E46 BMW Social Directory E46 FAQ 3-Series Discussion Forums BMW Photo Gallery BMW 3-Series Technical Information E46 Fanatics - The Ultimate BMW Resource BMW Vendors General E46 Forum The Tire Rack's Tire Wheel Forum Forced Induction Forum The Off-Topic The E46 BMW Showroom For Sale, For Trade or Wanting to Buy

Welcome to the E46Fanatics forums. E46Fanatics is the premiere website for BMW 3 series owners around the world with interactive forums, a geographical enthusiast directory, photo galleries, and technical information for BMW enthusiasts.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

Go Back   E46Fanatics > E46 BMW > General E46 Forum

General E46 Forum
This is the place to get answers, opinions and everything you need related to your E46 (sedan, coupe, convertible and wagon) BMW!

Reply
 
Thread Tools Search this Thread Rating: Thread Rating: 28 votes, 4.07 average. Display Modes
Old 07-18-2013, 11:34 AM   #1
Mango
10 years plus club
 
Mango's Avatar
 
Join Date: Mar 2006
Location: Southern California
Posts: 23,917
My Ride: M54B30
Exclamation Cooling system troubleshooting cheat sheet

This is a quick cheat-sheet that outlines requirements for a properly working cooling system, what to look for, and how to identify problems. Take note of these basic cooling system requirements:

1) Cooling system must be filled to capacity and be free of air bubbles

On a cold car, ensure the coolant/water level is correct per the float in the expansion tank. The level indicator should be between the two dots on the float stick. Also make sure the system is bled properly per the instructions in my cooling thread. Take your time doing this. Do not rush it.

If your expansion tank is low or empty or you see coolant stains, then you have a leak.

Most likely sources of leaks on these cars:

- Expansion tank
- Radiator
- Thermostat
- Hose at bottom of expansion tank

Least likely (but still possible) sources of leaks on these cars:

- Auto trans cooler
- Upper/lower radiator hose
- Hard coolant pipes under intake manifold
- Water pump
- Headgasket and/or cylinder ingestion

The above requirement met? Good! Proceed to #2

2) Water/coolant must be able to flow at sufficient volume and flow

The water pump is responsible for circulating water throughout the system. Think of the cooling system as a giant loop. If the water pump fins are bent, missing, or broken, the water pump cannot "drive" water throughout the system as required. Make sure the belt driving the water pump is also not damaged or broken.

The thermostat should also be opening and closing as designed. If the thermostat is closed or partially closed, water cannot flow and your chances of overheat go up.

There must not be any blockages in the system. Any sediment in the heater core, block/head passages, or radiator can cause a slow down of water flow and things will get hot quickly. Remember: that water/coolant needs to get to the radiator in order to be cooled and let back into the hot engine.

The above requirement met? Good! Proceed to #3:

3) Air flow

Once hot water reaches radiator, the way it is cooled down is by air on the outside flowing through the radiator fins. There's two ways this is accomplished:

a) Driving at speed.
Natural rush of air through the front of the car flows over the radiator effectively dissipating heat.

b) Fans.
Your belt-driven mechanical fan/pusher fan, or electric fan are used to move air over the radiator/condenser while at idle or when the air conditioner is used which helps dissipate heat.

Again, air must pass over the radiator in sufficient quantity at the correct moment. That is to say your mechanical and/or electrical-driven fans must be operating correctly when triggered by the appropriate conditions. Your fan switch must also be in working order to tell the fan to come on.

Causes of failure?

Automatic cars: Broken/missing fan blades, fan switch in lower radiator hose for pusher fan, defective pusher fan.

Manual cars: Defective puller fan (the one directly in front of the engine) or fan switch in lower radiator hose which is responsible for telling the fan to come on when the engine coolant gets hot.

Both cars: Blockage between the radiator and condenser in the form of dirt, leaves, bugs, etc. This will block air flow.

If your car is overheating, at least one of the above three main requirements is/are not being met.

If your car is overheating at idle (say in traffic) and you are sure that 1) you have adequate water in the system and 2) said water is air/bubble free, then air is failing to blow over the radiator.

