chromecarz00

I'm aware that the coolant tank leak is an issue, but I don't know where that leak typically is. I see coolant dripping when the car stops in front of the rear right tire. Tank or something else?

zedcat

I had a leak in that area and it was indeed the tank. There is a diagonal brace under there and I had drips of coolant on the brace. I had an indy shop do the replacement.

XR4Tim

Water pump is also in this area.

Macster

Could be a tank or something else. While the tank is over there and the one time I had a car manifest a leaking tank the coolant gushed out/down just ahead of the right rear tire, leaking coolant can flow a distance before it drips to the ground.

With the car on the rack though it should be pretty easy to tell if the coolant on the ground arises from a leak not from the coolant tank.

So get the car to a shop pronto. Regardless of where the leak is coming from it needs to be found and fixed and the sooner the better.

BBA

The overflow tank also drains outside of the car in that area. Start pulling the trunk carpet, if the tank is leaking either the carpet will be wet or the floor underneath will be. Either way you have an issue.

Abracus Ab Ras

Is it possible if the reserve coolant tank is not properly tightened, coolant might leak? I checked my coolant tank level recently but did not close it tightly. After a long drive found a large pool of coolant on the floor , coming down from near the rear wheel. Temperature needle stayed normal. I filled up and later drove around several time over a week, there is no coolant leak. Wondering what could be the problem!!

Macster

Oh, yeah. If the tank is not sealed properly, if the cap is not on correctly, the cooling system can't maintain pressure. It is pressure that raises the boiling point of the coolant.

Without sufficient pressure the hot coolant can flash to steam at the hottest places in the engine's cooling system and these pockets of steam increase the volume of the coolant and this can force coolant out past the cap.

BTW, these steam pockets represent localized overheating as the steam can prevent coolant from contacting the walls and removing more heat. So the coolant temperature gage won't register an increase in temperature since the coolant isn't getting any hotter. But the engine is at least in places.

This is what is so insidious about a bad cooling system that can't hold pressure.

It is imperative if the cap is removed that it be installed correctly. The cap is kind of prone to getting cross threaded. Also, if the cap is not secure anti-freeze residue can form which even if the cap is tightened can still result in leak.

The best way is if the cap is suspected of not being properly installed with the system dead cold remove the cap and wash/rinse it under hot running water. Use hot water to rinse the tank and where the cap threads to the tank.

Then top up the coolant level to around the min line. This is with the system cold so the coolant level shouldn't be at the max line as there will be no room to expand and you can get overflow. The older models have more room for expansion but techs tell me the newer models have less room so it is critical the coolant tank not be overfilled when the engine is cold as when it gets hot and the coolant expands it will force coolant out and this can be mistaken for a leak.

After making sure the cap and tank and tank threads are clean then carefully install the cap and be sure it is tight.

Run the engine, drive the car around until the engine is fully warmed up. I like to hear the radiator fans come on as then I know the engine is fully up to temperature. After getting the engine up to temperature you can make tent of alum. foil and put this over the cap/the fluid bay and after a while check it for the presence of water condensation. If you find some this can be from a leaking cap or the tank.

rob delorenzo

I know this is an old thread, but I will try anyway.
My car overheated about a week ago when the pulley from the alternator snapped off.

It kept leaking fluid from the overflow hose.
I replaced the cap, the water pump, and thermostat, I changed the coolant and oil and they both looked ok (no intermix)

This morning on a stone cold car, I went to pour in some distilled water and it immediately comes out the overflow hose above the right rear tire.

Does this mean the tank is bad?

When the previous tank went bad, the trunk was flooded with coolant.

Most of what I read on these boards says that is the symptom of a bad tank.
But my trunk is dry.
Can they crack or split on the inside of the firewall or in the drain flow path?

I can get a pressure tester from Autozone as a loaner, but it's a $250 deposit and a 2 hour bus ride (No second car)
Or I can buy one as suggested, but is it necessary at this point?

The more I can learn here the better before I do anything else.

I'm a recovering cancer patient, getting low on $$ and need help.

Thank you.

chromecarz00

It was for me and i think it's either tank or hoses for you, youve replaced pretty much everything else.

I would strongly suggest going for OEM as I've used aftermarket and it didn't help.

