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#422323
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2,271 Posts
Discussion Starter #1 (Edited)
Observation: Antifreeze levels go down over time and sometime an odor of heated antifreeze is noticed after extensive driving. Leak from somewhere underneath the expansion tank is noticed when removing the splash shield.

Hypothesis: Failed or about to fail expansion tank due to low-to-high temperatures during the year, and poor make up of the part.

Experiment: On Feb. 19th the coolant light came on warning of low coolant levels in the tank. Upon checking the level it was evident the car was functioning with low levels of antifreeze. The levels were brought to normal and after three days the level of antifreeze was examined again to find that the level had gone done about 1/4th of the distance. The checking was done with the engine cooled off. The problem is persistent and it validates the hypothesis of a failed or about to fail expansion tank or lower hoses. More parts may be defective that were not observed.

Method of action: DIY replacement of expansion tank, water pump (never been replaced), upper and lower hoses, temperature sensor, and serpentine belt. The serpentine belt does not show crack or wear but it has never been replaced based on the known car history.

Where to purchase the parts
: upon research it seems that Az Autohaus has the lower prices on the parts needed. Some of them are not OEM. Please see this link.

Questions and notes: The thermostat has been replaced when the car had 62k miles. The ac belt has never been replaced.

Result: TBD

Dear co-members of this great internet meeting place, do you have any advices, remarks about this project? Any info of suggestions are greatly appreciated.

This is eye candy:
 

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Depending on how many miles the car has now I would do the tstat if it has more then 50-60k on the replacement stat so you are not going back in again later to do it, I would do the belts as well as you stated.
 

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a man made of men like me
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839 Posts
Haha i like you, you sound like a mad scientist. I just did this as part of Inspection II before the winter and all went well, i got all my parts from autohausaz.com as well. I found that I had to replace the coolant temp sensor located on the bottom rad hose and the original one with gasket had leaked with the new rad hose, gasket is not sold separately so you need a new coolant temp sensor to fix the leak (if you have one like i did).

This can be done with minimal coolant lost due to the law of static pressure, just remove it with a fully cooled engine and you should experience no coolant loss.

Check the wiki keyword search Inspection II for more information on the coolant system DIY. good job :thumbup:
 

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#422323
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2,271 Posts
Discussion Starter #6
LOL, I think the lab-report approach may be turned some people off. What can I do, I'm a biochem major. :D I ordered the temp sensor as well. The total was $244. I decided not to purchase a thermostat, because it was replaced a short time ago and it's not as hard to replace.

I will update on the results.
 

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424 Posts
I'm taking on the water pump project this weekend. I just picked up an '01 330cic with about 70,800 miles. I have not taken on a DIY project of this size in many, many years. While I'm in there, I'll be replacing most everything but the radiator and will also post results.
 

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a man made of men like me
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839 Posts
the hardest part for me in this DIY was getting the rad hoses off, a serious pain in the ass. just be patient and keep tugging making sure the fastener is lifted up first. Do not use a flathead to pry as you will snap the plastic.

as for the water pump, i broke the water pump pully again trying to pry the pully off the waterpump with a flathead after the 4 bolts were removed. this chipped a piece off the outside of it and i had to pick up a new one for fear it would fray the belt. just telling you my errors so you dont do the same.

There are many great DIY walk throughs for this. good luck guys.

oh and i happen to like the scientific method, its clear concise and organized.
 

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Hi,
I have a 2001 325i in Brazil with the similar problem. The mechanic says some water resevoir has a problem.
I looked for the part in the oemparts.com but had some difficulty in finding the part. The mechanic gave me the following part # 1436239Z5E 2700N.
Can anyone help me find this part?
I thank in advance andbest regards,
Vitor
 

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Who is John Galt?
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1,404 Posts
Albo, I'm pretty much in the same boat as you. I'm looking around gathering all info for my coolant overhaul. Love the scientific approach, and the doc. attachment. I know that "wingspan" did something similar some time ago, and I'm going to check his experience with all of this. I've also heard of some kind of "coolant systems kit," although I'm not sure about the specifics. I think it was oembimmerparts that was offering this. Will look into it.

