when is hot too hot? - Mercedes-Benz Forum
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 14 (permalink) Old 07-26-2019, 07:20 PM Thread Starter
BenzWorld Member
 
Date registered: Apr 2006
Vehicle: 1992 190E sportline, 1993 300ce, 1993 300ce sportline, 1992 300sl
Posts: 82
Mentioned: 0 Post(s)
Quoted: 10 Post(s)
(Thread Starter)
when is hot too hot?

Since it is summer (as always) in south Florida, 90+ temp and high humidity, my 1992 300sl seems to be running way too warm. It reads 100 - 105 on the temp indicator almost all the time. That is in traffic, on the highway at 70+ steady state, and just cruising around. This is with the ac on, somewhat lower when it is off.

So far I have replaced the thermostat with an 80 degree one down from 87 degree, new coolant, new fan clutch, no leaks or coolant use. Condenser and radiator are clean and no external blockage. Using my IR thermometer the temp is @ 205-215 at thermostat housing, 200 at top radiator hose and I am seeing @ 10 degree temp drop from bottom hose to top hose (should I see more temp drop than this?))

Compression and vacuum is strong and it runs well after having the EHA tuned properly (thanks Pierre). He says it should be running much cooler - but most have said that these temps are normal and not to worry. Both AC fans run as necessary and it does not seem to rise over @110, but there has to be a reason for it to run so hot even when it is 80 degrees outside in early morning drive.

Is there any way to really check the radiator to see if it is clogged or obstructed or just change it out and hope for the best? It looks to be very clean and not sure if it has been change since the car was new. Is this the best option to replace the radiator as all else is new or working properly? What other things should I check?
sportlineguy is online now  
Sponsored Links
Advertisement
 
post #2 of 14 (permalink) Old 07-28-2019, 01:48 AM
BenzWorld Senior Member
 
Photodude's Avatar
 
Date registered: Apr 2013
Vehicle: 2004 E320, 2000 SL500
Location: Santa Monica, California
Posts: 450
Mentioned: 0 Post(s)
Quoted: 171 Post(s)
Coolant temperatures persistently in 100-105 C range is not normal… I just drove in 107 F ambient temp, in heavy traffic, A/C on… and temp gauge never went over 100 C. Original radiator on 19-year old car and I'm using standard 87 deg thermostat.

I would never suggest replacing Radiator as a diagnostic step, as long as there are no visible leaks and it performs well.

But, given your symptoms and what you have replaced already… radiator would be my primary suspect. The flow gets restricted over time and eventually radiator can't cope with extreme conditions. If this is original radiator, 27 years… I would replace it.
Photodude is offline  
post #3 of 14 (permalink) Old 07-28-2019, 09:38 AM
Outstanding Contributor
 
Date registered: Jan 2004
Vehicle: '03 SL500, '03 SL55, '97 SL320, (2) '91 300SL, (2) '91 500SL, '00 S500 -- all for sale
Location: Atlanta, USA
Posts: 4,061
Mentioned: 14 Post(s)
Quoted: 600 Post(s)
Quote:
Originally Posted by sportlineguy View Post
...I am seeing @ 10 degree temp drop from bottom hose to top hose (should I see more temp drop than this?))
I would guess that the temperature drop ought to be more than that. If you search the 'Net you should have an answer.

Another guess is that your car is running a bit hot because the radiator is less efficient now than when new due to minor internal and/or external blockage(s).

Whatever its cause, obviously this condition is disconcerting to you, but I do not believe it poses a threat to your engine. Maybe it would be prudent to look out for a bargain on a replacement radiator and do nothing in the meantime.
bobterry99 is offline  
Sponsored Links
Advertisement
 
post #4 of 14 (permalink) Old 07-28-2019, 02:22 PM
BenzWorld Extremist
 
Date registered: Jun 2007
Vehicle: 1995 SL 500 2017 AMG GLC 43
Location: SouthWest Coast of Florida
Posts: 926
Mentioned: 0 Post(s)
Quoted: 66 Post(s)
Quote:
Originally Posted by sportlineguy View Post
Since it is summer (as always) in south Florida, 90+ temp and high humidity, my 1992 300sl seems to be running way too warm. It reads 100 - 105 on the temp indicator almost all the time. That is in traffic, on the highway at 70+ steady state, and just cruising around. This is with the ac on, somewhat lower when it is off.

So far I have replaced the thermostat with an 80 degree one down from 87 degree, new coolant, new fan clutch, no leaks or coolant use. Condenser and radiator are clean and no external blockage. Using my IR thermometer the temp is @ 205-215 at thermostat housing, 200 at top radiator hose and I am seeing @ 10 degree temp drop from bottom hose to top hose (should I see more temp drop than this?))

Compression and vacuum is strong and it runs well after having the EHA tuned properly (thanks Pierre). He says it should be running much cooler - but most have said that these temps are normal and not to worry. Both AC fans run as necessary and it does not seem to rise over @110, but there has to be a reason for it to run so hot even when it is 80 degrees outside in early morning drive.

