Repair Upper Radiator Hose Neck

Ok, I know I cheated on this DIY, and didn't do the right thing (which is to replace the radiator), but with a $600 quote from my mechanic I decided to try to fix my cracked upper radiator hose neck. The OEM radiator alone runs about $200 give or take, wholesale.

It started with a leak in my plastic thermostat housing, which I took to my mechanic to change along with my water pump since the bearing was wobbling. That alone cost me $600 installed (housing, thermostat, water pump, antifreeze). As I've read on many posts for BMWs and Mercedes (and I'm sure for many other cars), when the plastic radiator necks and nipples get old and brittle they can break when you remove the hose. In my case, when my mechanic pulled the hose off the neck cracked with only about 1 inch left to attach the hose back. See the attached pictures.

My original BMW hose (which surprisingly is in good condition) has ridges inside the end, and the radiator hose neck also has ridges. Good for holding adhesive. Many folks on this forum and others have considered epoxy or gasket adhesives to help keep the hose on, but if you do nothing it will likely pop off at some point and immediately overheat. I looked at all the ususal adhesives by Permatex, JB Weld, Locktight, etc., and JB Weld Quik has a 4 minute set time in as low as 40 degrees f, and can work in operating temps up to 300 degrees f (radiators at 15 lbs pressure only get to about 230 degrees f). I cleaned both ends with acetone and sanded to rough them up a little, then I slathered the epoxy on thick inside the hose ridges, and in the plastic radiator neck ridges. I was pleased that when I pushed on the hose a quarter inch of the epoxy wrapped around the plastic hose stop on the hose neck, which pretty much assures it is secured on the neck and is not going to pop off. But, now replacing the hose it would require cutting and pealing it off. Not such a bad tradeoff. I have both a 1998 E39 and a 2004 E60, and I'll be on the lookout for this problem in my 2004 now too, since that plastic may also be getting brittle.

GPom

The part I don't get is you took it to a mechanic for the thermostat and water pump replacement. Then you decided to cheat death and do an epoxy repair in the radiator yourself. If you did the pump and thermo install, you would have saved enough to buy the new radiator. And gained some valuable experience as a bonus.

I sometimes use epoxy at work, and the resuts are always iffy - sometimes it holds great and sometimes not. The problem is you never know if and when it's going to fail. If and when this repair fails, you're going to have about 30 seconds to pull over.

Just my experience.

Jerry

This won't work for long. Replace the radiator.

I tried this myself awhile back... Go get a new radiator. The first time you get on the gas to pass someone or merge with traffic its gonna blow trust me.

Do a search for "JB Weld" and you'll find others who have done the same 'repair' (and from which I borrow my examples below).

As a McGyver, it's pure genius! It's worthy of reward, as it will get you home from a breakdown in the middle of your cherished vacation across country.

It will also buy you time to research & order the parts (which, for a radiator, are about $200).

And, if it wasn't the biggest danger to an engine's life blood, it would even qualify for the American Ingenuity award.

However, given that the cooling system kills more E39 engines than sheer miles driven, it may actually be Sanford & Sons to keep that repair in place long term.

I do give you kudos for ingenuity and cleverness - and for showing pictures which helps others stuck on the road with Internet. It would even be nice for you to stock the radiator, and then drive for as long as it takes for the ingenious repair to break again.

That would be of the best interest for all. Does it last forever or does it spring a leak in just a few months? Please do keep us informed as I hope it lasts forever - but I don't know if it will.

Mine broke in the same area. Broken engine mount caused it.

That "repair" will not hold up. Although the I6 cooling system seems to last a bit longer thamn the V8, a single overheat of an I6 generally spells doom for the engine. $200 for a radiator and a couple hours work will look cheap when compaired to blown head gasket and warped heads.

BTW: Look at the radiator cap. You will notice that it says 2 bar. That's not 15 psi, that is 29 psi. Our cars run at twice the pressure of most. Now how's your confidence in holding your cooling system together with some glue?

Not to pile on, but the epoxy will not hold. I just had to do a patch while waiting on a radiator to come in. It lasted around two weeks before the air bubbles became a leak. I got a CSF radiator for around $80 bucks from ******************.com.

auto part warehouse dot com

+1 to the above. And the radiator can be had for about $150 shipped. Given the risks and the cost, there is really no reason why not to replace it.

Originally Posted by GPom

The OEM radiator alone runs about $200 give or take, wholesale.

There was a post today where the OP bought a new radiator for about $80:
- E39 (1997 - 2003) > Notes from my cooling system overhaul

Originally Posted by cwpo1

I used a CSF radiator 80.00 from auto part warehouse dot com OEM replacement

Originally Posted by GPom

the plastic radiator necks and nipples get old and brittle they can break when you remove the hose.

The neck is fatal but lots of us simply replace the nipple (ask me how I know).

Originally Posted by GPom

JB Weld Quik has a 4 minute set time in as low as 40 degrees f, and can work in operating temps up to 300 degrees f (radiators at 15 lbs pressure only get to about 230 degrees f).

See also:
- E39 (1997 - 2003) > jb weld seems to have worked on my radiator...

Originally Posted by cwpo1

Not to pile on, but the epoxy will not hold. It lasted around two weeks before the air bubbles became a leak.

Your information is excellent!

And, the prices you paid are absolutely out of this world.

But, still ... I'm curious why you didn't just buy a new radiator nipple?

It would not hold with the clip broken.

It's been nearly a year since I did the upper radiator hose plastic nipple fix on my E39 using the high temperature JB Weld Quick epoxy ( JB Weld Quik has a 4 minute set time in as low as 40 degrees f, and can work in operating temps up to 300 degrees f. Rradiators at 15 lbs pressure only get to about 230 degrees f).

After 20,000 miles and a year, a lot of it on highways with max radiator flow, it holds great. Still very solid. I think the way I did it (see the pics) the epoxy latched onto the back of the nipple stop, and really grabs it. The specific high temp epoxy is excellent too.

If you have the time and interest in changing the radiator that's the best way to go, at about $200+ and a fair amount of time, but consider this as another approach if the rest of the cooling system is good. If not, change the water pump, housing and thermostat while you're in there.

It's a shame that BMW and some others make the hose nipples out of plastic, since they get brittle and can crack when you change a hose. Should be out of metal, but we're stuck with plastic, at least on these older E39s. I don't know if my E60 has metal, I hope so.

OP , dont play Russian roulette
Radiator costs 130$ , just replace it
You dont want to overheat your engine which cost $3000 - $4000 , dont you
GL

Originally Posted by champaign777

You dont want to overheat your engine which cost $3000 - $4000 , dont you
GL

When that repair goes, all the fluid will leak out fast.

Just ask these people (I stopped at 50 overheated ruined engines):
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