Lieutenant General 
Drives: E90 & Z4 Coupe
Join Date: May 2012
Location: MARLAND
Quote:
Originally Posted by AllBlackBimmer 
I actually read one of your posts where you said you replaced all the hoses and it was a waste. I wouldn�t disagree nor do I want to replace all my hoses.... I really only want to replace the hoses that are touched/removed/disconnected when doing the water pump and thermo.
I know the hoses might be ok, but I know the connections can sometimes break due to being brittle. I don�t want to get into a bind and not be able to complete the job and drive my car just because I broke a connection and can�t finish the job. ... also, the hoses might cost me another $50-100 at the very most... I think the u-hose that connects the pump/thermo is only $15-20, well worth the cost of replacement cost.
Did you ever replace your expansion tank or cap?
Anything else you think I should do while fling the water pump/thermo?
So here are my thoughts. First off every car sees a different driving environment that can affect hose life. The rubber hoses per se are not problematic, but the plastic connectors can be. I've not experienced either, but from reading for all these years on E90 post, the small diameter return line from the upper radiator hose and the plastic fitting at the OFH are the two hoses that are failure prone. Replacing the T-stat and water pump involve neither of those hoses/fittings. I think the plastic fitting at the oil filter housing breaks for some people because the OFHG leaks oil on the plastic, which with heat, changes the chemical composition of the plastic and eventually fails. Neither of my N52 have leaked oil in any amount that got on the fitting, so I've not experienced the problem with that fitting. If I was doing any type of cooling system maintenance, I'd definitely replace the plastic fitting with the aluminum one.
It's your car and your perceived level security, and your money, but I have to ask, why are you replacing the t-stat and water pump? The aluminum-bodied t-stat was problematic on the 2006 versions of the N52. Early on, BMW updated the t-stat to a plastic-bodied version, which doesn't have the problems of the original metal t-stat. I replaced my t-stat at 134,000 miles in 2011. 8 years and 230,000 miles later, I've never seen another trouble code for it. My 10-year old 93,000 mile '08 Z4 N52 has never showed a t-stat trouble code. If you've had the typical water pump codes, then you should replace the water pump, but since the t-stat comes out first to replace the WP, you don't necessarily have to replace the t-stat because it doesn't save any labor if the T-stat goes bad later after the new pump goes in. Like the updated t-stat, the updated WP in my car has been trouble free for 8 years and 214,000 miles. I think the updated parts for the t-stat and WP used on N52s after 2007 are better parts that fail less.
I did all the hoses on my car because I really only had concern about the U-shaped hose that runs between the t-stat and pump and only because it sits so close the the exhaust manifold and catalytic converters, but I thought if I was going to replace that hose then why not the rest of them? And I'm keeping the car forever and unlimited miles anyway... In reality I think the hoses are lifetime parts for most people, which is why I think it is a waste of money to preemptively replace them. I kept most of the hoses for emergency spares, and they have been hanging on the walls of my shop for years now. The u-shaped hose, the one I was really concerned about was in great shape too.
There are 4 hoses that attach to the thermostat. Based on my experience none of them would need replacement even though 2 of the 4 have plastic connectors. I found that the plastic connectors with the metal clips do not degrade over time.
I did replace the coolant reservoir cap after my car overheated when the pump died. The coolant reservoir in my car is original, 12+ years and 363,000 miles old. It looks okay to me. I don't go smacking it with a hammer or anything, but it has been through 2 deer hits to the front end. I studied the manufacture of plastic parts as part of my manufacturing engineering curriculum. Plastic parts are difficult to produce and have many variables (heat, pressure, base stock, time, cooling, etc.) involved to making quality parts, which means there is variability to their build quality. A few people lose a coolant reservoir tank, post about it on the internet, and all of a sudden OCD Bimmer owners, the 2% that read car forums on the internet, think they need to replace the tank on some interval basis. 98% of the E9X owners drive around completely and happily unaware of the ticking timebomb the coolant reservoir is...
Good luck with the maintenance.
__________________
A manual transmission can be set to "comfort", "sport", and "track" modes simply by the technique and speed at which you shift it; it doesn't need "modes", modes are for manumatics that try to behave like a real 3-pedal manual transmission. If you can money-shift it, it's a manual transmission. "Yeah, but NO ONE puts an automatic trans shift knob on a manual transmission."
Source: https://www.e90post.com/forums/showthread.php?t=1574673
Posted by: robthowe0193637.blogspot.com
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