Is there any way to really check the radiator to see if it is clogged or obstructed or just change it out and hope for the best? It looks to be very clean and not sure if it has been change since the car was new. Is this the best option to replace the radiator as all else is new or working properly? What other things should I check?
I live on the South West Coast of Florida. Had the same issue as you. Changed all the usual suspects. Always have the anti-freeze changed every 2 years with MB recommended additive. Still ran 95-100. Got tired of it. Bought and changed out radiator with the MB branded replacement. Now stays at 80 no matter what. Good luck.
Lee Wireless is offline  
post #5 of 14 (permalink) Old 07-28-2019, 10:50 PM
BenzWorld Member
 
Date registered: Sep 2013
Vehicle: 2002 SL600 Silver Arrow, 1966 300SE Cabriolet, 2009 Smart Cabriolet
Location: Phoenix AZ
Posts: 255
Mentioned: 3 Post(s)
Quoted: 66 Post(s)
I always get a kick out of Florida guys saying how hot it is. I know with the humidity you have it can be miserable but 90F really isn't all that hot. Here in the Southwest we'll be 110 to 118 for days on end and sometimes for weeks.
My SL600 handles these temps just fine A/C on, stop and go or freeway it stays at 95 to 100 unless I can find a stretch of road where I can maintain 85mph or higher then the temp will drop down to 87 to 90.
DORIAN likes this.
Silberpfeil is offline  
post #6 of 14 (permalink) Old 07-29-2019, 12:26 PM
BenzWorld Senior Member
 
alpac's Avatar
 
Date registered: Aug 2013
Vehicle: 1992 500SL, 1999 CLK 320 conv, 2015 ML350, (2011 ML550 gone, C320 wagon gone, 2005 C240 gone)
Location: Durham, NC
Posts: 570
Mentioned: 1 Post(s)
Quoted: 92 Post(s)
Quote:
Originally Posted by Photodude View Post
Coolant temperatures persistently in 100-105 C range is not normal…
I agree that this is not normal. We had temps within the 100-105 over here recently and my old 1992 500sl never went reached 90 even stuck in traffic.

Quote:
Originally Posted by Photodude View Post
I would never suggest replacing Radiator as a diagnostic step, as long as there are no visible leaks and it performs well.
But, given your symptoms and what you have replaced already… radiator would be my primary suspect. The flow gets restricted over time and eventually radiator can't cope with extreme conditions. If this is original radiator, 27 years… I would replace it.
Again I agree that replacing the radiator should be your next move. I had a very similar problem with my SL few years ago. It was always running hot (within 100 to 110) during hot summer days. I did the garden hose test through the radiator and thought the flow was really good so I initially ruled out an issue with the radiator. I also verified that there was no head gasket issue which there was not. So I replaced the thermostat and then the fan clutch which none of this fixed the over heating issue. I then decided to replace the radiator which was the last thing on my list to replace and no more over heating issue after that. Since then my car always stays within the 85 to 90 marks in hot summer day even when stuck in traffic.
alpac is offline  
post #7 of 14 (permalink) Old 07-30-2019, 02:05 PM Thread Starter
BenzWorld Member
 
Date registered: Apr 2006
Vehicle: 1992 190E sportline, 1993 300ce, 1993 300ce sportline, 1992 300sl
Posts: 82
Mentioned: 0 Post(s)
Quoted: 10 Post(s)
(Thread Starter)
Im going to check the radiator with a FLIR camera - if not properly functional I will replace and all hoses and report back the results.
sportlineguy is online now  
post #8 of 14 (permalink) Old 07-30-2019, 08:55 PM
Outstanding Contributor
 
mahunt's Avatar
 
Date registered: Feb 2008
Vehicle: 1997 SL600 Brilliant Silver Sport with grey/dark metal interior, 234K miles
Location: Lutz, FL
Posts: 1,969
Mentioned: 9 Post(s)
Quoted: 397 Post(s)
I live in Tampa and the gauge NEVER gets above 90 with or without the AC in summer (although I can't think of a reason to run the car without AC in summer).

It has never been an issue when I first got the car or now when everything dealing with the cooling system has been changed for new. Even with one flaky AUX fan, the temperature has never gotten above 90.
mahunt is online now  
post #9 of 14 (permalink) Old 08-07-2019, 07:42 AM
Lifetime Premium Member
 
rp930's Avatar
 
Date registered: May 2010
Vehicle: 1983 300sd, 1991 350sdl,1991 300sl(sold), 1996 sl320
Location: huntsville, al
Posts: 55
Mentioned: 0 Post(s)
Quoted: 13 Post(s)
Lifetime Premium Member
Pull T-stat, check opening in pan of water on stovetop. Even new ones can be bad. I can confirm.
rp930 is offline  
post #10 of 14 (permalink) Old 08-07-2019, 10:26 AM
Lifetime Premium Member
 
Benica's Avatar
 
Date registered: Sep 2010
Vehicle: 2002 Black SL500, 2000 Azure blue SL500, 2005 Silver (A209) CLK500
Location: Between Omaha and Honolulu.
Posts: 892
Mentioned: 4 Post(s)
Quoted: 196 Post(s)
Lifetime Premium Member
Being facetious...but....why A/C....when...you....have....a.... convertible? Why buy a convertible....
High 90's here....humidity? Sweat like a sauna! Top down and cruise along!

We are here on earth to do good unto others.
What the others are here for, I have no idea.
Benica is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > Mercedes-Benz Roadster Forums > R129 SL-Class

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may 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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 

Title goes here

close
video goes here
description goes here. Read Full Story
For the best viewing experience please update your browser to Google Chrome