Welcome to Bimmerfest -- The #1 Online Community for BMW related information! Please enjoy the discussion forums below and share your experiences with the 200,000 current, new and past BMW owners. The forums are broken out by car model and into other special interest sections such as BMW European Delivery and a special forum to voice your questions to the many BMW dealers on the site to assist our members!

Please follow the links below to help get you started!

Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > Z Series > E85 / E86 Z4 (2003-2008)

E85 / E86 Z4 (2003-2008)
E85 Z4 convertible and E86 Z4 coupe talk with our BMW gurus here.

Reply
 
Thread Tools Display Modes
  #1  
Old 07-30-2011, 10:17 AM
entropy4 entropy4 is offline
Registered User
Location: United States
 
Join Date: Jul 2011
Posts: 4
Mein Auto: Z4
Yet another Z4 Overheat question

Hi all, couldn't quite find anything that precisely matched my symptoms, so I was wondering if anyone might be able to help me troubleshoot.

I have a 2003 2.5 Z4 ~110k. It recently began overheating. This does not occur at highway speeds, only while idling. The odd thing is if it begins to overheat while idling i can rev to ~3000 rpm and the engine temp drops back to the middle. I've only really noticed the problem while the AC is on. Unfortunately it's averaging 100 degrees outside right now When turning on either AC or Heat the electric fan does come on, but if I turn on the AC, let the thermometer climb and then turn of the AC, the fan turns off too.

Kinda stuck here and hoping someone has some suggestions before I start randomly buying expensive cooling system parts.

FYI coolant system does not appear to be leaking and was bled when I replaced the expansion tank about a year ago.

Thanks in advance!
Corey
Reply With Quote
Ads by Google
  #2  
Old 07-31-2011, 03:43 AM
Pinecone's Avatar
Pinecone Pinecone is offline
M Mad
Location: Maryland
 
Join Date: Apr 2002
Posts: 10,482
Mein Auto: M Roadster/M3
Sounds like the electric fan is not working.

The electric fan should run whenever the AC is running.
__________________
Terry Carraway

'95 Alpine M3 LTW
'00 Dakar M Roadster
'02 Topaz M3
Red/White SRF #4 (Chassis 561)
Reply With Quote
  #3  
Old 07-31-2011, 05:50 AM
GeorgeT's Avatar
GeorgeT GeorgeT is offline
Officially Welcomed to the 'Fest
Location: Seneca, SC
 
Join Date: Jun 2007
Posts: 985
Mein Auto: '07 750i BMW; '03 Z4 BMW
If it cools down when you rev the engine, it sounds as if the water pump isn't fully working. If it were the fan, revving the engine would not have any impact.
Reply With Quote
  #4  
Old 07-31-2011, 10:21 AM
entropy4 entropy4 is offline
Registered User
Location: United States
 
Join Date: Jul 2011
Posts: 4
Mein Auto: Z4
Brilliant, I'll try replacing the WP later tonight.

Thanks for the idea!
Reply With Quote
  #5  
Old 08-01-2011, 05:57 AM
Pinecone's Avatar
Pinecone Pinecone is offline
M Mad
Location: Maryland
 
Join Date: Apr 2002
Posts: 10,482
Mein Auto: M Roadster/M3
There are two fans. An electric fan and one driven off the engine.

When you rev the engine, the engine fan moves fast enough to actually move air through the radiator. At idle, the electric fan assists if the temps get up.

Check the electric fan before you change the water pump.
__________________
Terry Carraway

'95 Alpine M3 LTW
'00 Dakar M Roadster
'02 Topaz M3
Red/White SRF #4 (Chassis 561)
Reply With Quote
  #6  
Old 08-01-2011, 06:28 AM
GeorgeT's Avatar
GeorgeT GeorgeT is offline
Officially Welcomed to the 'Fest
Location: Seneca, SC
 
Join Date: Jun 2007
Posts: 985
Mein Auto: '07 750i BMW; '03 Z4 BMW
Quote:
Originally Posted by Pinecone View Post
There are two fans. An electric fan and one driven off the engine.

When you rev the engine, the engine fan moves fast enough to actually move air through the radiator. At idle, the electric fan assists if the temps get up.

Check the electric fan before you change the water pump.
My '03 3.0 does not have two fans, only an electric fan.
Reply With Quote
  #7  
Old 08-01-2011, 06:28 AM
Ron Stygar's Avatar
Ron Stygar Ron Stygar is offline
19,585 Miles
Location: CT
 
Join Date: Mar 2002
Posts: 11,143
Mein Auto: Z4 M Coupe 6LL93033
Quote:
Originally Posted by Pinecone View Post
There are two fans. An electric fan and one driven off the engine.

When you rev the engine, the engine fan moves fast enough to actually move air through the radiator. At idle, the electric fan assists if the temps get up.

Check the electric fan before you change the water pump.
No fan?
__________________
.
.
Reply With Quote
  #8  
Old 08-01-2011, 07:35 AM
entropy4 entropy4 is offline
Registered User
Location: United States
 
Join Date: Jul 2011
Posts: 4
Mein Auto: Z4
Just looking at my motor, there is one large electric fan directly in the center of the radiator, I don't see a belt driven fan. I would very much prefer it to be a fan issue seing as how replacing the water pump apparently requires me to move the engine.
Reply With Quote
  #9  
Old 08-09-2011, 08:56 AM
entropy4 entropy4 is offline
Registered User
Location: United States
 
Join Date: Jul 2011
Posts: 4
Mein Auto: Z4
Just an update, replaced the water pump and the thermostat for good measure (It does suck that you have to move the engine to pull out the pump).

Needle's been hovering in the middle for two days now, keeping my fingers crossed!

Thanks for your input everyone!
Reply With Quote
  #10  
Old 08-09-2011, 07:06 PM
pal's Avatar
pal pal is offline
S54=Living on the Edge
Location: New Jersey
 
Join Date: Nov 2007
Posts: 1,486
Mein Auto: 2007 M Coupe, 2004 Audi T
When this happened to my Audi TT a few years ago it was the electric fan that had stopped working. Your symptoms also indicate a possible water pump issue which you have replaced so good luck!

To check for the fan, it should turn on automatically on a hot idling engine w/o the AC actually being on to regulate the temp by moving air. I don't know what the trigger temp is for BMWs though.
__________________
Euro headers w/relocated sensors|RPI scoop|K&N panel filter|KW V3s|OEM Strut Brace|RE RSMs|Zeckhausen CDV|SpeedBleeders|Stoptech Brake Lines|StopTech 4-pot BBK all around|SSR GT2-H 19x8.5/19x10|Potenza RE-11s
Texas Mile (March, 2010): 155.4 mph
Reply With Quote
Reply

Bookmarks

Tags
overheat, thermostat, z4


Forum Navigation
Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > Z Series > E85 / E86 Z4 (2003-2008)
Today's Posts Search
Thread Tools
Display Modes

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



Forum Jump


All times are GMT -7. The time now is 02:13 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
© 2001-2011 performanceIX, Inc. All Rights Reserved .: guidelines .:. privacy .:. terms