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A towing package was never available in North America for any year of the LS400, LS430 or LS460. IIRC, my owners manuals for the two LS400's I owned either prohibited towing or didn't say much or anything about it while the 1993 LS400 owners manual I still have for Europe has a number of pages devoted to how to tow safely with the LS400.
A towing package was available in other world regions for the 2000 LS400 with its components marked in the Toyota parts lists as being for "MIDDLE S.AMERICA OR W(TOWING PACKAGE)".
The radiator for the 2000 LS400 I drove for 11 years is part number 16403-50131. The 2000 LS400 radiator part number for ""MIDDLE S.AMERICA OR W(TOWING PACKAGE)" is part number 16403-50151.
LS400 with the towing package had an ATF cooler under the radiator but I never noticed or looked to see if my 2000 LS400 had one, i.e. I don't know if all 98-00 LS400 have the ATF cooler or if it was part of the towing package.
I idled the engines of both my 1990 and 2000 LS400 for hours at a time on a number of occasions when it was over 100 degrees and the coolant temperature gauges didn't budge at all off normal. I was a little surprised that my 2000 LS400 had only one electric fan in front of the radiator since my 1990 LS400 had two. The early LS400 sold in Europe never had more than one electric fan in front of the radiator.
We'd had ours idling at peaks of 111F in Vegas (The parking structure read at 116F) and 118F for Baker. Would be curious what Toyota did for these in the towing package.
Would be curious what Toyota did for these in the towing package.
It's hard to say. I just now checked my gen 1 LS400 owners manual for Europe and it says only to have the Lexus dealer install a towing kit including oil cooler, etc. It does't say if it's a transmission or engine oil cooler and it doesn't say what "etc." means. I do know that all years of the LS400 and LS430 with the towing kit have a maximum towing capacity rating of 2000 kg which is about 4409 pounds. I assume that the "oil cooler" is an additional transmission cooler based on what members of UK and European Lexus forum members have said over the years ... like in the following thread: https://www.lexusownersclub.co.uk/fo...0-as-a-towcar/
The transmission fluid is cooled through the radiator operating at 185 F...so plausibly it is returned to transmission at or above 185 F.
Secondary air cooling unit in series with return line could reduce that temperature further. (limited to rise above ambient)
Some information available online:
"At higher temperatures the transmission begins to slip, which only aggravates overheating even more. ... As a rule of thumb, every 20 degree increase in operating temperatureabove 175 degrees F. cuts the life of the fluid in half! At 195 degrees F., for instance, fluid life is reduced to 50,000 miles."
"The ideal range for fluid temperature is between 175 and 225 degrees, and every 20 degree drop in fluid temperature can help to double the life of your transmission."
Alternate temp, 170 degree, thermostats are available but I've heard it's not wise to use one in an LS as the ECU will constantly try to "compensate" back to 180 and run rich. Is this correct or would a 170 stat work...?
Alternate temp, 170 degree, thermostats are available but I've heard it's not wise to use one in an LS as the ECU will constantly try to "compensate" back to 180 and run rich. Is this correct or would a 170 stat work...?
The coolant temperature sensor addresses the ECU...so installing 170 F temperature thermostat will never achieve closed loop mode:
Anyone with a laser temperature gun that can measure transmission coolant temperature at transmission fluid metal lines at point entering and exiting the transmission cooler at bottom of radiator ..after driving.on a 100F day.
It's hard to say. I just now checked my gen 1 LS400 owners manual for Europe and it says only to have the Lexus dealer install a towing kit including oil cooler, etc. It does't say if it's a transmission or engine oil cooler and it doesn't say what "etc." means. I do know that all years of the LS400 and LS430 with the towing kit have a maximum towing capacity rating of 2000 kg which is about 4409 pounds. I assume that the "oil cooler" is an additional transmission cooler based on what members of UK and European Lexus forum members have said over the years ... like in the following thread: https://www.lexusownersclub.co.uk/fo...0-as-a-towcar/
Interesting info on Lexus offering the tow package. Maybe they did not offer it in the US since it's not a good idea / not popular. And maybe they had to do it in Europe because it is a requirement?
Most cars I know about (including my '91 LS400) have an ATF (called AT oil there, for some reason) cooler built in to the bottom of the (engine coolant) radiator, as the standard setup. This is an engine coolant - to - ATF heat exchanger, which will bring the ATF quickly up to engine temperature, and will then keep it pretty steady since the engine coolant temp is pretty closely regulated.
