Noticed a coolant leak again out of the short rubber hose (not sure the name) just below the water pump - the rubber tube is about 3-4 inches long and has two metal clamps around it. I've tightened it before and it stopped leaking for a while - it's back again. Do these clamps get tired, or is this a sign of some increase to internal pressure?!

James

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

If something is "tired," my money is on the the piece of rubber that has been doing its job for a quarter of a century.

As hoses go, the bypass hose is, by far, the toughest hose in the cooling system. So, if excess pressure was an issue, that would be the most unlikely place for it to manifest itself.

How do you go about replacing it - it almost looks like you'd have to disassemble the water pump to get this hose out? This may also be a good time do do a flush of the ugly green fluid.

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

Squeeze it when hot and cold to get an idea of hose strength.
You may just need to replace the hose clamps.
When I had my W126 water pump replaced, I had the bypass hose, a short 2 inch thing, replaced. It was not leaking.
The original old one was still fairly good after 20 years !

I don't think you need to remove the pump to replace the hose. Just go at it.
Soften the hose in boiling water and put soapy water on the receiving ends and wrestle it !!
good luck.

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD

Here is a recent thread on the same subject. There is an ebay seller that sells the short hose and a gasket and instructions at $17 no extra shipping.
Also on ebay silicone hose.
Coolant leak 240d

__________________
84 300D, 82 Volvo 244Gl Diesel

Which one is the thermostat housing - must be the aluminum housing that bolts onto the head?!

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

Removing the EGR valve is absolutely not necessary.

Are you suggesting that the bypass hose can be replaced without removing either the water pump housing or the thermostat housing?

I probably should not speculate as to what might be necessary for you. But I can say with 100% certainty that it is not necessary for me to remove the EGR valve when removing the thermostat housing. But my tool box might be better equipped.

What did he mean when he said "soften the hose in boiling water" and "wrestle it?"

Same here.

some people are kind of suggesting replacing clamps and maybe getting a little more life out of this hose but my suggestion is to just flat out replace it ASAP. this is the hose that will just blow out in a parking lot and ruin your day, ask me how i know.

it might seem like a pain to remove but it's not hard at all and is more than likely very necessary as these hoses are 20+ years old. better remove it under controlled circumstances than on the side of the road in the cold. and, as suggested, you can make it part of the bigger picture and replace some gaskets, your old thermostat, and purge that green coolant while you're at it.

i don't know if you have to remove the EGR or not but mine is gone and it makes working around that area a whole lot easier.

__________________
1985 300D - 1984 Euro 280E AMG Clone (SOLD) - 1978 280CE (SOLD) - 1983 300D (SOLD) - 1981 300D (SOLD)

Since the coolant flush procedure is pretty complicated on my 617 I may consider having an MB shop do the flushing. If I let them do the flush, should I replace the bypass hose BEFORE or AFTER they flush my coolant?

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

Do you want to spill new coolant or old coolant?

'nuf said...

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K