Strangest thing, Now, The front rotor is missing an apex seal... or somesuch... The engine is pretty much toast, but it runs, and it's getting me to work on about 5mpg for just two more days. I've got a new engine going in this weekend, but The add coolant stays on till the car is warm, There is plenty of 50/50 mix in the overflow bottle, checked the rad after I left it cool off a little and I can feel coolant in the upper rad hose. Has sufficient amount of oil in it... Very strange issue. Car is an 89 Turbo2.

 

you made sure its topped off on the cap coming off the waterpump(im sure you did, , but this is the only think i could think of)

 

that happened to me too. could be alot of things including a bad sensor.

noticed that when coolant level was low/thermostat closed, it messes with the sensor b/c water isnt being returned up the pipe.. check the level when its closed. you may have to just add some water everytime you start it.

good luck. at least your car runs.

 

Could be the rad cap....... if its leaking... it will not suck coolant in as the car cools, vent it off when it heats up... It its a cheapo, it will not allow the coolant to go into the overflow bottle at all... always run a cap from the dealer (mazdatrix sent me a bad one already, wasn't a mazda part)

Overflow hose could be clogged..

could have a pinhole in your lines...

REPLACE THAT FRIGGIN line from under the oil filter on the rear iron to the heater core when you change the motor.. (replace them all... but that f'r especially)

My 89 GTU did this CONSTANTLY..... Here's another trick for the 89-91's without the second cap on the water neck.. fill er up, run it for a while, let it cool off and then take the hose off the filler neck and fill that the whole way up and put it back on.... this takes care of air trapped in the hose, which is what the cap on the water neck on s-4's is for

 

Interesting. The motor has actually been R&R'd by a mazdadealership within the past 10k miles. I bought it from a guy that "said" it was blown. I'm not messing with it till I get it down to rotary resurrection and let him sort it out. I know for sure it's not in limp mode. But I will check for leaks, replace rad caps, and the hose on the rear iron.... It's a hard to find part most napa stores don't carry it in stock So I will most likely have to get it from mazdatrix. I'm replacing as much as I can during the rebuild.

Plug wires
New aluminum TID
plugs
air filter
SS oil cooler lines
SS clutch line
fuel filter
koyo rad
blackmagic fan
I'm now adding all hoses and rad caps.