ran at idle? The could be air pockets in the hoses, etc. Sometimes the thermostat will keep some of the air from purging. If you were at idle, the thermostat may have never opened because the air below it acted as insulation. Enough heat transfer happened with little circulation. Some thermostats come with a small hole (about 1/16") in the thermostat. This allows some minimal circulation and the air to escape the head and block. If a thermostat doesn't come with the hole, I drill it. I have a 1972 - 4108 on a generator. I don't know the differences with a 4107, but you could have an air bubble around the temp sender and are getting a false reading.

  3. #3

    Default Re: Perkins 4107 coolant system problems

    Quote Originally Posted by Lepke View Post
    Ran at idle? The could be air pockets in the hoses, etc. Sometimes the thermostat will keep some of the air from purging. If you were at idle, the thermostat may have never opened because the air below it acted as insulation. Enough heat transfer happened with little circulation. Some thermostats come with a small hole (about 1/16") in the thermostat. This allows some minimal circulation and the air to escape the head and block. If a thermostat doesn't come with the hole, I drill it. I have a 1972 - 4108 on a generator. I don't know the differences with a 4107, but you could have an air bubble around the temp sender and are getting a false reading.
    When reassembling my engine I noticed a little hole in the thermostat and wondered what it was later on when I was wondering about burping the engine I saw the little hole comment at this point I'm wondering how an air bubble can keep 3/4 of a gallon of coolant out of my system thanks for the comeback

  4. #4
    Join Date
    May 2015
    Location
    Oregon
    Posts
    122

    Default Re: Perkins 4107 coolant system problems

    Reassembling your engine? That changes things. If you had the head off, some head gaskets don't have all the holes for water passage between the head and block. They can create spaces for air to accumulate. Only running at idle may allow the engine to dissipate heat without the thermostat opening. If you get a bubble of air below the thermostat, the heat of the engine doesn't transfer thru air to the thermostat as well as thru water. So unless the engine gets way over temp, the thermostat doesn't open. The small hole in the thermostat usually allows the air to get past. But if yours has the hole then the air is somewhere else. Also at idle, the coolant pump circulation is much lower and may not push the air with enough force to get it past the thermostat.
    If your coolant measurements are accurate, then you have 3/4 gallon of air space in the engine, hoses, exchangers, etc.
    Bigger engines like my Detroits have a 1/2" bypass so there is always some circulation even if the thermostats are closed.

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