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-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 07-01-2012, 09:26 PM
DIY OCD
 
Join Date: Jan 2012
Location: Columbia, MO
Posts: 120
Running Hotter on HWY than City

83 300CD

Ambient temperatures in high 90s to low 100s last week or so. I've made two two-hundred mile round trips in the middle of the afternoon with the AC running, cruising between 70 and 80 mph. After replacing the thermostat (new one boiled and checked out prior to installation) and the temperature sender on the engine block, and of course filling and burping the cooling system appropriately (Zyrex g05 of course), I'm getting the following readings:

Between 70 and 75 mph, 100C
75-80 105C
80+ rising up to around 110C

The fan clutch seems to be working as there is no play, plus I don't think that's the problem because in town, in city driving even with the air conditioner on, the temp settles around 90 and never above 95C. It's just curious to me that its running hotter and hwy speeds than stop and go in town with the same ambient temperature readings. Seems like it's something other than t-stat or even radiator. Would the water pump be involved in a problem of this sort? Or perhaps a blockage somewhere?

__________________
1983 300CDT -- 177K
Reply With Quote
  #2  
Old 07-01-2012, 09:56 PM
funola's Avatar
Registered User
 
Join Date: May 2005
Location: NYC
Posts: 8,245
What temp is the stat? What temp did it open at when you did the boil test? Did you put the stat in facing the correct direction?
__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked
Reply With Quote
  #3  
Old 07-01-2012, 10:21 PM
DIY OCD
 
Join Date: Jan 2012
Location: Columbia, MO
Posts: 120
Stats a 90C at full open. Spring to block, so yes. Approximately 70/30 antifreeze to distilled water ratio.
__________________
1983 300CDT -- 177K
Reply With Quote
  #4  
Old 07-01-2012, 10:26 PM
Registered User
 
Join Date: Aug 2009
Location: MN
Posts: 1,253
radiator

You have found it's limits of heat transfer.

Either air is blocked from flowing through it (clogged fins with leafs, debris, bugs)

or

coolant is blocked from flowing through it (clogged tubes, in the old days - recore, now - replace)
__________________
Greg
2012 S350 BlueTEC 4Matic
2007 ML 320 CDI
2007 Leisure Travel Serenity
2006 Sprinter 432k
2005 E320 CDI
1998 SLK230 (teal)
1998 SLK230 (silver)
1996 E300D 99k, 30k on WVO
Previous:
1983 240D, on WVO
1982 300D, on WVO
1983 300CD, on WVO
1986 300SDL 237k, 25k on WVO (Deerslayer)
1991 350SDL 249k, 56k on WVO - Retired to a car spa in Phoenix
1983 380 SEC w/603 diesel, 8k on WVO
1996 E300D 351k, 177k on WVO
Reply With Quote
  #5  
Old 07-01-2012, 10:29 PM
DIY OCD
 
Join Date: Jan 2012
Location: Columbia, MO
Posts: 120
Greg,

I was thinking radiator. I examined the fins and they seem to be fine. Would just removing the radiator and taking it to a shop for a dip in the tank be sufficient, or should I spring for a new radiator? Also, how bad are these temperatures? Ive read on this forum that 100-110 is fine for the 617 because it's an iron block, but I've also read that thats too hot. Any thoughts on this?
__________________
1983 300CDT -- 177K
Reply With Quote
  #6  
Old 07-01-2012, 10:40 PM
Registered User
 
Join Date: Aug 2007
Posts: 972
Quote:
Originally Posted by npretnar View Post
Approximately 70/30 antifreeze to distilled water ratio.
You are not doing yourself any favors there. More isn't better when it comes to heat transfer.
Reply With Quote
  #7  
Old 07-01-2012, 10:52 PM
funola's Avatar
Registered User
 
Join Date: May 2005
Location: NYC
Posts: 8,245
yeah, change it to 50/50 for best compromise in cooling/ corrosion protection.
Have you checked the water pump belt tightness?
__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked
Reply With Quote
  #8  
Old 07-01-2012, 11:17 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,350
How's your transmission fluid level?
__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
Reply With Quote
  #9  
Old 07-02-2012, 01:38 AM
mach0415's Avatar
Diesel Weasel
 
Join Date: Mar 2010
Location: Lawndale, NC
Posts: 648
Quote:
Originally Posted by GregMN View Post
radiator

You have found it's limits of heat transfer.

