Where exactly do we look on the E39 radiator for telltale cracks?

Just for the record, over in this thread, I calculated my 2002 525i automatic has eight (8) cooling system hoses that can fail at any time (not counting the air conditioning, power steering, and automatic transmission hoses which don't carry coolant):
- how many heater hoses do we have?

Wow. That's just flat out scary BB. Good info as always.

Originally Posted by Mack

Wow. That's just flat out scary

It gets worse. In addition to the 8 main hoses, there seem to be 7 more associated with the heater core.

Hoses #1, #4, #5, #11, #12, #13, & #14 below 'appear' to be associated with the heater core based on this realoem diagram.

That would make a total of 8 + 7 = 15 rubber cooling system hoses in the BMW 2002 525i automatic (assuming no duplicate counts).

Is this count correct?

For the crosslink record, Elwood Blues has a 'momentary' failure of his cooling system, as yet unexplained, based on this thread today:
- Explain this temporary coolant leak

It certainly looks like the leak is at the same location as in this post:
http://www.bimmerfest.com/forums/sho...37&postcount=3

Originally Posted by granlund

It certainly looks like the leak is at the same location as in this post:
http://www.bimmerfest.com/forums/sho...37&postcount=3

It 'does' look very similar. I quoted you back to Elwoodblues in his original thread. Thanks.

Here's the picture you quoted, for reference, shrunken to 640x480 pixels.

It's a very strange location to have a leak in. There are no extending visible cracks from outside. It must be a stress concentration location. I'd be curious to see what it looks like from the inside.

In keeping with the pictorial nature of this cooling system failures thread, here are some pictures of chocolate milky coolant due to a transmission cooler which leaked into the cooling system:
- Help!!! found oil in my coolant and what's next...

WOW!! That just does not look good.

To follow up on the Elwood Blues thread, it turned out to be a hairline crack just above the upper hose neck (that's a common location apparently, even though one would wonder why stress in that particular spot):
- Explain this temporary coolant leak

My '02 525i is starting to give me warning to check the coolant level. I just notice yesterday water/leaks around the neck of the expansion tank. And according to some previous reading it is one of the weak links the the E39 cooling system, along with all the locations shown in this thread. I'm about 95K so I think it is time to undertake the CN90 overall DY. One think I can not understand though. How in the word do you get to the fan to remove the bolts? There is barely any space for me to put my hand in between the fan shroud to be able to remove any bolt. Is there a diff between the 02 525 and the 98 540?
Am I missing something ?

The fan is attached to the waterpump with a 32mm nut that is reverse-threaded. Put the 32mm wrench straight down on the nut between the fan blades and the serpentine belt pulley, and give it a good whack towards the driver's side. If it does not loosen, spray the back end of the nut with some PB blaster and wait 1h until you try again.

Kool...
I guess I was looking for a magik easy way.

But it has to be done..

Thanks Bud !

Originally Posted by bluebee

It gets worse. In addition to the 8 main hoses, there seem to be 7 more associated with the heater core.

Hoses #1, #4, #5, #11, #12, #13, & #14 below 'appear' to be associated with the heater core based on this realoem diagram.

That would make a total of 8 + 7 = 15 rubber cooling system hoses in the BMW 2002 525i automatic (assuming no duplicate counts).

Is this count correct?

#6 in this image was the little devil that took me the longest to find. Valve had a crack in plastic and when opened would pump coolant over board but never created puddles as it only opens when hot... And would burn up on motor.

AS a caution to other member..
Driving to work today I get the "CHECK COOLANT LEVEL" warning light. once I got to work I pulled into the parking lot, opened the hood and sure enough, water was steaming out of the bleeding screw on the expansion tank. Apparently that is where my leak was, and not the neck of the expansion tank as I guessed. As I tried to tighten the bleed screw I notice that it was very loose, actually it was broke and the top came off.
Had to wait for the car to cool off and use a easy-out to remove rest of screw. Went to the STEALERSHIP and got a replacement for........ $9.67. Amazing a little pc of plastic I could have had for $2.00 anyplace else. But they had me,.
I will attempt a complete Overall of the cooling system before the summer kicks in

I replaced my bleeder screw a few moths ago, same thing it split in half

I have had brass bleed screws for two years with no problems.. just don't over tighten them so they don't strip the plastic

Ordering an extra 1 or 2 from AZ Autohaus or Bavarian Autosport is a cheap insurance policy. After paying $ 10.00 for one at the stealership during an emergency, I picked up a couple of back-ups.

The brass bleeder screws are cheap and indestructible.

After 11 1/2 years and just 77783 miles I replaced the radiator on my 2000 540i. It was weeping at the area marked in red on "bluebee's" diagram. I never could physically see a crack. Just when it got hot coolant seemed to magically seep through the plastic just above the left hose fitting about 1 inch towards the side. After looking at the $$$$ I replaced it with another Behr from Pelican parts. I was surprised to find that the manual tranny V8 uses the same rad as the sixes. I didn't need to pull the fan. The fan guard comes out vertically once you remove the hoses from the overflow tank. I couldn't believe the "crap" (leaves and every flying insect known to man)that came from between the radiator and the A/C condensor. About a 3 hour job at my geezer pace.

Originally Posted by microswitch

My '02 525i ... I'm about 95K ...How in the word do you get to the fan to remove the bolts?

I have the same car, and my cooling system blew at the same number of miles.

