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Good morning!
Sorry for this post, but despite searching on a variety of terms and looking in the Information Base, I cannot find the handful of posts on this topic (except for the one using the Prestone flush kit--I found that one). In particular, I'm looking for one where someone added copper tubing to the nipples to make them more sturdy, securing them with JB Weld or some other adhesive. Are you the original author? Did you just find them yourself? Please point me to them. Thanks!
 

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Good morning!
Sorry for this post, but despite searching on a variety of terms and looking in the Information Base, I cannot find the handful of posts on this topic (except for the one using the Prestone flush kit--I found that one). In particular, I'm looking for one where someone added copper tubing to the nipples to make them more sturdy, securing them with JB Weld or some other adhesive. Are you the original author? Did you just find them yourself? Please point me to them. Thanks!
Chief ought to chime in here!


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I don't know if I ever posted anything but I've done this repair. What I did was cut off a couple of good plastic ends from heater cores in the local junkyard, then glued them back on with JBWeld with some sort of pipe inside. I don't remember the exact pipe I used (I think it was a type of 1/2 copper) but I do remember nothing was a perfect fit and I had to enlarge the plastic pieces to make the insert fit. I roughed up the plastic and metal pipe and the JBWeld seemed to bond to both parts well. I embedded some metal screen in the JBWeld as reinforcement on the outside. Afterwards, I drove the car for a few hundred miles and saw no deterioration.

I don't have any longer term history since I sold the car. It was later crashed and junked and when I saw it in the yard again (sad day....) the heater core repair still looked fine.

In my case, the core in the car had metal pipes. One side was damaged trying to get the hose off :banghead: so I that's whey I had to do the repair. After that, I bought a set of those funny hose pliers. For me, it was money well spent.
 

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Discussion Starter #5
Thanks, everyone, for the assistance! I haven't done the repair yet--after cleaning things up a bit, it didn't look broken.
 

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Thanks, everyone, for the assistance! I haven't done the repair yet--after cleaning things up a bit, it didn't look broken.
Here's my experience:

Had been continuously losing coolant but couldn't see where it was coming from. Sure enough, had coolant leaking at the heater core pipes and hoses in the plenum. Sure enough could see where the heater core inlet and outlet pipe nipples were erroded thin and had cracks. Thoroughly flushed the heater core out with fresh water then used compressed air to blow the remaining water out and dry the inside. Carefully cut the heater core inlet and outlet pipe nipples with my Dremel, including some cutting of the support that joins the two nipples. This was necessary to give more length to slip the copper pipe over. Carefully cut, and chamfered the copper pipes, including expanded the ends that slip over the heater core pipes with a copper pipe flaring tool. Used a gob of JB weld on the heater core nipples, slipped the copper pipe over, and then put another bead of JB weld over the copper pipe to sandwich it between two layers of epoxy. Let it cure for a over a full day, then hooked the heater hoses back on and filled and vented the cooling system. Started it up, no leaks, drove the car to work the following morning.

BUT THEN DISASTER! On the way home that evening with just 5 miles to go, the heater core burst open inside the car. Instant steam all over the inside of the windshield and hot wet carpets.

That was last winter. I fabricated a U from that same copper pipe and two 90 degree fittings, stuck that on the heater hoses and bypassed the heater core altogether...it was a miserable winter for my stepson driving that car. Had a little 12V plug in electric heater that barely kept the windshield defrosted.

So my assumption is that the slow leak of coolant had been going on for a while and never let the cooling system actually pressurize. The heater core eroded inside as well as at the inlet and outlet. Once I "fixed it" with the copper, now the cooling system was able to pressurize, and that pressure burst the compromised heater core.

So now sometime before next winter I have to pull the dash and replace the heater core altogether. At least that will give me a chance to replace some of those air flap servo motors too.

So my advice is go ahead and try the fix, since it's not very expensive to try, but don't get your hopes up.
 

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Prestone makes a flushing kit you can buy. the T in the kit can be cut apart, and the plastic bits can be JB-Welded into the heater core coolant lines after you cut them off to get rid of the split part. I did it successfully.
 

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Discussion Starter #8
Well, ultimately, I did end up having a leak. So, here is the repair procedure I used:

https://www.passatworld.com/forums/b5-garage/429698-fix-heater-core-leak.html

I basically followed most of the directions, with the following exceptions:

1. I did not drain the coolant. I did try and dry the nipple off (I only did one side) with some compressed air and to also remove some of the coolant from the core. But this really wasn't an issue for me because the coolant was so low to begin with.
2. I did remove the shroud at the bottom of windshield and I also removed the battery. It makes things a lot easier. This is a good time to replace that leaky cabin air filter holder, too!;) Some advice here: stick a crowbar in yer wallet and get a windshield wiper arm puller!! You'll never get them off, otherwise. Autozone, about $14.
3. To make the cut, I put a piece of painter's tape around the nipple at the second stop. I did this to provide a straight line to cut on and to protect the nipple from vibrations from the dremel as I was worried it might crack more during the trimming process.
4. I sanded the nipple very thoroughly, but carefully, including removing the raised arrow showing the flow direction (this was the inlet side). I don't think the copper will slide over the nipple otherwise.
5. I did not heat the epoxy during the install. It was a very hot day in Maryland when I did this repair, so I thought that would be good enough. I did give the copper tube a little twist (slowly!) as I put it on (maybe an eighth to a quarter turn?) to smear the JB Weld around a bit. But I also coated the nipple pretty thoroughly and the inside of the pipe, too.
6. I did not replace the brace between the two nipples.
7. I installed the rubber heater hose AFTER the copper pipe cured (over 24 hours--full cure for JB Weld is 6 hours, according to the package), so I didn't have to do the complicated bracing job described in the how to. To facilitate its installation (a tight fit, as warned in the original post), I put on a thin coating of dielectric grease. I figured that if you can use it on spark plug wires, it should be OK on this sort of hose and I assumed that any possible contamination of the coolant would be minimal. Don't know if any of that's true, but I guess I'll find out!
8. I was able to reinstall the original firewall gasket. If you trim it back a bit (take off the first "ring"), it slides right over the copper pipe.
9. I did not reuse the original clamp. I used a standard hose clamp. Just don't be an animal about tightening it up--but, really, it would be hard to damage that copper tubing and is a hell of a lot easier to use. By the way, the vise grip trick to get those original POS hose clamps off is brilliant! Worked like a charm.

I drove the car 75 miles today on the highway and the coolant level appears stable--before the repair, that would have caused the low coolant warning light to come on. Fingers crossed!

Of all the changes, the one I'm concerned about is not replacing the brace. How important do you think it is to replicate that part? I could still do it, I think, but fabricating it will be a bit of a PITA. If anyone has a thought about that, I'd appreciate it.




painters tape.jpg trimmed nipple.jpg prepared nipple.jpg trimmed gasket.jpg installed copper.jpg
 

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If you're worried about the brace I'd wedge something between the hoses and put a few zip-ties or something around both hoses. Should have about the same effect and it would be a lot easier than fabricating a new brace. Personally, I wouldn't worry about it...
 
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