Heat exchanger restoration

type11969 · Posted: Wed Dec 17, 2008 1:24 pm Post subject: Heat exchanger restoration

After taking a look at the couple of rusted areas on my heat exchangers and what seems to be a half quart of oil that has made it in to each, I decided to split them open to clean them out (no oily smelling heat!) and to make the welding repairs easier. I notched the joining flanges with a cutoff wheel every inch or so to aid in lining the halves back up and then I ground off the folded over flap. Here is the end result, after a decent amount of scrubbing:

Image may have been reduced in size. Click image to view fullscreen.

Does anyone know what the thick mesh material is on the aluminum U that sits in the exchanger half like so:

I'd like to replace it, it has absorbed a lot of oil and can't easily be cleaned without shredding it.

Definitely have my work cut out for me to get these repaired and back together but the increased heat output and decreased smell certainly will be worth it.

-Chris
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keifernet · Posted: Wed Dec 17, 2008 1:29 pm Post subject:

Try a thick "roven woven" type "heat wrap" material you can get at marine outlet type places to heat wrap hot pipes on marine engines. If you can't locate it local LMK I live in an area of S.TX with plenty of boat/yacht stores that sell the stuff...

busdaddy · Posted: Wed Dec 17, 2008 1:30 pm Post subject:

The mesh is asbestos based IIRC, try soaking it in warm Simple green for a day or 2. Or look at header wrap or wood stove gasket as a replacement.
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type11969 · Posted: Wed Dec 17, 2008 1:31 pm Post subject:

I've got some header wrap lying around that I was thinking about using but I don't think it is this woven rope variety you speak of . . . I will look around, thanks for the tip.

-Chris
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1969 VW Beetle - t4ed indeed
1971 Porsche 914 - jackstanded
1976 Westy - DD

Wildthings · Samba Member Joined: March 13, 2005 Posts: 52298

Wish someone would make some new SS covers or at least some repair pieces for around the pipes. Every air leak counts. Sad

WendyArmbuster · Posted: Thu Dec 18, 2008 11:53 am Post subject:

Somebody really should make replacement heat exchanger clamshells, in stainless or regular even. More people would have the ability to weld carbon steel clamshells together than stainless. I have been toying with the idea of making some, but trying to design them so that you don’t need a million bucks worth of press dies is challenging. They seem like they would be simple to make something crude, but they are actually pretty intricate. I think if a person waterjet or laser cut some sheet stock correctly, they should press into place with a wooden die and a bottle jack, then you could just weld up the seams. I estimate that the material and waterjetting should cost about $140 for all four halves, maybe a bit less if you made a bunch. Lets say 45 minutes to weld all 4 halves into shape. If I were making these I would charge like $220 for a set of 4 heat exchanger halves that you weld together over your existing manifolds.

Really though, the people that are already making heat exchangers should just sell the clamshells. Apparently the aluminum castings on the new manifolds are the part that sucks, so it would be the best of both worlds, if you had good manifolds but rusty jackets.

type11969 · Posted: Thu Dec 18, 2008 12:06 pm Post subject:

I think the clamshells could be replicated pretty easily if you were willing to sacrifice originality and maybe some functionality. For instance if the blower motor attachments were ditched that would simplify the clamshells. And if the lead off to the heater tubes wasn't as nicely contoured (imagine a straight tube going out as opposed to the nice sloping contoured sheet metal). Finally if the attachment to the fan housing could somehow be made with silicon tubing (an adapter of some sort to change the shroud attachment to a circular shape maybe), that would bring the clamshell down to basically 2 formed Us with tube inlets/exits and, of course, the formed flanges to go around the actual exhaust manifold. I think that would be pretty easy and inexpensive to make.

-Chris
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1969 VW Beetle - t4ed indeed
1971 Porsche 914 - jackstanded
1976 Westy - DD

cardinal0128 · Posted: Thu Dec 18, 2008 4:38 pm Post subject:

Is that mesh exposed to the air stream that flows into the cabin? If so, is there a risk here?

