My coolant seems to gurlge after every drive?
Im just driving normal speeds too...?
I checked the coolant resevoir tank and its full to the brim...
Cant figure this one out

 

I've been told it's normal. Interested in others' responses...

 

It's the coolant boiling as far as I know. Distilled water shouldn't boil but your coolant will so yeah our engines just get that hot.

 

I've got the same problem. Tried bleeding the air out a few times and the gurgle seems to get progressively better but hasn't completely gone away.

 

Its normal... it the heat that is generated from the rotaries...

 

I thought it was what youwsh said. either too much air is in there allowing fluid to boil, or a small leak is present. . .allowing air to get in.

 

If it is right after you drive then it is most likely not the coolant boiling. i dont know if you know how a coolant system works, but when the system presurizes there is not as much space for coolant as when the car is off. So it pushes some coolant into your overflow. When you turn the car off the pressure that forced the coolant out acts as a vaccum to pull the coolant back from the overflow into the motor again as it cools. So the sound you are hearing is the coolant actually being pulled back in.

It is possible that it is your coolant boiling. But as long as you have the proper radiator cap, right mixture of coolant, and prooperly working cooling components then you should be okay.

I would suggest that you guys get a temp gauge of some sort anyways. It always a good idea to have one.

-Austin

 

Dude - positive pressure becomes negative pressure?

correct explanation - heat causes expansion of the coolant out of the engine into the overflow. cooling of the coolant causes contraction of the coolant back into the engine.

Shut off engine and look at the PFC readout - temps go right up to 120C and then slowly back down. Of course it's boiling. Replace your cap with a 1.1 or 1.3.

 

That is the EXACT same thing that i said...

 

No it isn't. this is what you said: "when the system presurizes ... So it pushes some coolant into your overflow. When you turn the car off the pressure that forced the coolant out acts as a vaccum to pull the coolant back from the overflow..."

In other words, "the pressure that forced the coolant acts as a vaccum ..."

Not correct. Why?

Take a cold engine, pressurize it with a coolant pressure tester (Stant product) until coolant starts overflowing. Leave the whole thing alone overnight and if your car coolant system is in good shape, there should be no pressure drop nor coolant flowing back into the engine.

Close but not quite the same.

 

 

If it is gurgling, the first thing to check is that your coolant system is properly filled.

 

My 50/50 A-F/distilled water coolant used to gurgle on shutdown with the stock FD thermoswitch. Since I installed the Miata thermoswitch (essentially same as the FC thermoswitch in operation), the coolant stays cool enough that I now never hear it gurgle on shut-down.

 

how do i know its filled properly/

 

If its boiling on shut down you have a small leak somewhere (or too low pressure cap), you dont have the proper coolant/water mixture, or your temps are getting to high, any of these can lead to your coolant mixture exceeding boiling temp. You dont want boiling even when the car is off, it will still lead to localized hot spots and can help to speed up the death of your coolant seals. My car doesnt boil on shut down and its 110 F and higher out these days.

 

the term you are looking for is call "Burping" the cooling system.

its also in FAQ. you'll need a special funnel to properly fill it.
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/radiator-cap-funnel-eliminate-air-bubbles-342309/

which can be purchased here
https://www.rx7club.com/attachment.p...id=71347&stc=1
as well as some other automotive tools site


hold your gas pedal at high RPM while keep this funnel on the filler neck, and keep filling until it fills up to cap lvl. Its easier when u have someone help you with one or the other

 

This is the reason the FC (Miata) thermoswitch cured mine. It never boiled excessively before the change, just gave off slight gurgling sounds in hot weather shut-down.

And, it didn't have any of the other problems you mentioned.

 

I had this same problem, I put a new radiator cap on and no more gurgle.

 

x2

 

My gurgling, which ended when I went to the Miata thermoswitch, was a slight bubbling sound from inside the engine.

Gurgling from the O-F tank at shut-down could be a sign of needing a new rad cap.

Dave

 

Gurgling is not normal.

Did it begin suddenly or has it always been that way and if so how long have you owned the car?

Had another vehicle a few years back that one day gurgled hard. It was a thermostat stuck shut. Often they stick open but sometimes they stick shut. And I guess sometimes in between.

 

My radiator cap is fine though.. Fits on really t ight...

 

Possibly you have a pin hole leak somewhere in your system. Do you ever smell even the faintest hint of coolant? Have you ever climbed out of the car and thought "is that coolant I smell?" Then couldn't find the source and figured you were imagining things?
There are coolant lines behind the air pump and y-pipe that often leak and are nearly impossibly to check without dismantling your intake system. If one of these is slightly leaking it can dry up before ever hitting the ground and be just enough pressure relief for the cooling system to not finction properly. The other main possibility is a cap leaking, even brand new caps can leak.

 

Here's my suggestion:

1. If your temps are fine
2. If you aren't leaking coolant on the ground
3. If you aren't emitting a cloud of smoke that could hide 3-4 full army platoons

Just drive the car.