You need to investigate why. Either the fan(s) aren't operating properly (not blowing air or enough air) or your fan switch isn't telling the fan to turn on. (or both)

As you can see, there are too many possibilities of failure for the cooling system especially for a 10-year+ old car. It is best to replace it all.

Rough diagram:

__________________
OVER 1M VIEWS
Support our DMAX: www.Facebook.com/DMAXstandup
Mango is offline   Reply With Quote
Ads by Google

Guests, get your FREE E46Fanatics.com membership to remove this ad.
Old 07-18-2013, 11:55 AM   #2
Fatrusty
Registered User
 
Join Date: Jan 2012
Location: Vancouver Wa.
Posts: 83
My Ride: '04 325i
Wonderful! That is a keeper and nice an simple.
Fatrusty is offline   Reply With Quote
Old 07-18-2013, 12:46 PM   #3
Knight
Registered User
 
Join Date: Jan 2008
Location: NNJ
Posts: 2,803
My Ride: '05 330Ci | '01 325i
Bookmarked. Thank you sir!
Knight is offline   Reply With Quote
Old 07-18-2013, 01:00 PM   #4
Mango
10 years plus club
 
Mango's Avatar
 
Join Date: Mar 2006
Location: Southern California
Posts: 23,917
My Ride: M54B30
You're welcome! if you guys like this thread and it has helped you, please click the rating system on the top right and rate it a full five stars!
__________________
OVER 1M VIEWS
Support our DMAX: www.Facebook.com/DMAXstandup
Mango is offline   Reply With Quote
Old 07-18-2013, 01:04 PM   #5
BimmersGarage
Registered User
 
Join Date: Mar 2010
Location: Dallas, TX (USA)
Posts: 2,212
My Ride: E46 330i
Very nice.
Thanks Mango.

Sub'd.
BimmersGarage is offline   Reply With Quote
Old 07-18-2013, 01:12 PM   #6
Mango
10 years plus club
 
Mango's Avatar
 
Join Date: Mar 2006
Location: Southern California
Posts: 23,917
My Ride: M54B30
Quote:
Originally Posted by BimmersGarage View Post
Very nice.
Thanks Mango.

Sub'd.
Thanks. off topic but I'll be using your videos on the front wheel bearings this weekend. i'll watch them tonight or tomorrow to mentally prep myself. i know it's easy but I like to be prepared.
__________________
OVER 1M VIEWS
Support our DMAX: www.Facebook.com/DMAXstandup
Mango is offline   Reply With Quote
Old 07-18-2013, 05:05 PM   #7
BimmersGarage
Registered User
 
Join Date: Mar 2010
Location: Dallas, TX (USA)
Posts: 2,212
My Ride: E46 330i
Quote:
Originally Posted by Mango View Post
Thanks. off topic but I'll be using your videos on the front wheel bearings this weekend. i'll watch them tonight or tomorrow to mentally prep myself. i know it's easy but I like to be prepared.
Watch them as much as you like.. you can't wear them out!

If you need any help, I'll be available after 1:30pm Sat., just skype me.

NOTE:
Get yourself some new axle nuts & dust caps.
Don't bother trying to re-use the old ones.
BimmersGarage is offline   Reply With Quote
Old 07-18-2013, 05:10 PM   #8
Mango
10 years plus club
 
Mango's Avatar
 
Join Date: Mar 2006
Location: Southern California
Posts: 23,917
My Ride: M54B30
Quote:
Originally Posted by BimmersGarage View Post
Watch them as much as you like.. you can't wear them out!

If you need any help, I'll be available after 1:30pm Sat., just skype me.

NOTE:
Get yourself some new axle nuts & dust caps.
Don't bother trying to re-use the old ones.
Oh yeah. Trust me I have an army of brand new parts for the job. You know me Thanks!
__________________
OVER 1M VIEWS
Support our DMAX: www.Facebook.com/DMAXstandup
Mango is offline   Reply With Quote
Old 07-18-2013, 05:22 PM   #9
Yewzer B Lewzer
Registered User
 
Join Date: Jan 2013
Location: St. Petersburg FL
Posts: 1,881
My Ride: 2003 325i
Cooling system troubleshooting cheat sheet

Great post Mango, I don't need it today but tomorrow is another day...


