01-09-2024, 01:31 AM
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#1
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Lower Rad Hose Heater and Thermostat Coolant Circulation
Hey Ya'll,
A question I probably should have asked before installing my lower rad hose heater... With the engine off, the thermostat is shut right? So the coolant being heated wont freely circulate into the block?
Does anyone have experience with this, or can someone please shed some light on coolant circulation? Thinking maybe I should have installed a plane jane block heater instead.
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01-09-2024, 10:05 AM
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#2
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Quote:
Originally Posted by alex9000
Hey Ya'll,
A question I probably should have asked before installing my lower rad hose heater... With the engine off, the thermostat is shut right? So the coolant being heated wont freely circulate into the block?
Does anyone have experience with this, or can someone please shed some light on coolant circulation? Thinking maybe I should have installed a plane jane block heater instead.
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There is a bypass in the thermostat that still allows water to flow. Not a LOT, but it's enough to keep the system from blowing up with the water pump running while it's closed.
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01-09-2024, 10:46 AM
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#3
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If you have a IR temp gun you could check the temp of the lower hose and the block in a couple of places to see how the heat is transferred after plugging in that heater over night.
(edit, I see you haven't installed it yet)
I had that type of heater in an old Volvo 123GT and it worked great.
I'm not sure how coolant flowed in that though.
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01-09-2024, 01:55 PM
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#4
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Quote:
Originally Posted by shadow247
There is a bypass in the thermostat that still allows water to flow. Not a LOT, but it's enough to keep the system from blowing up with the water pump running while it's closed.
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The bypass (and heater core) is on the 'other' side of the cooling system from the main radiator hoses. The only flow that this will have is through the jiggle valve.
The oil cooler and heater hoses are reasonably easy to access and will have full flow 'access' to the engine with the thermostat closed.
-Charlie
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01-09-2024, 04:25 PM
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#5
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Quote:
Originally Posted by phattyduck
The bypass (and heater core) is on the 'other' side of the cooling system from the main radiator hoses. The only flow that this will have is through the jiggle valve.
The oil cooler and heater hoses are reasonably easy to access and will have full flow 'access' to the engine with the thermostat closed.
-Charlie
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Charlies idea is good.
I would do the heater hose.
Hose Heaters
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01-09-2024, 06:50 PM
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#6
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What is going on with your lower radiator hose? You have some intermediate assembly in there that I've never seen before?
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01-09-2024, 07:42 PM
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#7
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Quote:
Originally Posted by mtbtim
What is going on with your lower radiator hose? You have some intermediate assembly in there that I've never seen before?
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Might be the angle of the pic but that's the coolant heater there, with the belts in the background not related.
I'll see how she goes tomorrow morning, it's just getting colder and colder this week. This morning 2 cranks to turn over, at lunch when it sat unplugged for 5h it took maybe 7 cranks.
If I get bored/nerd out I may look for a better spot to plumb it in, ie somewhere behind the thermostat. Just hoping the diameter of the heater I have would match the new hose location diameter.
Thanks everyone!
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01-09-2024, 11:24 PM
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Quote:
Originally Posted by alex9000
Might be the angle of the pic but that's the coolant heater there, with the belts in the background not related.
I'll see how she goes tomorrow morning, it's just getting colder and colder this week. This morning 2 cranks to turn over, at lunch when it sat unplugged for 5h it took maybe 7 cranks.
If I get bored/nerd out I may look for a better spot to plumb it in, ie somewhere behind the thermostat. Just hoping the diameter of the heater I have would match the new hose location diameter.
Thanks everyone!
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I've never seen a "Coolant Heater". I'm guessing this is for people who live in really cold climates.
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01-10-2024, 02:36 PM
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Quote:
Originally Posted by mtbtim
I've never seen a "Coolant Heater". I'm guessing this is for people who live in really cold climates.
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He posted the weather for Edmonton... And -30's*F for overnight temps. I'd go for some sort of pre-heating if I was going to drive there in the winter...
Coldest I've ever had to start my own vehicle in was -10*F. My old WRX - and I usually ran only ~30% coolant on that (for better summer heat removal). -10*F is the freezing temp at those coolant/water ratios... Got lucky there, but it did sound like an old radial plane engine for a bit.
-Charlie
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01-10-2024, 04:17 PM
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#10
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You know it's actually working pretty well... This morning it was -24C (-11F) and it turned over in 2 cranks. That being said, I think this engine was rebuilt and is in perfect condition.
Going to go to -40 in a day or two, will report back then!
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01-10-2024, 05:37 PM
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#11
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Haven't lived in the cold belt for decades, I'd think a oil heater would be in the picture more than coolant.
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01-17-2024, 07:44 PM
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#12
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Quote:
Originally Posted by alex9000
You know it's actually working pretty well... This morning it was -24C (-11F) and it turned over in 2 cranks. That being said, I think this engine was rebuilt and is in perfect condition.
Going to go to -40 in a day or two, will report back then!
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How has it been? Do you find the heater is warmer on start up too? I live West of Calgary and we were just hitting -45*c with no windchill.
Thanks
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01-17-2024, 10:18 PM
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#13
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Quote:
Originally Posted by 1985bj60
How has it been? Do you find the heater is warmer on start up too? I live West of Calgary and we were just hitting -45*c with no windchill.
Thanks
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I think it's been working pretty well - although I'd probably just get a block heater installed if I were to do it again. A genuine toyota one. Either that or move this coolant heater to the other side of the thermostat somewhere.
That being said, since I installed this, I also installed a remote start so I haven't been the one cranking and feeling the effect. The remote starts successfully tho
ps. make sure you burp the system after the install or youll have massive air bubbles in the coolant system and overheat when it's -40C outside 
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01-19-2024, 08:32 PM
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#14
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No matter how good the engine is, you are basically destroying it by cranking while oil is pretty thick. Block heater is the way to go if you park your car outside.
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01-19-2024, 09:18 PM
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#15
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Quote:
Originally Posted by nissanh
No matter how good the engine is, you are basically destroying it by cranking while oil is pretty thick. Block heater is the way to go if you park your car outside.
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With the proper oil weight, you will not "destroy" your engine by starting it in colder climates.
A heater will allow it to start easier and warm up faster.
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