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

LinkBack Thread Tools Display Modes
Old 11-14-2000, 04:44 PM
Posts: n/a
I have noticed that the coolant level in the radiator of my 280E (W123) always drops an inch or so below the inverted 'T' guide, no matter how often I top it up.

Once it's dropped down a little, it stays there. And there's no leak, I've checked thoroughly.

The only thing I can think of is that it might be something to do with the radiator cap, which is marked '90', although there is an original M-B sticker on the fan shroud that says a 100 cap must be used.

I'm thinking the previous owner may have substituted a 100 cap for a 90 to prevent overheating, although this has never happened to me. Could this be the cause of the drop?

Any thoughts, gentlemen?

Chris Hunter

1977 W123 280E auto
Cayenne Pepper orange
Reply With Quote
Old 11-14-2000, 06:00 PM
Join Date: Mar 1999
Location: Tucker, Ga USA
Posts: 12,153
Coolant pressure is forcing EXCESS coolant from the system. It's going out the overflow hose whenever the engine is hot enough to push cap open. The latest cap for W123 is 120 & that is equal to 17psi.
Reply With Quote
Old 11-14-2000, 08:58 PM
Registered User
Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
The higher the number on the cap and THE MORE PROTECTION you will have. When the coolant system pressurizes, the coolant that is under pressure is less likely to boil.

Use the 120 cap. (1.2bar)

Donnie Drummonds
Reply With Quote
Old 11-14-2000, 10:41 PM
Posts: n/a
Thanks for the advice. I've just been down to my local dealer and bought a 120 cap. They looked at the 90 cap and proclaimed it non-original.

Now I just have to hope that the hoses on my car hold out at 1.2 bar, as opposed to 0.9!

Incidentally, I had the cylinder head gasket replaced on the car recently, and when the mechanic filled up the cooling system, he only put a little bit of anti-freeze in ... the reason being, "it is better to let the new gasket seal before full-strength anti-freeze is added." Mmmm. I'm not sure about that one, I might drain half the coolant and replace it with Mobil One anti-freeze.

Chris Hunter

1977 W123 280E auto
Cayenne Pepper orange
289,000km and goin' strong ... touch Zebrano.
Reply With Quote
Old 11-15-2000, 03:16 AM
Oliverp's Avatar
Registered User
Join Date: Aug 2000
Location: Toronto, Canada
Posts: 451
I have this problem in my 1989 300se, which cap should I be using?

Thanks very much guys!!!

Oliver Plante
1989 300SE 134k
1993 500SE 98K
Reply With Quote
Old 11-15-2000, 07:09 AM
Posts: n/a

I would recommend that you flush the coolant system as best you can, followed by a fill of 50% antifreeze.

I think the technicians reluctance to put in antifreeze must be based on some old wives tale.

Good luck,

Larry Bible
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles
Reply With Quote
Old 11-15-2000, 05:58 PM
Join Date: Mar 1999
Location: Tucker, Ga USA
Posts: 12,153
Most all cars after 1988 should be using a 140 cap (1.4=21psi). The newest cars use a screw on cap that can vary pressure up to 2bar.
Reply With Quote
Old 11-16-2000, 08:14 AM
Join Date: Sep 2000
Location: Sugarland, TX
Posts: 285
I think most dealers only stock the 140, but I used the 120 on my 91-300E and 95-S320.

Reply With Quote


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

Similar Threads
Thread Thread Starter Forum Replies Last Post
Coolant RED vs. GREEN CJ Tech Help 79 05-23-2009 07:07 PM
W124 Coolant level sensor plug drbrandini Tech Help 7 07-19-2003 02:44 PM
1988 190E coolant level sensor mertztr Tech Help 2 02-27-2002 12:32 AM
Coolant system over pressure? ndormor Tech Help 3 04-27-2001 03:44 PM
Mysterious Drop in coolant level carge Tech Help 1 11-19-2000 03:31 PM

All times are GMT -4. The time now is 04:22 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page