jq23lexus

Hello I have a 93 lS400. I just changed the fan bracket, plugs, plug wires, caps, rotor, tensioner pulley and idler pulley. Buttoned my car back up, took it for a long test drive and noticed the temp was a little over 3/4 on the gauge. Drove home, turned on the heater to get the car back to normal operating temp. Once cooled down, I let car idle with the A/C on for about 15 mins and noticed the temp was getting really hot again and the electric fans were inop. I checked the 30 amp relay or fuse with the plastic top and it was fine. According to the fuse box thats the only relay that corresponds with the fans. I called the Lexus parts department and they assured me that there are two round fan relays? Has anyone ever ran into this problem? If so, were are they located? Is there a fan/switch or relay on the bottom of the radiator? Sorry so long just trying to be as descriptive as possible!! Thank you for your help.

python

iTrader: (4)

the relays are located somewhere in the front bumper area,
https://www.clublexus.com/forums/ls4...oling-fan.html
also did it get hot on the freeway or after u got back in town?

jq23lexus

It got hot on the freeway and at idle. I just put new red coolant in before the test drive. I also noticed the t-stat was opening up. Thank you for your help

avalon42

iTrader: (1)

You did make sure the coolant was topped off right? Sounds like you were running dry there.

Och

iTrader: (3)

Theres a coolant temp sensor/switch on the bottom of the radiator, that switches the fans on when coolant in the radiator gets hot. Check that.

jeffls400

The relays are under the driver's side headlight...but I doubt that is your problem. Some ideas - Did you fill coolant through the fill plug near the thermostat?
From your symptoms, it sounds as if there may be trapped air in the system, which effectively means the system is underfilled.
The next possibility is the temperature sensor that is mounted in the radiator on the lower driver's side. If this sensor is bad, it will not allow the fans to run. If you unplug the sensor and the fans spin, the issue is most certainly with that sensor.
Also, when the engine temperature is above the middle of the gauge, does the main cooling fan on the front of the engine spin rapidly? If not, the mechanical fan clutch may be bad. Usually, with A/C running or not, this fan alone will be able to keep the engine cool, as long as the cooling system is full.
Lastly, double-check the routing of the serpentine belt.
Hope this helps.

Jeff

python

iTrader: (4)

a mixture of 60/40 or above will cause it to overheat

jq23lexus

I filled the coolant through the resevoir. Would that cause an air pocket? I had a dead battery this weekend, charged it up and took it for a test drive. When I returned my fans were on and my drive belt was coming unraveled and the temp was fine. I untangled the little strands of belt that was wrapped around the fan clutch. I checked to make sure the belt was decent and then proceeded to a friends house about a mile away. My temp almost reached the red H by the time I arrived. I immediately shut the car off. I stayed for about an hour and engine was cool on the way home. On the way home the car got really hot again so I turned on the heater and the engine cooled down.
When I arrived home the engine was hot again with the heater off. I checked the coolant and it wasn't bubbling and the fans were not working and the gauge was in the red? I am lost and totally confused!!! If this is caused by an air pocket. How do you burp the system? I will check the switch in the bottom of the radiator when I get home today. Thank you for your help.

PureDrifter

iTrader: (10)

yes, you're supposed to put coolant in through the inlet on top of the water bypass.

jq23lexus

Thank you for your help. Any ideas on getting the air pocket out of the system? Also I did not have to put that much coolant into the system. I used about 3/4 of a gallon of the 50/50 red toyota coolant.

python

iTrader: (4)

if ur belt is commin apart u have got other problems, idler pulley,clutch fan bearing, or some other problem with the pulley system...unless ur belt is so old and hasnt been changed in 10 years or more

Chilkoot

if you're hitting 3/4 temp at idle I'd be inclined to agree that it is probably not because of the electric fans not working, sounds like you're WAY low on coolant.

IIRC, the system takes 3 gallons to fill. The easiest way to make sure there are no air pockets would be to completely drain the coolant from all 3 drain *****, and refill from the thermostat housing. IIRC from my last flush it should take ~2-2 1/2 gallons through the previously mentioned thermostat housing plug and then you'll need to add the remaining with the engine running through the coolant reservoir. There's a good writeup on LexLS, which is the one I followed when I last did mine.

Again, not totally sure on this one, but once you do have your system properly filled you should be able to test the electric fans by turning on your A/C at idle, once the compressor engages the fans should come on. Somebody please correct me if I'm wrong, I remember reading this here somewhere.

FWIW I've driven two LS400's, one '90 and my current a '93, and I don't ever recall seeing the electric fans on.

Redhare43

I noticed my electric fan motor is siezed. (pt#88590-50110)
I do not see any replacement parts available.
Has anyone done a Dorman swap??

LeX2K

There are used ones on Ebay, or roll the dice with Dorman but their parts are generally bottom of the barrel.

mjhoutx

too old to bump a thread? my dad gave me his 91 LS400, odometer stuck at 138K, with around 600-800 miles on it. He was the only owner, All stock. Doing repairs after it sat for several years in the garage. One other cluster display that is faulty is the tachometer, which barely moves when revved hard. Temp seems to be finally working again, but is stuck at 3/4 when warmed up. pulled the relays and they looked ok, swapped one of the round relays out with a fresh one from rockauto but no change in the temp gauge. Ive ordered some temp sensors and will try to do a flush and fill. Any specifics on what antifreeze to use? Zerex red? Also, should I fill from the bypass port or in the reservoir? TIA