During the Louie adventure, as you know if you’ve been following this saga, I made the thousand-mile trip from Louisville to Boston with the car still wearing its original 45-year-old radiator that was probably as corroded internally as the original water pump and thermostat were. I got away with it largely because even though I was driving in unseasonably warm winter weather, it was still winter (to both a cooling system and a driver, 50º ambient temperature is very different from 90º).

    But in addition to the old radiator, an odd intermittent electrical issue rendered the temperature gauge unreliable, alternating between jumpy and hard-into-the-red panic-inducing, so I was never really sure what the damned cooling system was doing. It was a risk I do not wish to repeat.

    As I prepared to drive the car 900 miles each way to the Vintage in Asheville, North Carolina, I wanted to outfit it with a new radiator so I could be confident that the car was running cool even if I never got to the bottom of the jumpy gauge issue (and if one more person says, “You just need to ground the instrument cluster,” I swear I’ll hit them in the mouth).

    But I didn’t want to break the bank, either.

    There are many posts—some by me—on bmw2002faq.com about various 2002 radiator options. From an installation standpoint, the easiest is a new OEM radiator, as it bolts right in. Unfortunately, the list price is currently north of six hundred bucks. Discounted list is about $480, and non-OEM knock-offs show up for about $350.

    For many years, a popular, inexpensive option has been to use a radiator for an E21 320i. Unfortunately, the later 320i radiators have plastic top and bottom tanks, which, to some folks, are an anathema to use in a vintage car that otherwise has no plastic in the cooling system. However, the earlier 320i radiators were all metal. An inexpensive all-metal replacement radiator is the Spectra CU739; it is currently available at sites like Amazon and Rockauto for around $120. It’s a fairly lightweight metal radiator, and the fins between the tubes bend very easily, but I’ve had them in several cars, and they cool very well for short money.

    The downside is that the 320i radiator is not a bolt-in replacement. Not only is it physically larger than the stock 2002 radiator, its hole spacing is different. As you can see in my bad hand-drawn engineering diagram below, the original 2002 radiator has a horizontal hole spacing of 18 inches, whereas on the 320i radiator, it’s 18 5/16". The vertical hole spacing is substantially different; on the 2002 radiator it’s 10 3/8", and on the 320i radiator it’s 8 3/4".

    A number of websites show the process of fitting the 320i radiator; a particularly good example can be found at www.turningwrench.com. The commonly offered procedure is that you need to test-fit the new radiator, mark where the holes are in its mounting ears, drill new holes in the nose, and secure the ears with nuts and bolts.

    A further complication is that, on the original radiator, the ears with the mounting holes are flush with the back of the radiator, so they mount directly up against the nose. In contrast, on the 320i radiator, the side ears are on the front, so some sort of spacer should be employed between the ears and the nose so that when the bolts are tightened, they don’t bend the ears.

    When 320i radiator installations into 2002s first became commonplace, drilling a few holes in the nose wasn’t considered a big deal. Now, the older these cars get, the more you need to present a lawyer’s case for drilling any hole in the car, anywhere. So, while the Spectra’s $120 price is attractive, I was only interested in putting one in Louie if it could be installed in a cruelty-free fashion—you know, “No 2002s were harmed during the installation of this radiator”.

    So, can it be installed without drilling any holes? The answer is yes—and it’s not really that hard. What you need to do is alter the hole spacing on the radiator to match that in the car, rather than the other way around. There are three parts to this: Use ¼"-diameter lag bolts, elongate the holes on the left ear of the radiator to slide them over toward the right, and make little brackets to offset the bottom holes on the radiator so that they’ll line up with the holes in the nose.

    I shall explain.

    Use ¼" lag bolts. Because the mounting ears are on the front side of the radiator, you need longer mounting bolts. ¼" lag bolts are close enough in diameter to the original 10-mm screws that they’ll screw right into the original mounting tabs. On my car, three-inch lag bolts worked on the top, but there was a slight offset at the bottom requiring me to use 3-½" bolts instead. An 11-mm wrench fits the 7/16" hex head on the lag bolt almost perfectly, so you can pretend they’re metric.

    Elongate the holes on the left ear of the radiator. You need to use the mounting hole at the upper right as-is, and modify the holes on the left side of the radiator so the upper hole lines up with the one in the car. In the image below, I’ve begun to elongate the hole inward by grinding it with a Dremel tool. You need to elongate the hole so that when the lag bolt goes through it, it’s almost flush with the radiator core.

    Make little brackets to offset the bottom holes. Now that you’ve made it so that the upper holes in the radiator line up with those in the car, use the bracket material of your choice to attach the lower holes in the radiator ears to the existing tabs in the nose. If you use flexible material like pipe strapping, the bottom end will be flush with the nose, and you can use the original 10-mm screws, but if you’re using rigid brackets like the ones I made (pictured below), you’ll need to use long lag bolts at the bottom as well as at the top

    Test-fit everything and make sure the holes all line up.

    Once you’re sure that everything fits, you can cut either thin PVC tubes or short lengths of old fuel hose to act as stand-offs and provide some resistance for the mounting ears to push back against as you tighten the lag bolts.

    Before I forget, an additional mounting issue with the Spectra radiator is that the radiator is designed for use in a both a 320i automatic and a standard; it has the transmission-cooler ports integrated into the bottom of the radiator. I just leave the plastic caps on the ports, and put some foam tape underneath them. I’ve never had a problem.

    There’s still the hoses to deal with. For the upper radiator hose, the coolant neck of the 320i radiator is larger than that of the 2002 radiator, so you need the hose for a 320i, which is part number 11 53 1 267 971.

    The lower hose is a real pain. As I said earlier, the lower port on most 2002 radiators is angled upward to clear the a/c compressor, if it exists, so the standard 2002 lower radiator hose won’t work on the Spectra. On an early 2002 radiator, the port exits to the right, as it does on the 320i radiator, but that hose for that 2002 radiator doesn’t fit the Spectra very well. What you need is a hose that bends away at a 90-degree angle in as short an amount of space as possible. This link also does a nice job at showing how to modify the upper radiator hose from a Pontiac Sunbird (NAPA part #8393, also Gates part #21703). This is what I did. Cutting the hose correctly, coupled with mounting the radiator as far to the left as it’ll go, results in a fairly nice installation.

    Be certain that the bottom of the radiator hose isn’t rubbing against the frame rail. If it is, and there’s no way to reconfigure it so it doesn’t, you can take a spare piece of hose, split it, and put it between the hose and the frame rail to prevent abrasion.

    In addition to installing the new radiator, I think that I may have solved Louie’s possessed temperature gauge; replacing the alternator has, for now, made the problem go away. But even if it comes back, having a brand-new all-metal 320i radiator in the car, a new water pump, and a new 75º thermostat, I’m feeling pretty good about taking Louis to the Vintage.—Rob Siegel

    Rob’s first book, Memoirs of a Hack Mechanic, and his new book, The Hack Mechanic Guide to European Automotive Electrical Systems, are available through Bentley Publishers, Amazon, ECS Tuning, and Bavarian Autosport—or you can get personally inscribed copies through Rob’s website: www.robsiegel.com

    And stay tuned for Rob’s upcoming book, Ran When Parked: How I Resurrected A Decade-Dead 1972 BMW 2002tii And Road-Tripped It A Thousand Miles Back Home—And How You Can, Too.