Gotcha350

Buy another cap and try that.

rxmpvibes

Yeah, I understand. Mine has the radiator cap on the radiator. Yes, I purchased a new cap after these problems. Thats what the mechanic at Lexus said to do because he thought the old radiator cap was not holding enough pressure.

Correct, I have no misfire, no check engine light, no coolant in oil, and it passed the block test. It does not overheat when I bleed the cooling system with my Lisle Spill Free Funnel. However, while I'm bleeding the system I do see a few air bubbles pop up in the funnel every 10-15 seconds (this is why I think its either air or a potential failing head gasket).

When I purchased the car last year, the previous owner changed the timing belt, water pump, thermostat, and radiator all at Lexus last year (I went to the dealership and pulled the documents on this vehicle). The documents did say that the previous owner did experience an overheating issue but, I dont know how hot they ran the car. After the overheating issue the owner took the car to the dealership and they inspected the engine and it had no damage (not sure what tests they ran).

rxmpvibes

I did. I purchased an aftermarket 1.3 bar radiator cap to see if that would do the trick and fix the issue but, it didnt. I drove it long distance 1 day, checked the entire cooling system for proper levels (radiator and expansion tank) and when I came home I checked the cooling system and the expansion tank, fluid was way beyond the full mark and coolant splattered inside the engine bay. The next morning when I opened the radiator and looked down into the radiator it was dry (there was no coolant in the upper radiator neck).

However! What I can say is that the 1.3 bar radiator cap does a better job keeping the radiator fluid in the radiator longer than the 1.1 bar radiator cap.

rxmpvibes

UPDATE: I replaced the high pressure radiator cap (1.3 bar) with the Factory OEM radiator cap (1.1 bar) 2 weeks ago and I have put over 300 Miles on the car without adding or taking out coolant from the radiator and expansion tank. To my amazement, the expansion tank is not over flowing like it used to and the car has not overheated.

I have driven the car long distance on the hwy and have driven the car hard! And no I have not gotten the chance to do a compression test.

However, yesterday morning when the car was cool I went to check the radiator. As, I opened the radiator cap I coud hear air being released (sound was very similar when opening up a new bottle of Coca-Cola). When I looked down into the upper radiator neck it was dry (no visible coolant). When I took the car out for a drive and came back home I waited about an hour for the car to cool, opened the radiator cap to check the coolant, and there was some coolant at the upper neck of the radiator. Do some of you think it still could be a blown head gasket?

rxmpvibes

UPDATE: I put over 1,200 miles on the car and the car has not overheated but, I do believe there continues to be some air in the system after driving the car under heavy load. Because "sometimes" the coolant in the reservoir raises pass the full mark and does not draw back into the radiator and the radiator hoses feel inflated. If I don't release any air from the cooling system, the level in the reservoir will stay there or it might go down an inch.

To release the air pressure in the cooling system, I simply let the car cool for an hour, open the radiator cap to let the air out, and tighten it back on. In the morning when I pop the hood some fluid from the reservoir sucked back into the radiator (which is normal).

My issue is weird because one evening after work, I went up against a 2014 Mustang 5.0 MT and I floored it (my 06 430 kept up with him we were bumper to bumper I was shocked). After that event, I pulled into my drive way, popped the hood to check the coolant level in the reservoir and it stayed the same. It did not go up since I checked it that same morning!

On another evening after work I went up against a 2012 BMW 335I Coupe MT (sorry, please don't call me speed racer these are only tests, lol). I floored it, after the event I pulled up in my driveway and the radiator fluid went up in the reservoir and passed the full mark. Very weird!

ibidu1

iTrader: (1)

As a last resort you could try reverse flushing you heat exchanger. Undo both hoses and stick a water house to the outlet of the heater core. Then fully drain the block from the lowest points.

Then you could also raise the front end of the vehicle fill coolant. Let it idle and heat the engine and burp out the air in the system. Theres also a trick to put your hand over the spout of the radiator and with your other hand squeeze a radiator hose this also helps remove trapped air pockets. Do this many times and see if it works.