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E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 04-16-2015, 09:22 AM
gmak2012 gmak2012 is offline
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Some thoughts while doing a cooling system overhaul

This is on a 1998 528i. Both tensioners are hydraulic. I've been doing a bit of the work each night for an hour or so with the Water pump / Thermostat to come this Friday (April 17, 2015). Thanks to CN90, Bluebee, and others who have posted DIYs from which I pinched the pictures.

1. I put the front end up on the wooden "CN90" ramps and removed the splash guard. It's easy to tell that the AC tensioner is hydraulic because the shock portion is right there in the open. Also, on the topic of how to tell hydraulic versus mechanical with minimum effort: Look down from the top and if you see an aluminum metal cylinder of about 1.5 inches diameter, with a black plastic dust cap on the front, near the tensioner wheel - then it's a hydraulic tensioner. You can see the cylinder in this picture just above the wrench.
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2. This, by contrast is a mechanical tensioner.
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3. There is no Torx bolt in the hydraulic tensioner wheel. It is an 8 mm Allen key. I used an 8 mm Allen socket on a breaker bar (for comfort) to release tension. One cannot jerk or yank on the socket wrench to move the wheel and relieve tension. It is a slow steady clockwise move - hydraulics mean that oil has to be compressed.

4. The AC belt hydraulic tensioner looks like this. Note the aluminum cylinder to the left and below of the tensioner wheel - which is the black one on the right of the picture. I found that the tension mechanism itself can be removed and replaced by taking out the two bolts circled in red. There is no need to take off the tensioner frame (unlike for the serpentine belt tensioner. The belt is removed by i) Taking the black cap off of the tensioner wheel; ii) Using an 8 mm allen key on a socket wrench; iii) Inserting it securely into the bolt head inside the tensioner wheel; and, iv) Pushing the socket wrench gently in a clockwise direction. Then the tension on the belt is relieved and it can be slipped off of the AC pulley.
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5. The AC and Serpentine belt tensioner wheels are identical.

6. The Serpentine belt tensioner unit needs to be completely removed to replace the tensioner itself since there is bolt that holds it to its frame that is screwed in from the back of the unit.

More to come later.
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  #2  
Old 04-16-2015, 11:45 PM
djmjd djmjd is offline
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Just to add a bit of useless information, neither style of tensioner is truly hydraulic, both have springs in them. The 'mechanical' one is a torsion spring. The 'hydraulic' one is a compression spring. The hydraulic one does have oil in it so maybe it is a combination spring and damper?

Last edited by djmjd; 04-16-2015 at 11:54 PM.
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  #3  
Old 04-17-2015, 04:42 AM
gmak2012 gmak2012 is offline
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Cool Now you decide to get picky about terms?

Just using the terms that everyone knows from the hundreds of posts on the subject over the years, and BMW.

It seems the term hydraulic (belt) tensioner is also the one used by REALOEM and therefore the BMW parts system. By contrats, hère is the mechanical tensioner for completeness as our favourite B would say.

Since both are on the serpentine belt, it's pretty hard to make a case for the use of the word 'hydraulic' because it's on the same belt as the water pump. Perhaps they are wrong in focusing on the properties and actions of the viscuous oil in the cylindre (It must be doing something there, right?)

As well, it is very common to refer to parts that owe their fonction in part to the proprettes of flow pressure as 'hydraulic'.

Finally, sometimes, torque just isn't enough.. This is just to show you that English is a precise but slippery language where words can have multiple meanings even in the same combination. It's all about contexte.

Thanks for your input.
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  #4  
Old 04-17-2015, 04:51 AM
gmak2012 gmak2012 is offline
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Part Deux of the Cooling system overhaul

  • I've experienced the dread breaking of the nipple on the driver's side of the radiator [edit changed from elbow piece on right side...]. I'm going to try crazy glue in order to get on with the WP replacement - but I have two on the way from different suppliera. Since I'm not doing the rad at this time, I figure that it will be good to have a spare for the future - although I will have the removable hose clamp in place, stuff happens.
  • Because I'll have to take the upper radiator hose off to get the elbow out when the new part comes, I'm not flushing the system at this point. Because the housing still looks new and the thermostat works well, I'm not going there either. I'll be replacing 1/2 to 3/4 of the existing collant this time, and then replacing 1/2 when the plastic elbow arrives - so that may be good evough for .gov work. It's kind of like the multiple transmission fluid changes via the main pan without flushing. I'll make a decision as I'm in there. I do have to take out two bolts from the thermo housing to help pop out the WP, so who knows? :shrug:

  • If you're changing the pulleys on the either or both of the WP and PS, (waterpump and power steering), be sure to leave the serpentine belt in place until you loosen the nuts / bolts holding them in place.
  • I found that the PS pulley seemed to be stuck in place after taking the bolts out. I gently hit it with a rubber mallet. I moved slightly on one side. So I held the pulley at 3 and 9 o'clock and wiggled it until it came off. It's a nice thick pièce of molded plastic. Still, aluminium is taking its place. The WP pulley came off with no issue. It too is a marvel of plastic engineering. I'm surprised because of all the posts that have led me to believe that it is the consistency of saran wrap. Aluminium there as well... heh.
  • I will be hand tightening everything snug. I believe that final torque can only be done when the belts are back in place.

I'll be finishing this up, this AM, so final part to come.

Last edited by gmak2012; 04-20-2015 at 06:22 AM. Reason: fix nipple and driver side of radiator.
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  #5  
Old 04-17-2015, 05:40 AM
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bluebee bluebee is offline
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Quote:
Originally Posted by gmak2012 View Post
  • I've experienced the dread breaking of the elbow piece on the right hand side of the radiator.
I'm not sure which "elbow piece" this is, as on the driver side is the nipple that very often breaks, but I wouldn't call that the right side, nor an elbow ... so I'm a bit confused.

If it's the nipple, this may help:
- How to non destructively remove a broken radiator nipple (1)
See also:

- How to tell if you have mechanical or hydraulic belt tensioners (1) how to switch from mechanical to hydraulic (1) and what is the difference between the two types (1) (2)
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  #6  
Old 04-17-2015, 06:44 AM
gmak2012 gmak2012 is offline
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Et tu Bluebee. Yes, it is the nipple on the driver's side. Right as facing the motor. Sorry. My bad. I will be using the 9 mm socket to remove it from 'inside' once the new one arrives. In the meantime, how it broke leads to a décent crazy glue seal.

You might be interested in some photos I'll be posting when done. My old WP is a BMW one but has an impressive métal impeller. Also, there are some différences between my old fan shroud and the new one.

Last edited by gmak2012; 04-17-2015 at 06:46 AM.
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  #7  
Old 04-17-2015, 10:54 AM
crazy4trains crazy4trains is offline
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As Pete Rose would say, I BET that you will be going back in there within a few months replacing something else, and most likely that glued nipple. Just my opinion but you might as well buy yourself a new radiator. Aftermarket radiators are not too expensive and will likely save you future headaches.

Good luck.
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  #8  
Old 04-17-2015, 12:47 PM
gmak2012 gmak2012 is offline
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Ah. But I have all the facts and you don't

Quote:
Originally Posted by crazy4trains View Post
As Pete Rose would say, I BET that you will be going back in there within a few months replacing something else, and most likely that glued nipple. Just my opinion but you might as well buy yourself a new radiator. Aftermarket radiators are not too expensive and will likely save you future headaches.

Good luck.
When I bought the car over 12 years ago, it was still under warranty. The wholesaler I bought it from did all the work they could under warranty. That radiator has only about 30K miles on it. SO there.

I've already said that I have 2 nipples on order, only I called them elbows. What is it with you people? IN any case, one of the traps in replacing the nippe is breaking the two tags on either side - which DOES NEED A NEW RADIATOR then. I've replacer 2 tensioners, both tensioner wheels, Thermostat, thermostat housing, upper and lower radiator hoses; PS and WP pulley with aluminium; Water Pump; Idler wheel; fan; clutch; fan shroud; torqued everything to spec. Cleaned all rubber hoses with A535 (meant for protecting like materials in aerospace environment)

So why do you think I will be back in there? I haven't posted yet, but as I worked through the various areas of the overhaul, I judged what needed to be done as I got there. I took two bolts out of the thermostat housing to remove the water pump. I decided that I might as well take off the other two and see what was what. I replacer the thermostat and the housing - although the housing was still goodl.

Where exactly do you think I will need to go back to?

