So on my 95 the coolant dash gauge likes to ride just over half way. We’re is normal? I’ve heard just under half way 40% is normal. I’ve filled the radiator through the filler hole behind the thermostat housing. An done the bleeding procedures. Also when I drive on the freeway the temp gauge will go down below halfway. My car currently has the green coolant in it. But I want to swap it out for the long life red coolant. Is this possible? I’ve also used compressed air to blow out the fins on the radiator. It was dirty. Do I need to do some sort of cooling system flush? Would a bad thermostat cause the temp gauge to move from just over the half way point when in the city. An go even lower while driving on the interstate.

thanks you guys

 

yes under half was normal to see on my 97. if it was right at 50% i started to think my engine was overheating (which it did a few times due to air in the system). do you know if your radiator fan clutch is working as it should? they way the temps are moving indicates a bad fan, not a bad thermostat.

the bleeding procedures i found need to be done for at least 20 minutes AFTER the car gets up to temperature to ensure all bubbles are worked out once the thermostat opens. also i found it helpful to have the nose up in the air or higher as sitting on a inclined driveway to push those bubbles even further up/front and out of the fill hole (i used the fill hole at the t-stat housing to add coolant and not the reservoir).

it's easy to swap the coolant to red (which i recommend you do for the longevity of the water pump) but it will take much more than a drain of the radiator. there are drain ***** on the block itself to get all the coolant extracted.

 

How is the health of your cooling fan clutch? It uses a thermo-couple mechanical clutch to drive the primary cooling fan for the engine. The hotter the engine is, the more the fan is supposed to engage and spin. The cooler, the more it slips. They typically fail in two ways, completely open and the fan barely spins and you overheat, and seize fully engaged to where it's always spinning and cools your engine down more than normal.

The fan typically engages a lot when you start the car, but then opens up and quiets down quickly. Do you get a lot of fan noise tied directly to RPM from the engine? In the real world you typically hear a similar sound from big diesel trucks and their heavy-duty fans

As for the temp gauge, I believe this is where yours should sit and should never, ever move. Because yours is cooling down on the highway - that suggested to me the cooling fan clutch.

I'm just presenting the fan clutch as a possible failure point - this may not be it. It also could be the thermostat or other systems as well.

 

Yes I have a new fan clutch from the Lexus dealership I wouldn’t think a brand new part from the dealership would be bad. But I guess anything is possible. Do you know if the dealership would help me out of this part is faulty.

 

So I had to have my fan clutch replaced as well. I did it at an indy shop, they put some **** aftermarket part on. The clutch was broken, or they botched the install, and was constantly spinning like a diesel engine all of the time. The engine would cool off going down a mountain because the fan would be still spinning like mad even though the engine wasn't making heat as I was rolling down. Eventually had them replace with a true OEM part, problem solved.

It's possible, though highly unlikely that you have a failed part, or that the install was botched. It's possible to **** up the install and mess with the thermo-coil thingy in there clutch that controls it.

Did the car loose MPG after the clutch was replaced? Was the engine fan significantly louder all of the time after the replacement? Even in the summer in rush hour, my functioning fan doesn't spin nearly as much as the broken fan did. Did the car feel like it was dragging a boat anchor, loosing a lot of bottom end grunt below 2000rpm? Then I would suggest looking into the cooling fan.

If those don't sound familiar, then it's likely it's another issue.

 

So to be clear I had the ECU rebuilt by lscowboy. Before we I had the ECU rebuilt yes the car felt light I was towing a boat anchor. After the rebuilt ECU was put in the car performed a lot better. Felt like a V8. One night in my driveway running the car at idle I noticed the temp gauge rising above half way so I turned it off an ordered a new fan clutch from Lexus installed that an seems to be working. I’m thinking I might still have air in the cooling system MPG still isn’t the greatest as I like to have my foot in the pedal.

 

Yes my MPG isn’t all the good but that doesn’t help that I like to have my foot in the pedal. I’ve also changed out temp sensor in the drivers side lower corner of the radiator.

 

have you changed the coolant temp sensor on the engine? that's another culprit of poor MPGs.

also clean the MAF sensor as well and replace your air filter if dirty. small stuff make a big difference here!

 

So I have both sensors that mount just behind to thermostat housing I’m going to change soon as the rain stops. I will let you guys know my outcome as far as the MPG’s

 

UPDATE- so I just replaced the two sensors. The engine coolant one an the sensor for the gauge. So as far as the MPG’s go I don’t know yet as I just filled up the car today and I have only put 6 miles on since the new sensors have been installed. I filled the cooling system through the fill hole just behind the thermostat housing. Ive burped the system numerous times added more coolant. An my temp gauge is still right above the half way mark. I’m hoping with my new coolant reservoir cap it will self bleed the rest of the air out of the system. Also put in a new thermostat (from dealership) I have a new fan clutch as well as 3 new temp sensors for the system. I guess we will see.

 

Update so after replacing the two sensors an bleeding the system completely my temp gauge is just about the half way mark. I have to think at this point the my gauge cluster resistors could be at fault for the temp gauge reading. As we all know the needle should be on the middle or JUST below the middle mark. I bought a innova scan tool. An it does read a lot of data I’m still trying to figure it out. Also I’m pretty sure i need to change the cap an rotors. Cold misfires. Runs good when’s it a warmed up.

 

Timmy tool what product would you use to clean the MAF sensor? An how to. Thank you. I don’t want to mess anything up here.

 

this is what i like to use. youtube some how-to videos!

 

My ‘98 sits consistently at one hash mark above 50%, and has since I bought it 7years ago at 180k. I have done two timing belt / water pump services, coolant has been changed at regular intervals and new thermostat and water temperature sensors - all oem parts.

I have always just assumed this is where temp needle should sit since it’s been so consistent throughout my ownership.

 

Make sure you know your cooling system is topped off with no air bubbles in the system. So I changed all 3 sensors an everything seems good. Except my temp gauge on my cluster seems high. I have a scan tool an the temps seem fine. ***update*** after changing the temp sensor on the engine by the thermostat housing. Yes my MPG improved…- Do it.
Also after I checked an then changed my ignition caps an rotors (mine was pretty dirty) my car runs really good.

Make sure you disconnect the negative battery cable before you change this sensor out. (I would disconnect both cables while you do this repair the 95 ls400 Re learns “your” driving behavior an can adjust (if need be)
Via. ECU