Guenter;
Yes, there is an "O-ring". This overflow nipple snaps into the body of the radiator and can be purchased for a couple of dollars at any MB dealer. As long as the body of the radiator where the nipple attaches is not damaged, you can replace yours with a new overflow nipple.

I still think that a significant cause of broken water necks is excessive engine movement from old/broken motor mounts. On my 107, there is very little "slack" on this hose between the water pump outlet and the radiator. I tried to keep mine "backed off" to give it as much room as possible (also changed the motor mounts and have the copper pipe reinforcement). If you look through posts there are several instances of necks breaking while going over RR tracks, autocrossing, potholes, etc).

__________________
86 560SL
With homebrew first gear start!
85 380SL
Daily Driver Project

http://juliepalooza.8m.com/sl/mercedes.htm

I agree with that Strife
I also think that aftermarket radiator hoses are thicker than the oem
I bought one lately and it was a 1/2 " shoter and it was thicker material
I never put it on
This would put lots of strain on the radiator fitting

__________________
[B]Mike Y.
00 sl500 sport
88 560 sl (sold)

Aftermarket will vary. A friend replaced the older, stiffer (age?) MB hose on his 300E 2.6 with a Goodyear that was much more flexible than the original.

Many thanks Oliver ... I take that I need to spread the 'latches' on either side of the elbow fitting which will then allow the elbow to slide out for replacement of the o-ring ..... that's a bit of luck

cheers and thanks again

ps. I did have a chance to compare a new radiator hose with my old one (was going to replace all the hoses) and did notice it a lot 'stiffer' but simply thought that my old one was simply old and worn. However, was to cheap to replace it .... maybe I lucked out wrt radiator by leaving it alone

Guenter;
I noticed a slight weep around mine two years ago so I bought a spare. Have not noticed it leaking again so I have never actually done the replacement. Good luck and let us know how it goes. The plastic on these radiators becomes brittle with age and as you have probably read, the neck for the top hose often breaks off. My 1990 300E has 98K on it but has never been used as a daily driver so it has had far fewer heat-up cycles and does not sit outside when not in use. Radiator replacement is on my list but I believe I will wait and do all the things on the top/front of the engine that often need servicing sometime on or after 100K - water pump, short hose at thermostat housing, top timing chain cover leak, etc. I keep a careful check on the radiator but there are many stories of sudden, catastrophic failure around or after 10 yrs/100K that I am concerned.

Oliver,
Replaced the elbow on top of the rad this morning .... MB manual suggests to insert 9 mm round wrench from inside the rad to squeeze the elbow end so that it lifts out ....etc... to do this you need to drain some of the cooolant so it doesn't spill when you remove the hose .... NO NEED for any of this! Turns out the elbow lifts out very easily by just gently prying with a screwdriver (use the metal on rad as a leverage point). Pop the new elbow in with a little 'gentle' tap. I've got a '89 300e and the elbow mounting may differ on earlier cars so beware.

cheers

Guenter;
Good news! Don't know whether to replace my original tube now, since it is no longer leaking, or just hold onto it. Sometimes it is best not to disturb something that seems to be OK.

Activate your auxiliary fans manually, as to prevent overheating.

Does anyone know how to follow the brown and gray wire that activates the full speed auxiliary fan relay?

In the relay box, behind the fuse box, there is another box where the majority of relays are placed.

There are two plated relays that control the auxiliary fan (2 in some models) to protect the engine from overheating.

One of them activates the aux. fan at low speed (when engine reaches 105 degrees Centigrades) and the other activates the aux. fan at full speed, when the engine reaches 115 degress centigrades. (The water boils and evaporates at 100 degress centigrades).

Recently I had to climb some mountains with very hot weather (37 degrees centigrades) and the cooling system was working 15 degrees over normal maximum temp here.

To prevent engine from damages, I am activating the fan manually, as soon as I begin climbing, because the automatic activation begins too late.

However, I can activate only the low speed. There is a brown and gray wire that activates the full speed relay (I see it in the electric circuit and in the relay), that I cannot find, to intercept and manually operate.

Does anyone know where in the car does that wire goes from the relay box? Where does it travel below the engine hood?

I would thank a lot help on this.

At the same time, it is an idea for prevent the engine from overheating in very hot days.

Of course, this measure do not replace having a very good radiator, a working water pump, a working thermostat, and so on. It is just a complement.

Thank you in advance.

Old Beaver