TheSamba.com :: View topic - Three questions about Type 4 rear engine tin

Mon Nov 23, 2015 9:21 pm

For reference. Engine is a '76 GD-code Type 4:

Q1: Which tin should be on top where the left rear (#14) and center rear (#15) tins overlap and screw/bolt together?

Q2: Both the center rear(#15) and right rear(#13) tins have rectangular cutouts along their front edges where they butt up against the shroud. Any idea what these cutouts are for? They don't seem to align with anything. Are they to remain open to allow draining water or something??

Q3: I'm noticing my center rear and right rear tins don't seem to seal at all well against the fan shroud or alternator tin. During disassembly, I found fragments of some kind of thick black tape on the face of the shroud near where the left front face of the center rear tin would sit against the shroud. Maybe about 3 inches long or so. I got the impression some sort of seal was used but there wasn't enough left to tell much at all.
Looking at the diagram above, you'll see a part #19 near the right end of the right rear tin (#13). According to VW, this is p/n 021119543A, a seal 650MM (25.6 inches!!!) long and there are 2 of them used. Does anyone here know about these seals and where they are supposed to go? Please share as much detail as you know.

Mon Nov 23, 2015 9:26 pm

Wow. A new level of anal retentiveness. I joke because I to have faced this diabolical debacle. Only recently when my motor fell over and I had to re do some of these very pieces.

Yet I fail to find the strength to actually get up, go to the garage and see what mysterious path I chose?

Under or over :roll:

:lol: :lol:

Mon Nov 23, 2015 10:12 pm

I know you're just razzin' me, but I do want to make it clear this has nothing at all to do with authenticity and everything to do with trying to get my tin to fit and seal properly. The right rear tin was pried on by some gorilla with a screwdriver in the past and I need to get the center and right rear tins properly registered to the engine so I know which way to bend them to get them to sit against each other properly.

Which tin goes on top has a bearing on the angle the center tin sits, and it should be obvious which way is right, but because of the distortion of the right tin and possibly the right end of the center tin, I just can't tell any more.

The questions about the seals and cutouts is my effort to get an idea of what should and should not be sealed. Again, I thought it would be obvious when I put the tins together on the fan shroud, but it is not.

Heck, I could be asking about the right kind of screws to hold this stuff together, but I know better than that. :lol:

Mon Nov 23, 2015 10:25 pm

There was a foam sealing strip used between the tins and the engine originally, IIRC. It may have been used between piece of tin as well. I run beads of silicone in areas where the tin doesn't seal tightly and let it skin over well and then put the pieces together. This makes up for the original gaps along with any abuse the tin has taken over the years. Since the skinned over silicone will typically ooze out in a few places it will lock the tin to the shroud preventing relative movement, noise, and wear.

Without going out and looking I would say that the rear corner tin goes under the center tin. The slot for the one screw is there to make it easy to put the tin in place even with the screw already started.

Mon Nov 23, 2015 10:37 pm

Yes, there was some glued on foam on some seams and against the shroud originally, attached with sloppily applied contact cement like stuff.

Mon Nov 23, 2015 11:29 pm

This is a "Before" photo that shows the right and center rear tins in place against the shroud and alternator tins. You can click on the photo to see it a lot bigger.

Q1: Is the reddish goop that looks kind of like spilled strawberry jam the "contact cement like stuff" mentioned? Also, I wonder if that black residue to the left was what was left of the foam seal. When I pulled things apart, it was pretty much just oily goo.

Q2: Was there typically this much of a gap on the right where the alternator tin lip sits below the right tin? I have the original alternator tin and a better replacement and they both seem to intentionally flare out and down away from the right rear tin.

Q3: Back to the slot question posted earlier - is there supposed to be some kind of drainage? This seems contrary to sealing, but that alternator tin gap looks intentional (???)

Tue Nov 24, 2015 4:20 am

I recall asking myself the same question about whether the tin goes on top or under. I went with the roofing shingle concept where any rain getting into the engine bay would flow off the tin and over the seams, not into the seams. And like Wildthings, I use black silicone on any gapped or loose fitting tin. But I was also extremely fortunate to have a bone-stock unmolested engine to play with. All the tin fit nicely. Most of it still had the white stenciled numbers on each piece. :wink:

Can we see a pic of the square cutouts? I can't recall seeing those on the '77 I still wish I had.

Tue Nov 24, 2015 9:09 am

I know all in good fun :wink: I appreciate the level of detail when refinishing anything on old VW's. These little nuances get lost and are fun to back through and try to recreate.

My tin is sweet and perfect. It was also unmolested before I tore it apart. Ill have a closer look at my before pics and what it is now.

Tue Nov 24, 2015 11:27 am

I've been able to find one other "before" photo that shows the center tin in place under the left piece, which agrees with Wasted youth's shingle metaphor. The heat shield leg also seems to sit best against the left flange of the center tin as well.

