I think my heater core is leaking :(

Crap, if it's not one thing it's another. I cranked up the heat for the defroster for the first time this year and caught a familiar whiff, and the next day I had to clean the inside of the screen. I'm not seeing any drips or anything but the odor is unmistakable.

I have way too many projects to be digging into the dash again. I should have had it replaced when I paid someone to do the blend doors 4 years ago.

Has anyone had any luck with the stop leak in a can stuff, Alumaseal maybe? If I decide to try that should I try and drain some coolant out first rather than just dumping it in the overflow tank? I'm not sure if it circulates from there or not?

That stuff will just cause more problems than it'll fix. Bypass the heater core and drive with a heated blanket?
But seriously, it'll clog the radiator, restrict the thermostat, be a turd to flush out, and will only bandaid the heater core. That stuff is more of a "emergency get me home" stuff. Not a "postpone the repair" stuff.

If you put that garbage in the cooling system, you will then not only need a new heater core, but a new radiator and possibly more. I had an ALH in here once that some dumbass tried that and it plugged up the little vent tubes coming out of the head, upper hose, and EGR cooler, and cooked the engine.

Bypass the heater core if you have to keep driving the car until you can get it replaced, or pay someone to replace it. It sucks, but it happens. It lasted a good long time.

Well double crap. I'll look for the hoses. Are they obvious going in/out of the bulkhead? Should one be pinched off first to allow it to drain out? Any suggestions for pinch methods?

Does the A/C have to be discharged to swap the core? If so I'll be done with heat because it isn't worth a grand to me at this point.

You should give me the car. I will come get it. Stupid POS isn't worth anything.

Does the sealer need heat to circulate and deposit in hopefully the leaking parts? If not could you just take hoses connected to the heater core connections pour a small amount of sealer/coolant in and circulate it with a small pump?

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The point is, the material will still end up in the rest of the engine at some point, and could still fubar your engine. The hoses are right off the firewall. You could pinch one or the other to limit spillage.

oilhammer said:

You should give me the car. I will come get it. Stupid POS isn't worth anything.

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Not really the point. In the span of a few years and just 15k miles I've been hit with timing belt, clutch, turbo, fuel injector, cam cover, leaking coolant rail o-ring, and a bunch of other things. It isn't an inexpensive car to work on either. I needed this at the start of winter like a proverbial extra head hole.

If the engine is all stock you can take the o-ring out of the coolant cap so the system won't build any pressure and then it won't leak. I drove my golf like that for years and never had any problems until I turned the power up.

jayb79 said:

If the engine is all stock you can take the o-ring out of the coolant cap so the system won't build any pressure and then it won't leak. I drove my golf like that for years and never had any problems until I turned the power up.

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Interesting, I've never heard of this. Any idea whether it was running hotter as a result?

It shouldn't. These engines are cold blooded, especially in the winter. Just do it at your own risk.

If your location is Austin Tx. just bypass the sum*****.....you don't need it.

U4ick said:

If your location is Austin Tx. just bypass the sum*****.....you don't need it.

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It's going to be down in the 30s soon. A little warm breeze is a nice thing. Thank goodness the heated seats still work at least.

This story reminds me of my Dad's '67 bus. When I was a teenager coming back from a hunting trip up north when our milk froze and we had to stop at a store for candles to defrost the windshield to see to get home.

At least you're not up here right now.

Seriously. "Down in the 30s..." - here I need to work on my car outside. I'm hoping it gets up to the 30s before the end of the day.

Cheers,

PH

Powder Hound said:

Seriously. "Down in the 30s..." - here I need to work on my car outside. I'm hoping it gets up to the 30s before the end of the day.

Cheers,

PH

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We are going to have a string of a few sunny upper 40 days here, probably shut the furnace off

So it looks like I'll have a few days and a garage available over the holiday. Would any other parts be needed to do this job besides the new heater core? On this page it looks like the Nissens is the most expensive. Are they the best ones? Oddly there are two different Nissens part numbers here. Is mine a transitional year or something? I want to have the right part here when I start.

https://www.partsgeek.com/catalog/2000/volkswagen/beetle/climate_control/heater_core.html

I watched a couple videos and it seems like splitting the box would best so the A/C doesn't have to be discharged. The only issue I see is that there is apparently a clip on the back of the box that has to be pried of blind using a long tool. I assume people just leave that off on reassembly? How could you get it back on again? Does it cause issues leaving it off?

