My E36 Cooling System Overhaul DIY - NOT 56K Friendly!

[raisingM3]

Great DIY writeup - thanks op. I referenced this when replacing my water pump.

The pump bearing started to make a growling noise and a slight coolant leak had appeared a few days earlier. I located the noise and saw the fan pulley wavering, turned off the engine, and was able to easily wiggle the pump shaft. Sure enough, the coolant leak was coming from the shaft. Had 84K on the original pump with the metal impeller. Thanks to bf for providing a lot of good info for this repair.

I used the following in the repair:

Pump - OE w/Composite Plastic Impeller
Stat - OE Orig Temp
Stat Housing - MTC Alum
Coolant - Saab (cheaper G48)
Distilled water

[tEckniks]

G

Pump - OE w/Composite Plastic Impeller

why didnt you go with a metal impeller?

[raisingM3]

why didnt you go with a metal impeller?

From what I read in other threads it seems everyone agrees that the original plastic impeller was faulty, but some questioned the durability of the bearings in the metal impeller replacement design (excluding the high $ stewart). I don't think there has been many problems with the newer composite impeller. I found it interesting that BMW did not stick with the metal impeller design as a replacement but rather now supplies the composite impeller design.

[Womp]

thanks for the write up. very informational

[M3Rock]

Excellent write up; one of the best.

This past saturday I installed the Mz3 radiator , 17112227281 MZ3 radiator , in my 1995 M3. I followed your advice, except I cheated: I didn't remove the fan, I crawled under the car and gently coerced the fan blades over the fan shoud while pushing upward. I pushed it up about half way, then got back up top, tilted the entire radiator to the right about 45 degrees and slipped the radiator OUT. and left the shroud there. I never touched the hose to the external fill tank.
It's been two days and I don't see any difference in cooling with the Mz3 rad. IMHO, waste of money. Oh well. It was fun.

[BimmerM3inGA]

Glad you found the write-up helpful. I just had to change the expansion tank on my 1999 528i and there is very little difference between that car and the M3 with regards to the configuration of the cooling system. So this procedure would probably apply to many BMWs from that era.

Is that radiator supposed to improve cooling? My thinking when it comes to upgraded radiators on a street-driven car is that they don't necessarily improve performance, just longevity. It's the difference between replacing it every 80-100K miles or having it last the lifetime of the car.

[Seans M3]

I know this is a old thread, but just wanted to thank you for a good DIY. I used it to help me replace my water pump, T-stat & housing.

Just wanted to add that there is no need to get M6 bolts to remove the water pump cause the same 10mm bolts that hold the T-stat housing in are of the same size. Thats what I used to pull the pump out.

[WRXEATR]

I almost forgot that I made an Excel spread sheet that lists all the parts with part numbers and prices.

Here is a link to it:E36_Cooling_Overhaul.xls

FYI for those of you about to do this:

MANY of these parts are even cheaper@ rmeuropean.com

see here too:

http://www.m3forum.net/m3forum/showthread.php?t=296113

[Badgtho is back]

that's a veeryy very high quality write up... excellent!

[SIIDEWAYS]

I'm going to have to add a very critical piece that this otherwise good DIY write-up is missing. When installing the new t-stat housing (particularly if you go with an aluminum one), you need to ensure that the aluminum surface to which the housing attaches is clean of any build-up (i.e. crud/crust from dried old coolant). Use a scotchbrite pad and scrub the surface thoroughly clean (you can use brake cleaner if necessary). Next, use a sealant such as Permatex black silicone or Hondabond when attaching the new housing. Torqueing down the housing (which is all I did) is not enough to ensure a solid seal. Trust me on this...I had followed this DIY write-up to a tee when I did my cooling system overhaul a few months ago, and not long after, I developed a small coolant leak from the t-stat housing. Now I have to tear it all apart again...UGH.

[ButtDyno]

Preemptive thank you for this writeup. Looking at doing this in the spring.

[BimmerM3inGA]

OP here. Good call, SIIDEWAYS! That is a very important point that should be made. Shortly after installing it, my aluminum t-stat housing began to leak - and has been leaking ever since. About 3 weeks ago, I finally got around to fixing the leak. This entailed removing it (obviously), thoroughly cleaning both mating surfaces, and adding a bead of high temperature RTV silicone.

I edited the original DIY to include this information because it's very important. So thanks to SIIDEWAYS for calling me out.

You can only make the bolts so tight and like he said, it's not enough to prevent leaks if the housing isn't properly sealed. It's not that big of a deal to redo it. But why do it if you don't have to?

