View Full Version : Metal thrmostat housing?

04-14-2005, 10:23 PM
Hello all...

Is there any advantage to the metal thermostat housing that I believe was found on the M42 engines? I've replaced the plastic thermostats on our M44 cars pretty frequently due to thermostat failure. Maybe it's just a fluke. I keep using factory BMW parts and they only supply the one piece plastic housing with thermostat.

Any input as to the durability of the thermostat on the M44's? Thanks

04-15-2005, 02:44 PM
My car is one of the last '96 production date ti s that has the aluminum thermostat housing and I've never had any problems.

04-15-2005, 04:08 PM
is yours very early 96 production date? i thought all 96 and up (m44) were the crap ass plastic housings. nice that they switched from aluminum to plastic. sounds like an american car company trying to save a few bucks instead of our beloved BMW.

04-15-2005, 04:14 PM
I have to agree with Cali...maybe that car has a '95 production date?

Anyway, the plastic has never broken on me *knocking on wood* but the 'stat always seems to give up. Temp stays just above the blue...replace the t'stat, everything's fine...wait approximately 1yr...repeat. It's just a hassle. And the part isn't cheap...$40 list, I think. Thankfully the parts guy knows me and knows what I'm coming for so I'm getting it for about $20 these days. I guess I wouldn't mind the plastic housing if it used the same "normal" thermostat that the other cars use...but I should be thankful it's not the electronic style that the 6-cyl engines had!

04-15-2005, 04:32 PM
i hope i'm wrong and we can get aluminum housings ;)

EDIT: truth be told, i figured it was a custom piece that his company sold, not a stock piece. people have been looking for an aluminum housing to replace the plastic for a long time now!

04-15-2005, 08:37 PM
somebody told me that bmpdesign had an aluminum upgrade but I haven't been able to find it

04-15-2005, 09:43 PM
i've seen the part on understeer.

but i've never had a problem with the plastic piece. mine held up until 135k, but was a problem with the tstat itself, not the plastic cracking.

in general i don't have a problem with plastics as long as i can see and hold it. the technology is pretty solid, IMO.

04-15-2005, 11:15 PM
Hey guys,
My car is an early '96 production. Between '95 and '96 it seems BMW had too many M42 engines so they used them in late '95 and early '96. As of 9-'95 they were shipped and sold '96 models. So the great thing is that it's got the aluminum therm. housing and it's also OBDI.

04-16-2005, 01:29 AM
aaah, so you have an M42. doh! aceyx, any possibility of you hooking me up with the link off understeer? can't believe there is one available and i haven't heard about it :p

04-16-2005, 02:48 AM
aaah, so you have an M42. doh! aceyx, any possibility of you hooking me up with the link off understeer? can't believe there is one available and i haven't heard about it :p

only one I found was for the 6 cyls

04-16-2005, 05:49 AM
The thing is, I've never had a problem with the actual plastic housing either...love plastics! My dad spent many years in the plastics industry and it kept food on our table...BUT...my reasoning behind wanting the aluminum housing and corresponding thermostat is that the thermostat would "theoretically" be separate from the housing and therefore (again theoretically) a little bit cheaper to replace when it fails. And hopefully it wouldn't fail as often! Heck, maybe I'm just a defective thermostat magnet. Hmmm...

04-16-2005, 06:21 AM
ah, dangit; i need to learn how to read.

sik; are you using the BMW coolant? i know that many parts are very sensitive, so i wouldn't rule out prestone being responsible for the multiple failures.

the prices for the thermostats are pretty similar, ranging (at pelican) between 13.50 - 17.85 so i'm not sure if there's really a price savings adding in the cost of the alum. housing. plus, not sure if you can get just the valve itself.

if i were in a similar situation, i would talk with the customer service manager at your local dealer. it's possible they purchased a "bad batch," and you're just getting one after the other. if they're purchased within a year, it should still carry the warranty, but having them fail so frequently (and going through replacing them) would be my concern, rather than the price.

04-16-2005, 01:58 PM
I'm running BMW coolant now but wasn't in the previous ti. This one's only failed once and it's at fairly high mileage so most of my frustration may just be that I had problems with the old car and this one piled on makes it seem like a bigger deal than it is. Never tried an aftermarket one, though...perhaps that's what I'll do next time (if there's a next time.)

For now, I'll try to remain happy with the one I just put in. If it fails again, I'll revisit this thread and complain like I always do!

Thanks for the responses. I learned what I wanted to learn...apparently the plastic 'stats are not inherently bad based on others' experiences. Good to know.

04-16-2005, 03:06 PM
plastics aren't high on my list right now with all the broken plastic pieces i've had lately. aceyx, good to see that one can find sources for the plastic housing + thermostat for around the same price as the thermostat alone. i was also of the mind that a thermostat alone would be cheaper. i've just found that generally plastics become brittle over time and major temperature swings (i live in WI and am moving to CO so these things concern me). plastics breaking due to this factor when a metal wouldn't piss me off when it's done to save a few bucks. just my opinion.