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-   -   overflow tank overflowing!!!! (https://www.rx7club.com/2nd-generation-specific-1986-1992-17/overflow-tank-overflowing-639513/)

Atticus_ 04-05-07 05:36 PM

overflow tank overflowing!!!!
 
ok so what are the possable reasons for my overflow tank overflowing? it fills to the cap and overflows out the top while driving. but it does not do it right after i stop or idle or anyother time when i look under the hood. i just see all the coolant that it has shot out and is sitting on top of the tank and running down onto the intercooler. the guy at autozone keeps telling me i have a head gasket leaking and i keep telling him i dont have one. lol i assume vaccum leak but im not for sure. if the cap is bad then will it will up to the top? shouldnt it stop and the dump hose comming out on the side? it does that too but it also comes out of the cap. and it does not lower at all when i let it cool off. anyone have any idea???

87 t-66 04-05-07 05:41 PM

blown coolant seals. time to rebuild

reatrdedspleen 04-05-07 05:57 PM

maybe bad rad cap. replace it... its cheap.

otherwise, prolly a bad headgasket :fawk:

Sideways7 04-05-07 07:11 PM

My guess is that the coolant seals are blown, but I could be jumping to conclusions. A vac leak can cause the coolant to enter the overflow tank and not come back, but it usually doesn't cause it to overflow. Do you have white smoke on startup?
There is a simple test to check if the seals are cooked. Here is a link describing how to test this: http://aaroncake.net/RX-7/overheat.htm
And here is the relevant info copied from aaroncake.net:

Originally Posted by Aaron Cake
The best way to test for this condition is to look for bubbles in the coolant. With the car completely cold, remove the coolant filler cap. Now start the engine and look at the coolant through the filling hole. Do you see a steady stream of bubbles coming from somewhere in the engine? Now, rev the engine by grabbing the throttle lever at the front of the engine. Does the coolant bubble up and/or gush out? If these two conditions are present, it is a pretty good sign that the coolant O-rings are leaking and allowing coolant to enter the engine, and combustion gas to enter the coolant.


Aaron Cake 04-06-07 10:22 AM

Also make sure to check the hose that runs to the overflow tank. As mentioned, a pinhole will cause coolant to enter the tank but prevent it from being sucked back into the engine.

BlueTII 04-06-07 11:27 AM

Most of the time it is actually the coolant seal retaining wall that has failed, allowing the seal to pop into the coolant channel. This allows exhaust gas to enter the coolant system, causing it to over-pressurize. It then expells coolant and hot exhaust gas into the overflow tank.

Shainiac 04-06-07 12:23 PM

Sounds like a coolant seal. My car is doing the exact same thing. Waitng on a rebuild. I eventually run so low on coolant because of this that it starts to overheat, very quickly.

BlueTII 04-06-07 12:28 PM

The more you drive the car, and overheat it, the less rebuildable it becomes. The plates will warp.


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