kiddoh

iTrader: (1)

Where should the coolant sit on the filler neck? Noticed that I can't even see the coolant when opening the fill neck, done an AST delete also.

Thank you!

TwinCharged RX7

iTrader: (14)

Should be pretty much full. Fill it so you can see it. If you drive it and it doesn't stay full after cooling down then you have a leak somewhere

c0rbin9

iTrader: (2)

Very timely as I was wondering the exact same thing. Mine isn't visible when opening the cap either, though my coolant was just changed and the system may still be working the air bubbles out.

DaveW

It always takes several top-ups to get it to where it's near the top of the filler neck after I drain and refill.

kiddoh

iTrader: (1)

Dang so I have been driving it without it being full, full as in its close to the nipple on top of the filler neck right? Like near the cap?

I didnt even think about the air bubbles haha

Thank you!

ZE Power MX6

iTrader: (157)

Should be near the top if you fill it correctly, even during the first fill. Mine might drop 1/8" during first drive after first fill, then should stay right near the hole that goes to the reservoir after topping it off.

Sgtblue

iTrader: (16)

OP, be sure to check the level of your expansion/overflow. As the car cools it should pull coolant back from there, but if it’s too low it’ll run dry.
Regardless, vacuum (on a tight, sealed cooling system) keeps the level near the nipple until the spring cap is removed. It’ll then drop a little, which is normal.

c0rbin9

iTrader: (2)

My coolant level is always well below the filler neck no matter how many times I top it up. It would seem that there is a leak somewhere. Any ideas on where to check?

Retserof

iTrader: (1)

First thing to check is the hose (an its clamps) to the overflow tank. If that hose has a vacuum leak, coolant in the tank won't be drawn back into the engine when it cools down. Also, the overflow tank's coolant level will rise until it overflows.

GoodfellaFD3S

iTrader: (213)

Have you gotten the 'add coolant' light and buzzer yet?

ZE Power MX6

iTrader: (157)

I suggest get a Lisle funnel and bleed the system, if you are still losing coolant after a good bleed and fill then you need to pressure test it.

large_x7

iTrader: (1)

Do you mean the hose that connects the AST to the overflow tank? Is that a vacuum line? I thought it was a coolant line.
This is the exact problem I'm having now. I flushed the coolant system last fall, so I thought the low coolant buzzers were from air coming out of the system, and I just kept topping it off. But on the last two drives, once the car has gotten up to temperature, it overflowed the overflow tank. Car is not overheating and running fine (well, regularly) otherwise.

EDIT: Also, how does a leak in that line cause those symptoms?

Retserof

iTrader: (1)

The hose from the AST to the coolant reservoir tank is a 2-way coolant line. When coolant pressure gets high enough, the pressure relief cap on the AST opens a little and allows expanding coolant to flow to the unpressurized reservoir tank vial that line. When the engine cools, a vacuum is created in the cooling system that draws coolant back from the tank via that line into the AST. If the tank overflows, the problem may be a small leak in the 2-way coolant line that allows some air instead of coolant to be drawn back into the AST. When this happens, coolant accumulates in the tank until it overflows and you keep having to add new coolant to the filler neck. Or, the overflowing reservoir tank could be due to a faulty pressure relief cap on the AST.

kiddoh

iTrader: (1)

Had the same problem with the leak, mine was one of the big hose connections for the radiator that can be seen when looking from under

gracer7-rx7

iTrader: (16)

You will want to do a coolant system pressure test to identify any leaks. Visually inspecting hoses and clamps usually is not enough to find all the leaks since leaks sometimes only present themselves when the cooling system is under pressure - i.e. the car is running. Plus, some hoses are difficult to see.

I've posted about that in the past. Here's one of my threads with a tool suggestion: https://www.rx7club.com/3rd-generati...-tool-1139888/

yurcivicsux

when filling the coolant back up you probably didn't remove the upper throttle hose to properly burp the system. its the highest point in the system.... once new coolant starts coming out you re-connect it, fill the reservoir to full and check it after a good run. it usually only drops like 250ml. if you don't you will have air problem over days. this is common issue for guys that don't know. if you watch gears and gasoline on youtube they struggled with this also.