broken radiator overflow nipple repair - Mercedes-Benz Forum

Go Back   Mercedes-Benz Forum > Mercedes-Benz Sedan Forums > W123 E,CE,D,CD,TD,TE Class
New User? Register - Forgot Password

BenzWorld.org is the premier Mercedes-Benz Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Display Modes
Old 10-08-2009, 09:54 PM   #1 (permalink)
BenzWorld Member
 
konstan's Avatar
 
Date registered: Jul 2009
Vehicle: 1982 300D Turbo Diesel, 1982 240D
Location: Omaha
Posts: 253
broken radiator overflow nipple repair

This was inspired by my broken plastic radiator nipple that connects to the hose that goes to the overflow tank, and also by the following threads:

http://www.benzworld.org/forums/w123...r-tab-off.html

http://www.benzworld.org/forums/w123...iator-fix.html

It seems that several people had good luck with the brass fitting repair of the overflow hose fitting in the stock Berh radiator.

Well, guess what, it appears that before I got the car ('82 300D), someone else has already done the brass fitting repair. I am sure it served well for years, but by the time I got it, it was leaking.

Here is the fitting that was in my radiator:



it is a brass 1/8" threaded by 1/4" barb fitting.

The repair has developed cracks and was leaking coolant.

It dawned on me that brass (fitting) and plastic (radiator) are not very good materials to glue together because the brass would expand a lot more than plastic would, and this is a radiator so this is routinely going to get to 200 F or so. The uneven expansion of brass and plastic is going to put stress on the glue joint and eventually will crack it.

A better "match" would be plastic glued to plastic. So I set out to find a similar plastic fitting. Even if the plastic that the fitting is made of is not the same as what the radiator top is made of, it would still have thermal expansion properties closer to the radiator plastic than brass!

I was able to find a similar fitting at Ace hardware:



I shortened the threaded part because it does not need to be very long (the radiator walls are only 1-2mm thick). I want to be able to thread it in the hole, with glue already on it, and then tighten it to the point where it 'bottoms out', before the glue starts to set.

I sanded down the barbed end until it fit inside the rubber hose tight but not so that it would break when I try to put the hose on it.



Another nice thing about gluing plastic to plastic is that glue that is specially formulated for that can take advantage of the fact that plastics can be softened by the glue thus increasing the bond strength). Here is the plastic-specific glue I used:



Here is the fitting glued in place:



This glue job isn't like a JB Weld deal, where you would see a bead of glue (or, in some cases, a big blob of it). The glue is clear and the bond is made by altering the plastic surfaces by slightly dissolving them, so no bead or blob of glue here.

I have not yet done any kind of pressure test, but the repair seems to be very solid.

The barbed end flexes better than brass did, so any external stress put on the fitting does not transfer to the glued part entirely; the flex in the fitting takes on a lot of that stress and does not pass it to the glued joint.

I hope this helps someone who has a similar problem with their stock Behr radiator.

Last edited by konstan; 10-08-2009 at 09:57 PM.
konstan is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 10-08-2009, 10:35 PM   #2 (permalink)
BenzWorld Member
 
Date registered: Dec 2007
Vehicle: '95 E320 Wagon & '98 BMW M3
Location: Northeast
Posts: 311
While a clever solution, and something I'd do as a temporary fix... it's asking for a potential overheat and stranding down the road. BMW's face the same failure with plastic end-tank radiators, typical lifespan is 60-100k or 5 yrs. Cooling system plastic components just need to be replace periodically...
bmwpowere36m3 is offline   Reply With Quote
Old 10-09-2009, 05:40 AM   #3 (permalink)
Lifetime Premium Member
 
MBDiagMan's Avatar
 
Date registered: Mar 2007
Vehicle: 99 SLK230 Kompressor, 5 Speed Manual
Location: Wild Blue Yonder
Posts: 1,115
Lifetime Premium Member
Here's a very good permanent fix. I did this many years ago on my wifes 300TD. I was really proud because I thought it all up on my own. It was before I had even heard of the internet.

What you use is a mag wheel valve stem. These were sold way back when mag wheels didn't use a regular valve stem and I'm quite sure you can still buy them. They are a valve stem with a flange on the back and then a nut that tightens it into place with a rubber washer at the flange and at the nut. There is a steel washer between the nut and the outer rubber washer.

Clean up the hole so that the rubber washer can lay flat. Disconnect the upper radiator hose and push a piece of baling wire through the vent hose and all the way to the upper radiator hose neck. Pull the wire through and put the valve stem on it with the cap end toward the radiator. Put a bend or two in the wire after the valve stem so that you can pull the valve stem through the top of the radiator and pull it out the hole. Put your rubber washer, steel washer and nut, in that order on the wire and push it all down the wire and thread the nut in place and snug it up.

