[kaboom28]

I've always been curious about these coolant pipes, why plastic? And is it plausible is upgrade to superior material that wont spontaneously combust or am I giving in to the hype about these parts being so unreliable. Design choice?

Plastic due to cost mainly. There's no reason to make relatively expensive parts out of metal when a plastic part design will satisfy the performance and service life requirements the car maker has set. The cooling system on these cars is full of plastic parts, and some last longer than others.

In addition to cost, you also need to engineer the entire system holistically and not just a coolant pipe. You need to take into consideration thermal expansion of mating parts (need them to expand and contract similarly), mechanical vibrations and movements (plastic gives, metal doesn't), corrosion (no iron due to liquid coolant), and galvanic reaction (engine is aluminum so mating material need to be selected properly). I would love to see the engineering decisions that were made when they designed the car.

 

[Sev1980]

so i bought a set of febi hoses to do this job in 2018 and never did it. i still have them, the longer one is made in china. need to double check the shorter one.

I completely forgot about this job and my e46 has 141k miles, with the rest of the cooling system completely replaced. Ive driven up steep grades in 100+ heat and havent had issues, but after seeing Jason's video last night, im thinking it might be time to do this job.

To your guys' point, my e46 is a forever car. maybe i should sell these hoses and just get OE before I tackle the job... Thoughts?

 

[Sev1980]

is it true the OE pipes, even original dont blow up like jasons?

 

[LeverThis]

Gen-yoo-whine parts were NOT as impressive as I'd hoped- the hose itself was Turkish
(think Rein from a few years back) and the ends were better. But while they were
good, they were no more impressive than the Gates. And yet, everything was noticeably different.
Maybe it came from the same industrial complex, but it came out of different machines.

I noticed something similar on the last water pump I changed in December 2021 when my (Behr Hella) Expansion Tank split on the seam after 88k miles and less than 5 years. The late 2021 Jen-You-Wine water pump looked exactly like the Saleri pump it was replacing, save for the roundel.

In late 2016, however, I had installed a genuine BMW pump on my back up e46, and that one looked different than any of the Saleri water pumps that I subsequently installed on the other e46s I've worked on. The 2016 genuine was a different water pump than the 2021 genuine.

E46es are going away, as will the parts.

Yup ... there have been lots of e46s in the boneyards in recent years and that can't continue forever ... eventually they will become scarce and so will parts production. Many OE makers seemingly already shifted e46 parts production to cheaper locales, and that should mean that even the genuine parts will be made there as well.

not yet Amish

Lol ... might need to learn Russian before going full Amish ... those guys seem pretty adept at finding workarounds to scarcity.

 

[LeverThis]

To your guys' point, my e46 is a forever car. maybe i should sell these hoses and just get OE before I tackle the job... Thoughts?

But what is OE for these pipes? I don't think there is a clear reference for that. Since 2016 that I've been working e46s I've only seen genuine and then cheap aftermarket as options here. Its not Febi (many report fitment issues) and I wouldn't trust Rein at this point.

Despite the discussion here, genuine BMW is the best bet for the hard coolant pipes for the time being. At FCP Euro, one of the genuine pipes (11531705210) is $50.99 and only $3.30 more than the Febi, while the expensive one (1537502525) is now only $96 (I think I paid $120+ a few years ago) while the Febi is $38 cheaper.

Especially for a forever car, $40 savings isn't much compared to the risk of needing to redo it or the pipes not fitting in the first place.

is it true the OE pipes, even original dont blow up like jasons?

From what I've seen online, genuine tend to leak slowly as shown in post #6 above. Maybe eventually they do crack and dump everything, but the green waterfall seems to give a warning first.

I'd love to hear about any reports otherwise ...

 

[Sapote]

Turns out one of his hard coolant pipes cracked without warning. This is unusual.

After seeing the leaking pipe, I am thinking about getting some copper water pipe at HD and shape it into form then I will have coolant coper pipes

 

[herrbrahms]

I've always been curious about these coolant pipes, why plastic? And is it plausible is upgrade to superior material that wont spontaneously combust or am I giving in to the hype about these parts being so unreliable. Design choice?

I agree. Someone should extrude them out of aluminum instead of ABS plastic and sell that as an upgrade. Replacing an expansion tank is a minor chore. Replacing coolant hard pipes is a lot more serious. If I'd had the option to put in proven aluminum hard pipes, I'd have done that and also sent away for the reengineered GAS CCV replacement, then I could've said goodbye to ever pulling my intake again. I already replaced the knock sensors, crank angle, even the starter while down there because I work on my cars out of necessity, not for fun.

 

[applehugger]

When I did the hard lines on my E46, I looked for some kind of metal replacement. ECS tuning sells a kit that replaces only one of the hard lines with an aluminum one made by URO. Reviews are very bad on fitment and only having one metal line doesn't make much sense, plus I've had nothing but bad experiences with ECS.
As the original plastic hard lines on my E46 lasted 230k miles and 23 years (and were not leaking when replaced), I felt confident using original plastic ones again.

50's kid may have made a silly choice, but it was a choice he made 8 years ago, and he's consistently put out some of the highest quality E46 repair videos on YouTube, so I can't fault him much. I also appreciate that he owns his mistakes, and now we know of a different failure mode that can show up in poor-quality hard line replacements.

 

[Effduration]

so i bought a set of febi hoses to do this job in 2018 and never did it. i still have them, the longer one is made in china. need to double check the shorter one.

