x2delight

well today i changed my thermostat and my radiator since the radiator drain lug was stripped...


the gauge on the car is still going up to like as far as H and then it will go down if i continue to drive...

i dont understand why it does this.. i was told it would be the thermostat.

and i dont mean the gauge goes down slow.. it will shoot down to the regular level.... after it reaches the H..

J-Rat

iTrader: (2)

Have you made sure all the bubbles are out of the coolant system?

x2delight

welll i flushed the cooling system of course.. how do i make sure all the bubbles are out of the system???

ilike2eatricers

Did you used a OEM Mazda tstat? Aftermarket tstats are known to not run correctly in our cars. Do a search on "Mazda thermostat owns" or something like that.

J-Rat

iTrader: (2)

Well, first off you fill it using the bleed screw on the side of the radiator out. Then once water starts coming out of that, you put it back on, and keep filling. Then, what I do is, heat up the car in neutral, then let it sit. Once cold I check the level. Sometimes you can get in more coolant.

And as always, after I do coolant work, I always check the coolant level first thing, every day, for like a week.

x2delight

yes mazda OEM Thermostat and Radiator cap...



i dont have a bleed screw on my radiator...i have a s5 but a s4 radiator BUT not setup like a s4 with the bleed screw... all i used was the radiator... soo i dont have a bleed screw... any other ideas?

J-Rat

iTrader: (2)

wacky temp sender? You said that it remains cool after it shoots to "H", correct? And you can drive it all day long and it wont overheat?

x2delight

well lets say it morning and i go out to warm up the car... after i let the carm warm up for like 5 mins.. i go out and drive it nice and nimble to get it up to operating temps...

during this time the Temp Gauge will remain at the Correct level...

after driving hard for lets say 5-10 mins i can see the gauge rising.. the gauge will go as high as H then like once it hits H i continue to drive and it will shoot down to Normal like after 30 secs after hitting H

x2delight

btw i forgot to mention that it does it over and over after the first time..

J-Rat

iTrader: (2)

That is completely wierd. Ordinarily I would say thermostat, but yours is new, correct? And this is the same problem you had before you replaced your thermostat?

I wonder if a weak water pump could cause this....

x2delight

yeah.. same problem before i changed the thermostat and the radiator cap..

Templeswain

Um, not sure this helps but I have the same problem when I swapped out in an s4 motor into a 91.

The temp gage on my cluster loves to shoot up sporatically. Goes all the way to "H" and then back down to the middle. Sometimes it does this when the engine is no where near full operating temp.

I read somewhere on the Mazdatrix wedsite that the s4 and s5 sensors are different and wont read correctly between the two.

Though I have no idea if this is systemically related to s4 radaitors too?

Maybe give mazdatrix a call tomarrow about it?

x2delight

well before i did my radiator swap i had a s5 radiator anyways and it still did it... still no clue wtf is going on... its kinda making me worried...

Templeswain

I have no idea how to test if the sensor is faulty.

But here's an idea.

The sensor as far as I know is located below the oil filter section, on the top of the housing.

If memory serves, its right below the height level where
the rear rotor housing says MAZDA 13B or whatever.

On s5 it's a flat slip connector. on s4's its a rounded slip connector.

Maybe someone put in an s4 sensor before you got it?

Or maybe its dirty as hell and that's messing it up?

Although that might be a long shot because I've never had a problem with dirty water temp sensor......BUt there's always a first for everything.

RotaryForce13B

'll tell ya what, their is nothing I hate more than cooling problems! My S5 was doing the same thing only during interstate driving at about 70 to 80 mph. Around town driving was fine it always stayed mid way on the gauge. To start off the first two things I bought was thermostat and cap. I had no luck it was still getting hot. You can check your thermostat by putting it in a pot of water and heat up the pot of water to what ever your thermostat is set to. Use a thermometer to check temperature. Once you get the water at the right temperature, you should see the thermostat open. If it doesn’t open, get another and check it before you install it. I have had a brand new one not work properly. Anyways at that time, my water pump was starting to leak from the weep hole. So, I bought a new pump thinking all of my problems were solved. Wrong again! Then I was thinking that just maybe that my radiator hose was sucking shut I bought new hoses and was still left with my S5 getting hot. Now I am thinking the clutch on my fan is bad so I installed a new 16-inch electric fan (puller) and also robbed a 10-inch electric fan (pusher) off a turbo II. I still had no luck! By now I was about to lose it until one day I had to make a trip to Wal-Mart and it all came clear. While walking back to my car I noticed antifreeze dribbling from under the car, I open the hood and there it was my freak'n radiator was leaking from the seam where the plastic tank and the aluminum meet together. So then, I went out and bought a new radiator and bingo all of my cooling problems were solved! So I guess it was the radiator the whole time.

Good luck
Warren Springer
90 GXL
89 GTU
(2)88 10th Anniversary
86 GXL
I know I'm SICK!

Templeswain

, you should see the thermostat open.! If it doesn’t open, get another and check it before you install


There's so much to comonsense that I completely ignore.

Drrrrrrrr.

Why, it never occured to me to just actually field test it,

I will be doing this upon all thermostat installs.

Mazda OEM or not.

Kenteth

For what its worth, I had the auto tranny overheating the radiator, which in turned overheated the water coolent, in turn the engine. On 100+ degree days, crusing at 80mph meant jumping the thermastat off the h every 15 minutes. 100+ degree days with the heater on full blast trying to get home. Damn that sucked.

I learned my lesson though: One of these days I was heading to Bell fouche (70ish miles) and at about the 30 mile mark, the tranny stumbled once, and lit up the rear of the car with white smoke. In less than 5 seconds both lanes of the internstate were covered in thick white smoke, everywhere. Cars behind me completely stopped on the interstate, (fortuantely i was near an exit). By the time I made it up the exit, was billowing out smoke. I pulled over and looked under the car to see that tranny fluid had been leaking out where the gasket blew. Hit the exhaust and was flaming up. A construction worker came running up with a fire extinguisher to help out, but it appeared as though the trans fluid had mostly leaked out. I coasted down the hill to a gas station where I had lunch and tempted fate.

Bought four quarts of tranny fluid. Filled her up and drove 30 mph on the service road the entire way home.

Got home, flushed out the tranny and installed a new gasket and filler. That was the last time i took her on the interstate in hot temps, but im sure she would do fine now in the winter.

In any case, the manual tranny won't have that problem

SureShot

Here is another possibility.
My 87 had metal erosion in the water pump housing.
The 1/8” bleed hole in the partition between the inlet & outlet side was 3/8”.
The bypass port under the stat port was chamfered out ¼”.

Maybe when you pull the stat to check it, look at the top edge of the bypass port under the stat & see if the spring loaded disc under the stat closes it.

Bukwild

coolant seals are going. Mine did the same thing before it over heated. It would start and then go right to 75% up the guage and then go down to 30% down the road a little. You might want to pull the plugs and see if you have coolant on them. If so rebuild the motor now before you ruin your engine. Trust me you will blow your motor if you mess around and wait. I did