The plastic coolant tank in my car keeps overflowing with coolant. it seems like the the engine is not sucking the coolant back in and is just filling the overflow tank up. im pretty sure its not a blown coolant seal causing this problem because the car runs great and it has no smoke coming from the exhaust at all. any help would be great and the car is a 86 gxl in case that helps. o and idk if this would cause a problem (besides that stupid constant buzzing noise) but the wire to the coolant level sensor came off the sensor when i replaced the radiator a while back.

 

The small-diameter hose that runs from the rad filler neck to the overflow bottle may have a small air leak. That could cause the problem since the coolant would not be sucked back into the rad as it cools. In other words, the flow would be one-way, into the bottle but not back into the rad. Check the hose for air leaks (not coolant leaks) or just replace it and use zip ties at both ends to seal the connections.

Otherwise, do the "champagne test" to see if you have a blown coolant seal. Search the forum for info on how to do that.

 

What Go 48 said is true. Also, any other vacuum leak. I had a leak around the water pump seal. It wasn't leaking enough coolant to find it for a long time. Once I replaced the waterpump, it was all good. I also changed over to Evans Cooling NPG+. Good product.

https://www.rx7club.com/showpost.php...1&postcount=11

 

ok thanks for the help guys and how should i check the hose going from the rad filler neck to the overflow bottle for air leaks? im not quite sure how i would do that besides taking it off and plugging one end while i blow into the other

 

That'll work. Best to replace it. Inexpensive piece of hose, couple of zip ties--simple.

 

Don't forget that the cap may be faulty too! It may not be holding pressure. Either the primary seal for pressure or the secondary for recovery tank. Also, clean both surfaces.

gd

 

well i went out and pulled off the hose from the rad filler neck side and plugged the small hose that is atatched to the other side of the overflow bottles cap leaving the cap on the bottle. i blew into the hose and noticed a tiny air leak like a pinhole size air leak coming from the cap i think meaby the hose but would such a small hole cause this to happen?

 

Reread post #2. Replace the hose--no big deal.

 

ok i will replace the hose as soon as i can but as of right now my budget is 0 dollars, and just to make sure would such a small air leak cause this problem? I will also do the champagne bubble test as soon as i can but right now its to early i have to wait till my neighbors go to work

 

OMG! Post #2: "That could cause the problem since the coolant would not be sucked back into the rad as it cools."

Key word is could. No guarantee that this is, in fact, your problem, but for a couple of bucks you can find out. In any case, if you have an air leak in the hose, you should replace it anyway.

 

ha aight sry i just like to make sure

 

Well i went to do the champagne bubble test and it turned out to be more like a geiser test as soon as i started cranking the engine coolant came shooting out so ummm ya on the very slim hope would air bubbles in the system cause that? or is my motor completely screwed?

 

Doesn't look good. A little overflow might be OK but a "geiser" is not good. Start the engine with the rad cap off and see if you get bubbles when the engine warms up. A little turbulence is to be expected, and a little overflow as the coolant/engine heats up. But bubbles and/or foam and "geiser" is not good.

 

ok i appreciate all the help when i get back from my doctors appointment i will actually start the engine with the rad cap off because i only cranked it for a couple seconds the first time because i wasnt expecting the geiser and it was inside my garage and i didnt want to soak everything on the ground around the car. so ill push the car into the driveway and do this all over again

 

Ya let it run for a bit and see if it keeps bubbling.

If it's not a coolant seal and it's not the hose or cap leading to the reservoir then there could be a hole or leak somewhere else like any other coolant hose, cap or the radiator. When the coolant cools off it shrinks and creates a vacuum to suck in coolant from the reservoir. If there's a hole anywhere then it'll suck in air instead.

 

I have been chasing the same problem on my car for a couple months. I think it was the primary seal on 2 seperate Stant radiator caps. I could hear a very faint hiss at the rad cap when the car is hot. If I press on the cap the tone of the hiss changes a bit, so I know it is coming from the cap. I installed a higher pressure cap that seems to have seals that are more durable, but I will find out for sure on my next track day. I have not had the problem on the street since installing the new cap, but this really only happened at the track.

My car runs fine, and it never looses any coolant, it just pushes it into the bottle and does not recover it.

I pressure tested the cooling system, then removed the radiator and had that tested seperately. I checked the overflow bottle itself, and the tube going to it.. all were fine. I replaced all the coolant hoses as well.

When you are testing things with the fill cap open If it shoots a bunch of water out when you start the car that is not a big deal, and pretty normal. You will want to look for bubbles as it runs.

 

My two cents:

Simply put, Stant is ****. Sadly, they are all I can afford. I had to crimp the tabs on my Stant caps to make them work. The one hose on these cars that seems to be a problem is the driver's side heater core hose. Watch that thing like a hawk, because it loves to soak up oil (leaking from the oil filter tower) and leak. But I would suspect your problem is either a cap or overflow hose leak.

Edit: Fix that coolant level sensor problem ASAP. That buzzer might just save your butt one of these days if you get it all working properly.

 

sry i have been pretty busy and havent been able to work on my car the last couple days but the last time i did run it i noticed coolant flying off of the fan so it might be a water pump seal is probably bad any more help from you guys would be great. all of the things you guys have suggested have been helpfull and i really appreciate it

 

Well, ya gotta find out where the coolant is actually coming from before you can repair the problem. Could be coming from several sources if the fan is throwing it around. Dry up everything and track down the specific source of the leak.

 

my car did something similar, and it was the waterpump. (still is :P)

champagne test wont work properly until you burp the system and let it sit overnight. Don't even try and do it when the car is already hot. so much air pockets that it'll just keep bumbling randomly.

If you test it when the car is cold and it still does it, then it may be the coolant seals. If tis not smoking at startup you may be safe for now.

If it is the waterpump bearing like me, then its sucking in air instead of coolant (seems like 1/2 and 1/2 since my coolant does get sucked back in, just not all of what is pushed out)

Check around the water pump. It won't look like much at first, maybe 1-2 white streaks of dried coolant. After a few weeks its VERY noticeable.

 

um to the op, can you stop your fan with your fingers? (assuming your using the stock clutch fan) might be building pressure because your motor is getting to hot maybe?

 

yes actually i am able to stop the fan with my finger pretty easily

 

has this been resolved yet? because my car is doing the same thing

 

well i figured out the waterpump is leaking a decent amount so im pretty sure that is my problem (at least part of it) this may be a dumb question but depending on the condition of the water pump can i rebuild it? or would it be cheaper and easier to just buy a new one or get a used one?

 

you can get them from atkins for $85 thats the cheapest oem i can find. there are cheaper ones out there. but there just oem replacements. im not sure if it matters tho but ive had bad luck with non oem