Cooling Issues
Thread Starter
Driver
Joined: Feb 2004
Posts: 99
Likes: 0
From: North Carolina
Cooling Issues
Fellas, thanks to some threads here, I learned how to bleed my coolant system after a thermostat replacement (should have learned long ago....I"ve had this 98 since 04 lol).
Anyhow... I'm still having weird issues. The reason I thought I needed a new thermostat was because my car was overheating in traffic, especially with the AC on. Otherwise, it ran at normal temp.
After replacing thermo and bleeding the system (or, attempting to, anyhow), I noticed a few weird things.. when test driving with the heat on full blast, I got plenty of very hot air coming out. When I'd come to a stop however (again, with heat on full blast), I would get luke warm to ambient temperature air coming out (and you'd think the air would be hotter at a stop!?).
When I ran the AC in park (keep in mind the temp outside wasn't all that warm at 75 degrees F), the temp gauge would rise more than normal, but far from the red zone as it did before I changed the thermostat.
Any thoughts??
Anyhow... I'm still having weird issues. The reason I thought I needed a new thermostat was because my car was overheating in traffic, especially with the AC on. Otherwise, it ran at normal temp.
After replacing thermo and bleeding the system (or, attempting to, anyhow), I noticed a few weird things.. when test driving with the heat on full blast, I got plenty of very hot air coming out. When I'd come to a stop however (again, with heat on full blast), I would get luke warm to ambient temperature air coming out (and you'd think the air would be hotter at a stop!?).
When I ran the AC in park (keep in mind the temp outside wasn't all that warm at 75 degrees F), the temp gauge would rise more than normal, but far from the red zone as it did before I changed the thermostat.
Any thoughts??
Lexus Champion
Joined: Dec 2011
Posts: 4,078
Likes: 87
From: Birmingham, AL
the heated air will not be hotter at a stop (engine is at idle)
also, did you pay attention to the orientation of the thermostat when installing (bleed hole up)?
if you have over 200K miles, it is likely you need a new radiator - they eventually clog up!
also, did you pay attention to the orientation of the thermostat when installing (bleed hole up)?
if you have over 200K miles, it is likely you need a new radiator - they eventually clog up!
Last edited by LScowboyLS; Sep 20, 2012 at 02:36 PM.
Thread Starter
Driver
Joined: Feb 2004
Posts: 99
Likes: 0
From: North Carolina
Check for debris between the A/C condenser and radiator. Leaves find their way in there and if you have a collection, it can be a significant disruption of air passing through the radiator.
Thread Starter
Driver
Joined: Feb 2004
Posts: 99
Likes: 0
From: North Carolina
I pulled the thermostat housing off to see where the bleeder hole was...but the thermo fell off before I could take notice. I oriented the hole upward and put everything back together.
I left the bleeder valve off as the car warmed up to temperature ... but never noticed (that I could tell) fluid moving. The operating temperature was holding steady at normal levels, however.
When I turned the AC on full blast, the temperature rose quite a bit above normal...but I never saw the auxiliary electric fan on the condenser unit kick on.... At what point should this fan come on?
I left the bleeder valve off as the car warmed up to temperature ... but never noticed (that I could tell) fluid moving. The operating temperature was holding steady at normal levels, however.
When I turned the AC on full blast, the temperature rose quite a bit above normal...but I never saw the auxiliary electric fan on the condenser unit kick on.... At what point should this fan come on?
Thread Starter
Driver
Joined: Feb 2004
Posts: 99
Likes: 0
From: North Carolina
Thanks, checked and looked very clean of debris. I'm wondering if there is a blockage in the radiator now. I do have over 225k miles on the radiator...
Thread Starter
Driver
Joined: Feb 2004
Posts: 99
Likes: 0
From: North Carolina
I'm thinking that the system just isn't getting bled ... no coolant is being pulled back in from the reservoir, even though I've changed the thermostat twice now (to orient the air hole) - there was coolant loss in the process, but didn't notice the level change in the reservoir.
Any thoughts?
Any thoughts?
Trending Topics
CL Community Team
Joined: Aug 2011
Posts: 4,173
Likes: 1,006
From: Japan
The reason I thought I needed a new thermostat was because my car was overheating in traffic, especially with the AC on. Otherwise, it ran at normal temp.
After replacing thermo and bleeding the system (or, attempting to, anyhow), I noticed a few weird things
Any thoughts??
