My heat exchanger restoration project updated 10-1-11

[scrivyscriv]

[tootype2crazy]

I use an oxy/acetylene torch with a small brazing tip. I use flux coated brass rods. Heat the metal until it glows orange and then get the torch into the area to be brazed and add the rod just behind it and go in circular motions as you move along with the torch ahead of the rod with the torch at a flat angle, preheating the metal. And wear dark sunglasses while brazing.
_________________
air-cooled or nothing for me
1978 Sunroof Deluxe Bus (daily driver)
1978 Transporter (mom's, making into a camper)
1970 Single Cab 2.1 turbo/EFI 6 Rib, 78 front beam, vanagon backing plates on rear (project)
2001 GTI VR6 (wife's)

[vwwestyman]

My heat exchangers have been soaking for most of the day in the phosphoric acid, and are significantly less rusty looking. I'll leave them in overnight to get the rest.

Do I need to do anything special after they're done soaking? Just rinse them off and rinse them out?

I've got the flame proof paint too. Should I just rinse 'em off, dry them, and paint away?

--Since typing that, it appears from the Krud Kutter website that yes, you should rinse then paint. It also states that allowing it to dry on unpainted metal will protect it up to 12 months. I wonder about painting them, and then redipping them after it is cured, to add a layer on the inside? Hmm.

I think I'm going to use some high-temp silicone to seal up all the edges once the paint is cured. I'm not super concerned about if it doesn't look real pretty.

BTW, the price has gone up! At my Home Depot, they only had Behr brand concrete and etch cleaner which google told me was phosphoric acid. That was $20/gallon! I found some more at Mendards under the name Krud Kutter Driveway Cleaner/Etch for about $13/gallon. They (Krud Kutter) offer several other rust preparations that all just contain Phosphoric Acid, per their website. Just different labels for different uses. (I find this is true of many different cleaning products.)
_________________
Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[vwwestyman]

Well my VHT Flameproof painting attempt was a disaster!

I had decided to leave the acid layer on the exchangers, because the Krud Kutter site said it was OK for some paints. The website also said that you had roughly 48 hours after rinsing to paint before rusting occurred, but I had flash rust very quickly when I rinsed the first layer off. So I sprayed another layer, which killed that rust and decided to leave it on.

Last night I was able to paint the things and I was careful to get each layer on after 10 minutes or so of the one prior, like the cans say. I believe I did two layers of primer and three of the black top coat.

So then I baked them and stunk up the whole house! I should have had a fan in the window, I guess but I did have all the windows open and the kitchen fan on most of the time. But the smoke alarm in the kitchen went off when I switched to clean mode and the house still smelled this morning. I think part of the smell this morning is maybe it permeated the furniture so I febreezed everything.

But this is the result:

After brushing off with my hand really quickly:

I can see some of the marks left by the acid under what appears to be the first layer of primer.

So what it looks like is that the first layer of primer stuck, but the second layer of primer didn't stick to the first, and the two separated for some reason? Weird.

Any thoughts as to why? I did stick them in the oven when the paint was still tacky in some places because the can didn't specify a dry time between painting and baking and I figured that the initial warming of the oven would finish drying the paint as the baking started.

So do ya'll think the problem was the acid? (Looks like the first layer of primer stuck just fine so I'm not sure this is it.)

Or the fact that it wasn't totally dry when it went into the oven?

Some freako thing that happened?

Where should I go from here? Attempt to clean up all the loose stuff, spray a new layer of top coat, and rebake it? (With a fan in the window!) Assume that the primer layer that stuck will protect it OK?

Maybe I'll just slather a big thick layer of high-temp silicone all over the cases, and waterproof and insulate them all in one fell swoop!
_________________
Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[Mr.Duncan]

Looks like whatever paint was on them to start with was not stripped off.

And that it peeled up from under the new paint.

Here are mine after painting with VHT and cooking in my oven... (smelled my whole apartment up)

_________________
(Owner) www.vintagecarleds.com

Red 1971 Squareback Thread
Red 1966 Beetle Thread
---------------------------------------------------
1971 Green Super Beetle (sold)
1966 Ghia (sold)
1971 Blue Super Beetle (sold)
1966 Java Green Std Beetle (sold)
1971 Red Squareback (sold)
1966 Red Beetle

[vwwestyman]

[ROCKOROD71]

Every direction on the VHT can must be followed for success. There is a good thread in the stickies detailing the process. I sandblasted my heater boxes, used the dremel wire wheel to get any small missed spots, then painted with VHT primer as directed, then with the top coat as directed. Then you have to let them cure for a while before baking, like days. I let mine sit for like 10 days, then I baked them. mine came out much like Mr. Duncan's did. I think the acid dip is where you failed. The VHT needs CLEAN CLEAN metal to adhere to. No rust, no paint chips, no oil or grease. Clean metal.

