SamGrant951

What psi do our cars run at when up to temp?

10psi - 15psi ok to test with?

Car left a spot of coolant on the ground so I pulled the fans and found this:



Just started leaking, radiator only has about 40k miles on it, hoses are all a year old or so...I tightened everything up and now have a pressure tester on it.

Thought it was the radiator at first but now thinking I might have gotten lucky.

thanks!

theedge

The cap is a 1 bar unit (14PSI) so I wouldnt go much over that. I would go to 14 psi, I once had a tiny pinhole in a hose that I only found using high pressure (IIRC, 10 psi didnt make it leak, it was a tiny pinhole).

Techno Duck

I test at 13psi, just under the cap pressure Brian mentioned.

fortysixandtwo

Test for whatever the cap is rated for. Unless the cap is stuck, the system will not see above its rating.
For a point of reference, on several occasions, I've pressurized the system to 25psi, so if you go a little over to 16 or so psi, I wouldn't loose any sleep over it.

User 41221

+1 Definitely take it to 15psi. The cap is rated for 1 bar, which is 14.4 psi, so 15 isn't putting any stress on it, and since the object is to find a leak, it needs to be at the cap limit. I do this all the time and have never had an issue.

SamGrant951

thanks guys, no leaks at 10. will take it to 15.

fortysixandtwo

Depending on how involved you want to get into leak checking, one of the best way to find a leak is to test the system without coolant. While under pressure, spray water with a little bit of dish soap added. This will form bubbles where the leaks are.

SamGrant951

15 and held fine, no leaks.

Tom M'Guinn

I zip tied a plastic baggie over the end of the overflow hose, so that I can tell between overflow and leaks.

I generally use 15psi to check for leaks, letting it sit for while...

ehall

I routinely go to 15.

Keithr726

I go to 15psi as well, helped me find a small leak at coolant neck at the front of the head.

944Willie

I just tested mine to 15 and let it stand for 45 minutes without any drop off. You may not see the leak but the drop off will be the real test. A real slow leak may take 15-20 min to show.

onspeed

i thought the cap was 16psi