Is it normal for an fc's radiator top hose to be hot and the bottom to be cold? Or is my thermostat stuck?

 

how "cold" is cold?

 

Well its outside temp. And I felt the hoses after it sat for about an hour and the temp was still rather high. The top was very hot and the bottom was outside temp

 

If the upper hose is hot, the thermostat has opened and is not stuck.
Your rad core could be obstructed, have you felt across the face of the matrix to see if there are cold spots?

 

The temperature is all the same on the rad. The engine doesn't overheat according to the thermostat, but earlier today after a half hour drive or so I could hear the coolant sizzling in the engine and I thought it may be air in the system.

 

The car doesn't leak a drop of anything so that's out of the question. Do the hoses run from bottom to top. As in the coolant start pumping from bottom hose and goes through block then re enters the rad through top?

 

you mean gauge, right?

 

That's what I meant yes. As of right now I just checked it again and its been nearly three hours and the block is still pretty warm and the hose is still warm

 

have you recently serviced the system? added coolant? ran it with the cap off? i dont trust the factory gauge anyway...

 

But the gauge is back down on "C"

 

And now I haven't bled it yet, bought the car a few days ago

 

any mods done to the car? also, what is it?

 

It's 1990 all original except for a walbro fuel pump and racing beat exhaust

 

No, exactly the opposite.
Coolant leaves the engine through the thermostat/upper hose and reenters through the lower.

 

Also I'm not sure if its relevant but my whole intake pipe and manifold was the most hot part of the block to the touch that I could find compared to the other front faces of the block

 

And by pipe I mean the OEM plastic tube

 

snail or no snail?

 

Gxl non snail

 

I am pretty sure it is air in my system judging by the symptoms. It's also bubbled before when I've taken off my rad cap. I'm going to bleed it tomorrow

 

I have an issue with mine as well I think one of my hoses needs more tightening , I burped the coolant system for like 20-30 mins and still seems like air is in it...I can hear a noise from the coolant system sometimes after i shut the car off amd when i squeeze a hose it goes away.

My guess is a hose is letting air in somehow , but nothing leaks...it really stumps me.

Engine is rebuilt by rotary Resurrection and has 2k miles.

Thermostat is a brand new oem mazda 180 bought from mazdatrix

 

if it makes a percolating noise after you turn it off its the radiator cap not holding enough pressure. its more of an annoyance than a problem.

 

I'm mainly just concerned if my engine overheated. I am not sure if it did or how I'd know with a rotary. It's my first one.

 

hot coolant exits the engine through the top hose, gets cooled in the radiator and then goes into the engine though the bottom hose, so you WANT the top hose to be hotter than the bottom one, every car is like this, except the BMW's with 7 radiator hoses...

 

Idk how to explain it. The caps are both new so idk...I just hope no air is getting in. I've considered a higher pressure cap like a 1.1 but I don't want to put more stress on the coolant system (coolant seals), my current cap is the stock 0.9 iirc. I got it from mazda trix. I'm running one flat Cap one pressure