Hi to all!! I have been reading loads of threads about cooling problems such as leaks, coolant seal problems etc... but i can't find any help

A few months ago i replaced my stock radiator with a Fluidyne high flow radiator after a crack has appeared on the top of the stock radiator. From then onwards, i have been having problems with my coolant levels. Both my stock AST and plastic tank are full but the level in the filler neck is low (i can still see the coolant though).

I have replaced both lower and upper main coolant pipes and all small coolant lines going to and from the AST. I have noticed that the coolant in the plastic line is well above the F mark.

Please note that i don't have any starting problems or smoke or bubbles coming out from the filler neck. I also noticed that almost every time that i open the filler neck cap i hear air escaping and i can see the coolant going down until it settles at a lower level (a bit lower than the coolant line going to the AST).

I have now decided not top up the filler neck and see what happens.

Could this be a sign of a coolant seal failure? Can anyone please help?

 

It could be a sign, but I wouldn't panic just yet. There are lots of coolant hoses that can fail, causing coolant to leak out, and air to enter the system. I would suggest that you give ray crow a call, and pick up the following:

Thermostat
Coolant hose kit
filler neck cap
AST cap
FC thermoswitch (optional, but recommended as it turns the fans on at a lower temp)

I purchased the above parts (including thermoswitch) for around $200 about a month ago. The FSM will help you locate and change out all of the coolant hoses, as well as replacing the thermoswitch (if you decide to change that). You may also want to inspect your AST for leaks, as this is a common failure point as well.

Don't forget to fill the system with distilled water, and remove the air when you are finished ( this might take several attempts before all of the air is gone).

Also, even if you do have the dreaded "coolant seal failure", the above mentioned items should be replaced during a rebuild anyway, so your not wasting money on them.

good luck, and keep us updated.


*edit*

I just realized your not in the U.S., so I don't know how helpful ray crow will be to you, or what the parts I mentioned will cost.

 

When was the last time you've replaced the caps?

 

1. That's good.
2. Are you sure air is escaping, and not being drawn in by a vacuum? Air escaping would not be good if the car has thoroughly cooled. A slight vacuum is normal - that's how the coolant from the OF tank is drawn back. The coolant level dropping slightly is also normal in the case of relieving a small vacuum when you open the cap as the rubber parts expand somewhat as vacuum is released.
A small amount of air space may indicate a small leak in the coolant return line, in one of the caps, or in some other hose, etc. Turbo coolant hoses are notorious for leaking and not leaving any traces.
3. That will MAYBE tell you something.
4. Not necessarily, although it could be very early signs of that.

Do a pressure test to help pinpoint any possible leak points. Remember that this will not show up leaks in the coolant return line, since that will remain unpressurized.

 

Hi Guys!! Many thanks for your feedback!! My caps are still the original ones. I am going to replace them today or tomorrow. I drove again the car and the level remained at the same place (just a bit below the coolant line going to the AST). The AST is full to the brim.

As Dave mentioned before, i was mistaken about the air escaping, its actually vacuum that i'm hearing.

I never had any problems with coolant levels before i replaced my radiator. An other thing that i have observed is that if i top up with coolant at the filler cap, leave the car on idle speed, leave it untill the fans start twice and check the coolant level when cool again, the coolant would be full as should be. The level only goes down when i drive the car (sounds crazy !!). Any ideas?

 

Anyone?

 

Did you replace the caps?

I've had several coolant leaks. All of them pin hole leaks which would never drip on the ground. I would occasionally get a faint smell of coolant, but couldn't locate it. Then sometimes 4-6 weeks later the hose would give up.

There are several more coolant hoses that are not up front with the radiator.

One hose is under the oil filter attached to the firewall. This hose is also attaches to a what mazda calls a "quick release" on the engine side. This is made of plastic and contains a couple o-rings this can crack.

Two hoses are on the opposite side of the engine also attached to the firewall they go to the heater core.

There's a short L-shaped hose under the throttle body.

There's another longer hose that runs under the uim from the filler neck to the throttle body.

There's also a short hose that attaches to the turbos that can be seen if the airpump is removed.

There may be one more one the turbos.

There could be a couple more but I'm pretty sure I got em all. There's also hardlines attached the turbo that supply coolant but those rarely go.

 

Hi to all! I didn't have the time to change the caps. Hopefully i'll change them this evening. I also noticed that after a drive i can smell coolant in the engine bay. Does this indicate a leak?

 

if it smells like coolant it is more than likely a leak somewhere.

i could smell coolant under my hood also turned out to be the hose going to the firewall.

look for discoloring and you should find your leak.

 

If i use fuel line hose to replace the small coolant lines, would these be good?

 

I would contact Ray at Malloy Mazda and order the coolant hose kit and let him know which hoses you just recently changed out and he'll remove them from the kit.

The preformed hoses will keep their shape once 100c coolant is running through them. A straight hose bent to fit may become flexible and close up causing overheating.

Malloy Mazda , Ray Crowe is the parts manager, gives great prices to RX-7 owners, tell him your with the rx7club. quick shipping:
(888) 533-3400 , (703) 490-8170 , fax: (703) 490-3864 , hmkparts@aol.com

email will probably be your best bet.

 

you can take any hose you want over to an autozone or a pepboys and get it replaced. Just ask for heater hose. No biggie.

 

Hi all again! I changed both caps but to no effect. Same level

I have also checked most hoses and there doesn't seem to be any leaks. However, i haven't checked the ones attached to the turbos yet. Is there an other hose beneath the air pump too?

Here are some pics i took. (Not very clear though. Took the pics with my mobile).

I have booked the car for my mechanic for next week. Hope its a leak and not a coolant seal.

 

you need to add water at the overflow bottle, thats why it has marks on the plastic bottle top for full or low.

add water to the full mark and see if it drops.

 

Hi all! I had a run with the car and the level is still the same (at the filler neck). However i have noticed that the level in the overflow bottle has gone down by one level. (The level is well above the F mark. Just on the third mark from above.)

The fact that i have changed the radiator to a Fluidyne one and the airbox is pressing a bit on the upper hose, could this have any effect on the coolant level ?

 

anyone?

 

any ideas?

 

it shouldnt have an effect.
if you over fill the bottle then you will have to wait for the system to push out the extra coolant before you can tell if you have a problem.

 

Thanks agian, bryant

Does anyone know if there is any hose beneath the airpump?

N.b At times i can smell coolant even from the inside (after a hard run). I have checked the hose going to the firewall but all seems ok.

 

Do you notice it to be worse on the inside of the car? Take a look at the heater core.

 

The front turbo coolant line is behind the airpump. It would be hard to see it with all of the intake and airpump installed.

 

Thanks Adam c.
I'll try to check that hose too before i'll take it to my mechanic. ......

 

If you can see coolant every time you take the cap off, and dont get a buzzer going off when you start the car, dont worry about it.

Its completely normal for the coolant level to drop a bit when you fill it up. Normally to just under the level of the takeoff to the AST, but sometimes a bit lower.

These cars have stupid cooling systems that never work right (tongue in cheek obv but not far from the truth)

My motto is fill and forget; unless i get a low coolant buzzer or my temps rise on my defi, which i never have - and they never do.

 

Bobfish, i never had any difficulties with the coolant level before i changed the radiator. There must be a leak somewhere. The level at the filler has always been full (up to the cap).