djspock303

Ok I must be missing something like a switch or something, please advise.

When i bought the car i drove it and it does not overheat as far as the gage goes, goes about half way up and stays there. However it did bubble when I arrived to my garage. All week i drove it but if the A/C was on it would bubble in the reservoir tank.

Last night i replaced the lower hose, thermostat (180f) and thermostat gasket. I replaced the upper return hose. The fitting for the trans/oil cooler i put some thread dope on it to seal it from any leaks. I flushed it earlier this morning and ran distilled water in it to test make sure there were no leaks. Ran the car for 30 min with the heater full blast and ran the car for about 45 min with the A/C full blast and no bubbles.

I went to the Toyota dealership to get red coolant because the previous guy had alcohol based green coolant in there that was flushed away.

I also picked up a OEM radiator cap, the one i used in the morning test was the Oreillys OEM replacement 13psi cap.

Filled with it back up, put oem cap on. With no heater and no A/C i got bubbling in about 5 mins of idling in the driveway.

I checked for headgasket leaks, and milky oil, oil cap, the old coolant didnt look bad. What am I missing?

Once it cools off im going to try that Oreillys special OEM cap again as that is what i used all week long. My only thoughts are there is a switch i am not aware of or the Radiator itself has gone kaput.

The car always goes just a tad above the halfway mark, it never creeps or goes to H. But i for sure don't want boiling coolant/water in my res tank.

Thoughts, ideas, suggestions?

TRACKMKIII

Still sounds like you may have and air pocket in the coolant system. Are you using one of the filler jugs to burp the system?

djspock303

I saw those the yellow jugs with the plunger. Ill pick one up sometime a little late for that now.

I put the car back up in the slanted driveway and jacked it up in the air. Ran the heater on full bore blast with the temp all the way up. Pulled the rad cap and let it blow out the air bubbles. Took about 20 mins of that then incrementally started lowering the speed and the temps about 2 to 1 minute at a time. At about 72 f i put the rad cap back on and just watched from the spill over tank. Eventually i had it with full bore blast A/C blowing. Used the throttle wire at times to get the rpms up so i could watch it. I would say it was a successful burp.

Drove to a friends garage last night to check out a new turbo for his race car. We pulled out a temp gage blocked the res tank link with some vice grips and had the A/C at full blast. Temp stayed around 184 and no boiling or anything. It would have to be over 212 or close to 212 to boil or a bunch of air but thats all seemingly gone now.

When i drove it home i heard some gurgling and the reservoir tank not "boiling" is that normal for the car? Once it cooled down i checked the levels this morning in the rad they are full, and the reservoir tank is between the low and full line?

Its that gurgling thing when the car shuts off drives me crazy, just never had that before?

ClarkKent

Check to make sure you Water Control Valve is functioning correctly. It is the valve mounted against the firewall near the master cylinder. Should open when Heat is on and close when A/C is on.

djspock303

Ok its been a process of elimination reminds me of my old Jeep lol, man I hate cooling issues.

Ok so thus far Upper Hose Replaced, Lower Hose Replaced, Correct thermostat replaced, correct rad cap replaced, Toyota Red 50/50 replaced, bleed system.

The water valve seems to be doing its job.

Here is the thing when driving around with no A/C on cool all day long 100f outside no issues. It only boils the coolant when driving under a load with the A/C on. Today heat index as 104 and I had the A/C on, after about 1.5 hours of driving it boiled the coolant in the res tank.

I am down to a couple of things Replacing the Radiator maybe its just time and under it load it cant keep up? The indicator gauge operates at just a tick above half, even with boiling coolant in the res tank it doesnt climb higher than that. Water Pump seems operational and fine, i have just replaced the Serpentine belt.

I dont have the tale signs of a head gasket leak, but i havent bought a "exhaust gas/block tester kit either - no milky white oil cap residue, no white exhaust, no power loss when driving.

I did pick up a new ECT sensor today but on this car unlike the IS300 its at the bottom of the fing radiator so i would have to drain it again first, the add all the coolant back and bleed the system again.

I am half tempted with this high milage car just converting it over to Evans Waterless Cooling.

The other night we had the thermo on it and it was around like 198-200. It's like when the A/C is on it brings it up to 212.

