More problems, coolant overflow not working?
 

So my car is running fine, no electrical problems now.

But one problem is my add coolant light will come on, and my radiator will be empty, but the coolant overflow is still full.

I don't know if it is a split in the line or what, but the car isn't overheating or anything. But the coolant overflow is always full even though the radiator is getting low.

Whats up with that?

You obviously have a serious coolant leak issue you need to deal with before you worry about the overflow.

Start the car and just let it sit there and run until you see where the coolant is coming from.

If the exhaust smoke is white.........

Odd thing is no coolant leaks, no white smoke at all, nothing like that. The only place I could think of a leak would be the lower radiator hose. It's a bit old, probably the original.

It doesn't burn coolant or over heat though.

I would doubt a coolant seal failure because the engine has not even 15k and was broken in right.

Two spots to check. If you have S4 check under the intake manifold. There is a hose that runs between the upper and lowers sections. It can pop and you will nevver find that leak. Drove me nuts to find it one time. The second one is the heater core hose. It is right under the oil filter up to the firewall. That one will always fail every so often due to the oil weaking it.

It's an S5.

It leaks very slowly, I have to add coolant maybe once every two or three months

Pressurize the system and look for a leak. The reason the coolant is low and the overflow full is because the coolant is leaking out somewhere and the air is leaking in killing the vacuum that will pull the coolant in from the overflow.

If the pressure goes to zero and there is no coolant on the ground, check under the carpet....... UNDER the carpet as a heater core or line might be bad. If not................ seal time.

I hope it's not a seal... I have a low mileage RR rebuild, and I'm going to be frustrated. It burns no coolant at all. I just get a little blue smoke, no white.

Replace the radiator cap? Not really sure on a FC, but on FBs the cap is what controls the overflow tank's activity. If the cap goes bad, it can sometimes force fluid out to the tank, but not let it back in the way it should as the radiator cools down. Sometimes it will do just the opposite. Since you're not leaking, and not burning, this is where I'd start.

Good luck.


.

Check the small-diameter hose between the rad and the overflow bottle. If the hose is not completely sealed, the coolant in the bottle will not be "sucked" back into the rad as the engine cools. Therefore, the bottle will continue to fill up as you add coolant to the rad. Maybe the hose has a small slit or it is not sealing at the connection points.

So what happens is you top off the rad, the engine heats the coolant, coolant flows to the overflow bottle as it expands, as the engine cools and tries to suck the coolant back into the rad it cannot apply a vacuum to the hose because there is an air leak in the small hose. Just a possibility. I've seen it before.

Yeah I'm gonna check it out really well when I get home.

I'll post up when I check it

How do you know it's not burning coolant?
Can you take pics of the spark plugs tips?


-Ted

No coolant smell and no white smoke at start up.

I can pull them and snap some pics

Take it from someone who has been there, I drove a car for 20,000 miles with bad seal on the rear rotor. I never knew it until I had the seals fail on the front rotor, then I figured it out.....

Telltale signs:
Engine starts a little harder than it should.
On cold days, engine seems to start on one rotor and then kick the other in after a couple seconds.
My spark plugs where only slightly grey, not enough different than the other rotor's plugs to be noticeable (except maybe to a trained observer).

I doubt that Kevin made a mistake on the coolant seals and as long as you don't go beating on the car when it is stone cold, you should be ok. I would guess that the coolant seals are Ok.

Car starts and runs great, I don't beat the shit out of it. I drive it grandma like most of the time, just redline about once a day, maybe twice sometimes.

The car runs perfectly, just seems like there may be an old line with a hole in it somewhere.

I had Kevin rebuild the engine, but I didn't change any lines or anything else other than spark plugs and the fuel pump, and the upper radiator hose.

So my guess is a hose with a split somewhere.

I've not gotten to check it out yet because the temp dropped drastically here. It's been in the low to mid 50's for the past few days.

Does not sound like seal issue. No smoke no single rotor start up.
How much coolant in 3 months?
Pressure check it, cold and hot. Let it sit for a while. I have had pin hole leaks in hoses or fittings that did not show cold. Pin holes in hoses common, fittings rare.
One never showed any puddles under the car at client's home or shop. Finally found that there was a pin hole in a fitting, coolant was spraying on to the exhaust manifold thus never reaching the ground. Not enough to make any steam. This thing was tiny. You could hardly see the stream. Would not leak cold. This is a one in a million.

My experience in order of failure-(not seal related)
slight coolant loss - Radiator, heater, manifold hoses, radiator, heater core fittings, heater core.

Over flow tank over flow(not seal related): Radiator cap 95%, hose between radiator and tank 5%. If the bottom rubber of the cap is swollen or extends past the metal disc replace it. Use a quality cap if you do not use Mazda. Do not go cheap.

Just a builders hint: When change a motor, if you have not before the motor popped, replace all the hoses save yourself a lot of grief. Make sure all fittings are clean no rust or corrosion.