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post #108 of (permalink) Old April 3rd, 2019, 14:54 Thread Starter
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Join Date: Sep 2015
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Update after a long absence

Hey ya'll! As I mentioned a few days ago, I finally have the car back on the road since my last post which was around 2 months ago. There was a lot of rain and I also had no time to work on it until last week. I went ahead and installed two electronic gauges since I could no longer trust my original gauge. 1 of my temp gauges is reading the coolant temp as it exits the engine and the other temp gauge is reading the temperature of the coolant after it has left the radiator. Its been pretty nice to monitor both temperatures and see how my radiator and thermostat are performing

But anyways, I have been driving the car since Thursday of last week. I haven't gone far or to the canyon road yet. I've done nothing but 30 mile drives or so and I am really happy with the temperature of the car. When driving, the temperature exiting the engine is reading at about 188 F. On the other hand the temperature exiting the radiator will read at around 135 F. Only at idle is when the car begins to raise a little higher but nothing out of the ordinary. At idle I can expect the temperature exiting the engine to read at around 190-195F. At one point it even reached 205F but that was only once. It likes to sit at around 195F at idle. On the other hand, the temperature exiting the radiator will begin rising and the minute it hits 179F the T stat opens and I begin seeing both my temperatures drop. So the car is actually acting pretty damn good.

The problem
Unfortunately, there is now a new problem. The car is throwing a lot of coolant to the reservoir when it gets up to temperature. It fills it all the way to the top and eventually begins spilling it from the reservoir hose as I drive. This really is annoying and I can't figure out why it is doing it. I suspected my radiator cap although it wasn't old. So yesterday I went ahead and purchased a new cap but still the problem exists. Most of the coolant will flow back out of the reservoir after the car cools down. The problem is that its not enough coolant flowing back from the reservoir.

This morning I popped the radiator cap off and found that the level of coolant was nowhere near the cap although yesterday it was fully at the top. I also checked the reservoir and it was not all the way up to the top anymore. I wanted to add coolant to the water neck as I have been doing for the past few days but at this point I think the more I add the more it'll send to the reservoir. I am hoping that maybe this is normal and that the cooling system just needs to regulate itself which is why it has been spilling out the reservoir but I dont know at this point. I am going to drive the car without adding anymore coolant and see what happens. Hopefully the issue is that its spitting out because I keep filling the radiator cap all the way to the top but I doubt it.

Any suggestions? One of the MR2 guys in my area said his 3S did that when he had a blown head. But I'm not fully buying that yet.
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