I have no leaks or fluids under the car so not sure where to go from here, i dont want to tear it down and put on a new head gasket per say, ill use blue devil before going threw that hell.

I am seriously thinking just converting to Evans, and adding proactive head gasket sealer.

djspock303

Ordered a Denso Radiator OEM replacement today for 86.09 shipped to the door. After taking it up to my friend shop we did all the tests leak down, block, rad pressure etc all signs are pointing to the radiator.

More to come!

Titten

I'm not sure if I missed it, but have you checked that the mechanic fan clutch is in good condition? My GS was doing similar to yours, and my fan clutch was toast. Also check your aux electric fans. The new radiator shouldn't hurt, either. Who knows how old yours is/was.,

Titten

Also, make sure you have your radiator shroud intact and in place. Good luck.

djspock303

The electric fan is coming on when it is suppose to, and the clutch belt driven fan doesnt seem to be spinning loosely, seems to have proper torque and it does move air. The waterpump and seals have already been replaced. I will update after the Denso Rad goes in but it wont be here until wed next week. After tons of research on mkiv supras, and old gs300s here are all the things you have to go through that can cause cooling drama and not in any particular order. I will list them out by part cost and labor later as most of the time its process of elimination

1. Failed Thermostat
2. Bad Radiator
3. Bad Clutch Fan
4. Bad belt driving the clutch fan
5. Bad hoses
6. External Leak
7. Internal Leak
8. Failed Head Gasket
9. Bad Radiator Cap
10. Clogged Catalytic Convertor
11. Failed water pump
12. Failed ECT switch
13. Failed Gauge Switch
14. In Proper Coolant Mixture
15. In proper bleeding when filling

Yarbird

My gauge reads alittle above halfway I always thought that was normal so I guess I am having the same problem? Ive also never seen bubbles but I do not sit and watch so does that mean I could have the same problems?

djspock303

*Yard i would say if you do not hear gurgling and you look under the hood and see no bubbling in your reservoir cooling tank you have nothing to worry about. When the car is up to temp it should be about half way on the gauge. Usually overheating issues the needle indicator would be pegged all the way up in the red, but in my case it does not.
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Update 7-6-14 my replacement Denso Rad came in yesterday and i just got back from the lake, not sure if ill have time until this Friday to put it on, may have to burn some vacation days.

I also located the "Engine Coolant Temp Sensor" location on the GS300 first gens. (I plan to proactively also replace this) Whoever placed that there should be shot on sight, any ideas how to get to it painlessly? (See photo 2 for reference) *coolant temp sending unit is in the gauge cluster, prob replace it too but it seems to be operational

I have not codes if i have not stated that already from the scan tool.

Man i feel dumb, i didn't realize at first in the front that is a huge Air Condition Condenser and the radiator sits behind it lol

joewitafro

Best way to get to that sensor is to unbolt the dipstick from the manifold and move it out of the way, and reaching in there and undoing the plug on the sensor, and using the correct size socket and extension to reach in there. Have the new one ready because coolant will come out. I did this on my car when I first got it and it was a pain but I figured it out.

ClarkKent

Yep, you can get to it. Just looks bad at first but you can get it out.

djspock303

Status Update.

Took about 1 hour to get everything Jacked, Drained, and pulled. Took about 2 hours to get everything back in but most of that was cleaning and ensuring hoses did not have leaks etc. Not really to bad on a GS300 at all. However looking back even though my Fan Clutch was fine and working I probably should have replaced it too being that it was easy access. There are some things i like about the GS300 compared to the is300, lots more room is the main thing!

Also after the bleed and some heavy driveway testing, i went for a test drive on the highway with the AC full blast no more bubbling woooowhoooo!!!! I think the radiator i pulled was the orginal one with 230k miles on it, also you can see tons of debris over time. The other problem i noticed last week when replacing hoses the gunk that the Green Antifreeze and Toyota Red can create is pretty freaking nasty, took a lot of flushing to get what i could out but its like a white & rusty scaly gelatin. Please people stick to water and water wetter or Toyota red dont put green in ! : woot:

Enjoy the pics,

TRACKMKIII

Glad you got it fixed! You are definitely correct never mix green with the Red Toyota coolant.