Push the wire back through and out the upper radiator neck and reconnect the upper radiator hose and the vent hose. It works great.

BTW, for you City Folks, a coat hanger makes a suitable substitute for baling wire.
MBDiagMan is offline   Reply With Quote
Old 10-09-2009, 06:15 AM   #4 (permalink)
BenzWorld Senior Member
 
Date registered: Jul 2008
Vehicle: 1985 300td, 1983 Datsun Maxima Diesel
Location: Houston Texas
Posts: 513
Quote:
Originally Posted by konstan View Post
This was inspired by my broken plastic radiator nipple that connects to the hose that goes to the overflow tank, and also by the following threads:

http://www.benzworld.org/forums/w123...r-tab-off.html

http://www.benzworld.org/forums/w123...iator-fix.html

It seems that several people had good luck with the brass fitting repair of the overflow hose fitting in the stock Berh radiator.

Well, guess what, it appears that before I got the car ('82 300D), someone else has already done the brass fitting repair. I am sure it served well for years, but by the time I got it, it was leaking.

Here is the fitting that was in my radiator:



it is a brass 1/8" threaded by 1/4" barb fitting.

The repair has developed cracks and was leaking coolant.

It dawned on me that brass (fitting) and plastic (radiator) are not very good materials to glue together because the brass would expand a lot more than plastic would, and this is a radiator so this is routinely going to get to 200 F or so. The uneven expansion of brass and plastic is going to put stress on the glue joint and eventually will crack it.

A better "match" would be plastic glued to plastic. So I set out to find a similar plastic fitting. Even if the plastic that the fitting is made of is not the same as what the radiator top is made of, it would still have thermal expansion properties closer to the radiator plastic than brass!

I was able to find a similar fitting at Ace hardware:



I shortened the threaded part because it does not need to be very long (the radiator walls are only 1-2mm thick). I want to be able to thread it in the hole, with glue already on it, and then tighten it to the point where it 'bottoms out', before the glue starts to set.

I sanded down the barbed end until it fit inside the rubber hose tight but not so that it would break when I try to put the hose on it.



Another nice thing about gluing plastic to plastic is that glue that is specially formulated for that can take advantage of the fact that plastics can be softened by the glue thus increasing the bond strength). Here is the plastic-specific glue I used:



Here is the fitting glued in place:



This glue job isn't like a JB Weld deal, where you would see a bead of glue (or, in some cases, a big blob of it). The glue is clear and the bond is made by altering the plastic surfaces by slightly dissolving them, so no bead or blob of glue here.

I have not yet done any kind of pressure test, but the repair seems to be very solid.

The barbed end flexes better than brass did, so any external stress put on the fitting does not transfer to the glued part entirely; the flex in the fitting takes on a lot of that stress and does not pass it to the glued joint.

I hope this helps someone who has a similar problem with their stock Behr radiator.
Hi
Looks good to me. Thanks
jkubica is offline   Reply With Quote
Old 10-09-2009, 07:07 AM   #5 (permalink)
BenzWorld Member
 
konstan's Avatar
 
Date registered: Jul 2009
Vehicle: 1982 300D Turbo Diesel, 1982 240D
Location: Omaha
Posts: 253
Quote:
Originally Posted by LarryBible View Post
Disconnect the upper radiator hose and push a piece of baling wire through the vent hose and all the way to the upper radiator hose neck. Pull the wire through and put the valve stem on it with the cap end toward the radiator. Put a bend or two in the wire after the valve stem so that you can pull the valve stem through the top of the radiator and pull it out the hole. Put your rubber washer, steel washer and nut, in that order on the wire and push it all down the wire and thread the nut in place and snug it up.
I was trying to figure out how I could get a nut on the inside. The baling wire is a great idea, BUT - how do you actually tighten the nut from the inside??
konstan is offline   Reply With Quote
Old 10-09-2009, 07:10 AM   #6 (permalink)
BenzWorld Member
 
konstan's Avatar
 
Date registered: Jul 2009
Vehicle: 1982 300D Turbo Diesel, 1982 240D
Location: Omaha
Posts: 253
Quote:
Originally Posted by bmwpowere36m3 View Post
While a clever solution, and something I'd do as a temporary fix... it's asking for a potential overheat and stranding down the road. BMW's face the same failure with plastic end-tank radiators, typical lifespan is 60-100k or 5 yrs. Cooling system plastic components just need to be replace periodically...
I kind of see where you are coming from; I would venture to guess that my fix, or even a brass fitting fix would last about 5 years, so that would be equivalent to another radiator

