GuyHoozdis

@Acrad , thank you for the links to the parts list (and everyone else with your guidance too).

I read through the thread about replacing a radiator. I noticed that you liked someone's comment saying it isn't worth doing yourself. I'm taking that into consideration.

I haven't driven, nor started, the car since this has happened. It has just been sitting. What sort of things is it safe for me to do? Obviously not drive it long distances. I was thinking that I'd like to clean off the places where I see the pink crusty stuff and then run the engine so that I can see the problem happen. Is that safe if I am monitoring the temp or too risky? I could hook up my code reader and watch the temp to make sure I didn't cross into unsafe conditions. Is this reasonable or a bad idea?

If my code reader gives me a reading on the coolant temperature (which it does in a KOEO), then does that mean that my thermostat is functioning properly?

Acrad

I would probably tackle it myself but it would depend on how soon one needed vehicle back in operation.

If you don't want to purchase a pressure tester you might be able to rent one for a lot less from local auto parts store. If radiator is faulty it would likely show it self without even starting it up.

IMO as long as your topped everything off, didn’t drive anywhere and monitored temp you should be fine

chuyrobles

1. No pic is necessary. The cap can be tested; you cant go by looks.
2. That’s a good sign, It’s not conclusive but encouraging.
3. Stuck thermostat counts as blockage, but also a collapse hose.
4. Put the thermostat in hot water and use thermometer to measure at what temp, the thermostat opens, if at all. With thermostat still installed, leave rad cap off as the engine warms up. Once engine is at normal temp, look inside the rad to see that coolant is swirling.
1š look at the weep hole, located at bottom of pump. With belt off, the pulley should have no play; side to side and in and out.

ASE

Save yourself the time and effort ... install a new radiator cap ... if removing the thermostat for testing ... no matter the result, replace with a new one ... crazy to reinstall even if it tests "good". Yes, you should test to establish if it is the cause or a contributor to your overheating problem.

ballistice

Good advice right there. I also recommend changing the thermostat while you have it out. Both are so cheap it's not worth reusing. And the old cap can go in your tool bag for a spare along with your old serpentine belts.

You definitely want to check them both as part of your diagnostic. Also get a mechanic mirror and flashlight so you can check weep hole on water pump and freeze plugs for seepage.

GuyHoozdis

Is it possible that my reservoir could have fluid in it and the system itself not have as much coolant as is needed? I checked the owners manual and it said there should be around 14 quarts (16 with the rear heater).

Before I started taking things apart or putting in new parts I thought I'd do a flush. I started by draining the radiator, but only got out about 6 quarts. Then I filled the radiator and was able to put in 14 quarts. After that, I tried doing some of the things that @chuyrobles suggests.

With the rad cap off, I started the engine. I had a scanner hooked up to monitor the coolant temp while I did this. I don't know what "coolant swirling" looks like, but I did see bubbles occasionally. I have the car on an incline and I would rock it a little trying to burb the system. I can't say I ever saw anything that looked like swirling though.

I stopped the engine, put the rad cap back on, and then I ran the engine idle for 10 minutes. It warmed up to 195 (reading from my scanner) after a few minutes and stayed there. The temperature gauge on the car's console was smack dab in the middle of the range and stayed there. The scanner was reading around 100 - 102 ambient temperature and 105 at the intake while all this was going on.

Was I just dangerously low on coolant? How is there coolant in the reservoir, but not the expected amount in the radiator? If I wasn't able to put 14 quarts back in I would think I have a blockage in the radiator, but that wasn't the case.

GuyHoozdis

I forgot to mention above; none of the warning lights that were on previously were on while I was letting the engine idle. I haven't cleared the DTC codes nor disconnected the battery.

Also, the A/C was blowing cold air the whole time. I tried to run the heater. Cranked the setting up to "HI", but it was still blowing cold air. I think that is because it was 100 degrees outside and even "HI" was below that, so that came out as cool air. Not positive about that though.

I am thinking that I'll do these tests next as I continue to troubleshoot.

1. Idle the engine until the engine warms up. Press gently on the gas pedal so that the engine RPM runs slightly over its idle RPM. While I'm doing this watch the thermometer on the console and the temperature reading on my scanner. If the needle is moving towards the red or the scanner is reading coolant temp approaching 220, then stop everything.
2. If the above scenario appears to be maintaining a reasonable coolant temperature, then I'll drive the car up/down the block several times. Again, monitoring coolant temp.

Honestly, I think that is as far as I would push it tonight. Do those sound like reasonable test scenarios? Is there anything else I should be monitoring?

GuyHoozdis

I have the time to work on the car if I want to.

Thanks to all the resources y'all have shared and reading I've done, I think it is a task that is within my ability too.

chuyrobles

It doesn't appear you drained out all coolant with proper procedure. You dont mention draining the engine block of coolant. That’s why you didn't come close to draining 14 qts. See link below.
https://www.clublexus.com/forums/gx-...-comments.html

Based on your initial description of your cooling issues and how on this last test, the engine did not overheat, Im more convinced you have a sticking thermostat. That’s how they sometimes behave; they work one minute, and not the next time.

GuyHoozdis

Thank you.

If I am replacing the thermostat should I replace any other components while I'm in there? Is it even worth trying to test the part or just go straight to replacing it?

chuyrobles

I would replace the thermostat and rad cap without question. They are relatively cheap and would rule them out as culprits should the overheating continue. Check the o-ring on the petcock for cracks. It should be ok, but a quick look since it is out is prudent. I dont recall how many miles on the engine … if over or near 200K, I would consider replacing the hoses.

Acrad

What all did you end up replacing on your vehicle?