I was considering replacing the fan motor also because it was making some noise when it's cold. Is that possible if only the heater side of the box is removed?

I've had most of the dash off before for various reasons. But only the center and passenger side. How hard is it to get the steering wheel off? Am I going to throw faults in the ECU? doing this? I don't have a vagcom.

Thanks!

OEM is most expensive. The part number is 1J1819031B.
The Nissens part number is 73921. They are both good quality.
Check idparts.com and www.1stvwparts.com to compare.
I would use those sites vs partsgeek to confirm fitment. Better prices too.
Sorry I can't answer your other questions, but I can't see how VCDS would be involved.
Just make sure your battery is unhooked before getting into the steering wheel.
Also, I don't see in the thread where you confirmed the heater core is leaking. There's
a few other places coolant could leak. EGR cooler is one, and it's pretty close to the cabin
air intake too... I'd hate to rip open the dash only to find a leak elsewhere.

STDOUBT said:

There's a few other places coolant could leak. EGR cooler is one, and it's pretty close to the cabin air intake too... I'd hate to rip open the dash only to find a leak elsewhere.

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Oh dear, you're right that would be a bad day. The EGR is in the engine bay though, right? Could it actually drip into the air intake? Would it not also leak onto the floor? I did have a coolant leak earlier this year but it was a bad o-ring on the rail behind the fuel injector pump. I haven't seem any drips since that was fixed.


The only symptom I can describe is that it smells like crazy when the heater is turned on. I noticed no smell at all from the A/C. I assumed that is because the door to the heater is closed when the A/C is on.



What else can I do to properly diagnose it? It is, I'm almost certain, the original core and almost 20 years old at this point.

20 years...yeah it's done its job.
Leaks are tricky because the belly pan can catch a lot of fluid without letting it onto
the ground. The EGR cooler is directly behind and below the rear of the valve cover.
It's actually bolted onto the intake manifold.
It's a metal cylinder about 10" long sitting horizontally. As you're looking at the firewall,
the hose on your left goes into it (from the heater core). A mirror could come in handy there.
Or see if you can get your hand down there with a paper towel to check for moisture.
But having said all that, your assumption about the heater blend door makes a lot of sense.

I’ve done several of these on our cars...... not hard just tedious.....
First off there are two different style hvac boxes..... one that splits and the other as one piece.
They claim if you have a manual heat control setup it’s two piece setup and if it’s digital it’s a one piece setup........well that’s BS....... all my cars are manual temp control and I have a one piece HAVC setup except one....
You can still remove the HC with the one piece HAVC left in the car.....I’ve done several...

The hardest part to get the steering wheel is the air bag, once that’s off it’s just held on with a large torqx bit screw......make sure you mark the shaft to the steering wheel .

I do recommend disconnecting the battery first before you start to disconnect anything first.
Thane it’s a matter of removing everything to gain access to the HAVC box.

There are I believe two hidden bolts on the engine side under the aluminum heat shield flapper tabs, they look U shaped and are about 1/2-3/4 wide.......the bolts to the back side of the HVAC box.
Also where the A/C goes through the firewall remove the bolt that attaches it to the firewall, do not break into the system.
This will give you enough room to pry the drivers side of the air box forward enough remove the heater core.... some here will not agree but for the last 4 I’ve had no issues.
You might need a 2x4 to help keep the HVAC box aft as you get the heater core out.

While your there you may want to replace what foam you can reach as it will be non existent

I’m sure the correct way is to pull the box and do it out of the car......for me I didn’t have the A/C equipment nor the time as I had to do mine in the middle of February in a barn with no heat.
The other cars were done ....well the same way...weather wasn’t a factor then it just worked for me.

That’s how I did mine....there are others that have done it and I’m sure they will chime in....
Good luck.

You could purchase or borrow a coolant system pressure tester, apply as much pressure as your cap holds, if you have a leak, pressure should drop. Then do a search for a visible leak. Beats guessing and often saves a lot of work, though good odds you are correct

csstevej said:

First off there are two different style hvac boxes..... one that splits and the other as one piece. They claim if you have a manual heat control setup it’s two piece setup and if it’s digital it’s a one piece setup........well that’s BS....... all my cars are manual temp control and I have a one piece HAVC setup except one....