My one tip to offer for the home baker is to used a piece of solid metal to lay the pieces on, or else some how hang or suspend the pieces when baking. I used tin foil to cover the racks in the oven, and anywhere on the heater box that touched the rack, the paint "melted" around the rack, leaving a little divot and exposed metal. It only happened on the boxes and not the other pieces I did (manifolds, u pipes) probably due to the weight.
These areas I just touched up with a few blasts of the top coat. I'm sure they'll be the first to rust down the road.
_________________
1971 STD BEETLE- DD-1st car, 1st love. keepin' it stock! 1600DP, Solex 34-3 Mexi Bosch SVDA Dist NOW w/POINTS
1977 WESTY "KrustyKamper" 2L FI

[vwwestyman]

I never updated the thread.

I eventually took the exchangers to be sand blasted. Got all that flaky paint off.

I used Rustoleum brand super high heat paint instead of the VHT paint for round two. I chose it for a couple reasons: First, it was a few bucks cheaper and I was feeling like I had put too much money in these "cheap" exchangers, ha ha. Second, according to the instructions on the can, each layer could be added after less time, and I didn't have to wait days to bake, just a few hours.

That round turned out much, much better. I suppose over the long term, we'll have to see how well they hold up but they look nice and the paint survived being dinged up moving the engine around when installing and some amount of scraping on the garage floor.

I used high temp silicone sealant to fill the gaps where the covers had rusted away from the exhaust pipes. I also used it to seal the exchangers to the fan shroud, and the heat riser pipes to the exchangers.

So far, it seems to be holding up pretty well.
_________________
Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[airschooled]

[vwwestyman]

[tootype2crazy]

My original VHT paint held up about a year, after which it started to show some signs of of coming off. Now I have a yearly pre-winter ritual where I hit the exchanger with weak muriatic acid in situ, then baking soda to deactivate the acid, then air dry and then slather on a thick coat of barbeque paint from the local fireplace store. That holds up real nice for about a year until I have to do it again. If you want to have some nice heat exchangers, live in the midwest, and drive year round it's just a thing that must be done.
_________________
air-cooled or nothing for me
1978 Sunroof Deluxe Bus (daily driver)
1978 Transporter (mom's, making into a camper)
1970 Single Cab 2.1 turbo/EFI 6 Rib, 78 front beam, vanagon backing plates on rear (project)
2001 GTI VR6 (wife's)

[FNGRUVN]

I thought I'd add to this thread on how I fixed the other style of heat exchanger. This style of heat exchanger is easier to fix than the OP's exchanger, since you're only wrapping one pipe.

Here's what I started with. Typical wallowed out end, with the shell flopping around, sawing through everything it touches.

At first, I tried to just weld sheet metal strips end-to-end to cover the holes. It looked like hell and was turning into a puzzle and I hate puzzles. Plus, I read where busdaddy says the weld will crack between the pipe and the shell.

So I got an idea to use slices of pipe, cut in half and welded to the repair metal. Then weld the repair piece in place.

I used some 2" OD x 1/8" wall pipe and cut four 1/4" wide pieces.

I cut these pieces in half and then took a 2" hole saw to cut out the sheet metal.

I welded the sheet metal to the pipe pieces and cut the sheet metal to size.

All I had to do after that was weld them in place. I tacked the new pipe section to the exhaust pipe. If the weld breaks there it won't be a big deal. I hammered the new sheet metal to conform to the shell as I tacked it in place.

I'm pretty happy with the results. Now, I just have to do five more, but it beats shelling out about $700 a pair for new ones.
_________________
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." - Benjamin Franklin

[tootype2crazy]

Thanks for adding this information to my thread! I appreciate it. Good job, too.
_________________
air-cooled or nothing for me
1978 Sunroof Deluxe Bus (daily driver)
1978 Transporter (mom's, making into a camper)
1970 Single Cab 2.1 turbo/EFI 6 Rib, 78 front beam, vanagon backing plates on rear (project)
2001 GTI VR6 (wife's)

[FNGRUVN]

Thanks. You had a tougher task with wrapping two pipes, but you did an excellent job.
_________________
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." - Benjamin Franklin

[ivwshane]

[BusBerd]

[vwwestyman]

Wow, sometimes it is weird to re-read your own words years later!

I would say overall they have held up decently well, though there are speckles of surface rust starting to show up over the shells. Not terrible by any means, but also not like new by any means.

I think in general what I would say is I've probably gotten my money's worth out of the project from 2014, but maybe next time I have the engine out for a while and plan for the Bus to be "down" for a little while, I may plan to redo the project to extend the life of the heat exchangers. Maybe whenever that happens, I'll separate as described in other threads and remove whatever it is that is lining the insides.

Since that time, I have used Master Series paint for some other projects. I'd need to research how it holds up to heat, but I bet it would probably do a good job of protecting these things.
_________________
Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[edhnb]