I completely forgot about this job and my e46 has 141k miles, with the rest of the cooling system completely replaced. Ive driven up steep grades in 100+ heat and havent had issues, but after seeing Jason's video last night, im thinking it might be time to do this job.

To your guys' point, my e46 is a forever car. maybe i should sell these hoses and just get OE before I tackle the job... Thoughts?

yes, sell your Febi pipes and buy the genuine BMW part…OE a is a different term..

I have looked at a lot of M54 coolant pipes - Genuine and aftermarket - and I don’t think whoever made/makes them as the Genuine BMW part, makes them for the aftermarket..at least not in the US…

in other words I have never seen an aftermarket pipe with the quality of the genuine pipe.

 

[Weste46]

...My factory ones are at 301k miles with 40 track days. 🤭 I should probably replace those hm.

 

[herrbrahms]

In addition to cost, you also need to engineer the entire system holistically and not just a coolant pipe. You need to take into consideration thermal expansion of mating parts (need them to expand and contract similarly), mechanical vibrations and movements (plastic gives, metal doesn't), corrosion (no iron due to liquid coolant), and galvanic reaction (engine is aluminum so mating material need to be selected properly). I would love to see the engineering decisions that were made when they designed the car.

I would venture that galvanic corrosion is a bigger consideration than thermal expansion for this application, since each hard pipe is attached to a rubber hose on one end that will absorb any additional thermal expansion that occurs using aluminum rather than ABS. I would definitely not use copper pipe because the engine isn't copper.

In fact, if I was proficient at TIG welding, I'd be tempted to weld aluminum pipes into the head and block respectively, and call it a day. Who needs sealing o rings?

Metal fatigue would also be only a minor concern since the pipes have plenty of support as they are constructed now. The block pipe in particular has a beefy bracket to hold it in place. If you replaced the single piece pipe/bracket that exists now with a metal pipe, metal bracket, and two rubber bushings holding the bracket to the pipe, you'd be good for a decade at least.

 

[alan53]

The hard pipes lasted the BMW life time of the vehicle which was 100kmiles i believe

 

[kaboom28]

I would venture that galvanic corrosion is a bigger consideration than thermal expansion for this application, since each hard pipe is attached to a rubber hose on one end that will absorb any additional thermal expansion that occurs using aluminum rather than ABS. I would definitely not use copper pipe because the engine isn't copper.

In fact, if I was proficient at TIG welding, I'd be tempted to weld aluminum pipes into the head and block respectively, and call it a day. Who needs sealing o rings?

Metal fatigue would also be only a minor concern since the pipes have plenty of support as they are constructed now. The block pipe in particular has a beefy bracket to hold it in place. If you replaced the single piece pipe/bracket that exists now with a metal pipe, metal bracket, and two rubber bushings holding the bracket to the pipe, you'd be good for a decade at least.

Ultimately we don't know what BMW engineers were considering so we can only guess. But in terms of thermal expansion, when you connect two different metals together, they may expand differently and stress the connection point. Is this relevant at 100 degC, probably not if the metals are chosen properly. Can this be engineered around, probably but we'll never know what BMW was thinking.

Yeah Tig-welding a pipe in place of the hard coolant pipe(s) would be much longer term. However, I'm sure BMW didn't want to do that on the assembly line .

I would agree that metal fatigue can be engineered around.

 

[Sapote]

I agree. Someone should extrude them out of aluminum instead of ABS plastic and sell that as an upgrade. Replacing an expansion tank is a minor chore. Replacing coolant hard pipes is a lot more serious. If I'd had the option to put in proven aluminum hard pipes, I'd have done that and also sent away for the reengineered GAS CCV replacement, then I could've said goodbye to ever pulling my intake again. I already replaced the knock sensors, crank angle, even the starter while down there because I work on my cars out of necessity, not for fun.

Yes, why Mishimoto didn’t make aluminum pipes instead of the useless ET or radiator?

 

[Megalocnus]

Yes, why Mishimoto didn’t make aluminum pipes instead of the useless ET or radiator?

Since Mishimoto could't make their aluminum ET to fit properly, I wouldn't be the first to test coolant return pipes by them.
There were chinese hard coolant pipes available some years back, but fitment also wasn't great.
One of these is still availave: https://www.ecstuning.com/b-uro-premium-parts/aluminum-water-pipe/11537502525prm~u/

I got genuine hard pipes from the dealer.

 

[Archbid]

On a related note, Turkish and Slovakian subcontractors to the majors seem to do good work.

 

[Vass]

Not sure why y'all are hyping up the severity of the job of replacing these. Intake out-in is like half a day's work.

 

[cigma2312]

Not sure why y'all are hyping up the severity of the job of replacing these. Intake out-in is like half a day's work.

If you’ve done it before yeah, why waste the half day if you don’t have to?

 

[kaboom28]

Since Mishimoto could't make their aluminum ET to fit properly, I wouldn't be the first to test coolant return pipes by them.
There were chinese hard coolant pipes available some years back, but fitment also wasn't great.
One of these is still availave: https://www.ecstuning.com/b-uro-premium-parts/aluminum-water-pipe/11537502525prm~u/

I got genuine hard pipes from the dealer.

I have this installed in my car since 2/2021. Zero issues so far. During installation, the bracket on the pipe was slightly off. A slight nudge with my bare hand on the pipe corrected the misalignment.

 

[vtwagon]

I’m on original coolant hard pipes at 21 years and 108,000 miles. Safe to say they’re on borrowed time. Genuine will be going back in, that’s for sure.