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Discussion Starter · #1 ·
Hi all,

Over the weekend I did some upgrades for the cooling system (325i 2001 with 108k). I replaced thermostat (code P0128), water pump, temperature sensor and two belts. I want to thank you for your help during this upgrade.

But now I have some pitch noise. Sometimes it can be very loud. Sometimes it calms down. I suppose it comes from the new belts. Is it normal for the new belt to make the those noises or did I do something wrong. Another moving part that can make noise would be the new water pump (Graf, metal impeller).


I did not replace the hoses and expansion tank. I did notice there is small leak from expansion tank area after I put everything together. I guess that would be the project for the Christmas :)

The most difficult part of upgrading cool system for me is the disconnect the lower hose from the radiator. I ordered the hose but I could not take the old hose apart. I tried the hair dryer method. It works well for thermostat and lower hose but not for lower hose to radiator. Has anybody tried rotatory cutting tool to cut it? Thanks.

Harry
 

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Did you spill some coolant onto the pulleys/belts? That was the cause of my squeaking the last time I replaced my expansion tank. I just took some damp paper towel and wiped off the belts and the squeaking stopped. :)
 

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Discussion Starter · #4 ·
I did spilled some coolant to the belt when I did thermostat and water pump. But it have dried out overnight.


When I replaced the belts, I used T50 to loose the tensioner for AC belt. I tried T50 for the other belt tensioner and found it hard to do. So I used 16mm (or 17mm?) socket to do the job. After I put the belts back on, all the tension should go back to what it was. Do I need to adjust anything? The only pulley I touched is water pump pulley which I torqued at 10nm after I was done.
 

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I did spilled some coolant to the belt when I did thermostat and water pump. But it have dried out overnight.

When I replaced the belts, I used T50 to loose the tensioner for AC belt. I tried T50 for the other belt tensioner and found it hard to do. So I used 16mm (or 17mm?) socket to do the job. After I put the belts back on, all the tension should go back to what it was. Do I need to adjust anything? The only pulley I touched is water pump pulley which I torqued at 10nm after I was done.
Your tensioner is probably shot. Try removing the belt and spinning the idler and tensioner pulleys. Don't forget the A/C drive system.
If they spin freely, or there is any roughness, they should be replaced. You are looking for them to have very little spin with a dampened feel. This indicates that there is still lubricant in the bearing. If it were me, I would just replace them. They don't cost much, and they can cause serious grief if they fail. If you have a mechanical tensioner, you may want to convert to hydraulic. Not cheap, but much better than mechanical. You can get al parts from Max at oembimmerparts.com. They are a site sponsor, and everyone who has done business with them here has had a great experience.
 

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If you spill coolant, the water component will evaporate but the ethylene glycol won't and will contaminate the rubber. On another car where I ended up having this problem, had to take the belt back off, thoroughly clean and degrease the pulleys, and wash the belt with soapy water and a good scrubbing with a fiber brush. Squealing stopped. Of course, being a Ford 302 engine on a T-Bird made it much easier cause there was actually WORKING ROOM in front of the engine and the pulleys were all metal.
 

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Discussion Starter · #7 ·
Thanks for your valuable inputs.

I think the possible sources of noises are in three areas: 1) main belt and its tensioner; 2) AC belt and its tensioner, and 3) the fan itself.

I am going to do a divide and conquer:

1) I am going to remove the fan and start the engine to see if the noise is still there;
2) if the noise is still there, I will stop the engine and remove AC belt and start the engine again;
3) if the noise is still there, the problem should be in the main belt system.

What I am NOT sure is: can I start the engine at stage 1) 2),3)? I don't see why not. But I would like to hear from somebody who has done it.

If at stage 3), the noise is still there, can I remove the main belt and start then engine? The new water pump I put in might be the guilty party too.
Thanks.
 

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I had a sqeal at startup here and there the second year on my 06 and it was under warranty. The Dealer replaced the belt and the sqealing has never come back. So, the brand new replacement belt had no break in and did not sqeal when it was replaced to give you a baseline.
 

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Thanks for your valuable inputs.

I think the possible sources of noises are in three areas: 1) main belt and its tensioner; 2) AC belt and its tensioner, and 3) the fan itself.

I am going to do a divide and conquer:

1) I am going to remove the fan and start the engine to see if the noise is still there;
2) if the noise is still there, I will stop the engine and remove AC belt and start the engine again;
3) if the noise is still there, the problem should be in the main belt system.

What I am NOT sure is: can I start the engine at stage 1) 2),3)? I don't see why not. But I would like to hear from somebody who has done it.

If at stage 3), the noise is still there, can I remove the main belt and start then engine? The new water pump I put in might be the guilty party too.
Thanks.
You can run the engine at all 3 stages of your testing. just don't run it long on the 3rd stage, for obvious reasons.
 

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Discussion Starter · #10 ·
I am reporting back my test from yesterday.

It only took me 5 minutes to remove the fan clutch yesterday (automatic one). I am getting better at this now!

I took out the fan and AC belt. The noise was still there. I made a couple of videos for my testing:

Noise with main belt on:

With main belt off:
http://www.youtube.com/watch?v=QTDt7sjWXQE&feature=related

The tensioner pulley is a little bit free spinning. The idler pulley is not free spinning but I can feel rough spots when I rotated it.

I guess I will replace the tensioner pulley ($50), idler pulley ($30) and water pump pulley ($26). Any thoughts? Thanks.
 

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If you spill coolant, the water component will evaporate but the ethylene glycol won't and will contaminate the rubber. On another car where I ended up having this problem, had to take the belt back off, thoroughly clean and degrease the pulleys, and wash the belt with soapy water and a good scrubbing with a fiber brush. Squealing stopped. Of course, being a Ford 302 engine on a T-Bird made it much easier cause there was actually WORKING ROOM in front of the engine and the pulleys were all metal.
had the same resolution and worked just fine, put dish soap and run water over the belts while running
 

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Discussion Starter · #17 ·
I ordered idler pulley, tenisioner pulley with tenisioner (mechanical ) and water pump pulley. Since my expansion tank is leaking a little. I ordered the upper hose and the tank. They normally deliver them the next day. But this time, it won't come until Tuesday.

While waiting, I tried to remove the old idler pulley. Boy o boy, the bolt is so tight! I like to confirm before I apply more force: do I loose the bolt counter-clock wise (the normal way)? Thanks.
 

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I had the same noise. I suspected the tensioner pulley, so I pressed the tip of a long screwdriver onto the surface of the tensioner while it was running and then put my ear against the handle of the screwdriver. No doubts now! I was able to eliminate the noise by spraying WD-40 on the inside of the spinning tensioner pulley. I put a long skinny tube on the WD-40 spray can nozzle and was careful not to get too much on the belt. Wear safety glasses because it will spray up into your face if you do it while it's running like I did. I drove the car all day yesterday and the high pictch squeal is gone. It has been doing it for a long time.
 

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While waiting, I tried to remove the old idler pulley. Boy o boy, the bolt is so tight! I like to confirm before I apply more force: do I loose the bolt counter-clock wise (the normal way)?
Yes.
 

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Discussion Starter · #20 ·
I would like to report back the result of replacing the pulleys:

I replaced tensioner pulley, idler pulley and water pump pulley. All the high pitch noises are gone. Thanks.

Since noise came after the new belts were installed, my theory for the noise is that the new belts put more tensions on the old, bad pulleys to make them squeak.

Thanks everybody.
 
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