1.2 or 1.4 bar overflow cap for e39? stock

[Sleepyhead97]

Hello. Was wondering if there is a newer model stock cap say from a standard bmw with a lower bar rating than stock e39? Will any of the factory recovery tank caps with a1.2 or 1.4 bar rating fit the e39?

[BimmerBreaker]

Why do you want to do this?

Why not just bleed the system properly and use the correct components? I'm never sure why garage mechanics think they can out-engineer the thousands of well-paid BMW engineers who designed these cars.

The overflow cap should NOT set the pressure for the system anyways!

[Critter7r]

The expansion tank cap is designed as the weak link in the system, so when something else fails and the engine overheats, it's the first thing to go so that the coolant is vented in a relatively predictable manner instead of hoses blowing off randomly. There shouldn't be a need to vent the cooling system normally.

[Sleepyhead97]

All due respect anyone know the answer to my question.

I'm an doing this because I have an external head gasket leak and I want to reduce pressure on it. I did a block test it is purely an external leak.

[rob22sf]

after market by motorad part #T43 is 20lb instead of 30lbs

its basically a cap for a e34 525i , i have one sitting around, but im not sure if it will tread on to the tank, most local auto parts stores have them, i ran into your problem as well a while back, but i ended up not driving the car till i fixed the HG, good luck man

http://www.motoradusa.com/motorad_ca...l+L+%282494%29

[Sleepyhead97]

after market by motorad part #T43 is 20lb instead of 30lbs

its basically a cap for a e34 525i , i have one sitting around, but im not sure if it will tread on to the tank, most local auto parts stores have them, i ran into your problem as well a while back, but i ended up not driving the car till i fixed the HG, good luck man

http://www.motoradusa.com/motorad_ca...l+L+%282494%29

Thanks. I really appreciate it. I'll look into this soon.

[rob22sf]

Thanks. I really appreciate it. I'll look into this soon.

no prob bud, just be careful when you screw it on, I'm not 100% sure, I never got around to trying it, but from what I can remember it looked very close. let us know how it works out

[jp5Touring]

German auto solutions https://www.germanautosolutions.com/...12_bar_cap.php

they make some nice stuff

[pbonsalb]

I run the earlier 140kpa cap instead of the 180ka cap. Did not know there was a 120kpa cap. You can run zero kpa. Just keep the cap a little loose.

[slocar]

I run the earlier 140kpa cap instead of the 180ka cap. Did not know there was a 120kpa cap. You can run zero kpa. Just keep the cap a little loose.

WHAT?

Open system will boil the water instantly, overheat and spit it all out ... good way to ruin your motor.

[pbonsalb]

The OP wants to run lower pressure. 0 is possible. We do not know why he wants to run less pressure. Evans coolant, which I run, is fine at 0 pressure and boils at 370F.

[rob22sf]

his HG is blown, that's why he wants to run a lower PSI, KPA etc...

[Sleepyhead97]

Went to the parts store and picked up a radiator cap for a 1988 325i. Marked at 140kpa. It is the exact same dimensions as my 200kpa. I installed the cap in the parking lot, drove off seems to be working fine. The pressure of the hoses dramatically decreased from the 200kpa cap.