You need to set the opacity of your paint brush to 100% or go over the plate a couple more times
What have you done to your 100 Series this week? (7 Viewers)
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Eyedaho
SILVER Star
I don't think there's any need to turn on the heaters on our rigs, since there are no valves in the coolant system related to HVAC. Doesn't hurt, but I think it's not necessary for us right?
I just assumed that since the heater T's were so high up, I wanted to guarantee that those lines were flowing. I could be mistaken.
I believe @Eyedaho is correct here. Certainly doesn't hurt anything, but it's not like the Sequoia/Tundra of the same era that have a valve that opens/closes to prevent hot coolant from circulating in the cabin when you don't want heat.
On the other hand, that valve is just like the heater tees, so you (should) replace it every 100k-ish if you have a Sequoia or Tundra.
Eyedaho
SILVER Star
The HVAC controls only affect the air side of the heat. The coolant flows the same regardless.
Well then that bodes well for not having any coolant leaks
Or it would have been apparent whether I used the heat or not.
Thanks.You need to set the opacity of your paint brush to 100% or go over the plate a couple more times
Yeah, as far as I knew U.S. 100`s don't have heater valves.
2001LC
SILVER Star
We do not need to turn heaters on, to top coolant system. Since coolant flow, is constant (no shut off valve) through heater cores:
When filling coolant system. The FSM states: "Turn heater(s) on to full hot" I believe this to be carry over instructions, from much older type heater core system. One in which, there was a flow control valve that opened and closed. To control the coolant flow to and through heater cores. We do not have a fluid flow control valve any longer, so don't actually need to turn cabine heat on.
But, by turning cabin heat on, front and rear. We can confirm coolant flowing through heater cores, once engine at operating temp. By feeling the heat. If no heat or blowing only lukewarm. This tells us. The coolant system is low on coolant, has bad thermostat or a blockage. I've had on occasion, air bubble blockage in the core(s), mostly in front heater core.
Topping coolant system. Why park for 8 hours after engine reaches operating temp, with front end higher than rear:
First, As engine reaches high range of operating temp, coolant expands into expansion tank (reservoir). The expanding coolant, creates positive pressure within the system. The radiator cap, release pressure at a specific PSI. A weak cap, will release coolant into expansion tank to soon. This can result in lower than normal (optimal) operating temp. (Pressure = heat, Heat = pressure). A cap that is sticking, can result than higher than normal operating temp (pressure). This can result in coolant leaks, even blow the plastic top of old radiators or busting old tees.
As engine and coolant cools, it draws the coolant back into system from the expansion tank. The "cooling for 8 hrs" is to ensure it completely cools, contracting creating a vacuum. ("Contraction" meaning the fluid takes up less space as its molecules slow down and move closer together.) We want to check level, when system the coolest. We do not remove radiator cap until then, or we lose vacuum. We check before sun-up, heats the air and thus coolant, which begins to expand.
We park with front end higher than rear. As this place radiator cap, at high point of coolant system. Air moves to highest point. We can do with vehicle level. But than, heater Tee's are about same level as rad cap. So parking front end higher than rear (facing uphill), is very best.
We repeat, if we needed to add coolant. Why: Just in case we've air bubble(s), still within the system.
Reservoir, must never be below low (end of pick up hose within). Or we suck air back into the system, during cool down (vacuum faze). Reservoir hose must drop straight down to bottom of tank. Make very sure hose does not get hung up in inner shelf, or it curls upward and sucks air. The reservoir hose and it's cap, must not have any blockage.
We don't want air in the system, why:
First, too much air in system, and water temp sending unit, will read air temp. Which give false low temp reading on dash water temp gauge. It also gives false info to ECM. Which effects control system, like fuel trims and AT from shifting into high gear. This reading air temp, is the number one reason, the 2UZ engine blows, due to overheating. Since we think all is good based on water temp gauge, when in fact engine is way to hot. Since the low level is resulting in coolant not flowing throughout properly the system, and so, heat can't dissipating through radiator.
If just a little air in system, it collect in high points during cool down. Which is top plastic of radiator and plastic heater tees. This results in plastic drying out. It is one of the reasons, some radiator and heater tees, fail earlier than expected life. It also change to pressure within the system, so rad cap will not work properly.
When filling coolant system. The FSM states: "Turn heater(s) on to full hot" I believe this to be carry over instructions, from much older type heater core system. One in which, there was a flow control valve that opened and closed. To control the coolant flow to and through heater cores. We do not have a fluid flow control valve any longer, so don't actually need to turn cabine heat on.
But, by turning cabin heat on, front and rear. We can confirm coolant flowing through heater cores, once engine at operating temp. By feeling the heat. If no heat or blowing only lukewarm. This tells us. The coolant system is low on coolant, has bad thermostat or a blockage. I've had on occasion, air bubble blockage in the core(s), mostly in front heater core.
Topping coolant system. Why park for 8 hours after engine reaches operating temp, with front end higher than rear:
First, As engine reaches high range of operating temp, coolant expands into expansion tank (reservoir). The expanding coolant, creates positive pressure within the system. The radiator cap, release pressure at a specific PSI. A weak cap, will release coolant into expansion tank to soon. This can result in lower than normal (optimal) operating temp. (Pressure = heat, Heat = pressure). A cap that is sticking, can result than higher than normal operating temp (pressure). This can result in coolant leaks, even blow the plastic top of old radiators or busting old tees.