Sent from BimmerApp mobile app
__________________

^^Blue Ridge Parkway^^ '03 325i. '74 Jeep CJ-5. '93 Sailfish 170XL. '12 Westside SS Longboard. One of these four are sure to be running at any given point in time.
Yewzer B Lewzer is offline   Reply With Quote
Old 07-18-2013, 08:07 PM   #10
Mango
10 years plus club
 
Mango's Avatar
 
Join Date: Mar 2006
Location: Southern California
Posts: 23,917
My Ride: M54B30
Thanks Yewzer
__________________
OVER 1M VIEWS
Support our DMAX: www.Facebook.com/DMAXstandup
Mango is offline   Reply With Quote
Old 07-18-2013, 09:05 PM   #11
Vw6366
Registered User
 
Join Date: May 2013
Location: Stockton
Posts: 60
My Ride: 2003 325i
Cooling system troubleshooting cheat sheet

Thanks for the cheat sheet,


Sent from BimmerApp mobile app
Vw6366 is offline   Reply With Quote
Old 07-19-2013, 01:47 PM   #12
Mango
10 years plus club
 
Mango's Avatar
 
Join Date: Mar 2006
Location: Southern California
Posts: 23,917
My Ride: M54B30
Any time!!
__________________
OVER 1M VIEWS
Support our DMAX: www.Facebook.com/DMAXstandup
Mango is offline   Reply With Quote
Old 07-19-2013, 06:01 PM   #13
GuiltySpark
Registered User
 
Join Date: Feb 2013
Location: Atlanta, GA
Posts: 389
My Ride: 02 325xi
Lol, my upper rad hose wasn't leaking it just exploded. Nice abridged write up, thanks.
GuiltySpark is offline   Reply With Quote
Old 07-22-2013, 04:25 PM   #14
Mango
10 years plus club
 
Mango's Avatar
 
Join Date: Mar 2006
Location: Southern California
Posts: 23,917
My Ride: M54B30
You're welcome. Quick super-reminder for all the folks posting of cooling troubles today.
__________________
OVER 1M VIEWS
Support our DMAX: www.Facebook.com/DMAXstandup
Mango is offline   Reply With Quote
Old 09-08-2013, 12:10 AM   #15
Zpzp96
Registered User
 
Join Date: Aug 2013
Location: Texas
Posts: 69
My Ride: BMW E46 330i
Cooling system troubleshooting cheat sheet

I have a question.

My car has replaced expansion tank 4k miles ago. And my car occasionally show up low coolant light.
Whenever I check the coolant level, it is full. More importantly, whenever I open the cap, there is air coming out. There are air coming out from the bleeding screw too. Then the light go off for a good day or two.
It comes on again and off after two days. It can be removed by checking coolant level or letting the air out from the tank.

How and why the air goes into the tank while the coolant is not leaking? (Level is full)


Sent from BimmerApp mobile app
Zpzp96 is offline   Reply With Quote
Old 09-08-2013, 12:34 AM   #16
TurnersInOz
Registered User
 
Join Date: Dec 2011
Location: Brisbane
Posts: 527
My Ride: 2004 325i
If air comes out the bleeder screw, the system is not full and has not been properly bled.
When you say there is air coming out the ET cap, what exactly do you mean? You should never be opening this cap (or the bleeder) when the engine is hot, which is the only time there should ever be pressure in the ET.
TurnersInOz is offline   Reply With Quote
Old 09-08-2013, 02:07 AM   #17
Zpzp96
Registered User
 
Join Date: Aug 2013
Location: Texas
Posts: 69
My Ride: BMW E46 330i
Cooling system troubleshooting cheat sheet

Thanks for the reply.

Maybe the engine was still kinda hot... Not sure. I let the car cool down for two to three hours minimum in the garage.

When I open the cap to check the coolant level, I could hear air coming out. Sounds like phewish? Also similar but less volume from the screw.

As I mentioned, my car has replaced expansion tank and tank retainer 4k ago. As well as flushing new coolant. All done by mechanic. Not me..