Good luck

Macster

A leaking coolant tank doesn't have to put coolant in the trunk. When my Boxster coolant tank let go with a gush of hot coolant the rear trunk was dry.

I don't understand how adding coolant to a coolant tank can have coolant flowing out an overflow hose unless the tank is full to begin with. The tank should have minimum and maximum level lines molded in the plastic. As long as the coolant level is between those lines there is no reason to add coolant.

IIRC the coolant tank was recently replaced. Are you sure it is the correct tank for your car/model year? And is it hooked up correctly? Hard to imagine it could be hooked up incorrectly but...

rob delorenzo

The car leaks coolant as soon as I start it.

When I flushed it and started to fill it after changing the water pump and thermostat, it started leaking as soon as I turned on the engine. As the engine warmed up, the leak grew.

If I lean my head over the tank I can sometimes hear a gushing sound. I put a dry screwdriver in the hole and it came out wet.

Am I correct in thinking that I need to do both a pressure test and a test for hydrocarbons in the coolant? I can borrow both testers from Autozone.

I don't know if it's an overpressurization problem and/or a leak or crack in the tank. There have been a few times when I have added distilled water to it stone cold and it flows right out the overflow. This is not overfilling it, though.

I really only have enough $$ at the moment for one more shot at the mechanic. The tank is still under warranty, but the labor is not.

Macster

As I mentioned if the system is not properly and completely filled with coolant, if there are air pockets and there will be if the system is not filled with a vacuum lift system as the engine runs and as the air pockets get pushed around this can have coolant flowing back into the tank and overfiling the tank.

If the engine is cold when started and assuming the T-Stat is in place and installed correctly and not stuck open if the coolant leaks out from the tank then this is a sign of "head gasket" leak. I put "head gasket" in quotes because the info I have is head gasket leaks are rare. Most often the leak is from a crack in the head. In the case of your car's engine a combustion chamber (or a cylinder wall) has a crack that lets combustion pressure into the cooling system and this forces the coolant out.

You can drain the coolant. The button the cooling system up. Remove the spark plugs. Pressurize the cooling system. If it loses air pressure there's a leak. You might be able to hear/feel (?) air leaking from one spark plug hole. Or remove the oil tube filler cap and with a clamp on the hose from the AOS to the intake listen/feel for air coming from the oil filler tube.

Any air from a spark plug tube or the oil filler tube is not good. The engine will need to be torn down, at least the suspected leaking head removed, and the leak found and if fixable fixed. Otherwise the head will have to be replaced.

If a cylinder wall is found to be the source of the leak then the block is likely toast.

'course, there is the outside chance there is a bad head gasket but a careful examination of the head gasket should spot this.

rob delorenzo

Thanks Macster.
This doesn't look good then.
Would the engine run poorly or would there be inermix between the oil and coolant?
I did not see either of those when I drained and changed them both.
The engine runs strong, idles smooth, but does heat up to 180 rather quickly.
Will the hydrocarbon tester help determine if there is a cracked head?
If it is cracked, it's not worth repairing, is it?
From what I understand, that's 2-3k at least.
The thermostat is in correctly and works.

rob delorenzo

I think I finally found the culprit!
After a few times of trying to flush and bleed with just distilled water, I saw flow from under the bleeder valve! I guess it wasn't a big enough leak to be visible until I ran it for a few cycles.

Now I do have a few questions on replacing the valve.

Is it a good idea to put silicone or any kind of sealant on the threads of the screws?

I see that they need to be handled with kid gloves or it's new tank time.

I'm really hoping that this solves the problem.

Thanks for the help.

rob delorenzo

I think I finally found the culprit!
After a few times of trying to flush and bleed with just distilled water, I saw flow from under the bleeder valve! I guess it wasn't a big enough leak to be visible until I ran it for a few cycles.

Now I do have a few questions on replacing the valve.

Can anyone report success stories on replacing just the valve? The mechanic says he doesn't replace only the valves as he's had too many problems with them.

Is it a good idea to put silicone or any kind of sealant on the threads of the screws?
(obviously not around the valve)

I see that they need to be handled with kid gloves or it's new tank time.

I'm really hoping that this solves the problem.

Thanks for the help.