Chillin' Louie (Part VII: Hose Fabrication)

The tool you need

Way back in the introduction, I told the story of Ed Ellis ("Ellis The Rim Man" to you Bostonians) making the hoses for my E9 3.0CSi 22 years ago by the curb on Comm Ave. I watched as he crimped on one end, cut the hose longer than it needed to be, put it through whatever holes in the body it needed to pass through, threaded the other fitting onto whatever component it needed to attach to, test-fit the hose into the fitting, trimmed it to length, "clocked" the fitting at the desired angle, marked the orientation of the hose and fitting, then crimped the fitting on right then and there in the car with a hand-held Mastercool 71500 Hydra-Krimp. I asked him "How does anyone ever get this right if they don't have the car in front of them?" He deadpanned "They don't." 
  
At some point in the 2000s, I bought a used Mastercool 71500 Hydra-Krimp on eBay. These list for nearly $700 new. I forget what I paid for the used one; maybe half that. And now, due to the wonders of Chinese manufacturing, you can buy a tool that looks exactly like it and even has the gall to brand itself as a "Hydra-Krimp 71500," for under $200 on eBay or Amazon. You can also buy the Mastercool 71550, which is just the jaws that you set in a hydraulic vise, for about $150, but that doesn't let you do the easy one-handed "crimp it where it sits in the car" thing. 
 

My beloved Mastercool Hydra-Krimp 71500, with some of the rubber holders for the unused crimping dies crumbling in the lower part of the case.

If you think you're going to do a/c work on more than one car, the Hydra-Krimp is a tool well worth having. The alternative is to find a local custom a/c shop, as I did with my E9 22 years ago, or try to have the hoses made via mail order. Coldhose.com has a very nice page for custom hoses, allowing you to specify the hose fittings and clocking angle, for about $65 per hose, and that'll work adequately for long hoses with bends that can take up slack, but for short hoses, the odds of getting it wrong are high. The ability to do this in place—to pass the hose through the body and grommet, rotate the hose so its natural bend from being stored on a roll is oriented to your advantage, crimp on one end, thread it on, test-fit the other fitting, cut the hose to length, clock and mark the fitting, and crimp it on right there—simply never gets old.

Fitting crimped onto discharge hose from compressor when other end is already attached to condenser.

One note about the Hydra-Krimp. Over the years, I did have multiple instances of just-crimped fittings leaking. Whether it's just my tool or a characteristic of the 71500, I don't know, but I found that the tool tends to put preferential pressure on the top and bottom surfaces (12 and 6 o'clock), creating gaps in the crimp at 3 and 9 o'clock. I now crimp every fitting twice. I do it once normally, then rotate the fitting by 90 degrees and squash the raised parts that form at 3 and 9 o'clock back down. I've never had one leak since. Again, I don't know whether this is just me or a widespread issue.

Fitting sizes and angles

As I said in the last installment, there's an entire chapter in my a/c book about fittings, and another one about making hoses. I'm going to copy two very important tables for you. Here's the first:

Fortunately, unless you're doing something weird like drilling holes for bulkhead connectors, you rarely need to know exact dimensions; all you need to know is component port fitting sizes, and that nearly all the time, you need female o-ring fittings where the fitting size and the hose size are the same (that is, not "step up" or "step down" fittings). These are listed in the second table below.

From there, you can build yourself a little table of the four hoses you need to build to connect these four components, and the fittings and their angles needed on each end of each hose. Here's an example of such a table. Note that the angles I list are merely examples as well and are not to be taken as canon. 

On Louie, because I had the bulkhead connectors, there were actually six hoses. And because of the Clardy's block expansion valve, the connections on it were male o-rings, not female. I do these tables in Excel to keep them straight:

Note that, as I said last week, because the Clardy evaporator comes with o-ring fittings, every fitting listed in this table is an o-ring fitting. This is the first and only time I've ever had this happen. Every other from-scratch installation or rejuvenation I've done on a vintage BMW has had some residual flare fittings, generally on the evaporator.

Fittings come in a choice of straight, 45 degrees, or 90 degrees. With some fittings, it's completely obvious which angle you should use on a given component. For example, the upper condenser port is crying for a straight fitting.

No question about this one.

With others, particularly the compressor fittings, it's often a judgment call whether you use a 45 or a 90. The joy of making the hoses yourself is that even if you get it wrong, you're rarely out more than $20 in hose and fittings.

