Coolant Question
 

I am wondering where the hell my coolant is going on my vehicle.

I just added some coolant to my FD and did the burping technique.
- Removed coolant line from throttle body
- Added coolant to the t-stat filler neck
- Added coolant to the top, covered filler neck with my palm, and gently squeezed the radiator hose coming off the t-stat housing until coolant came out of the throttle body coolant line

So I topped off the filler neck and replaced the 16 psi cap.

After about 10 minutes I went and checked it and it was already low.

So I added more leaving the throttle body coolant line connected, and placed my palm on the filler neck and started squeezing the radiator hose again. After a few pumps coolant started leaking on the floor out of the overfill tank.

So does this mean there should be no air in my cooling system?

If so where could the coolant be going?

My car doesn't smoke or anything and I can't find any leaks, but it seems like its almost always low and the coolant level is never up to the filler neck for an extended period of time more than 10 minutes.

But tomorrow I am going to stop at a garage and see if they can throw a pressure test to see if there are any leaks.

Did I do anything wrong with burping it?

I'm just baffled. Thanks ahead of time for any help, Josh

coolant resevoir?

The coolant resivior is full up to the top line on the dip stick.

It usually takes me a couple of days to fully burp the cooling system since I do it manually like you're doing it. Take the car for a short drive, let it get to op temps. Come home, let the car cool down, check coolant level and fill as needed. Keep an eye out for leaks. Repeat for a couple of days till she stays full, else yeah, get it checked out.

Thanks yuichiror.

I will do just that.

I am curious if its possibly got an airlock which is contributing to my overheating problems.

When did you start getting overheating issues? Have you checked to see if your t-stat is any good?

2nd thread on same subject
 

There is another thread on this - thermostat has been suggested...

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/fmic-overheating-prob-438590/

Yeah, I have another thread on trying to get better ducting to my radiator after a FMIC install.

I have a t-stat coming from Ray @ Malloy and it should be here Friday.

On this thread I was just posting to see if I did the burping technique correctly and where the coolant might be going since lately it seems like its always low.

Since this was related to your other thread, if I knew these details, I may have answered differently. It's usually better to have one thread with all the details, rather than several that may be related.

Continual coolant loss is usually a sign of a leak somewhere. A pressure test should be done to see if a leak does exist, and where it is (external, or coolant seal). Your other thread didn't lead me to this conclusion. Of course, it may still be the result of your overheating problem (or a bad coolant seal could be the result of your overheating), but you won't know until you are further along in the diagnosis.

Thanks for the help and info Dave.

I will try and get a pressure test done this week.

I almost bought a test kit at Napa on Tuesday, but I found it hard to justify spending $100.00 on something I may only use once.

If you can squeeze the hose on the filler neck and it push's coolant into the recovery tank right then, you have a problem with the AST cap not sealing (there's no way you cna be generating enough pressure by squeezing the hose with your hand) to push coolant through that cap and into your recovery tank. You need to pressurize your system and see if the leak is obvious.

I apologize, I forgot to mention that I have done the AST elimination mod.

Same situation (assuming you have a pressure cap on the filler neck now) you should not be able to put the cap on and squeeze the hose and cause water to go into the recovery tank unless you
A.) didn't do the conversion correctly
B.) the pressure cap is not sealing the filler neck to the recovery tank.

You know I had a low coolant problem for a while on my car it turned out to be the cap on the coolant resivoir had a pin hole in it so I put some super glue on it and never had low coolant since .

Your kidding right ? The recovery tank is open to air, builds no pressure and therefore doesn't need a sealed cap.

^ Take this man's advice.


My AST cap wasn't holding pressure and I could force coolant into the overflow tank by squeezing the upper radiator hose not very hard.

I tested this out by switching caps from my Acura 2.2Cl and RX7 (both 1.1 bar) and the problem went away. I also made sure the hose from the AST to the overflow tank was sealed and would suck back in coolant instead of air as the car cooled.

The Acura cap works great on my RX-7 and my RX-7 cap works great on my Acura...... but not vice-versa! :lol2:

The only cap I have on my car is on the filler neck of the t-stat housing.

I have done the AST elimination mod with the nipple adapter on the filler neck.

Recently when I squeesed the upper radiator hose coolant would fill up my overfill tank.

But since then I have replaced the radiator hoses, t-stat, and found a small leak underneath the throttle body on the hard line that goes straight down from the throttle body.

After 3 days of sitting my coolant level has dropped about 1/2", so I still have coolant going somewhere.

Worst case scenario is that its a bad o-ring.

Not kidding It would come out that little hole and I would have to put coolant in it every other day ever since I did the glue thing I have had no mor problems .

I recently changed my radiator and didn't get all the air out and my car would start to over heat sitting at in intersection for too long.... once I let it cool I put more water in it and it didn't over heat anymore.

With the AST eliminated did you put a pressure type cap on the filler neck ? if you kept the plain one then you will never build pressure and when you squeeze the radiator hose coolant will move to the recovery tank. You must put the pressure cap from the AST on the filler neck unless you want to run a zero pressure system and run the risk of a lower temperature boiling point.

I have a 16 psi cap on the filler neck.