I've got an 86 non-turbo. Problem with coolant bypassing radiator and moving directly into overflow. Read previously posted threads containing similar problem. Just installed new Factory tstat and tested operation prior to installing. Also replaced rad cap with new oem. Problem still occuring. My question? After reaching operating temp flow to overflow tank begins. At this time checked lower rad house which is very hot to the touch however upper house is barely warm. Failed water pump? PS engine not running hot. Checked temp with bluepoint laser aprox 190-195 at normal operating

 

You either have

Bubbles in the system
Bad water pump
or Bad water seals


Jarrett

 

How doya know which one? Badseals or waterpump?

 

In the FAQ at the top of the page, there is the test for the water seals.

 

What Faq at top of the page? Please excuse me I'm new to this

 

Up at the top of the page on the line that says control panel, register, etc...there is a button marked..."FAQ" click that button!!!

 

https://www.rx7club.com/showthread.p...hreadid=181219

Click this link..

 

i have an '89 NA and i have identical symptoms. i have bubbles that stream into the overflow when up to temperature. just like u i thought it was the water pump and i replaced it, it was time the old pump was leaking through the weep holes a little but i still have that strange bubbling. i also replaced the rad cap with a greddy 1.3 bar one and the syptoms remain. my hoses are fine and my rad is in great shape. im pretty sure it is the water seals.
im going to rent the part from autozone to presurize the system and check for leaks or a loss of pressure.
hope u problems arent as serious as mine good luck

 

1.3 bar radiator cap!!!...

The water seals must be SCREAMING right now..