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Old 12-01-2015, 10:38 AM
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Join Date: Aug 2015
Location: Delaware!!!
Posts: 47
M130 over heating with new pump and thermostat

My 71 250 would randomly spike in temp, hot air from vent would turn cold. so i replaced the thermostat and water pump. Still having the same issue.
I drove it this morning, cold vent air and temp spike so i pulled over and let it cool. started up at normal operating temp and drove home (about 6 miles) and the air stayed hot and did not over heat.

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Old 12-01-2015, 02:15 PM
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Join Date: Dec 2007
Location: Houston, Texas
Posts: 1,148
Hi Don,

I don't know the answer, but willing to help guess at the variables.

Does your intake manifold have passages that open/close? My are stuck in warm weather position.

Does your air cleaner have open/close venting?

My experience has also been that the heater core is prone to leaking on the vintage cars. This manifested in water leaking into driver's floor pan and then rusting it out on The Emerald Bullet before I got it. The PO installed a cut off valve for hot water line to heater core. Check your heater core and the heater water valve.

1962 220Sb ~ The Emerald Bullet
1957 Ponton 220S

2001 S600 Daily Driver
The Universe is Abundant ~ Life is GOOD!
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Old 12-01-2015, 03:26 PM
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Join Date: Aug 2015
Location: Delaware!!!
Posts: 47
I know my heater core is not leaking, I need to check the intake manifold. It is carbureted and I do not believe there are any coolant lines going to it.
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Old 12-01-2015, 06:38 PM
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Join Date: Oct 2012
Posts: 11,058
You have air in your cooling system.

The worst case is a blown head gasket that is pumping air into the cooling system. This is not normal but I have seen it happen.

Take it to a radiator shop and let them look into the radiator while the car is running. If they see the right kind of bubbles they can tell you if this is the problem

You might also need your radiator boiled out. The transmission cooler is in the bottom of the radiator, inside of it, and these can get gunked up and restrict the flow. If this is the case your cooling system will void and pump air which is why you get the temp spike and the cold air at the same time.

Boiling out a radiator is not expensive and is something that very likely needs doing anyway.
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Old 12-02-2015, 06:33 AM
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Trevor Hadlington
Join Date: May 2014
Location: Worcestershire in England
Posts: 1,227
After filling up did you open up the heater controls to hot? If not it will never circulate the water though the heater . I opened up the brass nut on the top of the head to loose out air and re fill up before fitting it back in ,do after its cool ,not before.
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Old 12-02-2015, 06:49 AM
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Join Date: Aug 2015
Location: Delaware!!!
Posts: 47
Last night i bought a flush kit, drained the coolant and flushed about 3 times with water then filled and running water with peaks cleaner formula. I also noticed the bottom hose from the thermostat housing to the bottom of the radiator was not hot when the car heated up so i removed the spring and diaphram from the old thermostat and put that in.

The car has not over heated, runs a steady 150ish F i imagine i had some blockage because the overheating happened out of nowhere. i did have a little junk (looks like may have been old gasket material) in the containment i drained into and when it settled there was a chalky white residue at the bottom.

I appreciate everyones input and swift responses, i will let you know when i replace the water / cleaner solution with coolant how it does. supposed to run the solution "6 hours"
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