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Early Heat Exchanger Retrofit
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Pelican Technical Article:

Early Heat Exchanger Retrofit

Mark Jo

Applicable Models:

Porsche 911 (1975-89)
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     The car used for this upgrade is a 1982 911SC. This upgrade is one of the best bolt on improvements that can be done to the 3.0 liter engine. Now I am a newbie mechanic and through the help of the members of the Pelicanparts Forum, I tackled this project. It has been the hardest that I have tried, but the most satisfying.

     There were so many that helped I fear giving names in fear of leaving someone out. But the Pelican Parts Forum was essential to this project.

The results of my upgrade:   

  • Increase in horsepower. There have been claims of anywhere from 10-30 horsepower. There is definitely an increase especially in the higher RPMs. A rough guesstimate would be teens to twenty.
  • Flatter torque curve. The torque begins earlier, and is smoothed out throughout the RPM range. My SC lost some of the head jerking mid-range torqueiness, but there is now a smoother pull through all RPM
  • My clutch chatter went away. Not a typical result, but it did for my car. Maybe due to the increased torque
  • Also my car no longer backfires, and it also does not smoke in the mornings (as much). Again an atypical result. Before the upgrade my car was consuming a quart every 300-400 mile, but without the smoking I am hoping it may go away. Although I know exhaust system has not much to do with oil consumption, maybe my leaks were at the oil lines that got changed out.

Part that you need:  [ See Excel Spreadsheet Shopping List]

  • Either pre-1974 Heat Exchangers or SSI Heat Exchangers
  • 2 oil lines. One has a rubber section, the other is all metal
  • A 2-in muffler and muffler straps
  • 2 neoprene heater hoses (10" or 12")
  • 6 8mm barrel nuts
  • 6 12mm locking hex nuts
  • 6 exhaust gaskets (I used the asbestos with metal ring type, but the copper with asbestos sandwiched is supposed to be just as good if not better)
  • 2 copper muffler gaskets
  • All available at Pelicanparts
      - Darren was very helpful in finding me the right parts doing some research too.
  • 12 5/16" hex nuts(Fig 2)
  • 12 5/16" locking washers (Fig 2)
       - These two are needed if using the pre-1974 Heat Exchangers
       - The flange on the older Heat Exchangers are thinner then the current Heat Exchangers so these are used as spacers

    Tools that you need:

    • Metric Socket Set with extensions
    • Metric Hex Socket Set
    • Car jack
    • Jack stands
    • Flat screwdriver
    • 1/2" Drive extension
    • 13mm universal joint socket
      - For these universal sockets get the ones that are already u-jointed not a socket attached to a u-joint. THIS WILL NOT WORK
      - Also for these sockets, get ones that are 1/2" drive the small size of the socket itself helps with tight spaces
    • 12mm universal joint socket
    • 13mm and 12mm Crows foot sockets
    • 8mm allen wrench
      - Pelican sells the special socket tool
      - I used a Craftsman T-handle allen wrench. It may give better over all torque when removing nuts. Less chance of pulling to one side and snapping bolts. Or just make sure tool is well seated. But the socket tool is needed when torquing nuts
      - Or make your own. Cut the bend in a normal allen wrench off and put into a 8mm socket
    • Anti-seize
    • Penetrating oil
    • LARGE adjustable wrench (Channel-Lock)
      - Or Porsche oil line wrenches
      - Needs to be 32mm
    • Crescent wrench
      - Up to 300mm
    • New oil
    • Oil catch pan (i.e. turkey roasting pans)
    • 12 and 13mm open end wrenches
    • Propane torch
    • Oxygen-MAAP gas torch
      - Got this at Home Depot
    • Water squirt bottle
    • Latex gloves
    • Towels
    • Naval Jelly Rust Remover and wire brush
      - If you are restoring old Heat Exchangers
    • Note:All of these tools are for a pre-1974 Heat Exchanger backdate. If using SSI's some tools may not be applicable. SSI also provides some of the tools.