What year were these exchangers from?
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type11969 · Posted: Thu Dec 18, 2008 4:57 pm Post subject:

From a 76. The mesh isn't directly in the flow path, it surrounds that aluminum tin and that tin caps off the channels in the aluminum casting that goes around the manifold. Those channels are the flow path. Indirectly, yes, they are in the flow path. But my guess is that the .5 quarts of oil in anyone's heat exchangers poses more of a carcinogen risk than the potential asbestos in that mesh.

-Chris
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1969 VW Beetle - t4ed indeed
1971 Porsche 914 - jackstanded
1976 Westy - DD

fusername · Posted: Thu Dec 18, 2008 5:02 pm Post subject:

my guess is that stuff insulates the hot air flow from the outside of the heaterboxes. could probably just replace it with woven FG mat?
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type11969 · Posted: Thu Dec 18, 2008 5:08 pm Post subject:

I'm replacing mine with asbestos free header wrap . . . dont think it is necessary but while I am in there . . . .
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1969 VW Beetle - t4ed indeed
1971 Porsche 914 - jackstanded
1976 Westy - DD

Bookwus · Posted: Thu Dec 18, 2008 6:36 pm Post subject:

Hiya All,

Very interesting!

Has anybody tried disassembling a Type 1 heat exchanger for clean-out and renewal? I've been thinking about that and was just wondering if anybody out there in Sambaland had already "been there, done that" and had any tips.
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type11969 · Posted: Thu Dec 18, 2008 6:38 pm Post subject:

I would think that the integration of the control valve in the t1 exchangers would make it a bit more complicated but in the end, it is just sheet metal so it probably isn't too complicated.

-Chris
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1969 VW Beetle - t4ed indeed
1971 Porsche 914 - jackstanded
1976 Westy - DD

Bookwus · Posted: Thu Dec 18, 2008 6:43 pm Post subject:

Hiya Chris,

My thoughts exactly.

Just wondering if anybody actually had pulled a T1 heat excahnger apart. I'm a big believer in not having to reinvent the wheel.
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Wildthings · Samba Member Joined: March 13, 2005 Posts: 52298

panic311 · Posted: Fri Sep 17, 2010 6:00 am Post subject:

My heat exchangers are GRIMY! Is there a way for me to clean the insides, that appear to be covered in a layer of oil and grime, without taking them apart? Can I take them to a machine shop for a hot bath? Can I safely do something myself to save a few bucks? Thanks Very Happy

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type11969 · Posted: Fri Sep 17, 2010 6:19 am Post subject:

I think if you soaked the whole exchanger in hot water mixed with some simple green, etc, then followed up with some blasts of water through it, you might get some of that gunk out. But . . .

The consensus is that there is asbestos in the matting inside the heat exchangers . . . I'm not sure you would want to disturb it in this way.

-Chris
_________________
1969 VW Beetle - t4ed indeed
1971 Porsche 914 - jackstanded
1976 Westy - DD

panic311 · Posted: Fri Sep 17, 2010 6:30 am Post subject:

Yeah, that's kind of what I figured....I have gone a few winters without heat....why start now?? Wink

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"You don't need a weather man to know which way the wind blows"

1974 Westfalia (The Treehive)
1.8L running a single Weber Progressive and a 009 dizzy

type11969 · Posted: Fri Sep 17, 2010 6:41 am Post subject:

Take em apart, pull the asbestos out with the exchanger under water, use fiberglass matting instead (think exhaust header wrap cut into strips), and put them back together. Fix any pinholes, etc while you are at it, and paint the inside with some high temp paint. You can carefully unfold and then re-fold the crimp . . . I just cut off the crimp and tacked mine back together.

Having heat is nice!

-Chris
_________________
1969 VW Beetle - t4ed indeed
1971 Porsche 914 - jackstanded
1976 Westy - DD

panic311 · Posted: Fri Sep 17, 2010 8:08 am Post subject:


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