Charging fittings

I talked a little about this in the introductory piece. You need to have charging fittings somewhere to hook up the manifold gauge set, pressure-test, evacuate, and recharge. If your compressor has little Schraeder valve-like fittings on the back, you can use those as charging fittings (provided you have a gauge set that threads onto them), but it's really not a great idea, as there's a lot of discharge of refrigerant when you unthread the hoses.

The charging fittings on the back of the compressor (if it has them) are neat and tidy, but the refrigerant discharge when you unscrew the gauge hoses is anything but.

In contrast, the modern push-on R134a fittings really are a joy to work with, as the gauge set hose fittings snap onto and off them with zero refrigerant discharge. Unfortunately, you can't thread adapters onto the back of the compressor. Well, you can, but there's not room for the manifold gauge hoses on them. They're too close together. Many people elect to use in-line splicers with charging fittings on them on the two compressor hoses, as they're easy to reach. I've done it, but the look is kind of inelegant.

In-line charging fittings spliced into Kugel's compressor hoses. Looks a little busy, doesn't it?

For Louie, I used charging fittings that are integrated into the two compressor fittings. This makes for a very tidy-looking installation. I recall trying this once before and not having enough clearance between the innermost one (the suction fitting) and the block. The difference here may be that I'm using an old Seltec compressor whose ports are vertical rather than at a slight V angle like on the Sanden and its clones. It also may be that I'm remembering doing this on an M30 engine on one of the bigger 6-cylinder cars. I'm not certain, and I apologize for not knowing. But I love the result. If you're going to try this, install the compressor, and make sure you can thread both fittings onto it before crimping them onto hoses.

Pretty nice, eh?

Locating the receiver-drier

It really doesn't matter where you put the receiver-drier. In cars I've owned with dealer installations of the Behr system, it's usually in the nose, and the drier itself was a very specific unit with the inlet port facing down, a bracket welded to the side of the drier, and studs integrated into the bracket. In fact, the Behr installation template for cutting holes in the hose shows where to drill the holes for the studs. If you look at the photo below, you'll see that the bracket held the drier with the outlet fitting at 90 degrees to the hole in the nose, meaning that you want a 90-degree fitting on the outlet hose, and the fitting itself hangs through the hole. Driers of this design are still available, but the only ones I've found have flare fittings like they did 45 years ago, and that's the last thing you want in a new installation.

The original Behr drier with the integrated bracket and downward-facing inlet port.

These days, you generally use whatever compact o-ring drier you like, and some sort of a universal ring clamp. I typically use the Four Seasons 33260 "shorty" drier, as it's small (2 1/2" x 6 1/2"). Whether you put it in the nose or against the right inner fender wall is up to you. There's more room against the fender wall, and that location is more forgiving of slack in hoses, but you don't really need to interact with the drier, so having it tucked in the nose makes some sense, and does clean up the engine compartment.

For Louie, I repeated what I've done several times before. Used a 45-degree fitting at the bottom of the condenser and a 90-degree fitting on the drier inlet. I carefully cut the short zero-slack hose, connecting it to the outlet port from the condenser and orienting the drier so that the drier's outlet points straight out the hole in the nose. I used a straight fitting on the outlet port, slid the clamp onto the drier, marked the hole for it, clocked and marked the hose fittings, checked and re-checked that the drier's outlet port was still pointing straight back, crimped the input hose, then tightened the clamp and built the output hose and screwed it on. It worked really well in Louie.

I have to say that I was particularly proud of this one.

Bulkhead hoses

With all the work I did putting those damned bulkhead fittings in, I didn't like how far a straight #10 fitting jutted out, and there wasn't enough room to use a 45-degree fitting, so I tried something new. I took a 45-degree fitting, heated it with the torch, and relaxed the bend.

Bending a 45-degree fitting to more like 20 degrees

Not a bad fit.

Yeah, the plug wires are a mess, but without charging fittings spliced into the hoses, and with the receiver-drier tucked away in the nose, this looks pretty clean.

I think I beat the bulkhead connector issue in the last installment, but just to repeat: I had to use what are known as "short-drop fittings" to reduce the amount of standoff from the firewall. Usually I've used short-drops on the condenser fittings on cars like the Bavaria, E9, and E24 due to lack of clearance in the nose. This was the first time I'd ever used them for a standoff issue.

A short-drop fitting used at the top of the condenser of my 3.0CSi due to tight side-to-side clearance.

Short-drop fittings used in the footwell of Louie in order to reduce standoff. I hated the way everything looked, but when I buttoned things up, I hid them.

(Next: The wiring.)

--Rob

(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.)