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Fri Oct 14, 2016 2:11 pm

scrivyscriv wrote: Ouch! I need some aloe Vera gel for that burn!

actually - the flanges you welded in are probably the best solution for anyone except a pure factory resto.

Fri Oct 14, 2016 3:57 pm

I know the OP says he's not in to welding but honestly the slip fittings are one of the worst designs of the exhaust system. VW must have thought so too or they wouldn't have dumped them and gone to a fully flanged system on the T4. Not to mention modern engines are all flanged.. It took me an hour or two to get everything done with the engine out of the bus and it is a long-term solution.

Fri Oct 14, 2016 4:09 pm

scrivyscriv wrote: I know the OP says he's not in to welding but honestly the slip fittings are one of the worst designs of the exhaust system.

It's the worst piece of design on the whole car, IMO.

Fri Oct 14, 2016 11:47 pm

GTV wrote: scrivyscriv wrote: I know the OP says he's not in to welding but honestly the slip fittings are one of the worst designs of the exhaust system.

It's the worst piece of design on the whole car, IMO.

No! We can not let our inadequate knowledge get in the way of beautiful factory engineering! The aluminum heads MUST expand in the fore/aft direction while still maintaining a tight seal on all exhaust flanges. The T4 exhaust system gets flanges because the head has complimentary vertical exhaust, not competing exhaust angles.

By having a donut gasket with proper RTV, there is enough freedom in the joint to allow for a 0.06" (give or take) expansion of the aluminum T1 head from winter start to hellish hillclimb.

IF you are going to flange the joint, the only way to avoid cracking a weld or leaking at a seam is to use a gasket like the thick CB graphite compression gasket that can seal cold and hot, due to its expansion characteristics that match what the system will be doing during heat cycles.

Skepticism; don't leave home without it.
Robbie

PS- 70crew, do you have those exhaust clamps we threw away at your house? I'd like to cut them open to show this thread that clamps made these days are NOT as good as clamps made years and years ago. Those cad-plated clamps were utter shit. Perhaps I'll have to sharpie up an illustration otherwise…

Sat Oct 15, 2016 3:22 am

GTV wrote: scrivyscriv wrote: I know the OP says he's not in to welding but honestly the slip fittings are one of the worst designs of the exhaust system.

It's the worst piece of design on the whole car, IMO.

The OP (me) might be into welding if i was not time rich cash poor (i am out of work).
So my possible solutions for the joint between the heat ex and the exhaust are:
1) Building up the doughnut profile with HT silicone tape - prefered solution - can do it neatly and it has much cheapness using original clamps.
2) finding an appropriate 40mm silicone o-ring

Does anybody know what temperature it gets to in that area?

Sat Oct 15, 2016 7:53 am

I've used the donut clamps on my VW's for 35 years w/out leaks or issues. They do work well when the nipples are not undersized from rust. You also need to install the donut clamps in the right direction. One side of the clamp is meant to clamp down over the exhaust pipe side and the other side is smaller and is meant to squeeze down over the metal washer that pushes the donut up against the exhaust pipe flange, sealing it.

SSOO many folks don't get this and wonder why their clamps leak!

Sun Oct 16, 2016 6:00 am

...if it does leak a bit does it matter? The hot gasses have already been through the exchanger - as long as the engine compartment is sealed, and it does not whistle!

Sun Oct 16, 2016 7:42 am

wcfvw69 wrote: SSOO many folks don't get this and wonder why their clamps leak!

Please tell us where those magical exhaust clamps are to be had - or post a photo of some!
I have 7 clamp-halves at hand, both used and new, and they are all perfectly symmetrical . . . and obviously non-directional.

Sun Oct 16, 2016 8:21 am

kreemoweet wrote: wcfvw69 wrote: SSOO many folks don't get this and wonder why their clamps leak!

Please tell us where those magical exhaust clamps are to be had - or post a photo of some!
I have 7 clamp-halves at hand, both used and new, and they are all perfectly symmetrical . . . and obviously non-directional.