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Oh man, that is crazy. I wonder if it's year dependent? Do you recall which of your cars had the two piece? Mine is a 2000. I guess it's not a deal breaker if the core can be pried out the top and a new one pried in without ruining it. What exactly are you prying against? In other words what is bending? Is it distorting the platic box, and is it likely to break in the process? I have no capability to work on the A/C either which is why I don't want to remove the box.

I don't suppose you recall the wrench size for the wheel removal? I'll be without transportation once this comes apart so need to have everything handy. My other car has clutch issues.

I've never removed the airbag. I'm certainly anxious about it, but there seem to be enough how tos out there.

make sure you mark the shaft to the steering wheel

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Ah will do. I guess because it is splined and can go on crooked?

There are I believe two hidden bolts on the engine side under the aluminum heat shield flapper tabs, they look U shaped and are about 1/2-3/4 wide.......the bolts to the back side of the HVAC box.

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So these are cutouts in the heat shield that you lift to reveal the bolts? I guess the plastic and steel cowls need to be removed? Anything else in the engine compartment need to come out that you recall?

While your there you may want to replace what foam you can reach as it will be non existent

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The foam was already done by my old mechanic. I wish I'd instructed him to do the core at the same time.

Are there any tricks I'd need to know to disconnect the coolant lines to the core? I assume the entire cooing system needs to be drained? Which hose to pull to accomplish that? It's been done by my old mechanic when the timing belt was done but I wasn't present.

Thanks for the tips!

As far as I know, both heater core box styles use the same heater core itself. I've done two of these heater cores. Can be done in about 8 hours start to finish if you stay focused. I personally would suggest using a guide like one on vwvortex because there's stupid secret bolts that will drive you nuts. There's a bolt under the cowl panel, and two behind the heat shield, there's two removable u shaped pieces you can take off instead of the whole thing.

Also, when you do the heater core it might not be a bad idea to replace the quick disconnect fittings while you're there, because they can be brittle from time. Good luck.

Nero Morg said:

I personally would suggest using a guide like one on vwvortex

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Wow...wow^2 in fact I just read through it and then looked at the linked subthread to removing the dash which is just as long. That's just crazy. Curse you VW!

The 99 NB non TDI has a two piece,
the 2001 golf , 2000 golf , 2000 NB , 2001 NB , and 2003 NB all have a one piece HAVC box.
They are also all manual temp controls not auto controlled.

With everything disconnected/or loose you can pull aft (towards the rear ) the HVAC box enough to remove and replace the heater core without depleting the A/C system.

Where the ac goes through the fire wall you need to loosen the bracket that holds the lines to give you some flexibility.

As for the steering removal it was a torqx bit, don’t Romberg the size but fairly large .
I picked up,a set from Harbor Frieght that work good.

What Nero said about vortex , I had used that when I did my first one.....I think it took me about 11 hrs start to finish.

I have finally received the matrix, blower fan, and new hoses. Could someone who has done this tell me whether this seal is needed?

https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/heater-core-gasket/1h0819019/

I see it on some diagrams but not on all of them. The matrix only came with a little strip of cheap open cell foam, but not this part.

Thanks!

No, that part can be reused, so long as it's not deteriorated. They usually don't.

I'm going through the various threads on Vortex trying to internalize the process. It's difficult since all the photos have vanished. I can tell it's not going to be fun though.

A few questions:

Does only the plastic part of the engine cowl need to come off or the metal under pan as well? Rather than buy just the plastic fittings, I bought the entire two hoses thinking they're 20 years old and I'd just better. I'm not sure how accessible the other ends of them will be?

Do the plastic quick connects simply pull straight off the core tubes or is it necessary to release something first?

I'm thinking it would probably be advisable to start it after installing the new parts and re-filling in order to check for leaks and test the new fan motor. How much needs to be reassembled to do this? They actually say in the Haynes book to do this but don't talk about doing any reassembly first.

Must the lower center console between the seats come out?

I'm sure there will be more as I get into it

Thanks!

Little more help here-
MK4 heater core - TDIClub Forums