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  • Chillin' Louie (Part VI: Hoses, Holes, Grommets, and Bulkhead Connectors)

    Chillin' Louie (Part VI: Hoses, Holes, Grommets, and Bulkhead Connectors)

    Punching holes in the nose


    Before we make the hoses, we need to punch holes in a few places.


    The easiest ones are in the nose where the condenser lives. Hoses need to run there from the compressor and to the receiver-drier, so holes need to be cut. That immediately leads to two questions: Where and how big?


    There's a very useful table in my a/c book. You should buy the book anyway (seriously, you really should buy the book anyway), but I'll reproduce it below:


    Hose Size

    Commonly Used For

    Hose I.D.

    Hose O.D.

    Fitting (Tube) Size

    Thread Size

    Collar Nut Size


    Condenser to drier; drier to evaporator







    Compressor (discharge) to condenser







    Evaporator to compressor (suction)







    For the "where," there's a nose template on page 20 of the Behr installation manual, but you can basically put them anywhere you want, though it makes sense to put the hole for the inlet hose from the compressor at about the same level as the top condenser port, and the hole for the outlet port for the drier at about the same level as where the drier will go. Of course, that means you have to decide where the drier will go, and we'll get to that. 


    I marked the hole locations using the Behr template and drilled pilot holes, and didn't like them. I decided to use the Behr-located lower hole as the top hole, and put the lower hole directly beneath the top hole, as photographs showed it that way on my other '72 2002tii (since sold).


    IMG_6423_arrows.jpg The nose hole locations from the Behr template. I didn't like them.


    But before you drill the holes, you need to know how big they need to be. Which leads us to...


    The grommets


    Whatever the thick hooded rubber grommets were that were used with the Behr and other dealer-installed systems seems to be lost information. The Behr manual linked to above does list a part number, but googling it yields nothing. Astonishingly, I have yet to find a source for hooded grommets (ones with an overhang that faces forward) for a/c hoses. Companies like Nostalgic Air, Vintage air, Cold hose, etc sell generic universal a/c hose grommets that work for #6, #8, and #10 hoses, but a) they're not hooded so they're okay for the nose where you just want the hose not to get cut by the metal edge of the hole but not for the firewall where you want actual weather insulation, and b) the one-size-fits-all means they're a little loose for the #6 hose. Here's the link to them on Nostalgic a/c's site. I did buy them to use for the nose.


    The hole size for these grommets is 1 1/4". I have a hole saw that size (I used to have a Greenlee punch set which makes much cleaner holes, but I sold it in a round of garage cleaning this spring. D'oh!), so I had at it.


    IMG_6447.JPG The holes cut with the 1 1/4" hole saw. Yes I de-burred and primed them.


    IMG_6495_cropped.JPG ...and grommeted.

    Punching holes in the firewall


    Having punched the holes in the nose, the logical next step was the more harrowing one—punching the holes in the firewall. At one level, it's no different than the nose (it's the same sheet metal), but it's worse because:

    1. Unlike the holes in the nose, the firewall holes DO have to be weathertight.
    2. The clearance is tighter (you don't want to cut through a brake line).
    3. There's insulation on both sides you have to peel back or cut through.


    Seeing the 1 1/4" holes for the grommets I'd just cut in the nose, I had a visceral reaction—e.g., man, those are BIG-assed holes to cut in the firewall. Although I'd done, I believe, five other 2002 a/c rejuvenations, I'd never cut holes in an 02's firewall before. I had, however, cut holes in my E9 and my E24. I looked at the photos of the E24 installation, and realized that both the E9 and the E24 don't run hoses through the firewall at all. Instead, they both use copper pipes. They have to, as they run above the back of the glovebox, and hoses would never fit there. The copper pipes are much thinner than the rubber hoses, and thus the grommets and the holes that host them are smaller. That's why I didn't remember having the same reaction that "damn those are big holes."


    We now get into two closely-related topics. The first is exactly where to put the holes. The second is whether it's worth using bulkhead connectors instead of hoses.


    Exactly where to put the holes


    Every dealer-installed 2002 a/c I've ever seen has the hoses go through the firewall above the back of the exhaust manifold, then curve to the right to lean against the right inner fender wall or rest on the top of the right frame rail. The awful photo below is the only one of my cars I can seem to find, but you get the general picture—above the brake lines, and sort of above the exhaust manifold as opposed to tucked in the corner.