           So to start engage parking brake, chock front wheels (Figure 3), lift car and place on jack stands. My preferred method is to place a paper back book on my car jack and put under sump plate. Place jack stands under rear torsion bar covers (Figure 4) with a piece of carpet or padding to prevent damage. Then I use the factory car jack to raise a couple more inches. Alternate side to side not trying to raise the car too much at once. Once car is in the air try rocking the car back and forth. MAKE SURE IT IS SECURE BEFORE SLIDING YOUR HEAD UNDER 2700 POUNDS OF METAL. Take off both rear wheels. Try to soak all nuts and bolts: muffler strap allen nuts (2); cat heat shield nuts; cat-muffler nuts (3); cat-heat exchangers (6); heads-heat exchangers (6 barrel, 6 hex) with plenty of penetrating oil. Do this 3 or 4 times a day for a week if possible. Mine being a daily driver I only soaked for 3 days. Also keep in mind throughout this article that my car is a California car, so my rust was less then many of the cars that I got advice from. I did not do this, but it may be good to soak the two oil lines coming out of the thermostat towards the back of the car. Of these two, follow the one which is behind the other till you get to another junction of oil lines, and you may want to use penetrating oil here too.


           Remove all nuts (Fig 1 #10) holding cat heat shield (Fig 1 #7). Loosen cat-muffler nuts (13mm) (Fig 1 #3). Then loosen muffler strap allen nuts (Fig 1 #5A). Remove muffler. Remove six nuts (Fig 1 #15) holding cat to the driver side (DS) heat exchanger (HE) and the cross over pipes (Fig 1 #17) from the passenger side (PS) HE (13mm) (Fig 1 #15). I had a lot of trouble here. The nuts were rusted pretty good. You may want to use heat. Either the propane or the Oxy-Maap torch. But I just used muscle power. There are a few that are in tight spaces so use the crow foot, u-joint or open end wrenches. You will have to counter hold one side. I found that a 13mm socket on the nut side worked best. First turn the bolt till you hear the rust squeak (this will be important later) then counter hold and break the rust between the nut and the bolt. Also do not forget to take your O2 sensor (Fig 1 #6A) from the cat. Now remove your cat (Fig 1 #6), and cat heat shield brackets (Fig 1 #34. 12). You may want to fire you car up for a little to hear it without muffler and cat!

      While doing this disassembly you should be spraying penetrating oil on the heads-heat exchanger nuts.

      If you want you can disassemble the crossover pipes from the PS HE, but I didn't.

      Now take a DEEP breath.

      Removal of the Heat Exchangers

           Hope you searched the Pelicanparts forumabout the exhaust studs breaking. There are some horror stories. And this is what you want to avoid. Keep telling yourself you will be patient. The advice has been to heat/cool the nuts about four times before any attempts of removal. I would stress this for those of you living in rust inducing areas. I on the other hand gave each nut a very light try. And 2 hex nuts came off. Saved me a little time. Then I heated/cooled then tried the nut lightly (a bit harder then before). And if it was unsuccessful I tried again. Also remember to try to tighten before loosening. The key is to either feel the nut turn when tightening, or to hear the rust squeak. Those are the ONLY 2 situations when you should attempt to remove the nut. If you do not feel either you must continue the heat/cool cycle. Also after loosening the nut, spray some penetrating lube as you loosen the nut, thus lubricating the stud. You will notice the nuts are in extremely tight spaces and you will need to use a combination of the socket extensions, u-jointed 13mm socket, 13mm crow foot, 13mm open ended wrench to get to the nuts. On some, the u-joint would work well until the nut backs down and makes the space tighter, then I would have to switch to the crow foot as the nut came down. Make sure the socket or wrench is seated completely. Because you are working at angles, you DO NOT want to round the nut. Or else you will be in a very sorry position. For the barrel allen nuts, I used a 8mm T-handle allen wrench. Insert it through the holes in the HE's and again make sure they are fully seated or you risk rounding the nut! The T-handle gave me 2 places to place my hands so I did not risk pulling with the allen at an angle that could happen when loosening with a socket wrench. Also I think this 2 handed method gives a more sensitive touch when trying to tighten nuts to test for loosened rust. Disconnect the heater hoses in the front, and back of the heat exchangers. I forgot to and they ripped as I undid the last nut on the heat exchangers. My paper ones on the front had seen better days so I replaced both with neoprene hoses. The black ones with the wire embedded in the outer cover is convenient because you can trim the length of the hoses without seeing it unravel and make a mess. On the passenger side back, there is a long tube of flexible hose, connected to an elbow (Fig 1 #27), then to the heat exchanger. Take off the elbow and put aside, but keep the flexible hose. On the driver's side, there is a smaller length of tube (Fig 1 #29), then an elbow (Fig 1 #27). Take off both the elbow and the tube, set aside the elbow, and we will have to make modifications to this length of hose. It is very stiff aluminum tubing.

