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Discussion Starter · #1 ·
2000 E39 528i 6cyl- My main belt broke today (pump/alt/crank), so I installed a new one. Not too hard. Started the car and after about 10s had to turn it off. I noticed the radiator fan/pulley assembly basically rocking /tipping front to back and clunking as it did. What I could really see is the big fan clutch lock nut moving fore/aft and I assume the water pump bearings were too, but I could not see to confirm. It did not do this before I changed the belt. I can't imagine that I did anything to precipitate this by changing the belt. The only thing I touched was the 16mm nut on the tensioner. maybe the tighter belt is pulling more on the water pump? Doesn't make sense since the tensioner should keep constant tension. Any ideas as to why all of a sudden this is happening? Water pump bearings, fan clutch, loose pulley attachment? Coincidence? I'm stumped.
 

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Wingnut
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wp bearings...possibly why you lost the belt to start with. take the belt back off and feel your way around the rotating components for anything not right. the tension on the belt is held by a spring, there is no adjustment.
 

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Discussion Starter · #3 ·
thanks- I bought a new wp bc I can't think of what else it might be. When I get the new pump I'll feel around first before installing it. And here I was so happy I put new belts on...
 

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When you do the pump install, with belt off rotate the ldler pulley that's in the belt loop- these will eventually wear out (bearings) just as the WP has likely done.
You migh search this site or Google E39 cooling system refresh...your cars cooling system may need some addl preventative maint work- I.e. More parts.


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Discussion Starter · #5 ·
I think you're just (smartly) suggesting while it's all apart to just replace the idler/tensioners- they're pretty cheap. What about fan clutch assy? FYI- During original install, with the belt off, I did rotate and feel the pulleys, idlers and tensioners with my hand as best I could and they all rotated smoothly and no wobble or anything. I thought I did this with the wp pulley too but maybe with not the same force as the belt can generate. Just seems strange this issue did not happen before with the old belt.
 

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Typically many here will do PM on cooling system when it hits 90-120K mile mark:
- WP
- idler pulleys
- thermostat
- radiator
- main hoses
- maybe even fans clutch

Don't think you need replace tensioner sunless you spot an issue.

Cooling system is THE big weak area on E39- overheating, particularly I-6 motor, even for VERY short duration can do major damage.

Good luck/Bill


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Your pulleys should rotate with a little bit of resistance. If they rotate freely when you spin the pulley then you are due for a change. It's somewhat hard to explain but you just have to know how it should feel. If you want to know go to an auto parts store and have them grab a new one for you and spin it. The pulley/tensioners should be close to that.

When you replace the water pump be sure to properly bleed the cooling system. You just can fill the expansion tank and go. Also, BE ABSOLUTELY SURE that you don't overfill the expansion tank.
 

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Discussion Starter · #10 ·
Thanks for all the info. One thing I remembered this morning is that when the main belt broke my daughter was driving the car. She noticed power steering gone and battery light on so she drove it straight home (~1.5miles). When home, the temp gauge was in the red zone and illuminated. I can only hope that perhaps the water pump fried somehow and not the block or head warped or damaged. gulp...
 

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Thanks for all the info. One thing I remembered this morning is that when the main belt broke my daughter was driving the car. She noticed power steering gone and battery light on so she drove it straight home (~1.5miles). When home, the temp gauge was in the red zone and illuminated. I can only hope that perhaps the water pump fried somehow and not the block or head warped or damaged. gulp...
Well, this is bit of a reason to be anxious- let's hope the motor is OK. These aluminum heads on the I-6 DO NOT do well at all when overheated, but this was seemingly fairly short-duration -cross your fingers.

The instrument cluster's temp gauge is electronically buffered - the actual engine temp. can vary some +/- 15C or bit more until the gauge will move off the 12 noon mark. When you fire up the motor after the cooling stuff is complete, well before, put the instrument cluster into 'test mode' and dial up test #7; that will display the actual temp. (degree C) real time on the cluster so you can monitor changes.

Look here: http://mr-fix.info/bmw-e39-obc-hidden-menu-diagnostic-mode/

As the motor comes up to temp watch the reading like a hawk; if you see it moving past 95-100C and climbing, shut off the motor right away. Let your daughter know that she should NEVER run any car in overheat - pull over as soon as possible, turn off the key immediately.

Good Luck/Bill
 

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- Do a compression test in all 6 cylinders, if OK, then...

- Spend time reading forums on the topic of "cooling overhaul"...and spend $600+ to overhaul it.
 

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ALGhoul
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Wow but if she lost power steering she'll not be able To drive
It happened with me long back before I switched to electrical
Lost power steering and same time temp went to red once it done I was on the left side suddenly I parked on emergency area and switch it off
The belt shreded around all pulleys and big headache removing fan no tools call brother to bring it and bring new belt while Iam removing these traces and my tensioner wasn't holding the belt enough once changed everything is fine but I was able to drive home without fan just 5 km only then I went next day bought tensioner and put that bus fan and since that day Iam thinking of switching electrical and I've done it LoL have a nice day
 

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Discussion Starter · #14 ·
thanks CN90- for the compression test- should we look for matching readings or even on a 2000, should the compression readings be close to spec? Is it 220psi per cylinder? Anyone know?
 

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BMW specs in TIS for compression tests in E39 engines are:
I6s minimum acceptable 10 - 11 bar or ~145 - 160 psi
V8s minimum acceptable 12 - 14 bar or ~175 - 205 psi
TIS also says"approx. equal value for all cylinders" for all engines, but no value given for how approximate

A general rule of thumb (not BMW specific) is that all cylinders should be within 10% of each other.
 
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