Coolant Hose Life Expectancy

[Nanniepoo]

Car is '08 N62 188.5k miles

Just curious if others have experience with what I consider shorter than ideal/expected coolant hose life. Two have failed this summer; #7 end of May and #5 was maybe leaking for a while, but confirmed yesterday. This is annoying to me as I replaced nearly all hoses in 2018.

I replaced #7 January 2018 due to failure. Back then it was a slow leak and was arguably still drivable. This time it blew right after shutting the car off after our very first time towing (empty enclosed 10' cargo trailer) and was spraying coolant everywhere.

#5 was replaced June 2018 as "while I'm there" work when I did the water pump. I replaced a number of other hoses at the same time, again because I was there/preventative. I haven't pulled it off yet but it appears it's leaking from the molded section where the hoses connect to make the 'Y'. It maybe started as a slow leak for who knows how long but is now a steady drip/nearly a stream.

I did the valley pan and coolant transfer pipe work summer 2024. So there's a chance I damaged #5 when removing/reinstalling, but everything passed the pressure test after that work and I only added a tiny splash of coolant in March so seems it lasted 10 months or so even if damaged.

The point of my post is effectively all hoses are 7 years old now. Forced regular coolant changes due to relatively frequent need for coolant work (WP, aux WP/heater valves, coolant pipe). But hoses are failing 7-10 years, genuine BMW or after market. Is this expected? Should I just do another round of replacing hoses?

[80stech]

I haven't had any problems with hoses but I have the 3.0L. If you want piece of mind buy OE or at least a reputable brand and get, or make, a cooling system pressure tester.

[andrewwynn]

Replaced every coolant and power steering hose on my e70 while I had the motor out. They were still going strong at 196k miles 315Mm (k km) but it was ∞ easier to replace with engine out of the car and about 15% of the price of the replacement motor.

My e53 was 205 k miles and 22 years old with all original hoses so it's a little crazy hearing those ages.

Is your temp running outside of normal? Your pressure cap not releasing pressure? Is the coolant mix correct so the boiling point is high enough to keep pressure down? Seems there has to be some systemic issue.

I would do a head gasket chemical test on the coolant to at least discount combustion gases pressuring the coolant system. (often the cause of frequent hose failure).

–awr–

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[Nanniepoo]

Interesting feedback. Yes I agree if it's not crappy hoses, headgasket is suspect so I can do the chemical test or run engine with the pressure tester hooked up. For whatever it's worth, oil is always looked good, no tailpipe smoke, car has never overheated....

I have realized I overly trust major retailers and just buy their third party options. I have confirmed the "Y" hose that failed was actually my first FCP Euro purchase ever and I purchased Rein. Rein doesn't seem all that great in hindsight.

However, of note, I replaced that hose upon a recommendation from another member here while I was doing the WP. And it does appear to be a weak hose with many Google hits of it falling apart when being touched, presumably the BMW hose. Mine fell apart during disassembly and I was not aggressive with it...

I can't upload pictures because they're too big, but it doesn't look like a pressure failure. The adhesive or whatever they use in the molded section failed, so I'm thinking temperature and time. And for whatever it's worth Rein has changed the design. It's now a plastic Y with the three hoses hose clamped on.

I have become less anxious about it when I'm realizing of all the hoses the same one has failed twice, and the other one is a common failure, so maybe I just replace those again in 6 years preventatively if the X5 is still around.