Coolant flush

[jcrandall]

FSM procedure is not complicated, drain the coolant, rinse, refill.

Forgive the dumb question, but after you refill it you're supposed to burp the system by opening the "heater water valve". Anyone have a diagram that shows where this is? I'll take a good description or a picture.
Or maybe prevailing wisdom is that opening the heater water valve isn't necessary.

Thanks in advance

 

[hankinid]

FSM procedure is not complicated, drain the coolant, rinse, refill.

Forgive the dumb question, but after you refill it you're supposed to burp the system by opening the "heater water valve". Anyone have a diagram that shows where this is? I'll take a good description or a picture.
Or maybe prevailing wisdom is that opening the heater water valve isn't necessary.

Thanks in advance

High point in the system are the 2 hoses from the engine to the heater cores (one under the dash, the second under the driver's seat)...aka the hoses have T's.

I've drained/refilled mine 3-4 times, and from what I can tell the system doesn't need burping. I simply fill the overflow tank up to the fill line once I've filled the radiator. 2-3 cycles of start/drive/stop while allowing the system to get to operating temp seems to do the trick...I'll normally see the overflow tank drop ~2 inches once everything self-burps. I'll then fill the tank to the "full " line and that's it.

I've not seen a reference to a "heater control valve". To my knowledge, coolant always flows through the heater cores. The temperature you feel is controlled by doors in the front heater and the fan for the rear heat, interior temp sensor on top of the dash, and the control for the rear heater on the ceiling above the rear seats.

ETA...a quick google for land cruiser heater control valve looks like they came on the 80 series, but not on hundy's.

Steve

 

[PADDO]

FSM procedure is not complicated, drain the coolant, rinse, refill.

Forgive the dumb question, but after you refill it you're supposed to burp the system by opening the "heater water valve". Anyone have a diagram that shows where this is? I'll take a good description or a picture.
Or maybe prevailing wisdom is that opening the heater water valve isn't necessary.

Thanks in advance

I've always interpreted this to mean "put heater on max, blower on max" and let it run, radiator cap off, till the thermostat is open and you have hot coolant, circulating throughout the whole system.

 

[2003lx470]

I just do it "old fashion way".....burp the system through the radiator cap.

 

[jcrandall]

High point in the system are the 2 hoses from the engine to the heater cores (one under the dash, the second under the driver's seat)...aka the hoses have T's.

I've drained/refilled mine 3-4 times, and from what I can tell the system doesn't need burping. I simply fill the overflow tank up to the fill line once I've filled the radiator. 2-3 cycles of start/drive/stop while allowing the system to get to operating temp seems to do the trick...I'll normally see the overflow tank drop ~2 inches once everything self-burps. I'll then fill the tank to the "full " line and that's it.

I've not seen a reference to a "heater control valve". To my knowledge, coolant always flows through the heater cores. The temperature you feel is controlled by doors in the front heater and the fan for the rear heat, interior temp sensor on top of the dash, and the control for the rear heater on the ceiling above the rear seats.

ETA...a quick google for land cruiser heater control valve looks like they came on the 80 series, but not on hundy's.

Steve

I've always interpreted this to mean "put heater on max, blower on max" and let it run, radiator cap off, till the thermostat is open and you have hot coolant, circulating throughout the whole system.

Appreciate it y'all, got it - heater on max. Hankini, here's the reference in case you're curious:

 

[hankinid]

Appreciate it y'all, got it - heater on max. Hankinid, here's the reference in case you're curious:
View attachment 1020573

jcrandall...I took a look at my FSM ('01 LX) in both "Coolant" and "Air Conditioning" sections...no mention of a heater control valve.

Do you actually have a heater control valve on your '98 ?? If so, I'd open it. If not, your '98 manual may have that reference as a hold over from the LX450 manual.

Steve

 

[jcrandall]

Do you actually have a heater control valve on your '98 ?? If so, I'd open it. If not, your '98 manual may have that reference as a hold over from the LX450 manual.

