SHOoff11

Yeah, I fixed a leak where the engine block heater is and had to refill the system. The cooling system was replaced about a year ago.

lexusls4

My 99 has been doing this for about one year so far. It does exactly what you mention . I will check the thermostat next but you should also. This problem is very unpredictable . When I rise , it almost fluctuate .

SHOoff11

I just replaced my thermostat and radiator cap. The previous owner replaced the radiator, fan clutch, and I think the water pump.

timmy0tool

iTrader: (7)

funny you bump this, i'm actually experiencing overheating again too, but could be due to the high summer temps our state is seeing.

mine happens when sitting in traffic for over 30 mins with no air movement. my fan turns on like normal when the temp rises. when i see the needle move up, i kick the heater on and no hot air results until i rev the car holding at 2k rpms then the needle drops to normal. of course this is a tell tale sign of air in the system. time to rebleed, but how i wonder could air reenter the system. i could possibly have a leak (hope not).

SHOoff11

Mines the same way. I tried bleeding it again this morning like you saw in my other thread. I have some driving to do for work later so we'll see if it got fixed. If not I'm looking into replacing the ECT sensor.

timmy0tool

iTrader: (7)

i plan on changing my ECT sensor too at this point since i will be rebleeding anyway. why not do yours!

JohnAndic

I am trying to do this on my 97. I am slow so I don't get it. If I fill the coolant reservoir won't that be too much coolant in there? Why do I have to fill it up with more coolant? I just want the air bubbles out. I don't think I have less coolant then I need.

RA40

iTrader: (6)

Did you drain from the block plugs too? Just make sure that the reservoir level is at the full marker once at operating temp. Any excess will be purged due to pressure so it won't be overfilled. Having it under may lead to overheating and erratic temp readings with air in the system.

spuds

Start at post 64 thru 81 on my thread with pictures,81 shows filling it.Worked for me

https://www.clublexus.com/forums/ls-...acement-5.html

spuds

Thats not a reservoir per se.Its a pressurized component of the radiator.So yeah,you fill it to the line and thats correct.

JohnAndic

I didn't drain the coolant. I think I let some air into the system when I was cleaning the engine bay and disconnected the radiator reservoir. But I should be able to get the air out with this method. I am getting slightly higher temp readings which go back to normal when I run the heater.

JohnAndic

Thanks. I probably should change the Power Steering fluid also.

SO, unless I am mistaken. If I want the air bubbles out of the cooling system I need to open the reservoir and loosen the bleed hex nut. Run the engine for a while until it is at OP. Add coolant until all full line then tighten it all back up. Air bubble will escape the reservoir?

bradland

Cooling systems are designed to expel any air naturally but sometimes they can be a little contrary. There’s a short (approx 6”) hose attached at the base of the radiator cap inlet. It bends 90 degrees and points straight down. This is where air and any surplus coolant escapes. There are a couple more very small hoses attached to the reservoir. One goes to the radiator and the other snakes down below the thermostat. These small hoses can leak or become partially clogged causing random issues. If the system isn’t expelling air on its own I’d check all these tiny hoses for obstruction or leaks.
Edit- the hex nut is not a bleed valve.

spuds

So....The hex nut fluid filler is open,fill that with fluid until full,car running and heater on.Fill the pressurized 'not a reservoir' reservoir.Cap it up,go for a drive.Refill the 'reservoir' again after cooled off and car has siphoned in however much fluid it will.Go for a drive and do it again until the 'not a reservoir' reservoir remains at full line.
Its simple John,maybe my instructions arent,Im not a great teacher for sure.

MxRider28

(slow clap that picks up in speed and number of people clapping.. like in the movies)

So here's one for you gentlemen.. What would cause my temp gauge to be this DEAD? I've owned this '97 Coach Edition for a handful of years now. Temp gauge was always very 'lethargic' to move very much. About 2 years ago I blew a radiator hose off due to over heating from a failed thermostat. Every since I blew that coolant hose (hose didn't burst, just became so hot and pressurized that the clamp failed and allowed it to shoot off the port) my temp gauge has been BURIED; like more than 6ft under as you can see from the photo. What on earth would control the needle to get THIS out of wack?? I've replaced both the green coolant temp sensor, and the one on the actual radiator. I'm not sure how to confirm a failed coolant temp sending unit; but if my temp sensors themselves are good; what variables are left besides sending unit??


Temp gauge = BURIED... ?????


THANK YOU in advance for the advice! Cheers