Coolant won't circulate?
 

I have a TSP 402 LS2 in a Mazda RX7.

Here's what happened:

My old radiator started to leak, so I bought a new one and installed it. Burped the system and went for a drive. Everything was fine until I got on the highway, one of the radiator mounts came loose yanking my lower radiator hose off the thermostat housing causing a big mess. I immediately shut the car off, pulled over and got it towed.

Got home, reinforced the mounts, refilled with coolant. Let it idle for a little while with the radiator cap off, topped off coolant and garaged the car and haven't touched it for about two weeks.

I took the car out last night. Let it warm up a little and took it down my street. Noticed my temps started getting really hot (230F). Pulled over, shut the car off, popped the hood and my radiator was ice cold to the touch, lower radiator hose was barely warm.

I figured I have a stuck closed thermostat. Went and bought a new one at Autozone. Put it in. Started the car up again and let it run some until it started getting really hot again. Shut it down and my radiator was still cold.


Am I missing something?

Sounds like there might be a big-ass air bubble in the system.

Hmm.. That's what I was thinking

I leave the coolant crossover ports open as I fill the engine, a massive amount of air comes out. Then when the coolant starts coming out for a second or two, I install the crossover.

Since the coolant temp sensor is in the head, an air pocket forms and itll read very hot. Id loosen the crossovers and start filling it with more water.

Crossovers on the heads right?

Yeah, the 4 corners. Sometimes all 4 are interconnected, and some have a crossover on the front and two block offs on the rear.

http://image.gmhightechperformance.c...sover_tube.jpg

Other possibility would be a big air pocket in lower radiator hose, I like to drill a 1/4" hole in my thermostats to allow air to vent through them when filling cooling system.

i have ran into this on several engine swaps with the rad at different height compared to the engine,, i take the top hose off the rad and fill coolant right into the hose to fill the engine full of coolant first. this has always worked for me

You guys were right. It was just a big air pocket in the block. Cross over trick works well.

Good! :cool: