Alright, I researched this and checked a bunch of things but I want to know if this could be my problem. My coolant keeps spilling into my overflow resevoir after the car warms up, say thirty minutes of driving.I changed all my hoses except for the one that leads to the resevoir, but I tightened all the seals. My waterpump is working fine. My coolant in my thermostat housing neck smells sweet (not like exhaust), vice versa for my exhaust. My oil dipstick is showing no milky residue, and if I leave my cap off (which is a new OEM Japan 18 psi one) and start the car it sucks down instead of overflowing. BUT. .My radiator was replaced by the previous owner with a 90 something version, and the cap on it looks cheap, not only that he ghetto-rigged it by putting a piece of metal with gasket sealant under it. Don't ask why. Can this mess up the vacuum/pressure in the coolant lines so that it pushes into the resevoir without drawing it back in? Any Ideas would be awesome fellas!

https://www.rx7club.com/attachment.p...1&d=1201915910

 

have you actually checked the thermostat it might need to be replaced

 

I did actually. .It's OEM aswell. I noticed afterward though that the little pin isn't positioned where it's supposed to be exactly, but the upper rad hose gets tight after a few minutes so I know it's opening up as it should.

 

I would go ahead and replace the cap I'm sure the pressure is leaking and your thermostat not opening thats why the water is going to the reservoir tank because it doesnt have anywhere else to go. now my thermostat is only to 13 psi or something like that. that would be something else you could look at. maybe since the thermostat is so hard to open the water is just finding it's way out to the reservoir. i'm very sure the OEM Thermostat should only be to 13 or 14 psi.

good luck lt me know if tou need anymore help.

 

check if your rad cap is with the spring i think

 

Change the cap first!! Any bubbles in the over flow? If yes, your seals are blown. Check the FAQ, for the coolant over flow thread. It might just be a small enough leak to presurise the system.

 

Might also just be too much coolant in there. Empty the reservoir down to L, open the pressure cap and top off the system. Allow a couple days for it to dump coolant into the reservoir, assuming you have no issues. Then you can fill the reservoir to F if needed. I'd still replace the thermostat with a new OEM one and the pressure cap regardless.

 

^+1 I would first replace the thermostat with an OEM one before thinking about blown coolant seals. if your coolant seals were blown all the coolant would be spitted out by the fill up hole ( where the cap goes) not suked in. if the thermostat doesnt open the hot water is also going to come out and if hot enough youll get bubbles also. and yes the OEM thermostat for your car should only be for 13 psi not 18. Im very sure thats where your problem is at. and if the cap is faulty there will not be enough pressure to open the thermostat and the water is going to go straight to the overflow tank. so as i said before get a new thermostat and a new cap and go from there.

 

Well, I already replaced my thermostat with an OEM one though. My mechanic said it didnt matter if it was OEM or not but I researched here that it should, so I replaced both the cap and thermostat, and it kept doing this. The new cap has the spring seat. But When I put the old cap on, the resavoir doesnt fill up so fast. I tried filling the coolant resavoir just to the low mark and then topping it off, but it will still gradually fill until the friggin annoying buzzer goes off..wierd things is, it's stops when I give it some gas and let it drop back to idle. I know there isn't a blown coolant seal, but there is a leak somewhere that is pushing it out into the tank. for instance the radiator. There are a lot of bent fins, and that ghetto rigged cap thats up top of this thread. could that be my problem?

 

Ok..I have a suggestion..Bleed your cooling system,..maybe Read this thread. https://www.rx7club.com/2nd-gen-archive-72/filling-coolant-after-rebuild-383818/ and also..the S5's I believe,have NO CAP on the Radiator,which is Why the previous owner most likely did that Piece under the Cap "thingie"....when I replaced the Rad on my Car,what I did,which I thought Was appropriate,is I used Rad Caps,at Both Points..the Thermostat Neck,and the Rad.I joined the Overfow hose with a "TEE" fitting and then Put that Hose to the Overfow jug.it works like a Charm...TIP:Check the Overflow bottle.it may have a crack on the nipple to the Hose on the INSIDE of the Cap..or it really sounds like the hose isn't there at all..IF it is not then the Coolant can't get back into the Rad...I have the feeling that you have developed air in the system,and the Previous owner didn't Bleed all the air Out of the cooling system.When that happens your Car will get Hot Fast,Spew coolant,the Low Level sender will go Nuts,and of course your Overflow will be Full..anyhow..That thread may help you get the air out and Start fresh..Good luck,and post with results.STYX.

 

Maybe I am simplifing the problem but it's normal for coolant to go into the overflow as the car warms up. The water expands as the car heats up. It has to have some place to go, that's why it's called the overflow tank. As the water cools, the vacuum from the lower volume of water pulls the fluid back into the radiator. If the problem is something different than this, I apologize for wasting your time.

Brian

 

it goes into the overflow tank, but doesn't go back into the radiator at all. . .I'm goging to bleed the system and check for cracks in the tank now. . .keep yall posted

 

Alright. .I read the linked thread above and turns out, that there is a lot of air in there. I turned the heater on (with the car off but the key in), loosened the bleeder plug, and i constantly had to fill t for about twenty minutes even though I thought it was full. I drove it around for a while, and let it cool for 10 minutes, and took the filler cap of gently and it still needed to be filled a little. I tried that thing with the cap off and start the car but the coolant with shoot into the rad then come back up and over flow!?! I'm pretty positive I don't have a coolant seal blown, could this mean that the radiator is clogged or what?

 

If the hose going to the bottle has a leak, or if the overflow bottle cap is broken, coolant will not go back into the system, only air.

Change the hose and check the cap.

 

it's a new cap though. .OEM, and I secured all the connections on the hose, aswell as checked the tank for cracks. all fine. . but, my radiator has a bunch of bent fins and has the second cap (picture posted at very top), that has a peice of metal uner it with some kind of sealant. what I want to know is could this be the air leak, and what is the best way to fix it?

 

no suggestions?

 

go to autozone and rent a cooling system pressure tester and the adapter it should cost you 100 bucks which youll get back when you return it. block the overflow hose and pump 15psi into the system and youll find your leak. thats how i found where my leak was at. it happened to be the O rings on the intake manifold. i was already all scared and thinking a coolant seal was gone.

 

Yeah.. Polito has it...

 

yup. pressure tests are the best way to find leaks... well, vacuum leaks, coolant leaks, and fuel leaks anyway

 

well i burped my system completly, opening the thermostat and everything. . .and now the tank fills to the full line and doesn't pass it!. . .hell yea. hopefully this fixed my problem, we'll see. just to be safe I'm checking out the psi tester like you guys said. . thankx!

 

well. . .it's back. .just takes ten minutes longer to fill up then it did. takin it to the shop i guess, cause i'm out of ideas and i'm going to let my guy test and properly diagnose the problem, because i'm gettin to frustrated to think straight. thanx for all the help fellas.

 

hey skywalker you found out the problem?

fighting the same Demon


hybrid

 

Mines doing the same thing except it's stop expelling coolant when it's hot.
Unfortunately I know mine is a coolant seal on the way out.
Replace the line that goes from the rad to the overlow tank, it can have a crack in it that you can't see.
I would definitely get the car pressure tested.

 

no problem found yet. . .compression test is tomorrow. .i'll keep you guys posted.

 

hey. .there was a small leak in that cap( with the metal under it). I took it off and there was no gasket or real sealant, it looked like super glue almost. but my cap psi rating is 18, will that be a problem? In the haynes and from what you guys said up top its only supposed to be 14 or 15.