D24 Overheating?

[marco02_]

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?

[marco02_]

Also since a newer engine was swapped into the car does that have an effect on the radiator and would i need to switch to a pressurized system?

[Ulu]

The overflow should have a rubber  hose to catch can. I just painted a prestone bottle black and hid it behind the grill.

But you can use any number of cool vintage looking containers. The hose needs to go to within 1/4" of the bottom inside the catch can.

 

Btw, sounds like a lazy thermostat and or low coolant level.

 

Edited March 29, 2020 by Ulu

[Ulu]

12 minutes ago, marco02_ said:

Also since a newer engine was swapped into the car does that have an effect on the radiator and would i need to switch to a pressurized system?

The radiator should be OK. I ran my P15 closed system no problem with a stock engine. 

[marco02_]

20 minutes ago, Ulu said:

The overflow should have a rubber  hose to catch can. I just painted a prestone bottle black and hid it behind the grill.

But you can use any number of cool vintage looking containers. The hose needs to go to within 1/4" of the bottom inside the catch can.

 

Btw, sounds like a lazy thermostat and or low coolant level.

 

Thanks for the quick response. So on a open system it is normal for the coolant to spew out of the radiator when the engine heats up? Also how was the original cooling setup. Did it have a overflow tank from the radiator?

[50mech]

Sounds like an air pocket if this was an initial startup. Do you have a cooling system fill funnel. The type that lock on to the radiator and hold coolant above it so you can bleed it?

[50mech]

Guess it's also possible that 283 just pushes more than the radiator can flow....low pressure cap should alleviate that.

They don't normally spit, but also the fill level should be a couple inches lower than the top, not totally full or they will spit it out.

[marco02_]

19 minutes ago, 50mech said:

Guess it's also possible that 283 just pushes more than the radiator can flow....low pressure cap should alleviate that.

They don't normally spit, but also the fill level should be a couple inches lower than the top, not totally full or they will spit it out.

The radiator i am running right now has no way of building pressure at all. It has a vent to atmosphere at all times and the radiator fill cap. I will attach a photo i found from Don Coatney on the website.

[marco02_]

also every time it does this is spews about a gallon of coolant out of the overflow and afterwards just spews steam. Ive never owned a car with a open cooling system so the system seems strange but maybe some of you could help me on getting it working correctly because something seems wrong to me.

[Ulu]

All I did was put a pressure cap on the radiator and added rubber hose to that overflow pipe and put it into the bottom of a Prestone bottle hung behind the grill.

 

I drove that way for 60000 miles

Edited March 29, 2020 by Ulu

[Ulu]

52 minutes ago, marco02_ said:

also every time it does this is spews about a gallon of coolant out of the overflow and afterwards just spews steam. Ive never owned a car with a open cooling system so the system seems strange but maybe some of you could help me on getting it working correctly because something seems wrong to me.

Is oil getting in the coolant? Blown head gasket?

[marco02_]

29 minutes ago, Ulu said:

Is oil getting in the coolant? Blown head gasket?

No, actually no oil gets in the coolant. This only occurs when the thermostat opens up due to the heated up coolant that expands.

[61farnham]

 

Sounds to me you have air in system, try topping the coolant up just above the fins inside the radiator and run the engine up to normal operating temperature with the cap off the radiator and top up the coolant if it drops below the fins when the thermostat opens, you should see some air bubbles come thru the top hose into the radiator when the thermostat opens and the coolant circulates these will vent thru the open cap instead being forced thru the overflow. Let it run with cap off till you get no more bubbles coming thru put the cap back on and you should be good to go.

 

[Tooljunkie]

I know its not the right thing, but pull thermostat and try it. As mentioned there may be a flow issue through rad. 
heater hoses connected or plugged? 

[50mech]

4 hours ago, marco02_ said:

No, actually no oil gets in the coolant. This only occurs when the thermostat opens up due to the heated up coolant that expands.

Head gasket can also go in such a way that it pumps air into the water jacket and does what you describe. 

I'd try not topping it off, see if it finds a good level and stays there and is still able to keep itself cool....you'd be surprised how low they like to be for expansion. If it continues to do it until it's too low to keep itself cool then you probably have a head gasket leak.

[marco02_]

6 hours ago, 61farnham said:

 

Sounds to me you have air in system, try topping the coolant up just above the fins inside the radiator and run the engine up to normal operating temperature with the cap off the radiator and top up the coolant if it drops below the fins when the thermostat opens, you should see some air bubbles come thru the top hose into the radiator when the thermostat opens and the coolant circulates these will vent thru the open cap instead being forced thru the overflow. Let it run with cap off till you get no more bubbles coming thru put the cap back on and you should be good to go.

 

Ok ill try this and see how it ends up working. It might be a while until i get a chance. Thanks

[marco02_]

6 hours ago, Tooljunkie said:

I know its not the right thing, but pull thermostat and try it. As mentioned there may be a flow issue through rad. 
heater hoses connected or plugged? 

