E280 OM642 Coolant Hose Leaking at Thermostat Housing - Advice Please

Page may contain affiliate links. Please see terms for details.

johnsco

MB Enthusiast
SUPPORTER
Joined
Nov 22, 2008
Messages
2,656
Location
Leeds, West Yorkshire
Car
E280CDI SPORTS ESTATE and C200 KOMPRESSOR SE Coupe Auto (1.8 lit petrol)
This may seem like a simple question - I've replaced many coolant hoses over many years.
Usually they have fitted over an outlet and been secured by a jubilee clip or a hose clip
I've never seen one like this.
The hose disappears inside the housing.
There is a clip thingy on the outside of the housing.
I'm reluctant to go there until I know how it works.
Is the hose likely to be shot ?
How does it actually seal.
The rate of coolant loss is small
There is a small pool of coolant on the plastic housing underneath the joint.
It'll get worse !
Advice please.

P3080193.jpgP3080194.jpg
 
The hose teminates in a metal collar, with a slot in it for the clip to locate in. There's a rubber seal inside the thermostat housing (or it may be on the collar - I can't recall which) to make a seal between the thermostat housing and the collar.
 
Thanks E55BOF.
I can see the metal collar.
Do these tend to fail in one of these ways:
- - The seal between the housing and the metal collar - probably an 'O' ring ? - in which case a new pipe is not required
- - The bonding between the pipe and the metal collar ? - in which case a new pipe may be required
I haven't looked at the other end of the pipe ... although I can guess it is probably terminated the same way.
Thanks for your information, so far.
J.
 
No idea how they tend to fail, I'm, afraid; I've never had one go. I'd guess it would be the seal, though. I'd try replacing the seal, and see if that cures it; if not, then the pipe.

Top tip: if you siphon the coolant out of the header tank, and the front of the car is higher than the rear (slope, ramps, axle stands), you may find you lose very little if any coolant when you separate the hose from the thermostat housing. This worked on my OM642 in the CLS; I did not lose any at all.
 
Top tip: if you siphon the coolant out of the header tank, and the front of the car is higher than the rear (slope, ramps, axle stands), you may find you lose very little if any coolant when you separate the hose from the thermostat housing. This worked on my OM642 in the CLS; I did not lose any at all.
I second that. I didn't even have the front of the car raised and, with the header tank empty, the thermostat housing was above the coolant level.
 
Thanks E55BOF and FiveAlive.
That's a great help.
I'll get the seal and hope for the best.
I recently changed the stat on the W203 C200 Kompressor - I used the same trick - Draining the expansion tank meant that I could remove the stat housing without losing a drop of coolant.
I'll let you know how it goes.
 
So I went down to MB of Leeds.
My God - It's a bit posh for me in there.
I presented the guy on the parts counter with the part # (A 003 997 17 89) I'd got from Mercedes Parts Catalogue and asked him to confirm.
That's correct he said and came back with a completely different part # (A 026 997 68 45)
OK - Same Part ... 'O' ring with ID 36.3mm and section 3.6mm.
I said to him - You'd better give me the part # for the hose - just in case.
He wrote down: 211 501 54 82, which is clearly wrong, as that's the bottom hose.
He also said that it was not in stock and would have to come from the Fatherland.
The correct part # for the top hose from the rad to the stat housing is A 211 501 53 82.

Fortunately the job was a dream.
With the tank emptied the loss of coolant was negligible.
The clip came off easily with a screwdriver blade .
The pipe pulled straight out and the 'O' ring was split.
Cleaned up the pipe-end and the housing.
The new 'O' ring with a smear of silicon grease went straight into the groove on the end of the pipe.
The pipe went easily into the stat housing ..... Almost TOO-easily !!
On went the clip.
Refill coolant .
Run engine - Check for leaks - All OK.
Simples !



P3100205.jpg
 
Quite often we have to replace the pipe too as they corrode.
 
Quite often we have to replace the pipe too as they corrode.
There was just a trace of corrosion on the metal pipe end.
A good rub with scotch-brite removed it.
 

Users who are viewing this thread

Back
Top Bottom