    IMG_4061 (2).jpg The near-installed engine compartment hose location on Kugel's Behr system (after rejuvenation)


    When looked at from inside the car, they emerge near the lower left corner of the glovebox, This makes sense, as it's not far from where they go into the evaporator assembly.


    IMG_4040.JPG The near-installed hose under-dash location on Kugel's Behr system (after rejuvenation)


    Now, there is a template for cutting these holes in the Behr manual (see link above), but the illustration simply says "contact line at heater case" and "upper contact line," neither of which are unique locations. The main thing is understanding where the holes need to come out in the engine compartment, because the brake lines are on the other side.


    If you look in the above photo, you see a bunch of wires coming through the firewall below the hoses. They're going through a hole that is present, I believe, on every 2002. If you pull back the insulation panel at the footwell, you'll see that, below the gas/vapor line, there's a metal plug covered with sealant.


    IMG_6412.JPG The mysterious 2002 firewall hole plug


    If you pop the metal plug off, what you see is the back side of the firewall foam (and, in my case, some corrosion having formed under the sealant).


    IMG_6413.JPG Firewall foam

    In my a/c book, I think that I erroneously state that this can be used for one of the a/c hoses. That's wrong. It can't be. The reason why is that it emerges directly behind the brake lines. If you take a thin screwdriver or a coat hanger and push it through the center of this hole, you can see in the engine compartment where it emerges:


    IMG_6415.JPG Surprise!


    Even though you can't use this hole for an a/c hose, it's still handy to see this, because in order to properly drill the holes, it's absolutely essential to understand how what you see from the engine compartment side corresponds with what you see from the inside.


    In the above image, there's something important in the upper left corner. It looks like a rusty lump, but it's the clip that holds the upper corner of the firewall insulation in place. It's important because, from the inside of the car, you can see where the back of this firewall insulation clip is spot-welded in place. That provides a very useful reference point between the inside and outside views.


    Below, I've provided something of a road map to the inner firewall. I've drawn a black rectangle that highlights the approximate location for the dealer-installed a/c hoses. To the right of that is the firewall insulation clip. Next are two black circles split around the clip that holds up the gas and vent lines. The #2 circle on the right represents the hole you can drill if you want a hose to emerge in the very right rear corner of the firewall, behind the ignition coil. To the right of the #2 black circle, you can see a bulge in the firewall. That's the inner fender wall. You can't drill there. If you drill to the right of that, the hole will come out in the wheel well, behind the right front tire. That's probably not what you want (although I know someone who intentionally ran his a/c hoses through there). 


    IMG_6470_annotated_4.jpg The from-the-inside firewall road map you didn't know you needed. The rust has been wire-brushed off the "mystery hole." It was later re-plugged and re-sealed.


    Two questions immediately emerge: 1) Do you WANT to try to drill holes for hoses where those black circles are in order to tuck the hoses more neatly into the corner of the engine compartment? And 2) Is it even possible to drill the 1 1/4" holes  that you need for the commercially-available grommets in those locations? Good questions. I lost sleep over both of them.


    Eyeballing it with both the grommet and a 1 1/4" hole saw, there's not really enough room for a 1 1/4" hole at #2. But if you go back up to the table above, you see that one hole is for a #6 hose (3/4" outer diameter, fitting has 5/8" threads), the other a #10 (1" outer diameter, 7/8" threads).


    And so, if you're me, you think "a-HA! If I use bulkhead connectors instead of hoses, I only need to drill the holes large enough for the connector thread size, not for a grommet to surround the holes. I bet I could squeeze the hoses into that corner instead of having them emerge directly over the exhaust manifold. It'd be cooler and cleaner.


    And thus we look at...


    Bulkhead connectors


    bulkhead.jpg Typical polished a/c bulkhead connectors on a plate


    Let me say that, although some people tout bulkhead connectors because they provide a means of sealing up the firewall holes without grommets, I had already thought about and rejected them. In the first place, you usually see two (or four) of them on a shared polished plate, making them look way too modern, too hot-rod for me. I thought they'd look completely out of place in the engine compartment of a survivor 2002 like Louie. Second, because they're on a shared plate, you lose the ability to individually place them. And third, they create FOUR additional connections that can leak.


    However, I was swayed by two factors. The first was that I found individual #6 and #10 bulkhead connectors that weren't together on a plate. Coldhose has them. They even have grooves in them for rubber sealing washers behind the collar nuts for added bulkhead weather-tightness. This enabled the possibility of individual accurate placement, with the small #6 connector requiring only a 5/8" hole. I thought that could easily fit in the #2 black circle drawn above. (Instead of bulkhead fittings, you also can use male o-ring insert fittings that crimp directly onto the end of the hoses on one side of the bulkhead.)


