M42club.com - Home of the BMW E30/E36 318i/iS

DISCUSSION => Engine + Driveline => Topic started by: trashmanpenn on August 11, 2017, 12:28:39 AM

Title: Cooling System Pressure Test
Post by: trashmanpenn on August 11, 2017, 12:28:39 AM

I have the tools to do one, I'm just wondering what pressure I should pump it up to when doing the test. I can't seem to find it anywhere. It's a 1995 E36 318i. Thanks!

Title: Re: Cooling System Pressure Test
Post by: 1998ccc on August 11, 2017, 10:08:23 AM

The cap is sometimes marked with it's release pressure.  Not sure of the official spec but mine started leaking around 1 bar / 14.7 psi.  I wouldn't go much above that. 

Title: Re: Cooling System Pressure Test
Post by: monty23psk on August 14, 2017, 07:10:55 PM

29 psi

Title: Re: Cooling System Pressure Test
Post by: DesktopDave on August 15, 2017, 01:20:04 PM

+1 on the cap markings, usually on the center underside... Our cars are all 2BAR (or 29psi like Monty says). All M42s use a high-pressure 2BAR system. A lot of the pre-90 BMWs still use a 1BAR system, approx. 14psi.

I always test mine at 20-ish psi and see if it's still over 15psi after an hour or so. They don't have to be perfect from what I've seen. I'd pump it up to 30psi without worry but it'd take forever to pump the system up with my hand-pump HF tester. At high pressure I will use the hood as a shield from the pressure tank & cap.