Ok so i have this small problem. I keep overheating my 91 rex, only when pushing 100mph (not a joke) now I have already replaced the radiator, thermostat, waterpump, hoses, and i broke it down to air in the system, i put the car at like 45dergeese, on a lift and ran it with the cap off, now it takes longer to overheat and seems to happen at 110mph. someone at mazda said that there it suposto be a burp valve on the t-stat housing, mine has none and i looked on the MAZDA TRIX site, and it doesen't look like there is suposto be one,eccept for the 86-88 will this one fit on mine, or is there some other way to burp this thing....

 

no it sounds like your doin it right. the 89+ ones should have a bleeder on the side of the radiator at top. my old 89 didnt have one, so i just took the cap off and did it like you said, it worked for me.
maybe watter wetter or something similar would help

 

Slow Down.

 

Do you have the radiator upper and engine lower covers on???

 

radiator covers? do you mean te engine under cover splash guard, plastic crap, if so I don't , also i's running a flexalite black majic electric fan, but i started doing this way before overheating...

 

For proper cooling yes you need both the cover at the front of the rad at the top, and the lower engine cover which runs from the lower bumper/grill to around the oil pan.

If you don't have them then that is what your over heating at speed problem is coming from. They force most of the air that enters from the grill to go into the oil cooler and radiator. Without them the air tends to be sucked under the car instead.

At 100MPH with the covers on, you shouldn't even need the black magic fan on.