Over-Heating issue
#11
05-29-2020, 12:11 AM
Let me straighten stuff out. Once I filled the rad with coolant and then started my Blazer. I watched the coolant bubble and burp a bit. And watched the level drop. So I kept putting more in until it stopped bubbling and dropping. But as I said in my original message... My Blazer is still running abnormally hot. And I'm trying to be sure that all air bubbles are out of my coolant system before I go further into this issue.
They have a whole kit. It attaches, and is designed to let all the air out of system. Can run it "about an hour;" they also say "When the fans come on twice." In reality, when you stop seeing air bubbles then it should be bled of air.
Now.. if you see constant stream of tiny bubbles.. I have to make this case, that means air is getting in your cooling system somewhere. Could be head gasket. Could be other gasket. Could be more. But if there are NO bubbles then.. that is good.
You should, of course, also, see movement of the coolant. The water pump does that.
#12
05-29-2020, 10:56 PM
I think this would be a great opportunity to use one if the funnels from Lisle.
They have a whole kit. It attaches, and is designed to let all the air out of system. Can run it "about an hour;" they also say "When the fans come on twice." In reality, when you stop seeing air bubbles then it should be bled of air.
Now.. if you see constant stream of tiny bubbles.. I have to make this case, that means air is getting in your cooling system somewhere. Could be head gasket. Could be other gasket. Could be more. But if there are NO bubbles then.. that is good.
You should, of course, also, see movement of the coolant. The water pump does that.
They have a whole kit. It attaches, and is designed to let all the air out of system. Can run it "about an hour;" they also say "When the fans come on twice." In reality, when you stop seeing air bubbles then it should be bled of air.
Now.. if you see constant stream of tiny bubbles.. I have to make this case, that means air is getting in your cooling system somewhere. Could be head gasket. Could be other gasket. Could be more. But if there are NO bubbles then.. that is good.
You should, of course, also, see movement of the coolant. The water pump does that.
#14
06-11-2020, 11:11 AM
Not entirely sure what the problem was. Like I said in m original post the temp gauge told m it was overheating. So I went and put a new thermostat in. After pulsating bottom rad hose a few time I heard a burp then the coolant level dropped. So. Can only imagine that I had an air bubble and managed to get it out. Now it runs like a top!
#15
06-13-2020, 04:19 AM
Just for the curious out there about water pumps...
Corrosion is one aspect which can eat away either the impeller/rotor or the casing.
Any excessive clearance (1 - 2 mm or more which is about 0.05" to 0.07" can degrade the pumping efficiency of a centrifugal pump dramatically. What I have seen on water pumps.
What I have seen over the years:
Worn bearings and the impeller pushed away from the casing causing excessive clearance despite the impeller being fine.
Impeller completely rusted away (cast iron). Impellers nearly completely (I mean nearly completely eaten away by corrosion). Looked like a disc with some humps, instead of blades.
Broken axle. Looked fine from the outside and the V-belt kept the pulley in position inside the bearing. Once the belt taken off, you could feel the loose axle.
Spinning pulley on the axle, because of a bad water pump bearing.
V-belt routed the wrong way, therefore the pump turning the wrong way.
You see, there are possible failure scenarios.
The water pump forces a circulation through the block despite the usual design being a thermosiphon which could sustain a circulation even without pump. Now in stop-and-go traffic or different environmental conditions and loads on the engine this is not enough and you risk damage to the engine. Therefore water pumps have been in use for over 100 years.
A cooling system cannot over-pressurize if the cap is not blocked or obstructed. There is a safety valve there which vents over-pressure to the expansion tank. The expansion tank has a vented cap. Anything I have seen being blown off a cooling system until today always came down to broken clamps, clamps which had not been tightened correctly, broken off plastic and aluminium connectors, split or ripped hoses, rusted freeze plugs.
The system pressurizes because of heat expansion. The invention of the expansion tank and a cap with a two way valve made these systems pretty much maintenance-free. I would always change any vintage system to this setup. Better being less than stock but safe in regard to the cooling system.
To diagnose an overheat which is indicated by the dash always go the cautious way! Take it for real, stop, investigate, fix. Apart from a real overheat there can also be faulty sensors. Once it has cooled down or sat a while so the temperatures in the block have equalized a bit, take a reading with an IR thermometer. Check what the CT (coolant temperature) is reading on an OBDII scanner. Sometimes the ECU uses a different sensor than the dash. Sometimes the red "OVERHEAT" warning uses a different sensor than the gauge. Compare the readings to the gauge.
A word of caution: Never, ever open the cap on a hot system. Because of the pressurization above atmospheric, the coolant can be above boiling point. If you release the pressure by opening the cap it will immediately boil over in the whole system and cause an enormous pressure and hot water geysir.
Corrosion is one aspect which can eat away either the impeller/rotor or the casing.
Any excessive clearance (1 - 2 mm or more which is about 0.05" to 0.07" can degrade the pumping efficiency of a centrifugal pump dramatically. What I have seen on water pumps.
What I have seen over the years:
Worn bearings and the impeller pushed away from the casing causing excessive clearance despite the impeller being fine.
Impeller completely rusted away (cast iron). Impellers nearly completely (I mean nearly completely eaten away by corrosion). Looked like a disc with some humps, instead of blades.
Broken axle. Looked fine from the outside and the V-belt kept the pulley in position inside the bearing. Once the belt taken off, you could feel the loose axle.
Spinning pulley on the axle, because of a bad water pump bearing.
V-belt routed the wrong way, therefore the pump turning the wrong way.
You see, there are possible failure scenarios.
The water pump forces a circulation through the block despite the usual design being a thermosiphon which could sustain a circulation even without pump. Now in stop-and-go traffic or different environmental conditions and loads on the engine this is not enough and you risk damage to the engine. Therefore water pumps have been in use for over 100 years.
A cooling system cannot over-pressurize if the cap is not blocked or obstructed. There is a safety valve there which vents over-pressure to the expansion tank. The expansion tank has a vented cap. Anything I have seen being blown off a cooling system until today always came down to broken clamps, clamps which had not been tightened correctly, broken off plastic and aluminium connectors, split or ripped hoses, rusted freeze plugs.
The system pressurizes because of heat expansion. The invention of the expansion tank and a cap with a two way valve made these systems pretty much maintenance-free. I would always change any vintage system to this setup. Better being less than stock but safe in regard to the cooling system.
To diagnose an overheat which is indicated by the dash always go the cautious way! Take it for real, stop, investigate, fix. Apart from a real overheat there can also be faulty sensors. Once it has cooled down or sat a while so the temperatures in the block have equalized a bit, take a reading with an IR thermometer. Check what the CT (coolant temperature) is reading on an OBDII scanner. Sometimes the ECU uses a different sensor than the dash. Sometimes the red "OVERHEAT" warning uses a different sensor than the gauge. Compare the readings to the gauge.
A word of caution: Never, ever open the cap on a hot system. Because of the pressurization above atmospheric, the coolant can be above boiling point. If you release the pressure by opening the cap it will immediately boil over in the whole system and cause an enormous pressure and hot water geysir.
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Caroline Thatcher-Furness
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