           To take off the nuts you will need the oxygen-MAPP gas torch. A propane torch will not get the nuts hot enough, no matter how long you heat them--trust me I tried. So heat each nut till bright red. I even turned off my work light, and heated the nuts, and would check by removing the torch for a second to see if the nut was indeed glowing. For some nuts it will be impossible but try to heat all around the nut perpendicular to the exhaust stud, heating just the nut. Once it is bright red, give it a good long squirt with water. Watch out, the dripping water is HOT. As well as all metal parts within 6 inches of the nut. My engine was very oily and I was worried that I would start some fires--and I did. But they were very small, and I could just let it burn or blow them out. But it may be prudent to have an extinguisher on hand. The heat method is essential, and getting them cherry red is also essential. Remember patience. Nuts I could not get off with 15 minutes of propane came off with the oxygen-MAPP gas torch. Some nuts needed 1 cycle, others needed 3. So for each nut tighten and listen for the squeak. For some nuts I used more force then I was comfortable, in fear of breaking the studs, but if you heated multiple times, there is nothing more you can do. The stud will either break or the nut will give. Don't use full force till heating at least 4 times. After that just give it a go and hope for the best. For some nuts if there was no squeak I just semi-lightly tightened and loosened trying to "rock" the nut back and forth. And then continued the heat cycle. Some people suggest rapping the nut to help loosen the rust. But I did not in fear of breaking the stud. If a nut is stubborn, spray penetrating oil on it and move to another. Do not dwell on one or you will break it. Also when you get to the last couple on one HE, support the HE with a jack (padded with a 2x4 or a paperback book). This will keep from all the force being on one nut. And save the HE falling on your face. If you were lucky like me none broke and you sigh a HUGE sigh of relief. But for those of you in the rusty regions of the world, breaking one or two is inevitable. Check the forum for suggestions. Some suggest welding on a nut and turning the stud out. Or you can use the 2 nut method. Thread two nuts on, and tighten one onto the other, thus locking them and then turn the stud out. You can drill them out. Some members even had special jigs made to drill out the offending stud. And others used Snap-On tools that assist removing broken studs. I have no experience with this, so check with the BBS.

           Take a break. The worst is over, but the second worst part is next.  (oh and reward yourself by starting up the engine with no exhaust system whatsoever! The sound is incredible, especially if you rev it. And if you look under the car, you will see flames shooting out too!)

           This maybe a good time to check for oil leaks in the oil cooler (Fig 5) (fixed by 3 simple o-rings) and also to clean off the oil crud that has built up for years. I used 3 cans of brake cleaner and a wire brush and clean off an inch think layer of crud. This improved my shifting because it cleared up some crud from linkages and moving parts near the clutch helper spring.

