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MGB MGB overheating with a squealing noise from the engine

Pete L.

Freshman Member
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Folks,

I'm having a good bit of difficulty with overheating with my '79 MGB. The car has a NEW THERMOSTAT, a NEW TEMP GAUGE SENDING UNIT, NEW FAN BELT properly tightened I believe, recent hoses (2 yrs.) recent coolant change ( -10 ).

Two weeks ago the car started running hot after a short ride of about twenty miles at about 50-60 MPH. No steam, no fluids leaking from anywhere and no smell of antifreeze. The needle on the gauge was up to the leading edge of the red stripe on the hot end of the gauge face.
Thinking it was possibly a faulty gauge or sending unit I changed the sending unit, additionally I changed (today) the thermostat (195%) and filled up the coolant levels.

I then took the car out this and the needle was pinned to the hot end of the gauge and there was an intermittent squealing noise from under the hood. I pulled over, opened up the hood and again no evident signs of overheating EXCEPT that the lower radiator hose seemed SWOLLEN ?

Any help you folks could provide would be greatly appreciated.

Thank you,
Pete L.
 

JPSmit

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Pete, welcome, I am going to suggest that it is time for a new water pump - the pump binding or seized would account for the squealing. and, the lack of circulation the heat.
 

DrEntropy

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Thirded.

...and back flush the rad at the same time.
 
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Pete L.

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Gentlemen,

Thank you very much for the help, looks as though a new water pump will be ordered shortly AND I'll back flush the radiator as well...


Pete L.
 
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Pete L.

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Folks,

After a new radiator, water pump, electric fan sending unit, temp gauge sending unit, thermostat, and lower radiator hose, as well as new antifreeze the car runs fairly cool while in motion...sitting still for a few minutes sends the needle to the "H" !!! I've got to work on cooling the car at idle ???
 

MustangSix

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Overheating at idle indicates a lack of airflow. Are your fans coming on? Check all the wiring and the switch. Also, it's possible to wire these fans to run in reverse, so make sure you have not inadvertently wired them backwards. They should blow toward the radiator with the curved face of the blades facing the rad.
 
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Pete L.

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MustangSix,

They are indeed running in the correct direction, it seems as though the condition is improving. Even though we're in the middle of a heat wave the car is not warming up enough at a red light to start the fans...not a clue ?
My next move will involve replacing the thermostat housing with an earlier unit, rerouting the upper radiator hose and putting a 12 inch fan on the front of the water pump. This set-up also requires a fan shroud. I've seen this modification a number of times both with and without the front pusher fans and it seems to work well.
 

David_DuBois

Jedi Warrior
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Have you checked the actual temperature of the engine with a no contact thermometer? How about the voltage stabilizer for the fuel and temperature gauge? is it operating correctly, finally what about the temperature sensor in the head - is it operating correctly?
Cheers
 

JPSmit

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MustangSix,

They are indeed running in the correct direction, it seems as though the condition is improving. Even though we're in the middle of a heat wave the car is not warming up enough at a red light to start the fans...not a clue ?

are the fans coming on at all? what temp is that thermal switch set at?
 

DrEntropy

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A good source for different thermal switches and suchlike is Summit Racing. If you can't find a way to MacGyver the fan trigger point with what they have on offer, you ain't gonna find it at all.
 
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Pete L.

Freshman Member
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Folks,

All seems well now that the weather is cooling off. Had a 200 mile drive last Saturday and the car behaved well...
 
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