Notices
928 Forum 1978-1995
Sponsored by:
Sponsored by: 928 Specialists

Coolant Level Sender

Old 11-04-2018, 05:52 PM
  #1  
awilli6
Rennlist Member
Thread Starter
 
awilli6's Avatar
 
Join Date: Oct 2010
Location: Memphis, TN 1987 S4
Posts: 1,005
Likes: 0
Received 27 Likes on 15 Posts
Default Coolant Level Sender

Hey gang,

I’m getting a check coolant level alarm on my 89S4. The level is fine. I’m not loosing coolant from anywhere. Is it possible to test the sender via a multi meter? Is there anything else I need to check? I did change my “J” hose on the bottom of the expansion tank. That fixed the leak I had. I let it run for 20+ minutes without the cap so I think it should have burped. I ran it so long the coolant was approaching the top. Not enough to spill out the top but it seemed like if I kep it running, it would have overflowed.

thoughts?
Old 11-05-2018, 03:08 AM
  #2  
Schocki
Rennlist Member
 
Schocki's Avatar
 
Join Date: Sep 2002
Location: Madrid, España
Posts: 2,159
Received 180 Likes on 150 Posts
Default

Theses sensors fail after many years. Happened to my GTS too, just get a new one from Roger and replace (easy).
Old 11-05-2018, 09:42 AM
  #3  
Kevin in Atlanta
Rennlist Member
 
Kevin in Atlanta's Avatar
 
Join Date: May 2002
Location: Roswell, GA
Posts: 7,966
Received 737 Likes on 445 Posts
Default

Not sure about this, but the float itself might be the failure point - the float after many years sitting in hot coolant begins to decay and swell.

I pulled two last weekend and they crumbled, leaving behind the magnet ring. The sensor did still work when I moved the ring out of range.

Maybe a 3D printed replacement would save them?
Old 11-05-2018, 01:12 PM
  #4  
Schocki
Rennlist Member
 
Schocki's Avatar
 
Join Date: Sep 2002
Location: Madrid, España
Posts: 2,159
Received 180 Likes on 150 Posts
Default


Get a new sensor from Roger, done. Bridge the connector first to see if the warning disappears.
Old sensor after 20+ years in coolant. Not floating anymore.
Old 11-05-2018, 02:11 PM
  #5  
Kevin in Atlanta
Rennlist Member
 
Kevin in Atlanta's Avatar
 
Join Date: May 2002
Location: Roswell, GA
Posts: 7,966
Received 737 Likes on 445 Posts
Default

Originally Posted by Schocki

Get a new sensor from Roger, done. Bridge the connector first to see if the warning disappears.
Old sensor after 20+ years in coolant. Not floating anymore.

So a float replacement would restore the sender function?
Old 11-05-2018, 04:03 PM
  #6  
Schocki
Rennlist Member
 
Schocki's Avatar
 
Join Date: Sep 2002
Location: Madrid, España
Posts: 2,159
Received 180 Likes on 150 Posts
Default

Originally Posted by Kevin in Atlanta
So a float replacement would restore the sender function?
Yes, it would.
Old 11-05-2018, 06:00 PM
  #7  
Kevin in Atlanta
Rennlist Member
 
Kevin in Atlanta's Avatar
 
Join Date: May 2002
Location: Roswell, GA
Posts: 7,966
Received 737 Likes on 445 Posts
Default

So, here's a late revision of the sender.

The magnet is inside the plastic float. Seem to be easy project for 3D printing.


Dissected coolant level sender
Old 11-05-2018, 08:23 PM
  #8  
awilli6
Rennlist Member
Thread Starter
 
awilli6's Avatar
 
Join Date: Oct 2010
Location: Memphis, TN 1987 S4
Posts: 1,005
Likes: 0
Received 27 Likes on 15 Posts
Default

I cleaned the float and it began to work. Probably just temporary but there was a lot of gunk. I’ll plan to get another one and a metal expansion tank in the near future. Thanks for the help.
Old 11-06-2018, 12:43 PM
  #9  
Luis A.
Addict
Rennlist Member

 
Luis A.'s Avatar
 
Join Date: Aug 2001
Location: Milwaukee, WI
Posts: 669
Received 26 Likes on 6 Posts
Default

Generally I'm not a fan of ghetto fixes but I was able to effect such a repair which, a) being invisible, b)working perfectly and c) given the cost of replacement sensor, I was perfectly satisfied with and will be 100% reliable for decades to come. I fashioned a replacement float from closed cell foam. You need to clip off the bottom "T" disc that holds the float in place and salvage the ring magnet. The resulting foam cylinder is much smaller than the original material as it has much higher buoyancy. I added a SS washer for necessary ballast but it distorts the magnetic field so play with the new magnet/foam assembly to ensure it only activates the reed switch in one (low) level position. Initially mine activated at the low point but also at its highest point, which is not correct behavior.
Old 11-08-2018, 08:01 PM
  #10  
dpower$
Addict
Rennlist Member

 
dpower$'s Avatar
 
Join Date: Aug 2003
Posts: 257
Likes: 0
Received 3 Likes on 2 Posts
Default

All you guys know what and where everything is on these cars. For those of us not so educated...where on the car is this coolant float thing and how do you get to it? Thanks
Old 11-08-2018, 08:50 PM
  #11  
Wisconsin Joe
Nordschleife Master
 
Wisconsin Joe's Avatar
 
Join Date: Jan 2013
Location: Kaukauna Wisconsin
Posts: 5,925
Received 302 Likes on 231 Posts
Default

Originally Posted by dpower$
All you guys know what and where everything is on these cars. For those of us not so educated...where on the car is this coolant float thing and how do you get to it? Thanks
It's in the coolant expansion tank.
You get to it by lifting the hood.


Somewhere on here is a pic of what's under the hood. Labelled and everything.
There's a similar pic of what's underneath the car.

If someone would post or link that, it'd be great.

The coolant tank is at the back of the engine bay, on the passenger side (right side for left hand drive cars).
It has the 'radiator cap' on top.
It was originally white plastic. By now it's usually pretty yellow.
Old 11-08-2018, 09:08 PM
  #12  
jschiller
Racer
 
jschiller's Avatar
 
Join Date: Feb 2010
Location: Cape Coral, FL
Posts: 479
Received 85 Likes on 61 Posts
Default

Look here:
http://www.porsche928.be/index.php?p...ails-de-moteur
Old 11-09-2018, 03:42 PM
  #13  
dpower$
Addict
Rennlist Member

 
dpower$'s Avatar
 
Join Date: Aug 2003
Posts: 257
Likes: 0
Received 3 Likes on 2 Posts
Default

Thank you


Thread Tools
Search this Thread
Quick Reply: Coolant Level Sender



All times are GMT -3. The time now is 04:19 PM.