OK Got the Parts , NOW WHAT ?

[Drooby]

My first BIG JOB (for me at least) in this M50 will be to change the coolant.
Went to the dealer and coughed up $38.50 for 2 galons........ I am also thinking of going to Autozone for a new thermostat (is this necessary and I found 2 at autozone.... medium temp & high temp ..... whats the difference?)
I read the "how to" posted but i believe its for another engine.
Can Anyone tell me if the procedure is the same?
Also where the heck is this BlEED SCREW everyone is talking about

thanks for any advice ....

[Dave M]

I just did this on my 91 525im. First time, so everyone else can help where needed.

First step, drain the rad from the blue drain plug. Use a broad philips or flathead screwdriver. I placed a hose over the plastic 'output tube' at the side where the coolant will flow in order to direct it into a container and prevent the pet-blinding big mess. OK, I'll throw in a pic of the drain plug for fun. Make sure both O-rings are present (I lost one of mine at some point and it leaked a tad)
http://volcano.photobucket.com/albums/v11/dave_macisaac/Bimmer/Misc/Rad_Plug.jpg

Next step. Drain the block. The (19mm?) drain plug is located on the pass. side of the block tucked in behind the exhaust manifold. Might be tricky as I did mine with exhaust removed. Again, watch out for a face full of coolant as this ones hard to control. Flush as per brunos instructions.

Next step. After flushing and replacing both drain plugs, fill with 50/50 coolant/water mix. I had the front end of the vehicle raised, removed the top rad hose at the rad and filled it untill as much as I could. You might hear it 'glug glug' down through the engine if you take your time. Fill the rad through the expansion tank. Attach the rad hose and keep the front end raised.

Next step. Start the car and let the thermostat open. Rev the engine at the throttle body and watch for the coolant in the expansion to drop. Add when necessary. When it doesn't take any more, you should be full.

Next step. Bleeding. As long as we're talking about a M50 with integral expansion tank, the bleed screw is a small black plastic screw to the southeast of the rad cap if the front of your car is north (mine is). Its the only other item of note on the top of the expansion tank. I suppose bleeding may be combined with the last step, but it seemed to work this way. You're supposed to see bubbles as you loosen the bleed screw off and let it bubble untill a steady stream of coolant flows out (best done outside). I only saw a few sputters of coolant and called it a day. Maybe this worked, maybe it didn't. Everything seems fine so far.

While you're drained you may want to think about your coolant level sensor/O-ring, cheapcheap.

Good luck,

DAve M

[JR'Z 525]

Also, be gentle when retightening the bleed screw. It can break the head off if overtightened and has some age on it. Don't ask me how I know....
JR

[ryan roopnarine]

mr rickard advised me that you're best off getting a thermostat from the dealer, the 180f one...apparently he said that even the bma ones are differently shaped in comparison to the factory box part.


My first BIG JOB (for me at least) in this M50 will be to change the coolant.
Went to the dealer and coughed up $38.50 for 2 galons........ I am also thinking of going to Autozone for a new thermostat (is this necessary and I found 2 at autozone.... medium temp & high temp ..... whats the difference?)
I read the "how to" posted but i believe its for another engine.
Can Anyone tell me if the procedure is the same?
Also where the heck is this BlEED SCREW everyone is talking about

thanks for any advice ....

[Dave M]

Oh yeah, I drilled the hole at the arrow on the thermo as recommended (1/16").

[Tiger]

I recommends 60% water... 40% coolant... 50/50 is just too thick for heat transfer and engine runs hotter. Water is the medium for heat transfer so more water is better. The coolant is for freezing and acid protection... equally important but more water keeps our engine cooler.

[Drooby]

Oh yeah, I drilled the hole at the arrow on the thermo as recommended (1/16").


Will this thermostat work?

http://www.napaonline.com/cgi-bin/ncommerce3/ExecMacro/NAPAonline/search_results_product_detail.d2w/report?prrfnbr=15520742&prmenbr=5806&usrcommgrpid=68669561

I'm kinda inclined against putting anything in that isnt BMW ...esspecially if its not broken , I always thought the thermostat should only be changed when acting up?

[Tiger]

Changing thermostat is part of routine... There are a couple of ways it would go bad... First, the valve is stuck shut... and engine temp goes way up... then you know what happens...$$$

The other way it can go is broken valve... and engine runs hot and cold... hot when you are at local roads especially coming to a stop light... and go way down when you are on highway... Needle goes up and down alot... no real damage to engine since fans does help to keep coolant temp down... but fuel economy suffers.

So it is a routine thing that keeps these thing from happening for the next 50K+ miles. Thermostat housing is also one thing you should change if you still got original one... they will go bad and leaks... anywhere from 70K miles to 100K miles... Might as well do this one too at the same time as thermostat. You should have buy all the stuff from BMA... free shipping on $50+ order.

[Drooby]

thanks ,
I will get to this (& hopefully through with it ) today!!
Is there a difference between BMW thermostat and others like Autozone & Napa .... I would rather go get them then wait for them to come in the mail>

The difference in price : BMW is double price.

I also couldnt find where (or how to) it says to drill a hole in thermostat ......... anyone know?? - Wont it leak this way?

[Drooby]

thanks ,
I will get to this (& hopefully through with it ) today!!
Is there a difference between BMW thermostat and others like Autozone & Napa .... I would rather go get them then wait for them to come in the mail>

The difference in price : BMW is double price.(is it worth it?)

I also couldnt find where (or how to) it says to drill a hole in thermostat ......... anyone know?? - Wont it leak this way?


OK found out about the hole ...... thanks

[Tiger]

It is not that much difference... they work the same as OEM. Otherwise it would not be compatible. I wouldn't bother with the hole... if you don't have the overheating problem, then don't do it.

[Drooby]

I think in order for me to replace the thermostat , I have to take apart the fan housing (its right in front of it) to get to it
This seems like more than I bargained for ,,,,, any tips?