Clear list that I could check

1. Low coolant light was on occasionally.(on for minutes, go away, and it comes on again for minutes, and go away. As time goes, the duration gets longer.)
2. Coolant level indicator shows its full.
3. No more light shows up after checking coolant level.( after opening the cap maybe?)

I'm thinking there is way that air comes into the ET and it makes the sensor to read low coolant. So whenever I let the air go out, no more low coolant light.

Thanks for your help! I'm not really worrying about my cooling system since the car has replaced ET few miles ago and T-stat 30k ago. But just annoying to see the light...



Sent from BimmerApp mobile app
Zpzp96 is offline   Reply With Quote
Old 09-08-2013, 02:50 AM   #18
David McMahon
Registered User
 
Join Date: Feb 2013
Location: Suffolk, UK
Posts: 1,451
My Ride: '99 E38 740iL
Quote:
Originally Posted by Zpzp96 View Post
Thanks for the reply.

Maybe the engine was still kinda hot... Not sure. I let the car cool down for two to three hours minimum in the garage.

When I open the cap to check the coolant level, I could hear air coming out. Sounds like phewish? Also similar but less volume from the screw.

As I mentioned, my car has replaced expansion tank and tank retainer 4k ago. As well as flushing new coolant. All done by mechanic. Not me..

Clear list that I could check

1. Low coolant light was on occasionally.(on for minutes, go away, and it comes on again for minutes, and go away. As time goes, the duration gets longer.)
2. Coolant level indicator shows its full.
3. No more light shows up after checking coolant level.( after opening the cap maybe?)

I'm thinking there is way that air comes into the ET and it makes the sensor to read low coolant. So whenever I let the air go out, no more low coolant light.

Thanks for your help! I'm not really worrying about my cooling system since the car has replaced ET few miles ago and T-stat 30k ago. But just annoying to see the light...



Sent from BimmerApp mobile app
How about the ET Cap? Sometimes (especially on other cars) this is a popular fail point
David McMahon is offline   Reply With Quote
Old 09-08-2013, 03:23 AM   #19
TurnersInOz
Registered User
 
Join Date: Dec 2011
Location: Brisbane
Posts: 527
My Ride: 2004 325i
Quote:
Originally Posted by Zpzp96 View Post
I'm not really worrying about my cooling system since the car has replaced ET few miles ago and T-stat 30k ago. But just annoying to see the light...
It will be in your best interest to find the cause of this. You want to be able to trust what the car is telling you.

Personally I'd start by bleeding the system, so you can be 100% sure the level is correct. Once that is done, leave the bleeder screw alone and only check the level with the dip stick in the ET.

You might want to check the brand of ET that was installed. There have been reports of using off-brand tanks that have produced issues with the coolant level sensor.

You could also test your sensor by swapping the washer fluid and coolant level sensors to see if the issue continues or not.

As David points out, replacing the cap on the ET is also a very good idea, but I do not see how it would be causing this issue?
TurnersInOz is offline   Reply With Quote
Old 09-09-2013, 11:16 AM   #20
Mango
10 years plus club
 
Mango's Avatar
 
Join Date: Mar 2006
Location: Southern California
Posts: 23,917
My Ride: M54B30
Quote:
Originally Posted by Zpzp96 View Post
I have a question.

My car has replaced expansion tank 4k miles ago. And my car occasionally show up low coolant light.
Whenever I check the coolant level, it is full. More importantly, whenever I open the cap, there is air coming out. There are air coming out from the bleeding screw too. Then the light go off for a good day or two.
It comes on again and off after two days. It can be removed by checking coolant level or letting the air out from the tank.

How and why the air goes into the tank while the coolant is not leaking? (Level is full)


Sent from BimmerApp mobile app
When you say there is air coming out of the cap and screw -- I think you mean the sound of air. Don't worry about that. That's normal depending on pressure differences/temp, etc. That's not for you to worry about.

As said, just make sure the car is bled and the coolant level is where it should be. Replace the sensor. It's cheap and doesn't involve coolant.
__________________
OVER 1M VIEWS
Support our DMAX: www.Facebook.com/DMAXstandup
Mango is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Censor is ON





All times are GMT -5. The time now is 01:04 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
(c) 1999 - 2011 performanceIX Inc - privacy policy - terms of use