How does a lower hose heater work?

[pizzachef]

I just installed a lower radiator hose heater I bought from NAPA (looks similar to the one offered by diesel giant). After I wrestled the hose onto the both sides of the heater and reinstalled the hose, I looked at how the water flows. This heater will heat the water in the radiator and up to the t-stat. But the t-stat will be closed, so how can it warm the engine block? It must somehow right? Its driving me bonkers and I was so excited to have a warm engine engine for the rest of thie winter...

Can anyone explain it to me?

[nhdoc]

As far as I can tell a small amount of warmed coolant will circulate past the bypass at the thermostat at all times and through convective currents it will warm the coolant some in the engine. Not as effective as a block heater, but you probably knew that.

[t walgamuth]

when the stat reaches its opening temp it will open and circulate to the block. they arent as good as a block heater but are a lot better than nothing and a whole lot easier to install.

tom w

[kerry]

Originally Posted by pizzachef

I just installed a lower radiator hose heater I bought from NAPA (looks similar to the one offered by diesel giant). After I wrestled the hose onto the both sides of the heater and reinstalled the hose, I looked at how the water flows. This heater will heat the water in the radiator and up to the t-stat. But the t-stat will be closed, so how can it warm the engine block? It must somehow right? Its driving me bonkers and I was so excited to have a warm engine engine for the rest of thie winter...

Can anyone explain it to me?

Was it the 1 1/2 version? I have one but have yet to install it.

[pawoSD]

When I use mine it makes a huuge difference in cranking time when its super cold out. I can fire up my engine with a 10 second glow and 2-3 cranks if I use my heater overnight, even if it is like -10F outside. Without it its hit or miss if it will start at those temps...for my car anyways. Sometimes it will, a few occassions it hasn't.

Leaving mine on melts all the snow off the front of my hood/grille, warms the front of the engine, lower hose, and T-stat....it warms it pretty good, especially if left on overnight, which is what I usually do.

[pizzachef]

Originally Posted by kerry edwards

Was it the 1 1/2 version? I have one but have yet to install it.

yes, I'm pretty sure it was the 1 1/2". Getting the lower hose connection off without laying down in the slush on my back was tricky, but the only real hard part was muscling the hose on the heater.

I didn't think the heater would heat the water over 180*F to open the t-stat. Maybe it will...

Does the engine oil go though the radiator? I suppose that oil may get heated in the radiator from the water in there but that seems like it would take forever.

[t walgamuth]

the engine oil does not go thru the rad but it will be somewhat warmed by the heater.

tom w

[gregszustak]

I have a lower hose heater about 2 inches from the thermostat housing.
Thermostat housing gets hotter than hell. Heats by convection, I guess water on the other side of the thermostat is heated by the housing itself.
When the car is facing the wind it doesn't seem to retain the heat as well.
1 crank at -5 F and she's going as long as the wind is coming from the back of the car, not blowing away the heat.
Temperature Gauge reads a little below 40 on cold mornings.

[toomany MBZ]

If I understand correctly, the water pump is running all the time. Yet with the t'stat closed will not circulate cooled water, as it is trying to draw against a closed "door". Once said "door" is opened, coolness ensuses. A heater on the lower hose with engine off, will warm all water in engine, albeit not very effectively, as heat moves upward. There is no "switch", t'stat, on lower hose, so it is always open.

[t walgamuth]

this is a description of a typical american car t stat.

in a benz it never pulls against a closed door since it is a diversion thermostat. when the car is cold the coolant circulates back to the block without going through the rad. as it warms it is diverted to the radiator.

tom w

[toomany MBZ]

Originally Posted by t walgamuth

this is a description of a typical american car t stat.

in a benz it never pulls against a closed door since it is a diversion thermostat. when the car is cold the coolant circulates back to the block without going through the rad. as it warms it is diverted to the radiator.

tom w

Am unfamiliar with a diversion t'stat. Help me understand the difference.

[vstech]

am I missing something here? the thermostat is up against the upper hose, not the lower one. the lower hose is open to the thermostat/ and the block. and thermodynamically, heat does not rise or fall, it equalizes. Warm air rises due to it being lighter than the denser cold air, but water convection acts differently. heating a tank of water, causes brownian motion in the heated portion to draw the colder water toward it, equalizing the temps.
so, a lower hose heater will heat the radiator, and the block equally, but the radiator will be loosing heat MUCH faster than the block will be heated.
of course I could be full of it.
John

[JackG]

Originally Posted by toomany MBZ

Am unfamiliar with a diversion t'stat. Help me understand the difference.

The tstat does not block all fluid, there is a by pass so fluid can go around the tstat

[t walgamuth]

but this is not the explanation of a diversion stat.

there has been a ton posted on this subject. i am too tired to explain it tonight. i suggest you try a search. there is a diagram in the fsm about it and there also should be one in a haynes manual as well.

all benzes have had them at least since the early sixties. also volvo, bmw and saab. also some opels. in case you have repair manuals on any of those makes.

tom w

Flow diagram.