An Exhausting Exchange

In his 101 Projects for Your 911 author Wayne Dempsey proclaims that replacing the stock heat exchangers on a 911 motor with SSIs will take two hours. This assessment of the time required is pure fantasy. It is also an example of the typical misleading information which the amateur wrench finds in all kinds of shop manuals and how-to-do-it publications.

Anyone who has pulled a box wrench out of his Craftsman toolbox knows that instructions found in the usual after-market manual are to be taken not with a grain of salt, but with a spoonful. And what one is not told is more often as material to the overall success of the operation as what lies beneath the inevitable black-and-white photographs featuring a greasy finger pointing to an obscure fitting. My favorite, and perhaps yours as well, is the ubiquitous cop-out: “Installation is the reverse.” Sure.

For those of you who do not live with air-cooled, flat-six motors of the older variety, SSIs are a style of heat exchangers that were fitted to early 911 motors before the exhaust was routed to the driver’s side to accommodate a catalytic converter. The installation of a set of used SSIs on my 3.2 Carrera motor, replacing the stock exhaust, took the usual turns and involved the common travails of the shade-tree mechanic. I did not rely on or believe Dempsey’s two-hour projection. I knew better. Any project which requires the use of penetrating oil on old and rusted fittings, and possibly the application of heat from a torch, is full of potential for disaster, or at least an expensive trip to employ the professional-wrench solution.

A gallery to compliment this text: one of the pair of stainless heat exchangers, sitting innocently on my work bench (photo 1); next we see the pieces installed, along with its companion for the other side (photo 2), with a very nice Monty muffler spanning the two, the Monty being also made of stainless T-304 steel, all the way from Australia (photo number 3). In between the following took place:

The seller of the used SSIs was kind enough to include the special wrench which is made to fit around the heat exchanger to get to the nuts for the SSIs at the exhaust ports, at least the half that do not use barrel nuts. However, it did not fit the newer nuts I bought from Stoddard’s. A half-inch sized wobbly socket I just happened to have in my tool box did work. Barely. · The barrel nuts were just slightly offset from the holes in the exchangers making the 3/8 drive socket difficult to remove the barrel nuts. Pounding the socket into place had obvious consequences. My ¼ drive set barely lined up nicely and served the purpose on installation. · Half the nuts came off without a hitch, mainly because they had been removed not too long ago by Jim at Steinel’s during the conversion work (from 2.2 to 3.2-a much longer and more expensive story). · The other half, however, would not budge. Several days of soaking in penetrant, just as the “101” book speculated was needed, had no effect whatsoever on the nuts which had been in place for about 18 years.

We have now gone past the two-hour mark by at least 3 hours, maybe more. · Fearing breakage of the exhaust port studs, which would necessitate putting the car on a trailer and sheepishly taking it to a professional, I tried heat. But my torch had too wide a flame. When in trouble, call friends. So I called Jeff Bernstein, who happened to have a very neat little oxygen-acetylene outfit with a small torch the tip of which was just the right size to heat the nuts and not destroy anything else on the bottom of the engine. In less than two hours we had them heated, coerced, and off. No broken studs. Experience, touch, heat, and patience paid off. I sacrificed two Budweiser’s to the garage gods. Jeff went home to spend the remainder of that Sunday with his family.

The studs, now exposed and waiting for the installation, would not readily take the new nuts, even with a bit of vigorous cleaning of the threads. So a call to another willing EBR member, Mr. Houck, brought a set of dies to apply to the studs to assure a smooth fit for the new studs.

In the usual SSI conversion you purchase two OEM style oil lines, since you are replacing the one from the muffler side back to the scavenger pick-up point. So I bought them in advance of the job. My conversion, however, utilized Aeroquip lines and an aftermarket thermostat. So one of the lines proved to be superfluous. The vendor took it back with a small re-stocking fee. More work for UPS.

Getting the heater hoses in place took more than the usual forcing and pushing.

We are now so far past two hours it is not amusing.

Last hurdle: the rigid oil line from the scavenger pick-up point will not line up with the attachment point on the internal oil cooler. It is a light aluminum material, so the application of force is a risky proposition. Insertion of a handy piece of conduit into the line (more proof that you never throw anything away) and pulling it into place does the trick, after coaching via a phone call from Rick.

It is back together, but an oil leak appears. The scavenger pick up point shows a seep of oil, possibly from putting pressure on the fitting to get the other end in place. Maybe it is not square to the attachment point.

Remove muffler and left side heat exchanger to get at fitting. Give it a bit more turn. Pray. Drive it.

The Black 911 is now on its trailer, waiting for the first event of 2003. MidOhio with our friends of the Allegheny Region. Two hours indeed.

© Rose Lane Garage/W. S. Cline 2003

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