After replacing thermo and bleeding the system (or, attempting to, anyhow), I noticed a few weird things
Any thoughts??
That is strange to me. You may have your reason that you did so but I have never experienced the overheat caused by the aged thermostat.
Aged thermostats tend to open the gate due to the reason that the wax inside is missing a little by little and it causes the bigger water flow even at low temperature conditions. This is surely the over cooling. In the past, I have replaced nearly 15 thermostats and all the reasons were longer time to warm up or over cooling.
Your overheat might be caused by some other reasons, I guess. Judging from your posts, the water flow is not very good. Something is blocking it or the water pump not functioning properly. Clogged radiator might be the another reason to consider.
ClubLexus Stories
Celebrating Lexus & Toyota from Around the Globe
8 Tips for Improving Your Hybrid or Plug-in Hybrid's Efficiency!
Michael S. Palmer
10 Best Lexus Models No One Remembers
Joe Kucinski
TRD Off-Road Premium: Best 2026 4Runner, Except This One Thing
Michael S. Palmer
Top 10 Lexus & Toyotas to Drive Before You Die!
Joe Kucinski
Top 10 Lexus/Toyotas With The LEAST 5-Year Depreciation
Joe Kucinski
Lexus LC500 Convertible Auction: A Preview of Rising Values?
Brett Foote
GX 550 vs TX 550: Best 3-Row Luxury Lexus Family Hauler
Michael S. Palmer
9 Best Lexus Models You Can Buy for Half Price (And 1 You Shouldn't!)
Joe Kucinski
2026 Lexus NX Buyer's Guide: Models, Features, Prices & More!
Brett Foote
Lexus Champion
Joined: Dec 2011
Posts: 4,078
Likes: 87
From: Birmingham, AL
I agree with Yamae - clogged radiator or water pump broken (like blades broken etc.) would be good suspects
the radiator is not that expensive and a great idea to change at 200K anyway, that would be the first thing I would do after replacing the thermostat - both are very easy repairs!
PS - I am not a fan of cleaning a radiator internally i.e. "having it boiled", this never does much, just replace it, much better for several reasons!
PS2 - if you replaced the thermostat, you did use the real Toyota part, right? - also, I would insist on the real Toyota radiator and avoid aftermarket unless I was in a real financial bind.
the radiator is not that expensive and a great idea to change at 200K anyway, that would be the first thing I would do after replacing the thermostat - both are very easy repairs!
PS - I am not a fan of cleaning a radiator internally i.e. "having it boiled", this never does much, just replace it, much better for several reasons!
PS2 - if you replaced the thermostat, you did use the real Toyota part, right? - also, I would insist on the real Toyota radiator and avoid aftermarket unless I was in a real financial bind.
Thread Starter
Driver
Joined: Feb 2004
Posts: 99
Likes: 0
From: North Carolina
Definitely looking like a blockage somewhere. The temperature, at times, fluctuates too quickly (according to the gauge), I don't think the water temperature could change that fast...I'm thinking steam to water to steam (air in the system).
Does it overheat with AC OFF? If it doesn't overheat w/o ac but does with ac on, and aux fan doesn't come on there is your problem. I went through similar issues with my Z recently. It used to overheat in traffic/idle ONLY when AC was ON. I replaced whole bunch of other things and it came down to burnt aux fan(I blame previous owner for ghetto rigging with aux fan relays). Ever since then it's been good.
Rookie
Joined: Aug 2012
Posts: 65
Likes: 1
From: Kentucky
You could test the fan by unplugging or jumping the switch on the radiator. It is locate on the left( drivers side ) lower corner.
I can't remember if unplugging it or jumping the connector made the fan run, but I tested mine this way. It should runat high speed
The fan also runs at low speed when the A/C high side pressure reaches a certain level. If the system is low on freon it may not ever run.
I could easily see coolant flow in mine with the ( fill/ bleed ) plug near the radiator hose removed.
I can't remember if unplugging it or jumping the connector made the fan run, but I tested mine this way. It should runat high speed
The fan also runs at low speed when the A/C high side pressure reaches a certain level. If the system is low on freon it may not ever run.
I could easily see coolant flow in mine with the ( fill/ bleed ) plug near the radiator hose removed.
Last edited by Lexinky; Sep 25, 2012 at 09:07 AM.
Thread
Thread Starter
Forum
Replies
Last Post
LVLarry
GX - 1st Gen (2003-2009)
15
Feb 19, 2008 04:37 PM