      Oil Lines

           Okay, now it is time to tackle the oil lines. The oil line in question begins at the oil thermostat (Fig 6). If you remove the passenger rear wheel, you will see the thermostat and 2 oils lines. You will have to remove the on in front of the other, because the one we are interested in is the one in back. This oil line goes towards the rear of the car, turns into a flexible section, bends and follows the rear of the engine crossing over to the drivers side, then turns to the front and plugs into the crankcase on the driver's side of the engine. After the flexible section it is bolted to the engine for support, as well as in the wheel well, supporting both oil line coming out of the thermostat. The new oil line is made up of one piece with a flexible section that will attach to the thermostat, then it will connect to an all metal oil line, cross over to the driver's side on the FRONT of the engine (Fig 8), and then plug into the crankcase.

           First thing is to drain the oil. Because my car was on jacks getting penetrating oil I could not warm the engine, but it was still okay. Just drain at both the oil tank and the sump cover. Then replace the plugs because the oil will keep dripping out while you work on the oil lines.

           If you check the BBSthere are many horror stories at the thermostat too. Because the thermostat is aluminum and the oil lines are steel, if the nut is seized on, the threads on the thermostat are prone to breaking off with the oil line. Some people have just used a cutting wheel to cut through the nut and then break it off, since it is just a compression fitting. Check the bulletin board for more detailed procedure. The Bentley Manual says to heat the nuts which I did with both propane and the oxygen-MAAP gas torch. But in the end I just used brute strength. The nuts are 32mm, so I used a large pair of channel lock pliers. I actually braced the thermostat with my toes on the lines coming out from the bottom of the thermostat, and twisted. Careful, I smashed my finger against the inside fender but both came off, no breakage. If you plan never to use the oil lines again, the cracking the nut way may be the safest, but I have California emission laws to worry about. Also it is a good idea to have a catch pan here because of residual oil in the lines. But the jack stand may get in the way. So it may be good to put some plastic and newspaper under the passenger rear jack stand way in the beginning of the project. Also disconnect the oil support bracket in the wheel well. Save the rubber because you do not want the support to rub the oil lines and crack them. Once you get both nuts off follow the rear to the rear of the engine and take off the support nut. You can also disconnect the first piece from the second by using the channel lock pliers and counter holding the nut, but I left it in one piece. I then followed the oil line to the side of the crankcase and removed it there. Again have a catch pan ready. Now the oil line if off. You may want to drain it, and plug the ends before anything contaminates it. Now just plug in the first new oil line, with the flexible section. Bend that down and you will see a support bracket and a hole in the front of the crankcase to support the oil line (Fig 7a). Then connect the all metal oil line, bring it around to the driver's side and then connect there. Voila, you are done. Fill it back up with oil and start is up again and listen to the flat six!

      (Note: found some leaks in the junctions of these oil lines @ 2 weeks post-op, be sure to tighten well)


           If you are keeping your heating system, you should check condition of your forward hoses (going into the cabin) and change if necessary. The black hoses that are available from Pelicanparts are the best, because unlike the red cloth hoses, the wire is embedded in the material so cutting the hoses is not messed up by the unwinding wire. On one of the side (not sure which since it has been a while) the heat exchanger flange is very close to the inlet into the cabin, and the hose will need to be cut or else it will be crushed if you try to use the full length. I suggest trial fitting the hoses, and then attaching them at the cabin inlets end first, and only. Then move to the back of the car, to the hoses coming from the engine bay. On the passenger side you do not need to make any modifications just take the elbows used for the stock HE's off from both diver's and passenger's side (Fig 1 #27). Attach the hose to the end of the new HE and let it dangle. On the driver's side you will have to remove the silver hose (Fig 1 #29) from the engine compartment and using a hacksaw cut it in half. Eyeball the length by putting the HE in place. It will be a tight bend for the hose but it can be done. So at this point you have 2 hoses hanging at the front of the car, and two HE's hanging off their respective rear hoses.


