Heat Exchanger Conversion- converting your later model bus to 72-74 style heat exchangers I will add photos to provide visual aid on sunday 10/22/2000

Note: I take no responsibility for the results obtained from using these directions. They are to be used as a guide only and the viewer takes full responsibility for the results of their work!

Why?- reduced cost, better flowing exhaust system, more readily available parts. It's a simple process

Parts required-  72-74 style heat exchangers and a muffler to match post 79 mufflers should work as well. new copper gaskets to go between head and exchanger and gaskets to go between muffler and exchangers.  pre heat pipes that go through engine tin to the exchangers and carry fresh air from the blower .  also the plates that go on top of the exchanger inlet from the engine cooling fan UPDATE!!!
you need 72-74 style pipes from exchanger to the flappers they are different from the later model ones despite what the part suppliers tell you!!!

Procedure-  remove old exhaust system
                            -remove lower engine tin- 2 pieces
                            -remove muffler
                            -remove exchangers and assorted pipes NOT the pipes going from the exchangers to   the flappers, these are the same CORRECTION!!! the are NOT the same!! you need 72-74 style ones!!! and will be used with the new exchangers, they are very expensive new. I got one new from busdepot and one from a junkyard that looked as if it was put on right before the bus was scrapped, the rest of the exhaust system was completely rotted away but this on was still powder coated, sometimes you just luck out! I paid 5 bucks for it and FI fuel pump! that pipe goes for $70 new! If your exhaust studs are damaged you should replace them. Proper replacements are hard to find but you don't want to have one snap in the head this would be very difficult to remedy.

          - putting the older style exchangers on

                    The alternator bracket that used to help support the original style exhaust system will get in the way of the metal tubes from the blower. If you want to use them you will have to cut off the part that hung down to support the exhaust.  (if you are doing this conversion you likely are aware that many parts for the latter model system are not available new and you thus do not plan on putting junkyard parts on your bus to bring it back 100% stock so you shouldn't mind doing this)
                          PLEASE NOTE!!!! with this setup there will be additional stresses on the exhaust
                                                            studs as they will be they ONLY thing supporting the exhaust
                                                            system. all the more reason to use new ones!
 using new copper gaskets between exchanger and head put the new exchangers on.  If you don't get a tight seal here hot exhaust gases will be blown against your heads!  It is  royal PITA to get the exchangers on with the gaskets. I had to resort to using assembly fluid although i am aware that this may result in a poor seal, i just got too frustrated.

All right you are mostly done!!

    now put on your muffler. i have a pacesetter extractor muffler and it is difficult to get it to line up properly. it also does not have the built in studs like the vw mufflers so you need to use bolts.  I have used regular steel bolts and had no problems but many suggest stainless. remember use new gaskets! They go for 3.50 i believe from bus depot.  An nos or oem 72-74 type muffler is superior and is also available in stainless! They are not much more than the pacesetters which i am somewhat dissapointed with.

now simply attach the tubes from the blower and the tubes going to the flapper as well as the plates that cover the gaps on the top of the exchanger inlet from the engine cooling fan. these also help support the exhaust system so they will help take some stress off the studs.
you may want to use some high temp silicone to assure a tight seal on all your ductwork

A note on parts-
    Dansk heat exchangers have a reputation for poor fit you may do better getting used ones. Or if possible new ones. I have one new one from the busdepot and one used.
    The pacesetter muffler is inexpensive and is supposed to be more free flowing but the original style are easier to fit.
    IT IS A VERY GOOD IDEA to paint all the parts with a high temperature paint, inside and out. I really like the dupli color product i find it to be durable and long lasting. This will dramatically increase the life span of your exhaust and heating system.
Another tip to increase heat output is to wrap the exchangers and the tubes going to the flappers with header wrap such as thermo tech. I would not suggest using this on the exhaust pipes coming from the heads as it will bring the temp of those pipes to almost molten levels and will result in a shorter life span. (this is why this material is not commonly used by race car drivers anymore. wrapped headers would only last for one race) Also wrapping the boxes may result in higher operating temps in the warm months but i have no evidence of this it is just my intuition.  I do think that wrapping the tubes to the flapper will have no adverse effects and will significantly increase heat output as they are not insulated in any way as they come. as such a tremendous amount of heat is lost radiatively and conductively through them.

A good source for parts is the bus depot camper3.JPG (5366 bytes) they have many otherwise unavailable parts and are very knowledgeable. Also for used parts try http://home.earthlink.net/~shrike3/parts/nixyard.html can't beat these prices and great used parts!
thanks to the type2 mailing list for their assistance and knowledge type2

Any questions comments corrections? please email me !  jbaldwin@bu.edu