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- #21
Interesting.
Folks, thanks for educating me on this.
I have to admit, someone (whoought to does know) told me it works this way, but I was dubious. (shhh, he may be listening)
Other goings on with the cooling system confused things.
1) There were a couple of not so obvious low level seeps at slightly loose hose clamps.
Seemed like coolant consumption. Not - just loss. All tight now.
2) My truck runs hot and variable - bordering on overheating.
With hot weather coming on, we'll see if it gets bad. TBD
I'm told (same individual) that a lot of Landcruisers just normally run hot.
Nothing at all is wrong. Don't worry - be happy. Just drive it.
Hmm. It still bugs me. There has to be a reason. Why some and not others?
Summing up all the stories I read here, I'd say there are 2 kinds of trucks.
1) Practically never gets over 195F, no matter what. These guys have all kinds of radiators, BTW.
2) Runs hot and variable. 210-220 not uncommon under load. Nothing wrong and no apparent cause.
I have both 0.9 bar (13psi) and 1.1 bar (16psi) pressure caps.
I also have a coolant system pressure gauge so I can watch exactly what it does. It does a lot of things.
1 mile after cold start, about 155F, the system is already hitting pressure limit and pushing coolant out.
Both caps work as advertised. Either 12.5 or 15.5psi peak pressure is what I see. Over and over.
Even more interesting - It "breathes" under steady state conditions.
Cruising along the freeway, completely warmed up, flat ground, system pressure and temperature rise and fall together.
No obvious reason why it decides to rise and fall.
Pressure will hit peak for couple of minutes, then slowly drops to about 2/3 peak, stay there for a while, then repeat.
Emphasizing that high pressure and high temp go together.
Took a test drive last Sunday here in Phoenix, late afternoon, sun falling. HWY 60 east, 202 northwest, Beeline Hwy north.
Temperature about 103F and probably dropped to 98 or so during the drive. Pretty warm but not extreme.
1.1 bar pressure cap installed.
213F at 11psi, 218F at 15.5psi. Cycling up and down.
Temp peaked at 222F after slowing down to turn around after a higher load uphill section.
That seems to be stored heat showing as higher temperature for a couple of minutes with reduced airflow.
It slowly drops down to 195 or less at idle with A/C on, given a few minutes.
Another thing - Air conditioning cutoff.
My Engine Coolant Temperature (ECT) Cut Switch turns off the A/C at 220F, and back on at 218F.
The FSM says it should cut off at 226F and back on at 217F (with hysteresis).
May have to replace it because it normally runs in that range and I loose A/C.
EDIT p.s. All of this behavior was with a CSF 2517 all brass radiator, in good shape.
Later, changed to a TYC 1918 aluminum / plastic tank radiator - the pressure vs temperature behavior changed signifigantly, even when just warming up, well below normal thermostat opening temperature. Also, overflow tank level became much less dynamic. It didn't push coolant out into the tank until the engine was good and hot, ambient conditions were hot, and higher heat load.
Folks, thanks for educating me on this.
I have to admit, someone (who
Other goings on with the cooling system confused things.
1) There were a couple of not so obvious low level seeps at slightly loose hose clamps.
Seemed like coolant consumption. Not - just loss. All tight now.
2) My truck runs hot and variable - bordering on overheating.
With hot weather coming on, we'll see if it gets bad. TBD
I'm told (same individual) that a lot of Landcruisers just normally run hot.
Nothing at all is wrong. Don't worry - be happy. Just drive it.
Hmm. It still bugs me. There has to be a reason. Why some and not others?
Summing up all the stories I read here, I'd say there are 2 kinds of trucks.
1) Practically never gets over 195F, no matter what. These guys have all kinds of radiators, BTW.
2) Runs hot and variable. 210-220 not uncommon under load. Nothing wrong and no apparent cause.
I have both 0.9 bar (13psi) and 1.1 bar (16psi) pressure caps.
I also have a coolant system pressure gauge so I can watch exactly what it does. It does a lot of things.
1 mile after cold start, about 155F, the system is already hitting pressure limit and pushing coolant out.
Both caps work as advertised. Either 12.5 or 15.5psi peak pressure is what I see. Over and over.
Even more interesting - It "breathes" under steady state conditions.
Cruising along the freeway, completely warmed up, flat ground, system pressure and temperature rise and fall together.
No obvious reason why it decides to rise and fall.
Pressure will hit peak for couple of minutes, then slowly drops to about 2/3 peak, stay there for a while, then repeat.
Emphasizing that high pressure and high temp go together.
Took a test drive last Sunday here in Phoenix, late afternoon, sun falling. HWY 60 east, 202 northwest, Beeline Hwy north.
Temperature about 103F and probably dropped to 98 or so during the drive. Pretty warm but not extreme.
1.1 bar pressure cap installed.
213F at 11psi, 218F at 15.5psi. Cycling up and down.
Temp peaked at 222F after slowing down to turn around after a higher load uphill section.
That seems to be stored heat showing as higher temperature for a couple of minutes with reduced airflow.
It slowly drops down to 195 or less at idle with A/C on, given a few minutes.
Another thing - Air conditioning cutoff.
My Engine Coolant Temperature (ECT) Cut Switch turns off the A/C at 220F, and back on at 218F.
The FSM says it should cut off at 226F and back on at 217F (with hysteresis).
May have to replace it because it normally runs in that range and I loose A/C.
EDIT p.s. All of this behavior was with a CSF 2517 all brass radiator, in good shape.
Later, changed to a TYC 1918 aluminum / plastic tank radiator - the pressure vs temperature behavior changed signifigantly, even when just warming up, well below normal thermostat opening temperature. Also, overflow tank level became much less dynamic. It didn't push coolant out into the tank until the engine was good and hot, ambient conditions were hot, and higher heat load.
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