           Working on either side, put the gaskets (Fig 1 #31) on the head studs. Some people have used peanut butter to hold it in place; others curve the gasket to keep them in place. I curved the gaskets and they still fell, just angle them so they do not fall off, it is frustrating to keep them all on. The fit the HE into place making sure the gaskets are in place. Do not use gasket sealer, it just creates a mess by turning into a hard irremovable mess. I suggest you start from the middle barrel nut to hold the HE. Just put it on with a couple of turns to hold it in place. Now is a good time to place or attach the front heater hose to the HE. If you tighten all the way the HE all the way up there may not be enough clearance between the two to get the hose on the HE. Then start putting on the other 2 barrel nuts and locking nuts. I would put the "spacer" hex nut on the stud (not screwed on because the nut should be bigger then the stud) and hope the threads hold that in place. Then stack the appropriate nut with a locking washer, with some antiseize goop in between. Then screw the nut on (Fig 9). Use the same method for the barrel nuts. There may be some resistance for the HE to fit flush to the heads and that maybe the aluminum heater hoses at the back of the HE's. Either they were cut too long or short, but I did have to force my HEs some to get the aluminum hose to bend appropriately. Tighten the best you can. Be sure to use a lot of antiseize. You remember how hard it was to get the nuts off. Torque the ones you can (18 ft-lbs) there will be a couple locking nuts on the passenger side that are impossible to torque, but do the best you can.

      Double check all the connections, from the heater hoses to the cabin, the HE to heads, and the heater hoses to the engine compartment.

      Fire it up one more time before you muffle the poor girl.

      Then depending on your muffler type, you can reuse the old catalytic converter bolts with new gaskets to install the muffler.

      Voila you are DONE!!!!!

           Now put your wheels on, torque the nuts, take her down, roll her outside, fire her up and check under the engine bay for any leaks, the intial start up is the best time cuz you can see the condensation and see leaks at 2 cylinders, don't care cuz you want to drive her around--AWESOME.

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Comments and Suggestions:
John Comments: I removed the oil cooler and found the seal to have RTV or some type of sealant on them. All the surfaces look clean and no damaged where the seal are to seat. The old seals do not look like they had any leak points other than what could have been created by the sealant. When I replace the seals the tech article instructs to apply oil to the seal and install. Is the application of an RTV recommended when I reinstall?
July 28, 2011
  Followup from the Pelican Staff: - Sorry for the long delay in replying. We have recently added staff and are trying to get caught up. No RTV is needed.  
huba Comments: so.putting an early model heat exchanger on my 1978 911sc will give me more power? why?
April 26, 2011
  Followup from the Pelican Staff: The early heat exchangers had more exhaust flow. Increasing the engines ability to breath with increase the power. - Nick at Pelican Parts  
John Comments: I picked up the universal from Sears today and was able to remove nuts on exhaust pipes on 4 and 5 outside. I have to wait for the allen wrench tool from Pelican before I can remove the allen head bolts. The ones that are giving me trouble are the 2 nuts on the inside or engine side of the exhaust on the back two attachments. Did you still access these with the universal or is there another tool I need? I hit them again with WD 40 but the fasteners are very clean. The car has never seen winter. The heat exchangers were put on in 1997 but the car has only been driven about 3000 miles since.
September 14, 2010
  Followup from the Pelican Staff: I was able to get all of the nuts with the universal. BUT, it wasn't a universal joint, it was a universal socket, which is shorter. - Wayne at Pelican Parts  
John Comments: Great article. I am in the process of removing my right heat exchanger in order to replace the seal in the oil cooler. My question is which type of 13 mm universal socket 1/4 drive did you use. I have 2 types out there and I know its a very tight space to work in so I wan to make sure I get the best one. I have attacked one of the two photos I found on the sockets. If this is not the type that worked for you could you provide the brand or picture of it.
September 13, 2010
  Followup from the Pelican Staff: The one I used was a regular one available at Sears (Craftsman). See this photo for details on using the tool: http://www.101projects.com/911-rebuild/rebuild_CD/Photos/Chapter5-10/HTML/Page-5.htm - Wayne at Pelican Parts  

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