TriniLex

2005 RX
had waterpump and TB done 3 years ago
Coolant topped of
No debri on radiator
Radiator not leaking

On idle in park with ac on the temp gauge goes up the mark before the red line
When driving only goes up a hair above middle line.

I checked the fans while the car was turned on and both fans running

Any suggestions?

BlackLexRX

Sounds like thermostat going out.

TriniLex

I found that there are 2 thermostats available for this vehicle? Which one do I purchase or does it matter??

180 degree
https://shop.advanceautoparts.com/p/...erm=thermostat


170 degree
https://shop.advanceautoparts.com/p/...erm=thermostat

TriniLex

Can a bad radiator cap cause this as well?
Also to add every now and again I hear a bubbling sound from the passenger side engine.
Can air in the coolant cause this type of overheating?
thanks

BlackLexRX

Yes, replace radiator cap first. Bleed system of air too. For thermostat, what is the first letter of your VIN, 2 or J?

TriniLex

It starts with a 2
and I will buy a cap today
thanks

Toyotatam1

It's the thermostat,.There are2 types 170degree & 180 degree rule of toyotatam1s thumb is the warmer your climate the lower the temp stat.
What I mean by this is,,if you live in Scotland and it's freezing ,get the hotter stat for quick heat up
If you live in South America ,get the 170 and keep your engine cooler

BlackLexRX

Start with an OE radiator cap. Test that and if it doesn't heat up on idle, you probably good. If not go to thermostat. You dont need the housing (170-180 degree inlet), just the valve most likely. It is part #

90916-A3003.

You can find it at this website which is a forum sponsor. They sell direct fit OE parts. Higher than auto parts store, but original and correct. Here's the page I got that from and their website:
https://www.mylparts.com/oem-parts/l...MtM2wtdjYtZ2Fz

BlackLexRX

Ok, well I stand corrected, I presumed a variation in inlet position, nonetheless part number I gave is correct for your model.

Toyotatam1

Talking of Scotland! I've just brought a 2005/55 plate Ls430 ,116K everything done incl t/belt ,All pads/discs, receipt s for £3000 and only done 15k since
over past 3 years ,it's a good un! Gave it's maiden voyage today to scrub the discs of rust.
12 years old and feels like 4!

Toyotatam1

There's a simple test for your vehicle's coolant system! Take it to garage who do emissions test .
They rev your engine (preferably cool) @ 2000rpm for 30 secs then take off your rad cap and use their Emms tester to check for hydrocarbon s !
If it's over 50 ppm then your head gasket has a leak! This is why you hear bubbling in heater matrix

RXGS

iTrader: (2)

Make sure the fans are both working, one of ours failed

ukrkoz

Oh c'mon. Start with belt. Loose belt will do that. next shine light through radiator. Can you clearly see it coming through radiator honeycomb? MANY cars get debris all over radiator and then start chasing evasive cause of overheating.