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Discussion Starter · #22 ·
The common failure points for the E46 cooling system are not the connection fittings. The coolant expansion tank, in my experience, is a much more common failure point. In my cases, I've had to replace two expansion tanks, radiator and the hard coolant pipes residing under the intake manifold. I have never had a failure with the connection fittings of the coolant hoses. Now to be fair, when I replace the coolant expansion tank, I also replace the coolant hoses because I'm there already. I've had my car from 82k (2011) to now 235k

If you're a new E46 owner, there are a couple of links that you may want to read up on:



Edit: I've also had to replace the water pump once and the thermostat once.
Thanks for all the information guys. I'll read over the links.
 

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even the double ringed hard pipes felt sloppy and were all genuine parts direct from bmw park lane london
Sloppy? These 2 pipes were bolted to the block. I like to see a video showing the pipes were sloppy around when pushing with a finger.
 

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PSi would prefer 2 Orings.
You mean just like on the brake master cylinders, and calipers?

Oh, wait a minute....

Just cause it makes you feel better, does not mean it IS better. To think you know better than the BMW engineers is a bit arrogant. Especially when you clearly have not even done any research to understand what things actually ARE potential problem areas. Going on "feeling", rather than facts, you will spend a whole lot of money, and make your car LESS reliable. My car went >195K miles with NOTHING but normal, scheduled maintenance, a water pump at 125K miles, and a fuel pump at 170K miles. And my experience is not at all unusual for these cars. As I always used to ask all the engineers working for me: Exactly, what problem are you trying to solve?
 

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Thermostats and o-rings fail quite often. I’ve replaced my expansion tank 1 time in 200,000 miles.


Sent from my iPhone using E46Fanatics
 

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You mean just like on the brake master cylinders, and calipers?

Oh, wait a minute....

Just cause it makes you feel better, does not mean it IS better. To think you know better than the BMW engineers is a bit arrogant. Especially when you clearly have not even done any research to understand what things actually ARE potential problem areas. Going on "feeling", rather than facts, you will spend a whole lot of money, and make your car LESS reliable. My car went >195K miles with NOTHING but normal, scheduled maintenance, a water pump at 125K miles, and a fuel pump at 170K miles. And my experience is not at all unusual for these cars. As I always used to ask all the engineers working for me: Exactly, what problem are you trying to solve?
I am sure you are right but sometimes you look at something safety related and think mmmm
 

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Thermostats and o-rings fail quite often. I’ve replace my expansion tank 1 time in 200,000 miles.


Sent from my iPhone using E46Fanatics
I have replaced the tank twice and the O rings many times in 40 K miles,thats without all the other leaky cooling bits all now replaced with genune parts where possible and 2 water pumps.
 

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Personally, I just don't like all that plastic.

It's a prejudice having grown up with much simpler plastics.

Yes, that's not my graddaddy's bakelite-

I still don't like the plastic.

The brake caliper seal's a square section in the caliper,
and a cup seal in the master. There may be o- rings in the
pumps, but I've never looked.

t
 
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The parts the O ring services are a tighter fit from observation on brakes.
In all calipers, the O-ring sits in the cylinder's groove (same as the hose plastic connector with groove for O-ring) and the piston slides through the O-ring inner diameter. In fact I would say the brake O-ring is not compressed on the movable piston more than the coolant O-ring on the non-moving connector port.
And 29 psi max coolant vs hundreds of psi brake fluid, with just rubber O-ring.
 

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Do you know that the hard working brake caliper has an O-ring to keep the brake oil from leaking around the piston when you step on the pedal hard to avoid rear end someone? Do you trust the brake O-ring?
It's not an o-ring.
 

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In all calipers, the O-ring sits in the cylinder's groove (same as the hose plastic connector with groove for O-ring) and the piston slides through the O-ring inner diameter. In fact I would say the brake O-ring is not compressed on the movable piston more than the coolant O-ring on the non-moving connector port.
And 29 psi max coolant vs hundreds of psi brake fluid, with just rubber O-ring.
It's not an o-ring.
 

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Semantics. In either vernacular I would not use any typical O Ring composition in a brake caliper seal.
 

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Semantics. In either vernacular I would not use any typical O Ring composition in a brake caliper seal.
Agreed. I should have used the term brake caliper piston seal, but the idea is that to compare the brake O-ring seal and the coolant O-ring, and it is not the tighter fit in the brake vs. looser fit in the coolant design.
 
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