Last edited by gmak2012; 04-17-2015 at 12:50 PM.
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  #9  
Old 04-17-2015, 09:27 PM
cn90 cn90 is offline
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Forget glued nipple.
Get a new rad, I put in a Nissens rad for my 1998 528i in May 2006, so far so good 9 years later.
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  #10  
Old 04-17-2015, 10:46 PM
Nfs021 Nfs021 is offline
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The thoughts that go through my head when I work on any part of my car is the same as always..."don't F*** up"!
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  #11  
Old 04-18-2015, 05:20 AM
gmak2012 gmak2012 is offline
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The glued on nipple was temporary so that I could test the system for leaks without waiting for the new part. I used a super glue and it made a very good temporary seal. I tested and ran the car in traffic and on highway where it performed to spec with no leaks. By coïncidence, one of the new parts showed up during the day, so I replacer the nippe - training the rad first. I found the best technique was to put a cardboard roll with part of the boy cut away into the upper radiator hose connecter, push down on the remaining nipple part and catching it in the cardboard tube. The carboard tube with cut out ressembled an O2 sensor socket.

During the process of this cooling system overhaul, I have drained and refilled some or all of the system twice (once for the work, and once for the nipple replacement). There is nothing complicated about 'bleeding' the system of air. I followed this . The radio on in the background is annoying but the process is straight forward and idiot-proof.

1. remove both bleeder screws (one on the thermostat housing, one next to the overflow tank); Turn the key to the and position (don't start engins) and température to its highest level, fan to lowest level. I also put a charger on the charging post in the engine bay because DTR lights will drain the battery fast.
2. Add 50 / 50 coolant to the overflow tank until it is near the top;
3. Watch the bleeder valve on the thermostat housing. As the collant levels rise in the system, air is forced out hère.
4. Keep adding the 50 / 50 coolant a bit at a time to the overflow tank (slowly, in small amounts) until the coolant comes out of the thermostat housing bleeder valve without bubbles. Put the bleeder screw back in the thermostat housing and snug it down - don't overdo it and snap it, or strip threads if using bras.
5. keep adding coolant a bit at a time until coolant comes out of the overflow tank bleeder valve. Put the screw back it and snug it down gently.
6. Put the overflow tank cap on. Take the car for a drive. If the guage holds steady where it's supposed to be, take it out on the highway at high revs, come back into stop-and-go-traffice etc.
7. Park the car. Let it cool down (I'm waiting until the morning). After completely cool (not luke warm) - check for leaks on the pavement under the car. Open the overflow tank and adjust the coolant level to the "KALT" line. (Yes, I still have one of the old transparent overflow tanks. 17 years and counting).




Dear CN90: I have enormous respect for you, your ideas, and the creative DIYs that you have graced us with over the years. However, I must say that I am not impressed with the impeller on the HEPU pump. I put it in because I suspect the bearing in my existing pump is well on it's way to old age. Perhaps it is the solid quality impeller that is doing it in. I suspect that the reknown HEPU quality has seen better days. I will post pictures later when my wife emails me the photos. However, the impeller looked cheap with poor spot welds. The material was thin and the whole impeller just looked like it was made with shoddy craftsmanship. I'm crossing my fingers that the bearing is high quality and that the characteristics of the coolant flow won't lead to some kind of sub-optimal performance over time. I'm going to play with the old pump and see if I can remove the impeller. If so, I may swap it onto the HEPU. When I post the pictures of the two pumps (I haven't seen them yet) I hope that the analagous 1000 words will show what I mean.

I appeciate the idea about the radiator you have suggested, but maybe the quality 9 years on will not be the same anymore. Why should I replace a perfectly good radiator that is in excellent condition and likely has only 30K miles on it?

Last edited by gmak2012; 04-18-2015 at 06:25 AM.
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  #12  
Old 04-20-2015, 06:27 AM
gmak2012 gmak2012 is offline
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Here are some other points:

1. If you are replacing the PS and /or WP pulleys, break the nuts /bolts BEFORE taking the serpentine belt off.
2. The WP pulley comes off easy but the PS pulley is on tight. There is a very tight tolérance between the PS shaft and the hole in the pulley. To get the pulley off, I put my hands at 3 and 9 o'clock and wiggled back and forth. A light tap with a rubber mallet on one side gets the process started.