What I cant for the life of me figure out is, why, on a car where almost everything else is so solid and over-engineered (in a good way), did someone decide 'hey, lets put a plastic POS radiator in this baby'.
konstan is offline   Reply With Quote
Old 10-09-2009, 08:34 AM   #7 (permalink)
Lifetime Premium Member
 
MBDiagMan's Avatar
 
Date registered: Mar 2007
Vehicle: 99 SLK230 Kompressor, 5 Speed Manual
Location: Wild Blue Yonder
Posts: 1,115
Lifetime Premium Member
Quote:
Originally Posted by konstan View Post
I was trying to figure out how I could get a nut on the inside. The baling wire is a great idea, BUT - how do you actually tighten the nut from the inside??
The nut doesn't go on the inside it goes on the outside. I'm sorry my explanation was not clear. It's difficult to describe with words only.

Imagine the valve stem that I described were a bolt with a hole through the middle of it. You would be pulling the bolt through the radiator threaded end first and pull it on through the hole until it bottomed out against the head of the bolt. You would then thread the nut on the bolt from the outside and tighten.

Does this help?
MBDiagMan is offline   Reply With Quote
Old 10-09-2009, 09:11 AM   #8 (permalink)
BenzWorld Member
 
konstan's Avatar
 
Date registered: Jul 2009
Vehicle: 1982 300D Turbo Diesel, 1982 240D
Location: Omaha
Posts: 253
Quote:
Originally Posted by LarryBible View Post
You would be pulling the bolt through the radiator threaded end first and pull it on through the hole until it bottomed out against the head of the bolt. You would then thread the nut on the bolt from the outside and tighten. Does this help?
Yes, it is installed from the inside out. I like your out of the box thinking! If my glue job does not hold up, this is the next thing I will try!
konstan is offline   Reply With Quote
Old 10-09-2009, 09:42 AM   #9 (permalink)
BenzWorld Elite
 
Date registered: Mar 2008
Vehicle: 1984 300D
Posts: 4,557
Quote:
Originally Posted by konstan View Post
Yes, it is installed from the inside out. I like your out of the box thinking! If my glue job does not hold up, this is the next thing I will try!
Ugly or not JB Weld will take the temp better than Super Glue. However, I do not think JB Weld will stick to Nylon.

I would investigate the Temp range that the Superglue can take. I is most often listed on the back of the package.
300Dman is offline   Reply With Quote
Old 10-09-2009, 08:07 PM   #10 (permalink)
BenzWorld Member
 
Date registered: Dec 2007
Vehicle: '95 E320 Wagon & '98 BMW M3
Location: Northeast
Posts: 311
Quote:
Originally Posted by konstan View Post
I kind of see where you are coming from; I would venture to guess that my fix, or even a brass fitting fix would last about 5 years, so that would be equivalent to another radiator

What I cant for the life of me figure out is, why, on a car where almost everything else is so solid and over-engineered (in a good way), did someone decide 'hey, lets put a plastic POS radiator in this baby'.
Plastic is light and cheap, gone are the days of solid copper/brass radiators. All aluminum radiators are just too expensive for OE usage. I would be surprised if it lasted another 5 yrs... super glue for one isn't the best adhesive to be used since its brittle. So as you surmised the plastic nipple will flex more, so will the adhesive eventually cracking. Ideally you'd want some sort of epoxy for plastic. For my M3 a new Behr radiator was $150, well worth the piece of mind for another 5+ yrs.
bmwpowere36m3 is offline   Reply With Quote
Reply

  Mercedes-Benz Forum > Mercedes-Benz Sedan Forums > W123 E,CE,D,CD,TD,TE Class

Bookmarks



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Topic Author Forum Replies Last Post
leaking plastic overflow tube on top of radiator tuttebenne W124 E,CE,D,TD Class 7 10-23-2013 03:42 PM
Upper radiator small hose to overflow bottle lander91 W126 S,SE,SEC,SEL,SD,SDL Class 22 04-24-2010 06:45 PM
Broken nipple on fuel sender! turbogarrett W163 M-Class 6 08-04-2008 04:11 PM
Gurgling from radiator overflow tank quidam W163 M-Class 3 09-18-2007 01:46 PM
Broken Radiator Nipple Cheelyv W126 S,SE,SEC,SEL,SD,SDL Class 8 07-27-2006 08:36 PM


All times are GMT -7. The time now is 04:46 AM.



Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.1

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.