Here are your instructions for removal of fan shroud in a 2002 BMW 525i

---

REMOVE SHROUD: http://www.beisansystems.com/procedu..._procedure.htm
- Raise the E39 with a jack and put on jack stands (or ramps)
- Remove the under-engine shroud pan (nine #2 Phillips one-twist bolts)
- Draw the hose sequence or snap photos of the underside shroud hose routing.
- Protect your eyes from falling dust with goggles (I didn't and wished I did).
- Locate the auxiliary pump at the bottom driver-side corner of the shroud.
- Disconnect the press-pull auxiliary coolant pump electrical connector
- Slide the auxiliary pump toward the center of the radiator out of the
fan shroud sleeve by lining up the hose in the clamp and tugging gently
- Disconnect both coolant hoses from the fan shroud bottom
- They are held on with two dual-hose clips five single-hose clips, four
of which are on the bottom of the radiator, and one is on the driver's
side about half way up the shroud on the engine side.
- From above, follow the wire out of the auxiliary water pump to the
AUC (stink) sensor on the driver's side in front of the alternator
just under the upper radiator hose elbow.
- Press the plastic clip on the stink sensor connector and pull up to
remove the AUC sensor from the fan shroud.
- Remove the diabolically German 2-inch by 3-inch AUC sensor housing
by wiggling and coercing it, mostly pushing up from the bottom of
the AUC sensor housing and pulling the top of the AUC sensor housing
away from the shroud. Then, once it's a bit loose, switch directions
of force by pushing down on the AUC sensor housing, pulling the bottom
of the AUC sensor housing away from the shroud. You have to just do it.
- With a 3/16th flathead screwdriver pry out (only) the (center)
plastic rivet pin on the driver's side of the shroud near the upper
hose until you can get needle nose pliers on it to pull that center
pin out. Then pry out the base surrounding the center pin.
- Likewise, remove the rivet to the side of the expansion tank.
- Temporarily remove the expansion tank filler cap.
- With two screwdrivers, pry up the escutcheon around the bleeder screw
next to the expansion tank filler cap and remove the escutcheon.
- Replace the expansion tank filler cap.
- Study how the M-shaped rubber seal at the top of the fan shroud sits.
- Pull up on the two-foot long M-shaped seal at the top of the fan shroud.
- Lift the fan shroud up and to the rear of the car; you'll get about 4
inches of room to see the small hose that goes across from the expansion
tank to a nipple on the drivers side.
- BE VERY CAREFUL IN THE NEXT STEP (I broke the nipple right off!)
- Next to the nipple on the driver's side, pry open the original clamp
so that you can remove the hose (I think it's better to dremel it off
because I busted it with very little pressure exerted).
- Remove the fan clutch nut (see separate instructions) with 32mm fan
clutch nut wrench and 48-mm hole spacing fan hub bolt counterhold tool.
- Lift fan shroud and pull fan out toward driver tilting and wiggling
as necessary to get the fan out of the shroud; it will come out aiming
at the driver's steering wheel.
- Beisan says to remove the fan shroud from the engine bay at this point
but I don't see how you can with the expansion tank, it's three hoses,
and the electrical connector on the bottom still connected to the
expansion tank.
- Temporarily remove expansion tank bleed screw with a P3 Phillips
screwdriver.
- Dislodge the expansion tank from the fan shroud by pulling up and
toward the windshield to dislodge the two hoses at the bottom from
the fan shroud.
- Replace the bleed screw with a P3 Phillips screwdriver.
- Pull the drivers side of the fan shroud up and at the same time pull
the bottom hoses of the expansion tank away from the fan shroud.
- Pull the upper expansion tank house through the tunnel in the
fan so that it is not impeding removal of the fan shroud
- Finally, remove the shroud from the engine bay, leaving the expansion
tank still connected to the car.
- Disconnect the frail-looking electrical connector from the bottom of
the expansion tank.
- The Beisans say to place the expansion tank at a high location in the
engine bay but that only made my broken nipple leak more so I put it
at about the same level it was prior.
- As per the Beisans, I tried to keep the expansion tank overflow hose
high to keep coolant from draining out but whenever I raised the expansion
tank, coolant drained out of the broken nipple on the radiator anyway.
Eventually, while I was working on putting the fan on the water
pump, the expansion tank fell to the floor with a full thud, and
I had to jam a branch of wood from my plants into the broken nipple
end on the end of the hose to stave the bleeding mess.
- At this point, the fan is off, the shroud is off, and the expansion
tank is connected but lying on the ground.
- I have access now to the water pump bolt!

Originally Posted by microswitch

water was steaming out of the bleeding screw on the expansion tank. Apparently that is where my leak was, and not the neck of the expansion tank as I guessed. As I tried to tighten the bleed screw I notice that it was very loose, actually it was broke and the top came off

Here's a picture of exactly that, from today, from this thread:
- E39 (1997 - 2003) > Identify this part and oil leak, picture game.

Here is the top of the expansion tank with the nipple broken off:


And, here's the broken bleeder screw:


And, here's what it looks like from the other side:

Originally Posted by bluebee

In keeping with the pictorial nature of this cooling system failures thread, here are some pictures of chocolate milky coolant due to a transmission cooler which leaked into the cooling system:
- Help!!! found oil in my coolant and what's next...

Omg, that's a scary sight! I hope I never see that!

Bluebee/cn90, et al: given a parts budget of $300 (HEPU WP is a given, so WP +$230), what would get first priority?

If the radiator is the original one from 2000, $240 gets you a new radiator and expansion tank from Pelicanparts. Both of those would also be a lot easier to replace in conjunction with the water pump.