Coolant Flush w/o Thermostat - no heat? (1 Viewer)

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I'm doing a flush with thermocure since everything inside is rusty. Likely I'll be replacing the radiator but just wanted to try the thermocure first to see if this helps. Will also be replacing fan clutch as well while I'm at it.

I'm on my first flush and running the thermocure around to help clean everything up without the thermostat. However, it seems like the heat never gets hot even though the temperature gauge shows that it's in the middle. Is this because by the time the thermocure gets to the heater core it's cold? I've already been running the radiator without the cap on incase there is air in the system.

Thanks!
 
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I'm doing a flush with thermocure since everything inside is rusty. Likely I'll be replacing the radiator but just wanted to try the thermocure first to see if this helps. Will also be replacing fan clutch as well while I'm at it.

I'm on my first flush and running the thermocure around to help clean everything up without the thermostat. However, it seems like the heat never gets hot even though the temperature gauge shows that it's in the middle. Is this because by the time the thermocure gets to the heater core it's cold? I've already been running the radiator without the cap on incase there is air in the system.

Thanks!
the heater core is probably plunged did you check rear heater
 
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the heater core is probably plunged did you check rear heater

Yes, both rear and front are blowing cold. Could it be there was a bunch of crud so when I was draining it, I clogged it? It was working prior to me draining it and removing the thermostat.
 
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Elevate the front. A few inches/ driveway or curb is enough and let it run to get the air out.
I had rust and did 3-4 flushes and then again on day 2 until clear.
 
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Elevate the front. A few inches/ driveway or curb is enough and let it run to get the air out.
I had rust and did 3-4 flushes and then again on day 2 until clear.


Cool I will try this! I don't have any hills near me so I will try to jack the front of the vehicle up.
 
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I'd guess air pockets and no coolant circulating vs. both cores clogging at once. I typically see this after a coolant drain and refill on my 80 and when the heat starts to work I know that I've gotten most of the air pockets out.

You can also disconnect the send/return lines for your two heater cores and flush them out directly. Don't overdo it with the pressure but a good flow in both directions with the water hose can help flush out any sediment/chunks in the cores. Similarly you can do the same with any opening you can get a hose to on the block or rad. to help flush out debris, if there is any.

After all of that is done I also like to blow things out with a shop vac, with the hose in the reverse port that blows. You can put that into rad hoses, etc. to blow air through the block/radiator and help push the tap water/etc. out before you do your final fill/etc.
 
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You won't get any heat without a thermostat. Leave the thermocure in for a week and keep running the motor. After that flush and refill and put in thermostat and you should have heat again.
 
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You won't get any heat without a thermostat. Leave the thermocure in for a week and keep running the motor. After that flush and refill and put in thermostat and you should have heat again.

I thought that might be the case, what's weird is the factory temp gauge is back to where it normally should be after a while ( I know these might be slightly off) . Also touching the rad it's hot.
 
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When you flush the system, when you are done with the thermocure, you can see where the heater lines go in and come out of the heater core. Pull those lines and stick the hose in each end. Don't use full pressure of your hose, maybe a 1/4 of it and make sure whats going in comes out the same and you will see if the core is blocked. Dont forget the engine drain plug, accessible in the fenderwell, always a good idea to pull it.
 
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When you flush the system, when you are done with the thermocure, you can see where the heater lines go in and come out of the heater core. Pull those lines and stick the hose in each end. Don't use full pressure of your hose, maybe a 1/4 of it and make sure whats going in comes out the same and you will see if the core is blocked. Dont forget the engine drain plug, accessible in the fenderwell, always a good idea to pull it.

Thanks! Yup, I've pulled the engine drain plug and it was simple enough. I've filled it with 3 gallons of distilled water and the themocure. Is it ok to stick the hose in it with the tap water?
 
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Yep you can use tap water to flush, just don't turn up the water pressure all the way. When you refill I would use distilled and the green stuff 50/50. I like to dump 1 gallon of water and 1 gallon of antifreeze in a clean 5 gallon bucket and fill from that to ensure a proper 50/50 mix. Make sure you keep the heater blowing when you are cycling that thermocure for a week or more to ensure its getting in the heater core.
 
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One more tip:

When you drain that thermocure drain it in a 5 gallon bucket. I have a bucket of it in my garage that I throw rusty parts, nuts, and bolts in, leave them in for a few days and they are clean as can be! I soaked my old rusty tow hooks and they came out CLEAN! Thermocure is amazing stuff!
 
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One more tip:

When you drain that thermocure drain it in a 5 gallon bucket. I have a bucket of it in my garage that I throw rusty parts, nuts, and bolts in, leave them in for a few days and they are clean as can be! I soaked my old rusty tow hooks and they came out CLEAN! Thermocure is amazing stuff!
Good pro tip!
 
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I thought that might be the case, what's weird is the factory temp gauge is back to where it normally should be after a while ( I know these might be slightly off) . Also touching the rad it's hot.

The factory gauge is worthless in this/most situations as it is designed to show normal in a very wide range of temps. Get a Scangauge to see actual temps.
 

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