3. I found it easiest to put the PS pulley on from underneath the car. I used an aluminum pulley and it wouldn't fit. I used some sand paper wrapped around a suitably sized cylindrical bottle to gently enlarge the hole in the pulley. We are talking removing the coating inside the hole, and maybe 1 or 2 1/10s of a millimeter. I used a loctite bottle and wrapped the (thin) sandpaper around twice - this fit perfectly. STILL -> the fit was snug and I didn't want to continue sanding and run the risk of making the holà asymmetric. I put it on and lined up one of the three bolt holes appropriately. Then I tapped with a rubber mallet on that side of the pulley to bring it a bit closer to where I could thread the bolt a couple of trends. IF YOU DON'T GET THAT FIRST BOLT LINED UP, THERE IS NO WAY YOU CAN DO IT ONCE THE PULLEY IS ON. IT'S TOO SNUG. I repeated the process for each of the remaining two bolts and then gently tightened each bolt in sequence a couple of threads at a time to gradually move the pulley into place against the WP. It's the reverse of WP removal.

4.Putting the fan on was a PITA - as you've heard many times. The wrapped core trick didn't work because one has to get the fan thread on first. That's where the problem lies. I did this from under the car with my wife trying to hold the fan in place. I had to adjust it with one hand (she couldn't tell from her angle if it was perfectly vertical or not) and used the 'fan wrench' to gradually tighten the nut from underneath. WEAR RUBBER GLOVES OR YOUR TIRED HAND MAY LEAD TO THE WRENCH SLIPPING AND BOUNCING OFF YOUR FOREHEAD. Ask me how I know.

5. I used the following torques. No need to overtighten anything and risk shear on the bolts. I will say that I put blue loctite on the bolts holding the WP pulley in place - this is all that is keeping the pulley on, whereas the PS pulley is held tightly by the shaft as well. The nuts on the WP pulley and the bolts for the PS pulley can only be tightened once the belt is back on.

13 mm head bolts on the tensioners = 22 Nm
Thermostat housing 10 mm bolts (3 of them) - 10Nm
Thermostat housing 13 mm bolt holding the engins hoist = 22 Nm

water pump to engine = 22 Nm
Pulley to pump = 10 Nm, but with blue loctite.

16 mm bolt on the idler wheel - I didn't have the data so I used 22 Nm.

The bolts inside the tensioner wheels are snugged until the tensioner moves. Nothing else one can do here, really.

The bolts for the PS pulley are tight enough once the pulley starts to turn when tightening (even with the belt on).


6. To put the fan shroud in place, there are two tabs on the bottom that slide into two spots. There are also two horizontal tabs on the sides near the bottom that go into "hooks" on the radiator. I found it easiest to do one side first and then the other. It can be done from underneath and from above. I did both.


I have some pictures showing the différence between my new HEP water pump and the old BMW one. I must say that I am impressed by the BMW pump which actually had a solid metal impeller (It's stamped BMW on it). I am less impressed by the impeller on the HEPU pump. I'm really hoping that the bearing is of better quality.


THe HEPU impeller looks like two soup can lids with some tin vanes spot welded in between. The BMW impeller looks and feels like solid brass (just discolouration but it is well made) with full welds holding the vanes in place. Just look at the rim below the impeller on both and you can see the difference. I'm hoping that the HEPU bearing is full of magic because it broke my heart to replace that ageing BMW water pump. If anyone knows how to remove impellers, I would love to swap them.

Cheers
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Last edited by gmak2012; 04-20-2015 at 06:29 AM.
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  #13  
Old 04-20-2015, 07:52 AM
pleiades pleiades is offline
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Quote:
Originally Posted by gmak2012 View Post
water pump to engine = 22 Nm
Pulley to pump = 10 Nm, but with blue loctite.
Is your water pump pulley metal or plastic? If BMW plastic, don't use threadlocker. Loctite will attack and crack/shatter the plastic around the bolt holes.
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  #14  
Old 04-20-2015, 08:38 AM
gmak2012 gmak2012 is offline
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Thanks for the information.



Aluminium. Just switched. Thanks for that information though. I'm sure many will find it valuable.
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  #15  
Old 04-20-2015, 10:02 AM
kutcht1 kutcht1 is offline
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I agree with you on the Hepu water pump impeller looking VERY cheaply made. I have a new one ready to go in but have been hesitant as to find out what the one in right now looks like when I remove it. I also bought an inexpensive URO one and it feels VERY well made for a cheap pump.
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