Hey guys. today i was driving to work in my t/a and i noticed the temp was going wayy up. so i stopped and checked everything (first off, my gauge is off, had to check with a laser thermometer). While in the process of checking to see why the temp would be pinned high, i noticed my 4th gen overflow tank was filled....like overflowing, the neck was filled and coming out when i took off the cap. I did a little research and on the 4th gen forums, it says in order to run this overflow tank you need an 18psi radiator cap. if i get one, am i going to mess anything up? i'm just noticing that my 16psi one is dripping and not making a good seal and supposedly without having a high enough psi cap, the suction isnt great enough to pull the fluid from the overflow tank to the rad. any help is appreciated.

 

I just wanted to subscribe to this thread because in over 8 years this is the first I've heard about possibly using a 18 PSI cap on a third gen.

Although my first thought was about the leaking 16 PSI cap.

If the car has been fine up till now........

Its a little hard to even reach that 16 with a leak....

Definitely a defective cap. And I would clean the rad. fill neck where the cap seals as well.

 

Ok. I cleaned the neck last time. It's a new cap, brand new. I just finished putting in the new 350 and wanted all new stuff and since putting on the cap it has leaked a bit when getting up to temp. It wasn't until today that i realized that I was losing coolant to the overflow tank

 

The new cap that is leaking is a major problem.

Even if its a little. It does not take much to mess with a system that is supposed to be pressurized.

Find a new cap (I would stay at 16psi until told otherwise) and try it. If it still leaks than your problem is on the lip of the radiator neck.

I used very fine sandpaper on the lip of a fill neck to smooth out any imperfections. Just lightly.

 

Today I got a new cap from auto zone (although really reluctant to trust any of their parts still) and put it on. Had it idle for about 10 minutes to get up to temp and it didn't leak. Took the 15 minute ride into work and still no leaking. I guess just the cap at this point. I'm going to give it a day or so of driving to see if the coolant level remains the same in the radiator

 

Silly question.

When you filled the radiator, then you put coolant just to the cold fill line in the overflow tank. Is that correct ?

 

No, when I filled it I put coolant in the rad and ran the car until the thermostat opened. Then topped it off. Then did the overflow