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D24 Overheating?


marco02_

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Doing what I did allows you to collect the coolant and recycle it. It will allow for more complete filling as you never take the cap off. Just add to the bottle like a modern car. This gets the air out of the system, as it will blow out then suck back coolant as the engine cools.

 

This is not a true pressurized system, as the pressure developed is only the max head pressure of your catch can. If it has a foot deep of coolant, that's 64 psf or about half a psi.

 

The pressure isn't the key. It's the cold-siphon recharging of the system that gets the air out, and saves your coolant. That's a big deal, as a system can suck air, even if it's not leaking coolant.

 

I'm not sure what Plymouthy was referring to exactly. Many things could be wrong with bypass, gaskets, wrong thermostat, bad thermostat, inverted, miss-aligned or sticky thermostat, heater bypass routing, etc. Not an SBC guy, as I only owned 2 in 50 years, bone stock, and they always ran OK.

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19 hours ago, marco02_ said:

So i just got my 1948 d24 running after 40 years. The car has a 283 chevy and powerglide that was swapped in it .I got the original non pressure radiator rebuilt and a new water pump. I topped off the coolant and started it up and let it run for about 7 minutes when the thermostat opened and started spewing coolant from the overflow on the radiator. Is this a normal thing for these cars and if so how is the overflow routed originally so it doesn't spew over my engine again?

Just noticed the new water pump comment.  The bypass situation I mentioned earlier really only applies to truck sourced engines.  Cars rely on the internal bypass in the block and pump and the heater route to some degree.  When the pump was replaced did the gasket on the passenger side have the bypass hole?  If so, that plus the heater hose loop situation should be fine.

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3 hours ago, kencombs said:

Just noticed the new water pump comment.  The bypass situation I mentioned earlier really only applies to truck sourced engines.  Cars rely on the internal bypass in the block and pump and the heater route to some degree.  When the pump was replaced did the gasket on the passenger side have the bypass hole?  If so, that plus the heater hose loop situation should be fine.

Yes i do remember the water pump having the bypass you speak about but i will reconnect the heater just to make sure everything is ok. I still don't see how a bypass would help my problem because it doesn't prevent the coolant inside of the engine from expanding due to heating up. 

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The steaming part. Thats the issue here, and only a few things that cause it. 
airlock, head gasket leak or little/no circulation.lack of any pressure. 
i may suggest a 1/8” hole drilled in thermostat to purge air as well. 

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9 hours ago, marco02_ said:

 

Yes i do remember the water pump having the bypass you speak about but i will reconnect the heater just to make sure everything is ok. I still don't see how a bypass would help my problem because it doesn't prevent the coolant inside of the engine from expanding due to heating up. 

but expansion alone doesn't explain your problem.  Water only expands about 4% when heated from ambient to boiling.  So about 5 oz per gallon, far less than you are seeing expelled.  Leaves steam as the cause.  Bypasses allow the water to circulate preventing the hot areas, exhaust passages, exhaust valve seats etc,  from vaporizing.

Drilling small holes in the perimeter of the thermostat is a common fix for poor circulation when closed and trapped air when filling.  A couple of 1/8" holes will assure that air an leave the intake area.  A jack under the front to make sure that the air can move up and out is good too.  Newer cars often have bleed ports for that purpose. 

 

You can leave the cap off with the water level over the core and watch the water for circulation and the presence of bubbles.  Movement good, bubbles indicate gasket leakage. 

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Did you ever try to boil the thermostat on the stove to see what temp it works at?

It should open, once at the correct temp, within maybe 10 to 15 seconds.

 

If the water just barely starts to boil, just making the first bubbles that aren't rising, and it's not 100% open, it's toast.

And, it should not open sluggishly.

 

If you have a good nose you can generally smell combustion byproducts in the radiator, if the head gasket leaks.

The unburned hydrocarbons in the coolant smell like a car running too rich.

 

Pull the plugs and check the tips for evidence of one cylinder running quite different.

 

If you see one, I'd do a leakdown test on the cyl. 

If you get bubbles in the radiator, and the car isn't running, there's a leaky/bad gasket. Possibly loose/cracked head, Even a cracked block is possible.

 

 

 

 

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