124 Radiator top hose - PeachParts Mercedes-Benz Forum

chazola · #1 04-07-2004, 02:38 PM

i noticed some oil or atf has got on my radiator top hose (thermostat to radiator) in places and stained it causing a small amount of tiny cracks in the rubber. Seeing this is a $10 part, should I go ahead and replace it? Is it a straightforward job? (looks like just unding the clamps on each end)
While I'm at it, i noticed a company makes a metal re-inforcement for the top radiator neck where the hose clamps on. My radiator is about 6 years old and I'm a bit concerned about the horror stories of these breaking off. Any views on this?

cheers.

G-Benz · #2 04-07-2004, 03:22 PM

Radiator hose replacement is easy...simple on/off clamps and hose.

If your radiator has been replaced, it probably already has the reinforcement...most fail at around 100K (as did mine 4 years ago)...

MB STARS · #3 04-07-2004, 03:25 PM

You should replace your uper radiator hose,also your 1991 300E should have metal re-inforcement radiator insatlled. just remove uper hose look inside you should see metal re-inforcement ring in uper neck.

chazola · #4 04-07-2004, 06:08 PM

this might be a stupid question, but I take it I don't need to drain the system just to replace this top hose?

MB STARS · #5 04-07-2004, 06:17 PM

Yes you can replace uper radiator hose without drain the coolant first..........BTW summer is comming soon why you just put in a new thermostat in (play safe).

Mike Murrell · #6 04-07-2004, 06:35 PM

You may or may not have a metal insert in the neck. My '91 W126 car didn't, nor did the Behr OEM I replaced the original with. I searched high & low for one, both locally and on the WEB.

If you ever need one, good luck finding it.

chazola · #7 04-07-2004, 06:54 PM

**************.com has them in the 124 upgrades section, $19.95 for the 'kit'. Question is, do I open it up to see if I have it or not, then wait to replace the hose aswell, or just assume I don't and order it anyway?!

Ferdman · #8 04-08-2004, 08:43 AM

Chazola, you can replace the upper radiator hose without draining the coolant, but expect to lose some coolant in the process. If your thermostat housing is black plastic I would replace it with a metal housing while you're installing a new hose. Add sufficient 50/50 mix of MB coolant and water to replace the lost coolant.

Although I haven't seen one of the 124 upgrade kits that you mentioned I doubt that a kit insert will make the upper hose connection as durable as a radiator manufactured with the metal insert. The upper hose connection failed (1 1/2" of the hose connection broke off due to complete circumferential crack) on our 1991 300CE at 118,000 miles and the hose blew off. Fortunately it happened just as my eife was parking the car and no overheating resulted. I repaired it temporarily by removing the broken piece and securing the radiator hose to the remaining stub ... adequate for the 25 mile trip home, but I left the car in the garage until I installed a new Behr radiator.

#9 04-08-2004, 11:13 AM

I just replaced the upper and lower radiator hoses on my '91 300E. I also changed the thermostat.

I recommend that you premix a couple of gallons of 50/50 M-B antifreeze and distilled water. Then get yourself a piece of hose about 30" long. The ideal thing is to cut the metal ends off an old washing machine drain hose.

Open up the access panel to the front tow hook and you will see a drain petcock for the radiator. There is a nipple on the radiator that faces towards the wheel well. If you then look on the other side of the wheel well, you will find a rubber plug that will give you access to the nipple.

Remove the rubber plug and insert the hose from the outside, through the hole and onto the nipple. Place the other end of the hose in a shallow drain pan.

Remove the cap on the coolant tank to permit the coolant to drain better.

Now reach in and open the petcock with your fingers or use a long screw driver. (NOTE, When you close the petcock, do it finger tight only).

Coolant will drain into the pan.

After the coolant has stopped draining, remove the three bolts holding the cover over the thermostat and then loosen the clamp on the upper hose at the radiator end. Carefully twist the hose to get it loose from the radiator and take it off. Remove the other end of the hose from the cover for the thermostat.

Now loosen the clamps on the lower hose and work it loose.

Replace the thermostat with a new one and orient it the same way as the one you took out.

Install a new lower hose. Orient the clamps according to the marks on the clamp and the hose (if they are there). Tighten the clamps.

Put the upper hose on the radiator and slide the other end over the outlet on the cap for the thermostat.

Bolt the thermostat cover but don't over tighten. If the cover is not aluminum, get the new aluminum version before changing the hoses.

Orient the upper hose and clamps and tighten the clamps.

Remove the drain hose from the radiator.

Put the rubber plug back in the wheel well wall.

Tighten the petcock finger tight. If you use a screwdriver, don't over tighten.

Slowly pour the premixed coolant in the coolant tank. Allow it to work it's way back into the system.

At some point, you will not be able to put more coolant into the tank.

Start the car and let the coolant circulate.

After the thermostat opens, you should be able to add more coolant.

Turn off the engine.

Replace the cap on the coolant tank.

The next morning, top up if necessary.

I should have said that you should run the car with full heat on and the controls set to both upper and lower so that coolant is circulated through the heater core and the defroster. Do this before changing the coolant.

After you have finished, make sure you run the engine the same way to get full coolant circulation.

chazola · #10 04-08-2004, 05:36 PM

thanks for the advice- I actually have the metal thermostat cover and it was replaced with the hoses at 190k. somehow the oil or atf got on the hose after that.

I got a new hose from the dealer today, it felt a bit lumpy though so I blew on it...

G-Benz · #11 04-09-2004, 01:53 PM

Make sure you install the hose using new ferrets!

chazola · #12 04-09-2004, 02:14 PM

will do!

typical, as I was installing the new top hose I noticed the bottom hose has a nick in it, I'm guessing done by the not-so-great shop that installed my new belt/tensioner when I first got the car back in November. These hoses are about 3mm thick and it's about 1mm deep at the worst spot, like a flat-bladed screwdriver has hit it. Do you think this could create a weak-spot? Otherwise the hose is in good condition.

Maybe a glue/filler repair? as I'd rather not have to change the hose considering the mess the top one made! and it's more of a pain to get to...

oh btw: I was pleased to find I do have the metal re-inforcement in the radiator top connection

G-Benz · #13 04-09-2004, 03:37 PM

Check it for any signs of weeping or coolant residue near the damaged area. If there is, then replace it.

These hoses are otherwise pretty durable...

chazola · #14 04-09-2004, 04:01 PM

no weeping or coolant residue thankfully, I'll keep an eye on it though.