People who know they have a weak AT, or will be towing, often install an extra ATF cooler, which is an air - to - ATF heat exchanger, mounted in front of the radiator (to catch the cold fresh air) that is typically mounted after (in the flow circuit) the radiator-built-in AT oil cooler. Gives extra cooling, dropping below engine temp towards air temp.
My Honda Odyssey had a towing package that came with a little, weak, ATF cooler, along with the tow hitch, so it could be that is what Lexus sold in their kit.
Another thing towing does is to make you rev higher than normal. That puts extra strain on the PS system, even though the steering effort is not much higher. So it is also common to sell auxiliary PSF coolers that similarly mount in front of the engine coolant radiator.
Anyone with a laser temperature gun that can measure transmission coolant temperature at transmission fluid metal lines at point entering and exiting the transmission cooler at bottom of radiator ..after driving.on a 100F day.
Thanks.
I'd help, but it never gets more than about 90*F out here.
But on your general premise here, I'll point out that modern BMW's run with an engine coolant setpoint around 225*F (requires pressurization to prevent boiling - the coolant expansion tank release valve is 2.0 bar = about 30 psi), and use an ATF-to-engine coolant "AT cooler" in there. So they're bringing the ATF on purpose up there. Of course, they design for that. Another factor with AT's I believe is that they like to run at a constant temp. So if BMW wanted to run the engine hot for purposes of efficiency, they had a choice between designing an AT to run hotter, or using a colder but more variable ATF-to-air cooler. They chose the hotter, more stable, engine coolant AT cooler.
I'd help, but it never gets more than about 90*F out here.
But on your general premise here, I'll point out that modern BMW's run with an engine coolant setpoint around 225*F (requires pressurization to prevent boiling - the coolant expansion tank release valve is 2.0 bar = about 30 psi), and use an ATF-to-engine coolant "AT cooler" in there. So they're bringing the ATF on purpose up there. Of course, they design for that. Another factor with AT's I believe is that they like to run at a constant temp. So if BMW wanted to run the engine hot for purposes of efficiency, they had a choice between designing an AT to run hotter, or using a colder but more variable ATF-to-air cooler. They chose the hotter, more stable, engine coolant AT cooler.
Modern engines run hotter...to improve efficiency...but do not believe transmissions like to run at those same elevated temperatures...
Our cooling systems are designed to operate at 185F.....and transmission fluid is cooled and, or heated in part by the radiator...
The question is to what "degree".
Transmission life expectancy statistics suggest 175F over 185F operating fluid temperature significantly improves life of an automatic transmission....probably 165F would be better...
Not sure where life expectancy curve flattens out on lower end of transmission fluid temperature vs life expectancy ...but from a viscosity standpoint imagine140F would be close.
Do not have a laser thermometer....so if anyone does and can post readings...
Anyone with a laser temperature gun that can measure transmission coolant temperature at transmission fluid metal lines at point entering and exiting the transmission cooler at bottom of radiator ..after driving.on a 100F day.
Thanks.
My employer has a few temp guns that I can use for an evening. It's currently 116F here, so that should work. I'll grab a gun tomorrow and measure in the evening when temp is closer to 100.
I've never noticed the ATF cooling lines. Am I looking below the radiator on the drivers, or passengers side?
I've got a relatively new complete cooling system, everything OEM except the radiator itself. It is a Performance Radiator brand oe replacement - I would trust their product as much if not more than the oem unit.
Even in this extreme heat my coolant temps dont budge.
My employer has a few temp guns that I can use for an evening. It's currently 116F here, so that should work. I'll grab a gun tomorrow and measure in the evening when temp is closer to 100.
I've never noticed the ATF cooling lines. Am I looking below the radiator on the drivers, or passengers side?
I've got a relatively new complete cooling system, everything OEM except the radiator itself. It is a Performance Radiator brand oe replacement - I would trust their product as much if not more than the oem unit.
Even in this extreme heat my coolant temps dont budge.
The transmission fluid cooler fittings plumb into the radiator at the bottom.
Removing engine undercover is necessary to obtain accurate temperature readings....
Not sure which side is inlet or outlet flow for transmission....
06-30-18, 07:07 PM
Towing package radiator 1995 - 2000 ls400
