1990 RX-7 N/A problem with radiator pushing coolant to reservoir
 

Hi, I have a 1990 GXL N/A RX-7 with a manual transmission. It has a stock 13B engine. I'm having a problem with the radiator pushing coolant to the overflow reservoir, which then overflows and vents the coolant all over the ground. It is a recent problem and I have no idea why it started doing this. I have emptied the reservoir so it was at the cold level when the car was cold. The radiator was filled to the proper level but pushes coolant to the reservoir which then causes the low coolant sensor to activate intermittently. I'm not sure but the car might be pushing more coolant at low rpms rather than when it is actually being driven. If the car is left idling after being driven eventually the reservoir overflows and vents a large amount of coolant. The radiator then needs more to fill it up. The car cranks and runs fine and does not overheat. It's got 129,000 miles and has been maintained. Does anyone have any ideas why it is doing this? I'm concerned that it might be a problem with coolant jacket in the engine, which would not be good. It used to backfire and have problems starting but not anymore. Would a good first step be to pull the radiator and have it tested/cleaned or is the problem with another system in the vehicle? Thanks!

Take off the radiator cap and start it and let it run and idle for awhile, if it starts gushing out or you see alot of little bubbles that progressively get worse to gushing, teardown time

It sounds like you are in for a rebuild...unfortunately.

Unfortunately, this is indicative of a blown water seal or worse, a damaged casting. My first engine went down that way at 100+ mi/hr at Mid-Ohio. Don't worry, rebuilds are fun!

Hey buddy,

I had the same exact problem last year. Its time for a rebuild.

Thank you so much!

My 88 is doing the same thing. Only taken it on short drives around town and every time it pushes about a water bottles worth of water out into to the tank. I'm going to test it with a coolant pressure gauge and I may look at a new radiator cap if everything goes well. It's cheaper than a rebuild but will rebuild if I have too.

This happens if combustion pressure leaks into the cooling system. Not sure if a new radiator cap will help. Pressure test the cooling system. Might be time for a rebuild. When this happened to my car the only salvageable parts were the rotors. Good luck m8

A bad radiator cap can result in similar symptoms; it's just unlikely. The 38 year-old radiator cap in my SA is just fine. Bear in mind if you pressurize the system and have a failed coolant seal you will be pushing coolant into the combustion chamber.

Take off the radiator cap. Look into the water refiller if you see bubbles that go up when the engine runs?

When you drive has drived the car. Turn it off and wait an half hour. Start the car in 1-2 sec?

I did such a rookie mistake when I put the radiator caps back on. I swapped the caps and did not realize it until I looked at them the other day. So off for a test drive tomorrow. Yes the car would start in 1-2 sec. after sitting for 30 or so minutes.

Not like me to do such a thing, but it happens.

Sorry to say but my friend had this exact problem and he ended up saying screw it time for a rebuild.

When he opened it up almost everything was toast.
Unfortunately he opted for the ls swap afterwards.

Cheers man hope it is all well and it's just something minor

something i learned today