I don't have any pictures at the moment. I pitched all the olds ones I had as they were rusty. If you look at the diameter of the collars inside the clamp on the segments that grip the pipes, they are different sized. One side is meant to go over the exhaust pipe flair and the other side is meant to go over the donuts backer washer and squeeze the washer and donut up against the joint.

I bought my last kit from a VW parts guy. He's a 40 year VW guy and knows these old VW's better than most. When I bought this exhaust clamp kit from him, it was made by EMPI. I was venting about the leaks I was trying to eliminate. He "gently" asked if I knew that the clamps had to be installed the correct direction. I knew but let him explain it to me. He showed me the difference in the clamps inner clamping area from the front to the back.

Ironically, when I went and installed them on my bus, I initially still put them on backwards. When I turned them around, it was so obvious how much better they clamped and secured everything.

Sun Oct 16, 2016 8:22 am

Yes - an exhaust leak there is a problem. you'll get exhaust afterfiring, otherwise known as a backfire, from oxygen getting in and igniting the mixture in the exhaust. Not to mention a noisy exhaust

Sun Oct 16, 2016 8:32 am

Oops, I did take a picture for someone else in the past. This is obviously looking down. You can see the difference in the picture in the inside diameter of the gripping area to the top.

Sun Oct 16, 2016 7:11 pm

wcfvw69 wrote: You can see the difference . . .

Actually, all I see is a couple clamp halves tilted away from the camera so that the far side is more visible. I can arrange my clamps here (that have equal openings
on each side) so they look the same as your photo.

If the clamps were originally designed and intended to have an IN and OUT side, I find it extremely odd that there isn't a single mention of this in any
service manual or other literature, by VW or third parties, anywhere, ever. Nor will you find any clamps marked "this side out/towards muffer" or whatever.
Only the occasional guy on some Internet forum making these claims. It's usually
stated that it's because the tailpipe/H.E. stub is a little smaller in diameter than the muffler socket they fit into, but it is never explained how that is in any
way relevant, seeing as how the clamps do not touch the OD of any of those: they only clamp onto the flanged lip/conical washer.

I suppose some of the aftermarket clamps might have one lip longer than the other, but I'd say that's just the result of sloppy manufacturing (a very common thing
with VW aftermarket parts, y'know).

Based on the available evidence, I vote: Just Another VW Aircooled Internet Myth.

Sun Oct 16, 2016 10:27 pm

kreemoweet wrote: wcfvw69 wrote: You can see the difference . . .

Actually, all I see is a couple clamp halves tilted away from the camera so that the far side is more visible. I can arrange my clamps here (that have equal openings
on each side) so they look the same as your photo.

If the clamps were originally designed and intended to have an IN and OUT side, I find it extremely odd that there isn't a single mention of this in any
service manual or other literature, by VW or third parties, anywhere, ever. Nor will you find any clamps marked "this side out/towards muffer" or whatever.
Only the occasional guy on some Internet forum making these claims. It's usually
stated that it's because the tailpipe/H.E. stub is a little smaller in diameter than the muffler socket they fit into, but it is never explained how that is in any
way relevant, seeing as how the clamps do not touch the OD of any of those: they only clamp onto the flanged lip/conical washer.

I suppose some of the aftermarket clamps might have one lip longer than the other, but I'd say that's just the result of sloppy manufacturing (a very common thing
with VW aftermarket parts, y'know).

Based on the available evidence, I vote: Just Another VW Aircooled Internet Myth.

Believe what you want. I can care less..

Sun Oct 16, 2016 10:35 pm

kreemoweet wrote: wcfvw69 wrote: You can see the difference . . .

Actually, all I see is a couple clamp halves tilted away from the camera so that the far side is more visible. I can arrange my clamps here (that have equal openings
on each side) so they look the same as your photo.

I have seen more than four varieties of this style clamp, and I can't say I've ever looked for asymmetry. I CAN say with good authority that there are aftermarket clamps on the market today that do not have the necessary architecture to grab the flange on the muffler and washer. (They crush down radially, and should be avoided. Look for the classic EMPI gold-cad plated color.)

