Heater box and CO questions

[SYS64738]

Using a CO detector and looks like I'm getting a pretty high read in the cabin with the windows closed. (goes to 0 with the windows open) But if I hold it near the heat ducts it goes up even higher. (behind the seats, and somewhat on the dash)

So I assume this points to exhaust leakage into the heater boxes, muffler, or both? Although I don't see any obvious holes they all look very rusty and crusty. Also it looks like the cables to the heater box flaps are disconnected.

But I'm really only driving in fair weather and don't need heat so in the short term can I just disconnect the connector tubes that go from the heater boxes to the cabin pipes and cap the cabin pipes and let the heater boxes just blow out under the car? Or plug the heater box ends too?

Or is this a horrible idea and I really need to get these diagnosed, fixed or replaced? First priority is to solve CO in the cabin. Heat is not needed so could consider J-tubes, or also willing to replace heater boxes and/or muffler if it just makes sense to keep the whole system operational.

Appreciate any advice!
Thanks!
(also happy to post a bunch of pics I took of the underside if that helps)

[Era Vulgaris]

You can remove the plastic bellows tubes between the heater boxes and the body. No harm just letting the heat out to the atmosphere under the car. It's what happens when the heater box flaps are closed anyway (sounds like yours are stuck open). You want to allow air to flow over the heat exchangers, to dissipate the heat they create. If you don't, that heat will eventually soak into the heads, which is not good.

I would plug the holes in the body though, just so critters don't get into your heater channels in the rockers, and possibly into the cabin.

If it were me, I'd eventually get some replacement heat exchangers just to keep everything stock.
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Currently own:
66 Karmann Ghia, L390 Gulf Blue, under construction, here: www.thesamba.com/vw/forum/viewtopic.php?t=760505&highlight=
99 Mazda MX-5 10AE, Sapphire Blue Mica, 6 speed, LSD

Previously owned:
98 Porsche Boxster, silver, 2.5L -- 67 Karmann Ghia, Black, 1500sp -- 98 BMW Z3, Atlanta Blue Metallic, 2.8L I6 -- 75 Porsche 914, Laguna Blue, 2270cc -- 72 Porsche 914, Signal Orange, 1.7 FI -- 74 Karmann Ghia, Black, 1600dp -- 74 Triumph TR6 with O.D., sapphire blue

[runamoc]

[SYS64738]

Great, thanks both for the advice! Love the rattle can cap suggestion, i'll give that a try.

Re: the functioning of the disconnected flaps, are they supposed to be connected to one of those lever arms beside the e-brake? the cabling is all there but I can see that it looks like someone intentionally disconnected them and did a little curl back on the cable coming from the cabin.

i'm not going to mess with them now, will just disconnect the plastic tubes and let them blow out to dissipate the heat, as you suggest Era. but i'm just curious on the intended function of those flaps, and if they are closed where does the air then go? Is it forced back through the tubes and out the muffler? Or is there some other vent hole where the air is released?

thanks for my dumb questions!

[Era Vulgaris]

Yes, one of the levers by the ebrake will control the opening/closing of the flapper valves on the heat exchangers. Depending on the year of your car the other lever will control the opening/closing of only the rear floor heat vents, or both the front and rear floor heat vents.
_________________
Currently own:
66 Karmann Ghia, L390 Gulf Blue, under construction, here: www.thesamba.com/vw/forum/viewtopic.php?t=760505&highlight=
99 Mazda MX-5 10AE, Sapphire Blue Mica, 6 speed, LSD

Previously owned:
98 Porsche Boxster, silver, 2.5L -- 67 Karmann Ghia, Black, 1500sp -- 98 BMW Z3, Atlanta Blue Metallic, 2.8L I6 -- 75 Porsche 914, Laguna Blue, 2270cc -- 72 Porsche 914, Signal Orange, 1.7 FI -- 74 Karmann Ghia, Black, 1600dp -- 74 Triumph TR6 with O.D., sapphire blue

[Eric&Barb]

[SYS64738]

There's some of my pics showing the heater boxes from the rear, the muffler, and one of the disconnected cables. All looking very rusty, clearly some oil wetness coming down too.

[Eric&Barb]

[Eric&Barb]

[SYS64738]

Hey, thanks for taking a look and that's encouraging if you think they still look ok, I won't write them off yet. I will check those connections and thanks for pointing out the missing nuts in the tin sheet!

Unfortunately don't have great pics of the engine bay and the car is not with me at the moment. Will probably be some weeks before I catch a window to get it jacked up on stands again and have a chance to poke around.

Here's just one pic I had of the engine bay but really only showing one side where the air duct goes down to the heat exchanger.

Thanks!

[SYS64738]

While I'm at it figured I'd include the rest of the heater box pics I took, from the sides and front in case that gives any more detail on what I'm working with.
Thanks again for taking a look!

[runamoc]

the manifold pre-heater pipe being rusted away completely would give a 'clue' to were the exhaust fumes are coming from
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Daily driver: '69 Baja owned 45 yrs - Plan B: '72 Ghia
Yard Art: 2 Sandrails
Outback: '69 Ghia - '68,'69,'70,'72 Beetle - '84 Scirocco, GTI - Pair of '02 Golfs- '80 Rabbit Diesel
VW Wiring = It's just wires

[Eric&Barb]

[SYS64738]

Again, thank you both! Yikes, yes I see what you mean now. That pre-heat tube is totally destroyed, and all that soot.

So I assume this is a muffler replacement, yes? That heat riser tube is directly connected to the muffler? Any recommendations? I've been getting stuff from cip1 as they are near by in canada and ship well. There's a lot of dansk mufflers, and there seems to be different variations of heat risers, left side or right, and some dual. I think looking for right-side heat riser?

And thanks for all the tips on the engine, I will send more pics when I can, and really appreciate the problems getting pointed out.

Thanks!
Ken

[SYS64738]

I'm looking at this replacement muffler because it's the only I've found so far that appears to have the pre-heat pipe on the passenger side.

https://www.cip1.ca/vwc-113-251-053-ger/

Does this seem right, or should I be looking for something else?

[Eric&Barb]

[Eric&Barb]

This one would be the better buy if same price as the due to thicker metal and has same heat riser piping.

https://www.thesamba.com/vw/classifieds/detail.php?id=2714275
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In Stereo, Where Available!

[SYS64738]

Hi All, thanks again for the help and advice!

Got the new muffler installed and looks like that solved the CO issues in the cabin!

So all the other issues remain and trying to tackle them, but here's my most immediate issue now...

I started with tackling the missing screws in that tin sled beside the heater box so I removed it so I could clean it up and test the other screw sockets and the all seem good. But when I tried unscrewing the one side screw holding it to the cylinder case (if that's the right term?) the head just twisted off so now the rest of that screw is just embedded in the case metal.

So, two things, I need to get two more tin screws (as I only had the one) and wondering the size? 6x10mm?

And mainly what should I do now about this busted off screw? I could just put the tin back with 3 screws but without the one connecting to the block I assume it might be a bit rattly? I certainly don't have tools to bore out and re-thread that screw stud. Would it be a horrible idea to try getting a self tapping metal screw and twist it in there? (if that would even work?)

Thanks!

[Eric&Barb]

[SYS64738]

Thanks Eric&Barb!

I did end up getting some stainless screws but so far only have them in the tin and not touching the engine case so hopefully that's ok. (magnet sticks to the tin so assume it's steel)

Good suggestion on the drill plan. I'll give that a try. It's in with 3 screws right now (into the tin) and feeling quite solid, way better than before, but I'm sure if I can get it bolted to the engine case it will be better.