Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help




Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 05-29-2002, 11:41 AM
haasman's Avatar
Registered User
 
Join Date: Jun 2001
Location: San Francisco, CA
Posts: 3,097
Unhappy Befuddled ... engine temp ... after new Tstat

I am Befuddled:

My '91 300E coolant temp has been running at or just below 80c after ten minutes and more of driving at ambient temp of 60-70f. So I replaced the Tstat thinking this was the problem.

The car still hardly shows anything above 80c. Now I am wondering is it the Tstat or possibly a bad sending unit?

Questions:

-How do I test the sending unit to the temp gauge?
-Is sticking a thermometer into the coolant reservoir a good test of the true engine coolant temperature?

I checked the coolant and it does need more anti-freeze, it only goes down to about +5 degrees. Not a problem though here in N. California.

Any suggestions? Thanks as always.
__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)
Reply With Quote
  #2  
Old 05-29-2002, 12:45 PM
Registered User
 
Join Date: Dec 2001
Posts: 571
Did you use a dealer or OEM t-stat?
Reply With Quote
  #3  
Old 05-29-2002, 01:39 PM
haasman's Avatar
Registered User
 
Join Date: Jun 2001
Location: San Francisco, CA
Posts: 3,097
I used a dealer (MBZ) Tstat.
__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)
Reply With Quote
  #4  
Old 05-29-2002, 01:41 PM
Registered User
 
Join Date: Aug 1999
Location: Florida / N.H.
Posts: 8,777
Re: Befuddled ... engine temp ... after new Tstat

Quote:
Originally posted by haasman
I am Befuddled:

My '91 300E coolant temp has been running at or just below 80c after ten minutes and more of driving at ambient temp of 60-70f. So I replaced the Tstat thinking this was the problem.

The car still hardly shows anything above 80c. Now I am wondering is it the Tstat or possibly a bad sending unit?

Questions:

-How do I test the sending unit to the temp gauge?

Ohmeter at sending unit should read :
60C-110 ohm
80C-67 ohm
100C-38 ohm

-Is sticking a thermometer into the coolant reservoir a good test of the true engine coolant temperature?

Not really

Check that you have installed the right thermo.
Should be 87C for that car. That is start to open spec.




I checked the coolant and it does need more anti-freeze, it only goes down to about +5 degrees. Not a problem though here in N. California.

The least you should have is about 45/55 [af/h20].
A 50/50 mix will read -37C [ when hot]. -34F.

* The trivia question of the day is - When does C and F read the same ?
"Minus 40 degrees"

Any suggestions? Thanks as always.
Reply With Quote
  #5  
Old 05-29-2002, 02:27 PM
J.HIDALGO's Avatar
Registered User
 
Join Date: Jul 1999
Location: Jax, FL
Posts: 1,785
Somebody already mentioned this ...

on a different tread but, did you check the water pressure cap?
aka: coolant cap
__________________
J.H.
'86 300E

Last edited by J.HIDALGO; 05-29-2002 at 04:55 PM.
Reply With Quote
  #6  
Old 05-30-2002, 01:22 PM
haasman's Avatar
Registered User
 
Join Date: Jun 2001
Location: San Francisco, CA
Posts: 3,097
Thanks for the replies.

My guess is that the sending unit is bad. Am I correct in believing that the sending unit has two connectors on it. It is between the valve cover and the air cleaner?
__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)
Reply With Quote
  #7  
Old 05-30-2002, 01:38 PM
pmizell's Avatar
Benz Zealot
 
Join Date: Jun 2001
Location: Houston, Texas
Posts: 838
Haasman:

Yes, the coolant temp sensor is located on the head (two pole blue), second from the rear on your '91 300E. If you have a multimeter with a resistance function you can test it before replacing it. ($31)

~Paul

_________________
'91 300E, 212K miles
Reply With Quote
Reply

Bookmarks

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
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 07:10 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page