One think i did to the heater hoses is i plugged them at the water pump completely. Dont know if that could be the cause of the problem since could let it build too much pressure inside the engine before the thermostat opens.

[marco02_]

3 hours ago, 50mech said:

Head gasket can also go in such a way that it pumps air into the water jacket and does what you describe. 

I'd try not topping it off, see if it finds a good level and stays there and is still able to keep itself cool....you'd be surprised how low they like to be for expansion. If it continues to do it until it's too low to keep itself cool then you probably have a head gasket leak.

I tried this but didn't let it run for too long and even though the coolant level was low pressurized steam still wants to come out of the radiator. Ill try to get some air out of the cooling system and maybe pulling the thermostat. Thanks

[Plymouthy Adams]

I think a few people here need to read a white paper on cooling systems and how they work..!

[kencombs]

Losing a gallon followed by steam is much more than normal expansion.   Do you have a temp gauge?  What does it read?  An non-pressurized system will only expel coolant in excess of the system capacity at running temp. 

 

If it were mine, the first thing I would do is acquire a cheap IR thermometer ( I have a HF model, cheap and works well).  Use that to check the engine temp at various places..  That can help determine if the coolant is flowing, thermostat opening, radiator flow pattern etc.  A lazy/stuck thermostat will be obvious with this tool.

 

A SBC has no quirks in the cooling system, just as simple as they come, no common air traps etc.   In rereading your info about the heater hoses raises a question:  In that process did you by any chance block the bypass hose that allows some coolant to bypass the thermostat while it's closed?  If so, that could cause your symptoms since that bypass is what prevent hot spots and steam formation during warmup.

 

I really hope you overestimated the amount of coolant being pushed out because a full gallon and steam could be bad news.

 

edit to add pic:

Edited March 29, 2020 by kencombs

[Tooljunkie]

2 hours ago, marco02_ said:

One think i did to the heater hoses is i plugged them at the water pump completely. Dont know if that could be the cause of the problem since could let it build too much pressure inside the engine before the thermostat opens.

Think it causes an airlock. If you connect the 2 fittings with 1 heater hose it may help. 

[Tooljunkie]

I have a chemical test to check for combustion gases in cooling system. On some occasions i can smell it. This would be one i think. 
 

[marco02_]

2 hours ago, kencombs said:

Losing a gallon followed by steam is much more than normal expansion.   Do you have a temp gauge?  What does it read?  An non-pressurized system will only expel coolant in excess of the system capacity at running temp. 

 

If it were mine, the first thing I would do is acquire a cheap IR thermometer ( I have a HF model, cheap and works well).  Use that to check the engine temp at various places..  That can help determine if the coolant is flowing, thermostat opening, radiator flow pattern etc.  A lazy/stuck thermostat will be obvious with this tool.

 

A SBC has no quirks in the cooling system, just as simple as they come, no common air traps etc.   In rereading your info about the heater hoses raises a question:  In that process did you by any chance block the bypass hose that allows some coolant to bypass the thermostat while it's closed?  If so, that could cause your symptoms since that bypass is what prevent hot spots and steam formation during warmup.

 

I really hope you overestimated the amount of coolant being pushed out because a full gallon and steam could be bad news.

 

edit to add pic:

Hopefully it isn't anything too bad but i need to reinstall the bypass for the cooling system. But thanks for your help i will try checking tempuratures. 

[marco02_]

1 hour ago, Tooljunkie said:

Think it causes an airlock. If you connect the 2 fittings with 1 heater hose it may help. 

I will connect my heater hoses back on my car but my intake manifold doesn't have a provision for a bypass fitting. So ill just have to connect the heater hoses for now and hopefully it fixes my problem. 

[marco02_]

2 hours ago, kencombs said:

Losing a gallon followed by steam is much more than normal expansion.   Do you have a temp gauge?  What does it read?  An non-pressurized system will only expel coolant in excess of the system capacity at running temp. 

 

If it were mine, the first thing I would do is acquire a cheap IR thermometer ( I have a HF model, cheap and works well).  Use that to check the engine temp at various places..  That can help determine if the coolant is flowing, thermostat opening, radiator flow pattern etc.  A lazy/stuck thermostat will be obvious with this tool.

 

A SBC has no quirks in the cooling system, just as simple as they come, no common air traps etc.   In rereading your info about the heater hoses raises a question:  In that process did you by any chance block the bypass hose that allows some coolant to bypass the thermostat while it's closed?  If so, that could cause your symptoms since that bypass is what prevent hot spots and steam formation during warmup.

 

I really hope you overestimated the amount of coolant being pushed out because a full gallon and steam could be bad news.

 

edit to add pic:

Is that a l79 327? If so those engines are sweet. It also looks like it was in a tri five chevy previously because of the front motor mounts.