I respect the 1.4 bar "testers" and good for you if you have great results. I went with the original 2 bar cap (it was in stock , not the other or I would have put the 1.4) , but either way this cap looks cheap and I will inspect and replace more often from now on for cheap cheap insurance. I'm convinced it's the culprit of MOST coolant system problems. IMO

I actually have it for a different reason. I want it to vent, at 1.4 to show me that there is an issue. Waiting for a 2 bar cap to vent, good luck.

Like I said before, chances of you hitting 2 bar while driving is slim to none. But once you pull over, shut the car off, you might come back to a blown hose. I am not sure what the 2 bar cap is supposed to accomplish. The pressure increased temperature difference is negligible. I really do believe that it is meant to abuse the shit out of our hoses when the car gets shut off. Maybe it is BMW way of making sure the hoses fail when the car is shut down. It really is a retarded way to force a failure. I doubt it hits 2 bar, or even 1.4 bar often, but why would the cap be set so high?

If you want to say that BMW is a performance machine, Ferrari uses a system under 1 bar. No one else in the auto world uses a 2 bar system.

I'm telling you, BMW is making a killing on selling all these hoses, expansion tanks, and coolant for every used BMW out there. And it is a lot of cars with the 2 bar cap. A lot, like almost all of them.

Why I believe 1.4 is the way for me. When I turn off the car, and it hits 1.4, enough to vent it, I will know I have an issue somewhere.

If I have a 2 bar cap, and blow a hole in my expansion tank, I might be thinking the tank is old, and not even bother looking if there is some other issue.

If my hoses or tanks start to leak with the 1.4, then I know my components are due for a change. At least I will know I am not blowing them apart.

And we keep talking of hoses and expansion tanks. You guys are forgetting one part that every M62 suffers from. The valley pan. Unless you plan on including the VP gasket in every coolant flush, or system refresh, you are going to blow a hole in that one too.

I've read that if you lower the pressure of a system made to function at a higher PSI , you can create cavitation (surface bubbles) , this can cause the engine to run hotter.... :dunno:

Gio the rating of the expansion tank cap does not change normal operating pressures of the system. Normal operating pressure is around 1 bar.

This is a common misconception with the coolant cap, it only vents at that pressure it is rated for, but normal operating pressure of the system is the same regardless of the rating on the tank cap.

Exactly , if it was operating at 2 bar and we'd lower the pressure valve at 1.4 bar , then there would be a possible problem. But because it operates at closer to the 1bar mark then the 2 bar cap is totally irrelevant .

Makes sence....:thumbup:

Low coolant level gong means shut it down. Same thing you'd naturally do during catastrophic failure. Limping along isn't salvaging but rather risks low flow + localized hot spots. Also the OEM temp needle is a joke.

I know it's a joke. But I'm not driving daily with the KTMP on. There are cases when I do so though.
If you start loosing coolant with a 1.2 bar cap or a 1.4 bar cap, you can check where the problem is. With a 2 bar cap, usually it's catastrophic and you loose almost ALL of the coolant rather suddenly. This is my point.
G.A.S. tested thoroughly the pressure caps and here is their findings:

"So what is the solution? The system does not need to run that high of a pressure. In fact the industry standard for cooling system pressure is 1.0 to 1.4 bar. After doing extensive research and beta testing on several BMW engines, we decided on an optimum pressure of 1.2 bar. This pressure is high enough to maintain OEM pressure specifications up to 126 degrees Celsius (260F), which means that our cap will not alter your cooling system efficiency in any way. Apparently even BMW has seen the light, since most current BMW models now come equipped with a 1.2 bar cap.
Our cap will limit the maximum coolant pressure to 1.2 bar (17.5 psi) instead of the OEM spec of 2.0 bar (29 psi). Even something as simple as overfilling the coolant recovery tank a little higher than the recommended level will result in potentially damaging pressures when using the stock 2.0 bar cap.
We want to be very clear... cooling system components can fail due to cracking even at normal operating temperatures and pressures. Our cap will not guarantee you will never experience a cooling system component failure, but it will drastically reduce the chances of catastrophic ruptures.
The German Auto Solutions 1.2 bar Cooling System Cap uses 100% original BMW internal components that have been recalibrated to vent at 1.2 bar."

In layman words: If your system runs consistently at 126°C or over, the 1.2 bar cap will start venting. Meaning that your car has serious problems and IF you have the 1.2 bar cap, you can shut the car off and check what's wrong.
On the other hand if you have the 2 bar cap, it will NOT vent, the temp raise even higher. The cap will hold 2 bar, but maybe the other plastic & rubber components will NOT, hence a sudden rupture. Checking what's wrong, it's too late now. The damage is there, and the car is absolutely not driveable. This at best. If you are in a spot where you cannot safely pull over, you also run the risk of overheating, because with no coolant driving an additional couple hundred yards to a safe spot might do it.

Hope this clears it up. For me, the 1.2 bar cap (with OEM BMW safety valve) does the job rather nicely. If you are not comfortable with that, you can use the OEM 2 bar cap as designed (and curse BMW, if God forbids you run into a stuck closed T-stat, or whatever). There are people who don't change fluids because they also are designed lifetime (as per BMW), and we know there are arguments about that too. It's your car and you do whatever you please with it. :thumbup:

Well worded. I only like the 1.4 OE cap because it looks exactly like the OE 2.0. Otherwise, the 1.2 is probably a safer bet.

Another good point, If you overfill your coolant by accident, you have a bigger chance of rupturing shit with the 2.0 cap. So in reality, you can have a catastrophic coolant blow out while driving, not just shutting off.

Hey guys,

Any more update on the 1.4 BAR cap? I just ordered all the hoses, expansion tank etc and would like to use 1.4 BAR cap but wanted to see how this is going for you guys.

No negative effects. If your cooling system is tip top shape go for it