    The second was that because the Clardy evaporator has the expansion valve on the left, it makes for long hoses. The idea of ever having to replace either the evap-to-compressor hose or the evap-to-drier hose was daunting, and not academic, as my friend Jose Rosario had asked me to relocate his fender-wall-mounted drier in order to fit a set of headers.


    So I went ahead and ordered the individual bulkhead connectors, and drilled holes for them in the 1 and 2 black circle locations of the firewall.


    IMG_6468.JPG The individual bulkhead connectors. Man those collar nuts are big. You can barely make out the rubber washer in the big one.


    As you can see from the photo above, the holes for the threads may be much smaller than the holes needed for the rubber grommets for the hoses, but those collar nuts are big. I successfully fit the smaller #6 bulkhead fitting in the #2 spot, and the bigger #10 in the #1 spot, but in order to fit the collar nut on the #10, I had to use a Dremel tool to buy some clearance on the firewall insulation clip.


    IMG_6472.JPG Holes for the bulkhead connectors from the inside...



    IMG_6473.JPG ...and from the outside. Yes I de-burred and primed them.



    IMG_6480.JPG Bulkhead connectors installed. You can see where I Dremel'd clearance (Clarence :^) around the foam firewall clip for the collar nut.


    Having done this, let me say that I don't think I'd recommend this, and I don't think I'd do it again.


    Wait. What? Why not, oh wise and all-knowing Rob?


    Well, four reasons (yes, I enumerate everything like this):


    First, there's something of a misnomer about the ability of bulkhead connectors to enable tight right-angle turns. Yes, they DO make right-angle turns, but it's at the cost of standoff. That is, you have the physical height of both the bulkhead connector itself and the fitting that screws into it. Even if that's a right-angle fitting, it has stand-off. On the inside, I initially test-fit standard inexpensive 90-degree connectors as shown in the photo below, and had nearly three inches of standoff. I eventually went with more expensive "short drop" fittings to get them closer to the firewall as shown in the following photo.


    IMG_6528_enhanced.jpg The standard 90-degree fittings stood way off from the inside of the firewall.


    IMG_6577.JPG The short-drop fittings were closer in.


    Second, although the configuration does create a nicely tucked-in look in the corner engine compartment, as shown in the photo below, it makes the hoses come out in the middle of the passenger footwell (as shown in the photo above) instead of having them drop in in the corner close to the evaporator to which they need to connect. So that's a trade-off.


    IMG_6529.JPG Yes, the engine compartment side does look pretty clean.


    Third, the #10 suction line back to the compressor (the one that gets cold) sweats, and thus any metal fittings on it must be wrapped with cork tape so that it doesn't drip inside the car. If it's just a hose through the firewall, it only means wrapping the fitting that goes into the expansion valve. No big deal. But—and I didn't foresee this one at all—with bulkhead fittings, it means that that any metal on that fitting on the inside of the car has to be wrapped to keep it from coming in contact with humid air. That turned out to be challenging, and is the kind of thing that I hesitate to do until everything is installed and tested to be leak-free. It got done, but it all adds to the conclusion that I'd be unlikely to recommend this or to do this again myself.


    Fourth, although I said that, without bulkhead fittings, I was concerned about the length of the evap-to-compressor and evap-to-drier hoses, if those are unbroken hoses, they have the advantage that any slack in the interior hoses (there is zero space behind the evap assembly for hose slack) can simply be fed through the grommets, and the hoses can simply sag down onto the frame rail to accommodate the slack. With the bulkhead connectors, the evap-to-bulkhead hoses need to be cut to the absolute zero-room-for-error length before crimping them. I suspect, but do not know for sure, that this means that if, for example, I needed to pull the evap assembly to pull the heater box to replace the blower motor, I'd be less likely to be able to simply swing it way out of the way as I could if there were simply hoses through grommets. I suppose we'll see over the next 30 years :^)


    So, no, don't interpret this lengthy tome as an endorsement of the bulkhead connector approach.


    I was going to have this installment include the actual fittings and hose fabrication, but I think I'll stop now and cover that next time. Sort of like having the bulkhead connectors break up the long hoses :^)




    (My a/c book Just Needs a Recharge: The Hack Mechanic Guide to Vintage Air Conditioning can be purchased here on Amazon, or personally-inscribed copies of it and my other books can be purchased directly from me here.)





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