Good luck brother.
mo
 

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#422323
Joined
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2,271 Posts
Discussion Starter #11
Hi,
I have a 2001 325i in Brazil with the similar problem. The mechanic says some water resevoir has a problem.
I looked for the part in the oemparts.com but had some difficulty in finding the part. The mechanic gave me the following part # 1436239Z5E 2700N.
Can anyone help me find this part?
I thank in advance andbest regards,
Vitor
IDK what a water reservoir is on a BMW, do you think he might have meant the expansion tank? The expansion tank serves as a kind of resevoir for your mixture 50 % BMW coolant and 50% distilled water. They tend to crack since that part is plastic and deals with high/low temperature situations. It's a common problem on e46 BMW's.
 

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#422323
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2,271 Posts
Discussion Starter #12 (Edited)
Albo, I'm pretty much in the same boat as you. I'm looking around gathering all info for my coolant overhaul. Love the scientific approach, and the doc. attachment. I know that "wingspan" did something similar some time ago, and I'm going to check his experience with all of this. I've also heard of some kind of "coolant systems kit," although I'm not sure about the specifics. I think it was oembimmerparts that was offering this. Will look into it.

Good luck brother.
mo
Thanks. I ordered the parts from AZ autohaus. They had the lowest prices and I've had a good experience with them (limited one). Here's a summary of the parts:

17137787039 - Expansion Tank/Coolant Reservoir $48.92

82141467704 Miscellaneous Fluids/Treatments; BMW Antifreeze; 1 Gallon - $19.45

07119963200 - Oil Drain Plug Gasket; 14mm Aluminum Seal Washer; 14x18x1.5mm -$0.12

11531436408 - Radiator Hose; Lower to Thermostat Housing with Temperature Sensor Fitting - $20.33

17127510952- Radiator Hose; Upper Radiator to Thermostat Housing - $29.18

13621433077 - Radiator/Auxiliary Fan Switch; In Lower Radiator Hose - $16.61

4PK0865 - Serpentine Belt/Ribbed Drive Belt; AC Compressor - $5.98

6PK1538 - Serpentine Belt/Ribbed Drive Belt; Alternator/Power Steering/Water Pump - $17.96

11517527910 - Water Pump; Original Type With Composite Impeller - $85.78

Parts Total: $244.33
Refundable Core Total: $0.00
Shipping & Handling: $0.00

Total Before Tax: $244.33
Sales Tax: $0.00
Order Total: $244.33
I would have preferred to purchase the parts from Tischer since I used their "special deal" in order to validate and research my needs, but they never responded to my e-mails. Also, the uppers hose is still in good condition, also the belts show no visible cracks or wear, but I decided as a preventive measure to change them. The same goes for the H-O-H pump.
 

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ROLL TIDE!
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Autohausaz.com is very good. I have used them many times. Fast, free shipping rules!

Here are some vids I did on expansion tank and radiator. Gives you an idea of what to do.....


 

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just like that, he's gone
2016 BMW 535 M-Sport
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1,696 Posts
it's a 9 year old car on (most likely) it's original expansion tank. It's an easy remove and replace for around $70. Lots of DIY out there

ALL the rubber/plastic bits in cars will absolutely begin failing after 5 years.
 

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smolk, that video was awesome - thanks. You're probably out driving right now.
 

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ROLL TIDE!
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smolk, that video was awesome - thanks. You're probably out driving right now.
Thanks. I wish my production skills were better. Tough to make a decent video with one hand, while working with the other....:p
 

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Who is John Galt?
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1,404 Posts
Guys,

In dealing with overhauling the coolant system, how critical are the radiator hoses (top and bottom)?
 

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ROLL TIDE!
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23,977 Posts
Guys,

In dealing with overhauling the coolant system, how critical are the radiator hoses (top and bottom)?
Too cheap to be not critical IMO. But if you are trying to save a buck, you can probably get away without doing them.
 
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