As engine and coolant cools, it draws the coolant back into system from the expansion tank. The "cooling for 8 hrs" is to ensure it completely cools, contracting creating a vacuum. ("Contraction" meaning the fluid takes up less space as its molecules slow down and move closer together.) We want to check level, when system the coolest. We do not remove radiator cap until then, or we lose vacuum. We check before sun-up, heats the air and thus coolant, which begins to expand.
We park with front end higher than rear. As this place radiator cap, at high point of coolant system. Air moves to highest point. We can do with vehicle level. But than, heater Tee's are about same level as rad cap. So parking front end higher than rear (facing uphill), is very best.
We repeat, if we needed to add coolant. Why: Just in case we've air bubble(s), still within the system.
Reservoir, must never be below low (end of pick up hose within). Or we suck air back into the system, during cool down (vacuum faze). Reservoir hose must drop straight down to bottom of tank. Make very sure hose does not get hung up in inner shelf, or it curls upward and sucks air. The reservoir hose and it's cap, must not have any blockage.
We don't want air in the system, why:
First, too much air in system, and water temp sending unit, will read air temp. Which give false low temp reading on dash water temp gauge. It also gives false info to ECM. Which effects control system, like fuel trims and AT from shifting into high gear. This reading air temp, is the number one reason, the 2UZ engine blows, due to overheating. Since we think all is good based on water temp gauge, when in fact engine is way to hot. Since the low level is resulting in coolant not flowing throughout properly the system, and so, heat can't dissipating through radiator.
If just a little air in system, it collect in high points during cool down. Which is top plastic of radiator and plastic heater tees. This results in plastic drying out. It is one of the reasons, some radiator and heater tees, fail earlier than expected life. It also change to pressure within the system, so rad cap will not work properly.
This is great info, thanks.
Curious what does the dash water temp gauge look like when the coolant is this low? How low does it indicate and is it easy to tell the difference between too low and normal operating temp (which for me it already sits below 1/2 mark at operating temp).
And wouldn't the gauge rise indicating an overheat before the level got too low? I guess if you blow a Tee on the highway it's going to dump out fast but in case of a smaller leak like a water pump weeping or radiator leaking I imagine the coolant level would slowly drop to the point where coolant can get too hot but the level would still be above the temp sending unit so the gauge will rise appropriately to warn the driver.
But, if not I guess the thing to look for in an overheat scenario is a low temp gauge and not a high one, which is bonkers.
2001LC
SILVER Star
Low from leaks, heater tees blowing or not properly topping.
If coolant level to low, which is about at top of radiator core (seen, about 4" below bottom of rad cap gooseneck), seen when we look in radiator. It's also below water temp sending unit (WTSU). Gauge reads low, somewhere below 1/2 way mark. While WTSU is in air, rather than coolant. Coolant flow, is not complete through the heads. Heads over-heat, and so may block, depending on how low. As block gets hot, transferring heat to coolant. The coolant expands to point it may now reaches WTSU. Then suddenly, dash gauge shoots up into red. Very likely, heads have warp at this point. Engine likely is toast, as coolant now gets into combustion cylinder. If coolant reaches CAT, likely they'll also be damage also.
A little low we may run a tad hot. Plastic in coolant system, than expose to air. When it should be coolant, all the time. Will age, faster than normal.
Number one reason heater tees and top of radiator blow, is stuck radiator cap. It was heat, age and air that causes the plastic to weaken/crack. When we see badly browned, cracky radiators top plastic, pre ~20 years old. You can bet, coolant not properly flushed and topped at some point.
Do you know exactly how low will the gauge read when the coolant level is below the WTSU? You say it will read below 1/2 way... but my gauge already reads a bit below the 1/2 way mark at normal operating temp (187F-190F verified by scan tool).
Just curious if there's a detectable difference in the temp indicator gauge between WTSU reading normal coolant temps vs. coolant too low & WTSU reading air.
2001LC
SILVER Star
LC do tend to read a tad low on gauge. If your tech stream shows 184 to 187F, that gauge level is perfect.
You say it will read below 1/2 way... but my gauge already reads a bit below the 1/2 way mark at normal operating temp (187F-190F verified by scan tool).
Just curious if there's a detectable difference in the temp indicator gauge between WTSU reading normal coolant temps vs. coolant too low & WTSU reading air.
The LX gauge moves more and read a bit higher.
If gauge only 1/8 to 1/3, when engine is obviously hot. it's a clue we should check coolant system.
Spent about five minutes installing a Lutz Auto speedo corrector, replacing my failing (after 10 years) Yellow Box. The Lutz is far easier to set up and works flawlessly. Easy like pie.
Installed a new OEM radiator and upper and lower hoses. Overall a pretty straightforward job. Worst part was having to drop and re-install my skids.
Here is the original, 23 years old with 220k miles. It wasn’t leaking but was brown. Changing it definitely gives me a little more peace of mind.
Here is the original, 23 years old with 220k miles. It wasn’t leaking but was brown. Changing it definitely gives me a little more peace of mind.
yah the browning on the the top cap of the radiator gave me anxiety on mine
I’ve now shifted my anxiety to the ignition rod breaking. I think I have PTSD from a couple of decades of Land Rover ownership…
When I was 17 I had my radiator hose explode on me while sitting in traffic in my 76 VW Scirocco so ever since that experience I've very mindful of that water temp LOL we all seem to have a little car PTSD we carry with us.I’ve now shifted my anxiety to the ignition rod breaking. I think I have PTSD from a couple of decades of Land Rover ownership…