[Seans M3]

I'm going to have to add a very critical piece that this otherwise good DIY write-up is missing. When installing the new t-stat housing (particularly if you go with an aluminum one), you need to ensure that the aluminum surface to which the housing attaches is clean of any build-up (i.e. crud/crust from dried old coolant). Use a scotchbrite pad and scrub the surface thoroughly clean (you can use brake cleaner if necessary). Next, use a sealant such as Permatex black silicone or Hondabond when attaching the new housing. Torqueing down the housing (which is all I did) is not enough to ensure a solid seal. Trust me on this...I had followed this DIY write-up to a tee when I did my cooling system overhaul a few months ago, and not long after, I developed a small coolant leak from the t-stat housing. Now I have to tear it all apart again...UGH.

OP here. Good call, SIIDEWAYS! That is a very important point that should be made. Shortly after installing it, my aluminum t-stat housing began to leak - and has been leaking ever since. About 3 weeks ago, I finally got around to fixing the leak. This entailed removing it (obviously), thoroughly cleaning both mating surfaces, and adding a bead of high temperature RTV silicone.

NOOOOOOOOOOOOOOOOOO

I just finished mine over the weekend!

[BimmerM3inGA]

Sorry, dude! Just keep an eye on it and if/when it starts to leak you can worry about it then. It's a very slow leak and I waited a couple of years to fix mine.

[SIIDEWAYS]

OP here. Good call, SIIDEWAYS! That is a very important point that should be made. Shortly after installing it, my aluminum t-stat housing began to leak - and has been leaking ever since. About 3 weeks ago, I finally got around to fixing the leak. This entailed removing it (obviously), thoroughly cleaning both mating surfaces, and adding a bead of high temperature RTV silicone.

I edited the original DIY to include this information because it's very important. So thanks to SIIDEWAYS for calling me out.

You can only make the bolts so tight and like he said, it's not enough to prevent leaks if the housing isn't properly sealed. It's not that big of a deal to redo it. But why do it if you don't have to?

Did you use a new gasket for the t-stat housing? Also, did you have to drain the entire radiator to do this fix? I'm thinking that may not be necessary, just drain the 2 upper/lower radiator hoses that connect to the housing, right? Oh, and remove the fan?

[BimmerM3inGA]

I had an extra gasket for the t-stat housing, so I used it. If it hasn't been in use for very long, I see nothing wrong with reusing, however.

I didn't drain anything beyond what came out when I removed the t-stat housing. It didn't really lose that much coolant and I just topped it off and bled it again.

If you have small hands and small tools, the job can be done with the fan in place. But it's so much easier with it removed.

[Seans M3]

I guess I'll just fix mine over the weekend when I replace my alternator. Why wait for it to start leaking

[BimmerM3inGA]

Good plan. Much of the disassembly work is the same, so it's not really like you're having to do it twice.

[rommelrules]

Is it possible to to do a radiator swap without having to remove the expansion tank or does it need to come off with the fan shroud?

[Seans M3]

I think you can move the shroud towards the engine & still get the rad out of there, you will have to remove the fan for more room.

[BimmerM3inGA]

The tank will have to come out. But it's not that much extra work. You really ought to replace it anyway. They are prone to failure along with the radiator, which should surprise no one.

[rommelrules]

The tank will have to come out.

OK, thanks. Just one last question before I tackle this-- I'm a total DIY novice and need everything spelled out for me...
When you say "The larger hose at the bottom of the expansion tank must be removed from the tank, but left in the car"
are you referring to the same hose that according to the Pelican DIY must be disconnected near the power steering reservoir?

Per Pelican: Also attached to the frame is the reservoir overflow hose. This hose winds around to the left side of the car,
and needs to be disconnected near the power steering pump (Figure 10).

I imagine removing it from the tank is a lot easier...

[Seans M3]

That hose does not need to be disconnected from the block unless you are replacing it. Just disconnect it from the res bottle.

[whatthedealee]

I'm going to attempt to do this, along with replacing all the pulleys, fan clutch, and even the heater core. I figure I might as well change out the heater core while all the coolant is flushed out of the system. I'm also going to flush the engine of coolant and try to flush it out a little more with a garden hose.

[BimmerM3inGA]

I'm going to attempt to do this, along with replacing all the pulleys, fan clutch, and even the heater core. I figure I might as well change out the heater core while all the coolant is flushed out of the system. I'm also going to flush the engine of coolant and try to flush it out a little more with a garden hose.

So, you like pain do you? Seriously though, the heater core isn't really a problem on the E36. Is there a particular reason you want to replace it? I'm not saying you shouldn't, just that it's a lot of extra work without much of a return on investment.

Also, I wouldn't recommend flushing the engine with a garden hose. There are all sorts of minerals in tap water that you don't want in your engine. A better idea is to pick up about 6 gallons of distilled water and use that instead - just fill it up and run the engine until the thermostat opens and let it circulate. Then drain it and repeat. Do that once or twice and it'll be thoroughly flushed without introducing all the stuff in tap water.