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Mon Jun 30, 2025 4:11 am

Hi folks.
There is this segment missing from my exhaust:

I can find various parts but nothing that fits it. Any ideas? It’s a rectangle going to a circle so it’s tricky to find a piece, and hard to fabricate.

Mon Jun 30, 2025 5:09 am

MountainBeetle wrote: Hi folks.
There is this segment missing from my exhaust:

I can find various parts but nothing that fits it. Any ideas? It’s a rectangle going to a circle so it’s tricky to find a piece, and hard to fabricate.

My guess is you have a 1981-83 Vanagon engine and heater boxes, with a Bay Window cooling shroud. The best fix is going to be finding a set of 1979 federal heater boxes, but they are one year only and thus not super plentiful. You should pull the heat exchanger and see what kind of gasket is used between the heat exchanger pipes and the heads.

Mon Jun 30, 2025 6:36 am

Definitely a Vanagon heat exchanger with a Bay window fan shroud, you'll either need to change the fan shroud or the heat exchangers to match them up.

Mon Jun 30, 2025 8:53 am

Thanks guys, that’s really great knowledge. When I got it I found the gap filled with tinfoil then wrapped in a kind of mesh tape. Oddly enough it hadn’t blown through at all.

Mon Jun 30, 2025 9:22 am

Ask the crew of Apollo 13 how to fix this.

Mon Jun 30, 2025 9:38 am

KTPhil wrote: Ask the crew of Apollo 13 how to fix this.
:lol:

Mon Jun 30, 2025 10:36 am

Personally I would get a piece of exhaust tube and make it rectangular on one side to slide into the fan housing, and round on the other and join the two together with a short section of silicone tubing.
Hammer and a vise

Mon Jun 30, 2025 10:39 am

MountainBeetle wrote: Thanks guys, that’s really great knowledge. When I got it I found the gap filled with tinfoil then wrapped in a kind of mesh tape. Oddly enough it hadn’t blown through at all.

The heat exchanger shell is only pressurized by whatever fan supplies your heating system and you mostly likely have no pressure against it at all since you don't have the special Vanagon fan that runs off the alternator shaft.

Mon Jun 30, 2025 7:20 pm

don't run it until it is fixed or you may have both engine and heat exchanger damage. you might be able to do a workaround using some aviation heat ducting that can be clamped on. I think it would get you by for a short while but it won't last. Good to 500F

Something like this and modify some clamps to hold it.

Mon Jun 30, 2025 7:55 pm

You might be able to get away with finding a set of 72-74 heat exchangers with really nice shells and swapping the shells over to your present Vanagon style heat exchangers. Others may know better about the fit.

Mon Jun 30, 2025 11:59 pm

'79 federal heat exchangers would be my pick, but we'd have to see the current exhaust setup fully to confirm fitment with the downstream pipes.

I also like that they're bolt-on to the '72-'74 muffler, which is available new in good quality. You'll need an adapter kit, (available from German Supply,) but none of the 79-83 components are available new that I know of, besides a generic muffler and tailpipe.

Robbie

Tue Jul 01, 2025 7:06 pm

What does the other side look like?

I believe I have the same setup in my '77. The PO trimmed the fan shroud on the left to fit the (I'm guessing) vanagon heat exchangers. Both ends of the shroud were sealed off. I was able to fabricate a duct on the right side to connect it but the left side is just not as simple.

So yeah, to correct this, you'd need '79 heat exchangers and possibly a fan shroud IF it was trimmed like mine. Which also means you most likely have the rectangular exhaust ports instead of the more common oval ports which restricts you from using other common heat exchangers... unless... you replace the heads...

Which is why I've simply left mine alone for the last 8 years or so.

Wed Jul 02, 2025 9:09 am

Thanks for the inquiries. See below the both sides. Left first:

Then the right side as it had been patched when I got it:

What the right is like after the tape and tinfoil was removed:

As a note, the left side exhaust pipes have subsequently been fixed and have a new exhaust connector block thingy, and the exhaust connector on the right has a new gasket, so looking better than these older pics.

Wed Jul 02, 2025 10:21 am

MountainBeetle wrote:
What the right is like after the tape and tinfoil was removed:

be aware. there are flaps that hang on rods that go through those holes. the flaps keep the hot air flowing one way.

Wed Jul 02, 2025 10:38 am

Generally speaking, there isn’t a simple way around this, is there, it’s just a whole new heater box with the right connector? (this one?: https://www.justkampers.com/vw-t2-bay-window-parts...-1979.html )
Mine is a 2000cc.

Is removing the old heater box a simple or complex affair? I see it appears only connected to the exhaust tubes with 4 screws and the hot air. On a scale of 1-10 what’s the difficulty? :?

Wed Jul 02, 2025 11:50 am

Pull your heater boxes before you order anything, as it's important that they fit your heads. WV made a lot of strange stuff over the years to adapt these engines to various commercial and military uses, while someone may have made custom modifications to the heat exchangers you now have. Your heat exchangers likely have the style of flanges shown in your link, but that is just not 100% guaranteed.

Do you intend to get your heat working?

Wed Jul 02, 2025 1:04 pm

Wildthings wrote: Pull your heater boxes before you order anything, as it's important that they fit your heads. WV made a lot of strange stuff over the years to adapt these engines to various commercial and military uses, while someone may have made custom modifications to the heat exchangers you now have. Your heat exchangers likely have the style of flanges shown in your link, but that is just not 100% guaranteed.

Do you intend to get your heat working?

I’ll do that.
I’m not that keen on having working heater boxes, but due to points folks here raised about the connectedness of the system at least up to if not from the boxes being important to engine temperature, I’m just happy to have things connected and sealed.

Thu Jul 03, 2025 2:03 pm

removing the heat exchangers could be as simple has just removing a few nut and bolts,it could also be a real nightmare,with broken exhaust studs,and pulled treads,uneven surfaces not sealing on install,

Thu Jul 17, 2025 3:23 pm

lil-jinx wrote: removing the heat exchangers could be as simple has just removing a few nut and bolts,it could also be a real nightmare,with broken exhaust studs,and pulled treads,uneven surfaces not sealing on install,

It technically could have been a 20-30 minute job with the back needing jacked, the push rod covers being unscrewed, the heat exchanger cables being unpinned, unbolting the exhaust, and the 8 boots holding the heat exchangers in being taken out. However it took 4 hours as half the tin push rod cover screws sticking. However the 2 exchangers are off. Here is the underneath. Do you reckon they are regular/stock 1978 connections?

Here are the two heat exchangers, both in poor/very poor shape

Thu Jul 17, 2025 3:59 pm

1979 or later square port