Coolant leaking out of overflow tube

Hey Everyone,

I recently repaired my header tank. But now I have a new problem. I found another owner with the exact same issue in this old post. But because it is an old post, I thought I'd post a new one.

http://www.ferrarichat.com/forum/206-246/255105-coolant-leaking.html

My car is running fine. But when I come home at night, I had to idle in the drive way while I removed my son's bike. After I had parked the car, I noticed a puddle of coolant on the drive way where I was idling. And a trail up the street. I found that it was coming out from the overflow tube. My coolant level is not too high. Why would coolant be running out?

Any ideas much appreciated,

Manny

 

Your radiator cap may be the wrong one, defective or not rated for the correct pressure. I don't know the correct pressure off hand but should be an easy check on the forum search function.

 

So it may have become defective? Because I've never had an issue before. Do radiator caps "break"?

 

They certainly lose spring pressure over time, and it was found on the 308s that a one step higher spring pressure was optimum.

So yes, all the OEM ones on our cars in the V8 section should be uprated...a search will find the rating. 1.4BAR, from memory...

14 -16PSI, up from 12???

 

1 bar = 14.7 psi, so the 0.9 bar cap, which I believe is correct, is about 13 psi.

1.4 bar = 20.6 psi, which I believe the system was never designed for. I totally don't recommend that.

When you say your header tank is "not too full," what do you mean? It should only be like 2/3 full to allow for expansion of the coolant. You probably have too much in it.

 

Manny,

The radiator cap is a spring and weakens over time, you'd be surprised how important it is because a new cap can actually assist in engine cooling
I found a two eared Murray brand at O'Reilly's and was impressed when temps declined

 

Hi Guys,

So I'm looking for a 13psi cap?

PantDino, my coolant level is about 1.5-2" from the cap.

Manny

 

I had exactly the same last year and found the radiator cap under the rubber seal had cracked.

Peel back the rubber and check for cracks in the metal.

Always worth buying two and keeping one in the boot as a spare.

1bar = 14.50psi absolute

 

Hi Tony,

Am I looking for a 1 bar cap? Or was that just an easy conversion factor?

 

Here's a thread discussing the pressure rating: http://www.ferrarichat.com/forum/206-246/236262-radiator-cap-pressure-rating.html

Freeman

 

Is it possible that just idling in the driveway was enough to heat up the fluid a little more than usual, expand it a little more than usual, so it drained? I've had the same thing happen. Drive the Dino on a cool day.....no overflow. Hot day......overflow. However, next hot day....no overflow. It's as my the Dino knew just how much fluid to drain from itself so it wouldn't overflow on the next hot day. Smart car! Or.......I'm just dreaming.

 

A 0.9 bar cap (13psi) is more than adequate for the 246 imho. Remember the cap is just a safety release if the pressure within the system expands beyond the design pressure. Its not there to regulate the pressure.

The expansion tank accepts the increased volume of water at full operational temperature (0.8 litres approx.) from the lower hose connection and must have at least 5cm (2") of air cushion at the top, I run my at about 8cm. The tiny top hose is there to collect steam and condense it back and also for vacccum release when the system cools down.

Water discharged from the overflow hose can be a number of causes but commonly its either the cap that's defective or there is not enough air cushion left at the top of the tank i.e "overfiiled"

A fully bled system is desirable to increase efficiency expansion and cooling but not critical, the system is well oversized for the heat generated from the engine under normal operating temps. The most noticeable areas for airlocks are the heater matrixes and these can be bled locally via the hoses.

In all cases do not cook the engine.

 

Excellent reply. Very informative and spot on

 

More boring than a thinking car, but same effect- the system ejected the amount it was overfilled. When the system cooled again the coolant volume decreased and you should have the correct amount in the header tank now.

But a little "less than perfect" = no problems. A little "more than perfect" = spits out coolant.

So a little less is better than a little too much.