There are probably some clamps that are asymmetrical and some that are symmetrical. Chances are we're all just looking at different clamps. It's the old two-colored suit story the Reverend used to tell us.

Flanged, properly,
Robbie

Sun Oct 16, 2016 10:43 pm

Nah Robbie,

This is a fact that these clamps made by VW and other vendors are exactly like the picture shown. I was educated about them back in the 80's. The parts guy I used at what was once BAP (John) know's his stuff as a 40 year VW parts veteran. As I mentioned above, he gently reminded me of this w/those clamps when I bought the kit.

You can lead a horse to water but can't make it drink. But then again, some people believe there was a shooter on the grassy knoll or we landed on the moon in a studio..

Signed, Mr. Happy with the stock, non-leaking heater box junctions on his 3 VW's with the clamps properly orientated. :D

Mon Oct 17, 2016 3:04 am

scrivyscriv wrote: Yes - an exhaust leak there is a problem. you'll get exhaust afterfiring, otherwise known as a backfire, from oxygen getting in and igniting the mixture in the exhaust. Not to mention a noisy exhaust

Even though the exhausting gasses have expanded in the larger volume of the heat exchanger, they will still be at positive pressure, so any minor leak will be outwards rather than inwards, I would have thought.

With a tuned carb, no backfiring and no noisy exhaust, no problem?

Mon Oct 17, 2016 3:18 am

wcfvw69 wrote: I've used the donut clamps on my VW's for 35 years w/out leaks or issues.

Out of interest compared average rainfall:

Arizona: 8in
UK 45in

So in 35 years...

My maths must be wrong I need a snorkel!

The buggers salt the roads too here and the rain is acidic.

...and the o-rings only seem to come in wire wool this side of the pond.

Mon Oct 17, 2016 6:54 am

Skater 8 wrote: wcfvw69 wrote: I've used the donut clamps on my VW's for 35 years w/out leaks or issues.

Out of interest compared average rainfall:

Arizona: 8in
UK 45in

So in 35 years...

My maths must be wrong I need a snorkel!

The buggers salt the roads too here and the rain is acidic.

...and the o-rings only seem to come in wire wool this side of the pond.

I get what you're laying down here about the salt and acid rain's impact on that junction and the rust it will cause. My assumption was not many people drive these classic VW's on salty winter roads. However, with acid rain in the mix as well, you should absolutely follow Robbies suggestion and install flanges at that junction of your exhaust system.

Mon Oct 17, 2016 11:37 am

Skater 8 wrote: scrivyscriv wrote: Yes - an exhaust leak there is a problem. you'll get exhaust afterfiring, otherwise known as a backfire, from oxygen getting in and igniting the mixture in the exhaust. Not to mention a noisy exhaust

Even though the exhausting gasses have expanded in the larger volume of the heat exchanger, they will still be at positive pressure, so any minor leak will be outwards rather than inwards, I would have thought.

With a tuned carb, no backfiring and no noisy exhaust, no problem?

Hmmm, try again on that one. Gasses expand with heat, and with combustion happening at 1000* f or higher, the exhaust gas in the heat exchanger has cooled and therefore shrunk substantially. It's why we can get away with a tailpipe smaller than our four manifolds; the gas shrinks in volume so much by the time it gets there. (Mass is still the same.)

Because the joint is only for one of the four cylinders, and the camshaft has some sort of overlap, it won't always be under tremendous pressure. There just has to be a few molecules of oxygen in there to catch any remaining fuel hydrocarbons and create exhaust combustion that we hear as backfires.

Robbie

PS- I don't recommend the flanges. I don't recommend the donuts either. I recommend doing whatever you decide is best for your car. I would love to see a third system that takes all aspects of the original design and function into account. So far I have never seen this.

Mon Oct 17, 2016 11:57 am

Maybe you could try smooshing a few fingers of the orange RTV all into the wire mesh donut, and build a layer on top of that once it cures. I think that would be about as close to a silicone O-ring as you can get.

Robbie, my exhaust is a non-stock header and muffler, and has a lot more flex than a stock exhaust - which, ironically, is the reason why donut clamps tend to leak, according to John at aircooled.net