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2000 ML 320
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27 Posts
Discussion Starter #1
There is a 1/4" hose coming from the drivers side of the coolant expansion tank that goes to a small nipple connection on the drivers side top of the radiator. For some reason, the nipple cracked and then broke off and i lost all the coolant. I have tried to JBweld the nipple back on and it worked momentarilly however it began to leak again.
THis seems to be an overflow return line although I cant find any diagram for it.
I clamped the line and drove it for quite a while yesterday with no ill effects.

Can anyone verify that this is a non essential line? My next step is to determine if I can find a plumbing fitting, threaded on one end, with a nipple on the other to JBweld into place as a permanent replacement, there is no way I am going to get a new radiator for this.

Any thoughts would be great.
Thanks,
Chris
2000 ML320
 

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Outstanding Contributor - Always Remembered, RIP
Zotye Auto 1.5T T600 2016
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52,804 Posts
chlubb said:
There is a 1/4" hose coming from the drivers side of the coolant expansion tank that goes to a small nipple connection on the drivers side top of the radiator. For some reason, the nipple cracked and then broke off and i lost all the coolant. I have tried to JBweld the nipple back on and it worked momentarilly however it began to leak again.
THis seems to be an overflow return line although I cant find any diagram for it.
I clamped the line and drove it for quite a while yesterday with no ill effects.

Can anyone verify that this is a non essential line? My next step is to determine if I can find a plumbing fitting, threaded on one end, with a nipple on the other to JBweld into place as a permanent replacement, there is no way I am going to get a new radiator for this.

Any thoughts would be great.
Thanks,
Chris
2000 ML320
Sorry to tell you this, but it is an essential relief line and if you close it off you will cause excessive pressure in the cooling system.
 

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Outstanding Contributor - Always Remembered, RIP
Zotye Auto 1.5T T600 2016
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52,804 Posts
chlubb said:
thanks, looks like i am off to make a new connection.
Good idea:thumbsup:
 

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2000 ML 320
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27 Posts
Discussion Starter #5
well, this is going to be an interesting fix, no one seems to have a 1/8" threaded body with a tube or flange on the other end to connect a 1/4" hose. hopefully jb weld will hold and be most of the fix.
thanks,
 

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ML430
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2,662 Posts
Which line are you talking about?



If it is the same one as that, it is the return hose for the power steering.
 

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2000 ML 320
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27 Posts
Discussion Starter #7
no, thats at the bottom of the radiator.
same side, but at the very top of the radiator, it runs on the drivers side of the engine and is held into place by 2 c clips that are attached to the side of the fuse box and back up to the coolant tank.
 

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2004 ML350
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43 Posts
Waterweld instead of JB Weld

chlubb said:
There is a 1/4" hose coming from the drivers side of the coolant expansion tank that goes to a small nipple connection on the drivers side top of the radiator. For some reason, the nipple cracked and then broke off and i lost all the coolant. I have tried to JBweld the nipple back on and it worked momentarilly however it began to leak again.
THis seems to be an overflow return line although I cant find any diagram for it.
I clamped the line and drove it for quite a while yesterday with no ill effects.

Can anyone verify that this is a non essential line? My next step is to determine if I can find a plumbing fitting, threaded on one end, with a nipple on the other to JBweld into place as a permanent replacement, there is no way I am going to get a new radiator for this.

Any thoughts would be great.
Thanks,
Chris
2000 ML320
If you can find it, try Waterweld also from JB. It cures in the presence of moisture and is a 2 part putty. It sticks to everything and I have used it to patch a cracked gunite pool undeerwater w/o draining the pool. It stopped a 2" per day leak ans savd my bacon till next sprink. It has a useable working time of about 2 minutes so be ready to go. It might be better than JB because JB can run a little when you apply it. Make sure the area you apply anything to is cleaned of any antifreeze residue. EG can act like a lube and may prevent the expoxy from adhearing. Try cleaning the area with denatured alcohol first.

Good Luck.

Lyle
 

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2005 ML500SE
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235 Posts
chlubb said:
There is a 1/4" hose coming from the drivers side of the coolant expansion tank that goes to a small nipple connection on the drivers side top of the radiator. For some reason, the nipple cracked and then broke off and i lost all the coolant. I have tried to JBweld the nipple back on and it worked momentarilly however it began to leak again.
THis seems to be an overflow return line although I cant find any diagram for it.
I clamped the line and drove it for quite a while yesterday with no ill effects.

Can anyone verify that this is a non essential line? My next step is to determine if I can find a plumbing fitting, threaded on one end, with a nipple on the other to JBweld into place as a permanent replacement, there is no way I am going to get a new radiator for this.

Any thoughts would be great.
Thanks,
Chris
2000 ML320
That nipple is part of what is called a "closed system". The way it works is when the coolant is warm and expands it goes into the coolant tank. When the coolant cools back down to ambient temp the negative pressure draws coolant back to the radiator. The radiator cap has a special valve in it to allow this. The idea is to eliminate all the air from the coolant to make the cooling more efficient. That tube should be air tight to allow the system to work properly.

Because that tank is a non metallic tank, a new tank would be the best way to fix it. Any compentent radiator shop can do this. I had this done on my GMC pick-up a while back with good results! Good luck!! :cool:
 

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2001 ML 430 - Silver
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115 Posts
There is a 1/4" hose coming from the drivers side of the coolant expansion tank that goes to a small nipple connection on the drivers side top of the radiator. For some reason, the nipple cracked and then broke off and i lost all the coolant. I have tried to JBweld the nipple back on and it worked momentarilly however it began to leak again.
THis seems to be an overflow return line although I cant find any diagram for it.
I clamped the line and drove it for quite a while yesterday with no ill effects.

Can anyone verify that this is a non essential line? My next step is to determine if I can find a plumbing fitting, threaded on one end, with a nipple on the other to JBweld into place as a permanent replacement, there is no way I am going to get a new radiator for this.

Any thoughts would be great.
Thanks,
Chris
2000 ML320

Chlubb, did you end up taking care of this problem? I have a broken nipple as well, the same one.

Thanks.
 

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ML550, W212 E350 4 matic, 1966 Corvette C2 convt.
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2,675 Posts
Any of the materials you have mentioned are a band aid and a temp fix. Get the correct parts including a new overflow tank. You have your entire engine at stake. One overheat will ruin not only your day but your engine also. Saving a nickle here can cost you big bucks or cause you to scrap the vehicle
 

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ML430
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21 Posts
I have the same problem and have tried everything to fix the nipple. I broke down and bought a new expansion tank from germanstar.net for 85.00. Quickest and safest way to cure what ails you.
 

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2001 ML 430 - Silver
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115 Posts
Well said guys. I found the expansion tank on germanstar for $84 as suggested, going to order it tomorrow since today's Christmas. Anyone have a doc or steps for replacing the expansion tank?
 

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E320/E250 Bluetec Ford F350 6.7l
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You have your entire engine at stake. One overheat will ruin not only your day but your engine also. Saving a nickle here can cost you big bucks or cause you to scrap the vehicle
ML320 have a computer program, that will shut off the engine before the dangerous overheat will happen.
Sounds like German engineers worry about American fools ;)
Plastic tanks are very hard to glue, because of the composite. I had good results in Crazy-gluing cracked spoilers and bumpers, but no glue worked on broken nipple on my W123 radiator. Finally I was able to enlarge the hole, thread it and screw in small plumbing fitting with hose connection.
 
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