radiator cap issues

2003se559 · Post by **2003se559** » Mon Jan 30, 2012 12:16 am

hey all well yasterday 1/28/12 i was droping off my wife at work when i noticed that steam(smoke) was coming out of my hood on the passangers side corner,so i parked the car i opened the hood and coolent was coming out of the radiator cap, so i grabed a towel i had in the car and try to tighten the cap, as i did this it started to leak more and more. I than left to kragens auto parts wich luckily was about 2 blocks away i noticed my temperature was going up so i turned on the heater at full blast, temp started going down to normal. long story short the cap seemed fine (purchased it about 5 months ago) however i purchased a new one so far problem solved, so i wanted to know if this is something normal maybe the cap was defective? any feedback is greatly apreciated. (my old cap was a 20 psi my friend told me to buy a stronger one since i went boost, the new one thats on the car now is a 16psi thats the one they told me was for my car. does this make a diference?)
thanks for ur input

Post by **occasional demons** » Mon Jan 30, 2012 7:55 am

The PSI rating on the cap is what lets coolant flow to the overflow once the pressure in the system builds enough to push it out. 20 psi is way too much. You are pushing the limits of the seals in the radiator, especially if it is stock. It may also raise the boiling point of the coolant past a safe temperature. You could overheat the engine without it actually boiling over.

If it was leaking at the cap, and a new one fixed it, it is prolly fine.

Edit: Did you top off the expansion tank after replacing the cap? Also check the coolant level at the cap when the engine is cold, to be sure the new cap is drawing fluid back in. If the old cap was leaking, it may have done it enough to let air pockets form in the head. If it is not recovering coolant, or the overflow has none in it, it could randomly overheat.

2003se559 · Post by **2003se559** » Mon Jan 30, 2012 12:51 pm

Ya I topped it of with coolant I don't have an overflow tank so just filled the radiator up. So u think am better off with a 16 psi cap rather than the 20 psi? I's there really a difference wether I buy it from autoparts store or dealer I mean quality wise?

Post by **occasional demons** » Mon Jan 30, 2012 1:23 pm

A 16 is a safer bet. Les chances of leaking. An expansion tank of some kind is also recommended. All the coolant that is pushed out leaves an air pocket in there. You don't want to risk a lack of coolant at the turbo.

A 20 psi cap will prolly never let any fluid out, but like I said, you are pushing you luck with the radiator tanks, hoses, water pump seals, etc. Once it leaks, it will have much more potential pushing the coolant out that failed seal.

FWIW, most cooling system testers have a warning on them telling you not to pressurize the system that high. A soda bottle will work as an expansion tank... A tall aluminum can would be a better bet.

2003se559 · Post by **2003se559** » Mon Jan 30, 2012 6:49 pm

Thank you sir

oh wait so what u think about not having an overflow tank do I really really need one or just keep an eye?

Post by **occasional demons** » Mon Jan 30, 2012 7:15 pm

occasional demons wrote: An expansion tank of some kind is also recommended. All the coolant that is pushed out leaves an air pocket in there.
A soda bottle will work as an expansion tank... A tall aluminum can would be a better bet.

Personally, I would use one. The old school radiators could get away without one, as the upper tank was large enough to hold enough air for expansion, without losing any fluid. The newer designs are made specifically to let the expansion tank handle the expansion and contraction of the fluid.
Another benefit of keeping air out of the system is there is less oxidation, and the coolant last longer.

2003se559 · Post by **2003se559** » Mon Jan 30, 2012 9:48 pm

any advice on a decent aftermarket coolant tank since the oem had to be removed since it wasnt compatible with my turbo setup lol nit enough room i guess.

Post by **occasional demons** » Tue Jan 31, 2012 6:59 am

From Danteneon's neon.