GuyHoozdis

Hello all! I'm looking for some help determining which part, or parts, I should be investigating to identify the cause of my problem. I pulled a P0117 code, but from the data I've collected I don't think it is the ECT sensor that is malfunctioning.

My question is, what do I check next?


----- The gory details below -----

Here's what happened.

1. I was driving and my a/c started blowing warm moist air. It was intermittent at first, but by the time I got home it was not blowing cold air.
2. There was a little bit of steam coming up from under the hood. The engine temp gauge was all the way to the left - like it is broken.
3. I could hear some gurgling, popped the hood and my coolant reservoir was empty. I let the car cool down.
4. I refilled the coolant (already had a jug in my garage) and let the car sit for a few more hours. I checked the ground for any obvious puddles and checked the reservoir that it was still at the level that I filled it to.
5. I started the engine and let it run, with the hood open, in my drive way for a few minutes. It seemed fine. Cool air was blowing out of the A/C. I decided to take it for a drive.
6. I took it for a short drive on main road, topped 45 MPH. I hit one or two lights, but for the most part was just driving. No issues. A/C still blowing cold air.
7. I wasn't far from home and decided to push it a little harder. Got on a high way and got it up to 60 - 70 and cruised at that speed. It was fine for a few minutes.
8. The A/C stopped blowing cold air and some lights lit-up on the dashboard. The check engine light, the slip indicator light, and the 4Lo light (flashing).
9. I let off the gas, took the exit, and pulled over. Turned off the engine.
10. A lot of steam was coming out from under the hood. Couldn't see it until I had stopped. I could hear the gurgling noise again, except much louder this time. I opened the hood and could see the coolant boiling in the reservoir. That's where the gurgling sound was coming from. I let the engine cool down, but drove the car home afterward. Didn't get on the highway going home. It was night at this point so it was pretty much a straight shot home.
11. Steam coming out from under the hood, again, when I got home. Coolant boiling in the reservoir again too. There was moisture all over the engine bay, but I'm not sure if it was from the steam or actual spray.
12. I haven't driven the car since that point. When the coolant stopped boiling I checked the level. It had dropped a little from where I had refilled it, but was still well above the min marker.

At that point I hooked up a code reader. The only DTC code given is P0117 - Engine Coolant Temperature Circuit low. That link has a section that talks about using a code reader to diagnose the ECT sensor. My expectation was that the ECT sensor would be broken and that my scan tool would show the reading from that sensor at one of two extremes. That's not what I found.

I took readings at different times of the day and saw that my ECT reading was always similar to the intake air temperature reading and the ambient air temperature reading. Doesn't that imply that my ECT sensor is working and, moreover, that the wiring to that connector is also good (i.e. no short/open in the sensor nor that section of the wire)? That's how I'm interpreting it.

What should I check next?

Acrad

Are you seeing any pink stains underneath and at back of motor?

What does your oil look like?

GuyHoozdis

Yes! I am seeing some pink crusty stuff around the radiator. What does that mean?

I just went and checked it and there is oil much higher on the dipstick than I would have expected! My maintenance log says that I'm not due for a change for another 1100+ miles.

Acrad

Just my $.02....If it is obvious leak on radiator you will need to get that replaced ASAP. After a replacement I'd do a coolant pressure test right away after radiator replacement to ensure you don't have a coolant valley and/or head gasket failure.

Where on radiator are you seeing the pink stains? Can you post pics?

GuyHoozdis

I looked at the back of the motor and I don't see any pink crusty stuff. There is nothing dripping/pooling under the car. I looked for any pink fluid or crusty stuff on top of the skid plates too - nothing there. I did see a small pool of pink liquid in the battery stand. I'm assuming it is from spray and there was enough there that it has pooled and not dried up yet.

Acrad

Can you tell what part of radiator it is leaking from? Upper hose connection is a common failure point.

IanG

Does the oil on the dipstick look clean or does it look milky? almost frothy?
Also what is the year and mileage on your GX?

GuyHoozdis

Standing on the driver's side of the engine bay - looking at the left side of the radiator. This is where I see the pink crusties.



If I had to guess, this is where the leak/spray is coming from.


This is the pool of liquid in the battery stand that I mentioned.


This last picture is taken from the front of the car. The splash/splatter on the hose seems to indicate that something was spraying from below - from the radiator side not the engine side. I felt the hose to see if it felt brittle or cracked. It does not. It is flexible and I could not detect any cracks or fissures in the rubber.

GuyHoozdis

No. The oil looks and feels normal to me. Definitely not milky nor frothy.

It is a 2011 GX460. 126K miles.

MrTorgue

That was very similar to where my radiator failed. You’ll want to replace that with a Denso/OEM spec part as well as all hoses and clamps. Yours just failed a little early. Mine was around 140~145k which is a tad early but my GX was a Arizona desert and Texas vehicle it’s whole life so meh that did it.

DO NOT CHEAP OUT! Do not buy cheap autozone or auto parts store off brand junk.

GuyHoozdis

Instead of addressing my questions below, it might be easier just to point me to a video or another thread that discusses troubleshooting / replacing a radiator. Thank you for all your help thus far!

I've never worked on nor replaced a radiator before, but I feel like this is work that I could handle. Is there any reason that I shouldn't? What sort of tests can I do to determine what might be wrong with my radiator? Can I disconnect hoses to make sure they are clear? Can I verify that fluid is or isn't running through the radiator properly?

I assume the pressure test would require a special tool. Could I rent the tool from AutoZone and do this myself or would you advise against that? My car is at home, so if I do the work here I'd have to get it towed to a shop to do this test. If I did the work myself could I just get a shop to run the test? I've replaced a head-gasket before. I don't know what "a coolant valley' means. How would I know if I have one or the other issues?

MrTorgue

I strongly recommend a Toyota or Lexus dealer replace it, you’ll get a good warranty for the part and labor. The coolant valley plate issue is a long pain in the *** job which involves removing the intake manifold.

Acrad

Here is a thread on radiator replacement

https://www.clublexus.com/forums/gx-...leak-help.html

If you replaced radiator and have thoroughly purged coolant system of air and not losing coolant from recovery tank a pressure test may not be needed.
https://www.clublexus.com/forums/gx-...-comments.html

Info on coolant valley but yours appears to be a clear radiator failure

https://www.clublexus.com/forums/gx-...late-leak.html

Example pressure tester
https://www.harborfreight.com/radiat...kit-63862.html

GuyHoozdis

Ah! So is it even worth inspecting any further? Just get on with replacing the radiator and hoses/clamps? I'm not familiar with "Denso". Is that a company?

Indeed! For the work I've done in the past I've ordered my parts from https://parts.lexus.com/. Is there a better place?

GuyHoozdis

Thank you for the links, @Acrad . Thank you, everyone, for your input and insight.

I'll let you know how it goes.