Either air is blocked from flowing through it (clogged fins with leafs, debris, bugs)

or

coolant is blocked from flowing through it (clogged tubes, in the old days - recore, now - replace)
X2 on this. Remove it and have it checked by a REPUTABLE radiator shop. Make sure the tanks are not rotted. I was able to have mine retanked a few years ago. The core was fine. A partially plugged radiator will do exactly as you describe at hwy speeds. The engine is producing more heat than the radiator can exchange to the air going across the fins and flues. OR, just replace it
__________________
Thanks,
Mark in NC

"Spark plugs?...We don't need no stinking spark plugs!"
1985 300SD "Der Silberne Schlitten" 420,000 mi


Wish these were diesel:
2003 Ford Club Wagon 130,000 mi
Reply With Quote
  #10  
Old 07-02-2012, 02:32 AM
Registered User
 
Join Date: Nov 2007
Location: Carlsbad, CA
Posts: 520
x2 + Fan Clutch

The radiator has to be good to go as others are posting but I'll bet on a not so healthy fan clutch.

A sick verses dead fan clutch will seem like it is working however at sustained higher rpms i.e. highway driving it may only be spinning at a fraction of what it needs to be to yank enough air through the radiator to keep coolant cooler while the engine is generating higher temps.

In other words it may not be engaging up as needed. Instead slipping and pulling less air resulting in lower heat exchange rates.

Around town rpms will be all over the place and the fan clutch may be handling the lower rpms and pulling adequate air thus keeping temps down.
__________________

1986 300SDL 440,xxx
Reply With Quote
  #11  
Old 07-02-2012, 08:28 AM
Registered User
 
Join Date: Aug 2009
Location: MN
Posts: 1,253
You don't need any fan at freeway speeds. If the problem was around town, then I would look for lack of air flow. No problem around town means the t-stat is working and the fan is working.

A new radiator is $233 at Fastlane. Click on the "Buy Parts" link at the top of the page.
__________________
Greg
2012 S350 BlueTEC 4Matic
2007 ML 320 CDI
2007 Leisure Travel Serenity
2006 Sprinter 432k
2005 E320 CDI
1998 SLK230 (teal)
1998 SLK230 (silver)
1996 E300D 99k, 30k on WVO
Previous:
1983 240D, on WVO
1982 300D, on WVO
1983 300CD, on WVO
1986 300SDL 237k, 25k on WVO (Deerslayer)
1991 350SDL 249k, 56k on WVO - Retired to a car spa in Phoenix
1983 380 SEC w/603 diesel, 8k on WVO
1996 E300D 351k, 177k on WVO
Reply With Quote
  #12  
Old 07-02-2012, 08:41 AM
funola's Avatar
Registered User
 
Join Date: May 2005
Location: NYC
Posts: 8,245
Quote:
Originally Posted by npretnar View Post
Stats a 90C at full open. Spring to block, so yes. Approximately 70/30 antifreeze to distilled water ratio.
The temps on the gauge you are seeing with 100F ambient with AC on and doing 80 mph may be consistent with the 90C stat you have. Try a 80C stat, that should bring the temps down.
__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked
Reply With Quote
  #13  
Old 07-02-2012, 10:24 AM
DIY OCD
 
Join Date: Jan 2012
Location: Columbia, MO
Posts: 120
Quote:
Originally Posted by mach0415 View Post
Remove it and have it checked by a REPUTABLE radiator shop. Make sure the tanks are not rotted. I was able to have mine retanked a few years ago.
Mach,

What was the cost of this procedure? Does anyone think it's more worth it to try this route or just spring for a new radiator?
__________________
1983 300CDT -- 177K
Reply With Quote
  #14  
Old 07-02-2012, 10:45 AM
Registered User
 
Join Date: Aug 2007
Posts: 972
Quote:
Originally Posted by 86-300sdl View Post
A sick verses dead fan clutch will seem like it is working however at sustained higher rpms i.e. highway driving it may only be spinning at a fraction of what it needs to be to yank enough air through the radiator to keep coolant cooler while the engine is generating higher temps.
At 80 mph, you don't need a fan to "yank" air through the radiator.

The symptoms of a bad fan clutch are precisely the opposite of the ones described here.


Quote:
Originally Posted by npretnar View Post
Does anyone think it's more worth it to try this route or just spring for a new radiator?
Considering that a new Nissens radiator can be had for under $200, it doesn't make sense to attempt to salvage a (presumably) 30 year-old radiator. But it also doesn't make sense to replace a possibly good radiator without additional investigation.

Last edited by qwerty; 07-02-2012 at 10:56 AM.
Reply With Quote
  #15  
Old 07-02-2012, 11:04 AM
Benzkid_300D's Avatar
Next gen. M-B enthusiast
 
Join Date: Jun 2012
Location: Columbia,SC
Posts: 35
My best guess is a partially clogged radiator... you CAN have it re-tanked and flushed for ~$60... but since the radiator is a pretty important part of the engine, I'd just spring for a new one

__________________


1978 w123 300D astral silver "Benzie"
1980 w123 300CD orient red "Benzie 2"
1994 w124 E500 "Big Black"
1998 w163 ML320 "Ole' Faithfull"
1969 Datsun 2000 roadster
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 07:21 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page