Steve

Good question, I cannot find one, so I don't think so. Either way, we're good though - appreciate it.

 

[OregonLC]

I believe it's just referencing turning the heat to 'hot' to get full volume of coolant through the cores.

 

[hankinid]

I believe it's just referencing turning the heat to 'hot' to get full volume of coolant through the cores.

I understand the thought...but from what I can tell, coolant flows in the same amount through both cores, no matter the set temperature of the front and rear climate controls.

Steve

 

[OregonLC]

I understand the thought...but from what I can tell, coolant flows in the same amount through both cores, no matter the set temperature of the front and rear climate controls.

Gotcha. I guess I had assumed that was an integral part of the heater core assembly. SOP is always to crank to 'high' when filling/burping to get the water to flow through the core.

So you're thinking it's a fully open system with the airmix doors doing the temp control? Seems like a lot of excess thermal energy in the cabin, especially during the summer! And under the seat for the matter!

OTOH, I've seen old-school cable operated heater valves weep before so a hard-piped system would definitely be more reliable.

 

[hankinid]

Gotcha. I guess I had assumed that was an integral part of the heater core assembly. SOP is always to crank to 'high' when filling/burping to get the water to flow through the core.

So you're thinking it's a fully open system with the airmix doors doing the temp control? Seems like a lot of excess thermal energy in the cabin, especially during the summer! And under the seat for the matter!

OTOH, I've seen old-school cable operated heater valves weep before so a hard-piped system would definitely be more reliable.

Turning the temp control to max is what I'm used to.

Looking at the FSM, there's nothing in series with the hoses to either heater core that will throttle the flow...it all happens through motorized flaps (doors) on the heater core housings.

I personally prefer a manual control for temp...it makes troubleshooting much easier, and it makes removing the core quicker.

I'm old-school enough to remember faucets controlling coolant flow during my "British phase".

Steve

 

[bdac]

I've used the Leslie spill free funnel on my old 80 series and it worked great for getting air bubbles out of the system. I haven't done a flush/fill in the 100 yet so I can't comment on that part.

 

[hankinid]

Deleted...dupe.

Steve

 

[GaFJC]

I did the complete flush with distilled water and switch from long life coolant to super long life coolant and now have coolant temps reading anywhere from 184 degrees to 193 degrees when warmed up and at operating temperatures. Previously read a very consistent 188 degrees. All temps from my scan gauge II.

The new temp swing seems odd. I believe, but a I am not 100% confident, that I've burped the system via through four warm up cycles (around town errands mixed with highway use) and refilled to the full mark.

Is it possible I still have air in the system causing these temp swings?

 

[jcrandall]

I did the complete flush with distilled water and switch from long life coolant to super long life coolant and now have coolant temps reading anywhere from 184 degrees to 193 degrees when warmed up and at operating temperatures. Previously read a very consistent 188 degrees. All temps from my scan gauge II.

The new temp swing seems odd. I believe, but a I am not 100% confident, that I've burped the system via through four warm up cycles (around town errands mixed with highway use) and refilled to the full mark.

Is it possible I still have air in the system causing these temp swings?

fwiw, after I replaced my heater T's, it took way longer to burp my system than I expected. Not necessarily cycles, but I ran the truck for quite a while, maybe 15 minutes? with the fill cap off. I hope someone who knows more than me will chime in for you.

 

[OG 91 LC]

I've used the Leslie spill free funnel on my old 80 series and it worked great for getting air bubbles out of the system. I haven't done a flush/fill in the 100 yet so I can't comment on that part. View attachment 1020681

Yup. I just bought this set up to do the coolant flush on the '06 Prius. Need to flush the coolant and replace on both the '96 and the '98.

Fill the bucket half way up with coolant.
Turn on blowers to high and temp at its warmest/hot.

Let the system cool.

Repeat.

While the vehicle is running and blowing hot air in the cabin have a person press on the gas at a steady rate while you squeeze on some of the coolant hoses.

That should do it.