I would still like to be able to compare with others (thanks, notchboy) so as to know for sure, as my bus originally had A/C and the compressor was removed and replaced with a hack tin patch by a P.O. I don't know that what remained of the original left tin was still in its original place.

Back to the rectangular cutout question. VW didn't put them there as decoration, and I'd really like to figure out if they should remain open or be sealed up. I've seen nothing to suggest they were added by a previous owner and they don't appear to align with any mechanical features. Here's a photo:

Tue Nov 24, 2015 11:45 am

Are there any fundamental differences in the slide-slot the tin rests in? Mine pictured is for 74. Maybe later tin has to accommodate the channels you show?

Tue Nov 24, 2015 12:20 pm

notchboy wrote: Are there any fundamental differences in the slide-slot the tin rests in? Mine pictured is for 74. Maybe later tin has to accommodate the channels you show?

I don't see any differences between our shrouds with respect to the "ledge" or "slide slot" that the tin sits on you've highlighted in red.

What are you referring to as the channels - are you referring to the tin forward edge cutouts? I'd posted that the cutouts in my last photo don't correspond to any mechanical features that I can see. Does your tin not have these cutouts?

Tue Nov 24, 2015 1:40 pm

I've got my center tin over on left, under on right. 73 dual carb. Might have done it wrong but didn't seem to make a huge difference to fit, in general it all took a bit of finessing. Ran bead of black silicone between as above.

Tue Nov 24, 2015 4:00 pm

eche_bus wrote:
I do want to make it clear this has nothing at all to do with authenticity and everything to do with trying to get my tin to fit and seal properly.

The two go hand-in-hand. You knew I'd say that.

Left 14 followed by center 15, followed by right tin. It all falls in place when it falls in place. There is a proprietary technique to rotating the right tin once it is over the oil fill pipe so it slips into place. I sure hope this is right,

You know you have to lay the muffler shield down before fitting those tins, then get the left side of the shield lined up with 14/15 sandwich, then the right side is not so annoying to line up from underneath.
Colin

Tue Nov 24, 2015 4:31 pm

I've wondered about the notches myself and can find no logical use for them, possibly another part gets punched out from the same sheet and infringes on a non critical area of the blank for that component?

Tue Nov 24, 2015 4:44 pm

Amskeptic wrote: eche_bus wrote:
I do want to make it clear this has nothing at all to do with authenticity and everything to do with trying to get my tin to fit and seal properly.

The two go hand-in-hand. You knew I'd say that.

Left 14 followed by center 15, followed by right tin. It all falls in place when it falls in place. There is a proprietary technique to rotating the right tin once it is over the oil fill pipe so it slips into place. I sure hope this is right,

You know you have to lay the muffler shield down before fitting those tins, then get the left side of the shield lined up with 14/15 sandwich, then the right side is not so annoying to line up from underneath.
Colin
Hi Colin,

I appreciate your help here! So left is on top, center below it. Got it. And if I understand correctly, it's important the shield foot is under the 14/15 sandwich so the angle of the 15 piece is correct and allows the right tin to sit correctly.

Do you know anything about where these tins were originally sealed and what the rectangular cutouts in the tin are for? Is the cutout in the right tin + the way it sits (big gap below) against the alternator face tin there to act as a drain or ???

Tue Nov 24, 2015 4:54 pm

busdaddy wrote: I've wondered about the notches myself and can find no logical use for them, possibly another part gets punched out from the same sheet and infringes on a non critical area of the blank for that component?

Quite possible there's no function, but I just gotta wonder why the right tin's notch sits about where the big gap between the alternator and right tin begins. Look again at this "before" photo. Why would the alternator tin's horizontal flange bend down and away from the right tin? I have two alt. tins and they're both shaped like this!

Tue Nov 24, 2015 9:45 pm

eche_bus wrote:

Do you know anything about where these tins were originally sealed and what the rectangular cutouts in the tin are for?

White caulk between right and center tin, white caulk sparingly applied to alternator face plate against fan housing, and a light caulk line along fan housing for left tin.

Cutout, as best I can tell is indeed a necessary drain for whatever air scoop water ingestion occurs or oil from sloppy fills. These tins all fit beautifully on the BobD, I gotta tell you. All hell breaks loose in a heartbeat the instant you have a backwards overlap or an annoyed disassembler.
Colin

Wed Nov 25, 2015 9:21 am

notchboy wrote: Are there any fundamental differences in the slide-slot the tin rests in? Mine pictured is for 74. Maybe later tin has to accommodate the channels you show?

That fan housing looks like the strange North American specification fan housing, with integral brackets for mounting an air pump, which was reputed to be something to do with exhaust emissions!?!