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Winter/Summer Pre-heating Box on ‘75 pics?


EuroTech
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Hello everyone, I have a 1975 USA delivered 2002 that still has the thermal reactor exhaust manifold but I’m missing the winter-summer box setup, I’ve looked around the forums and google searched in hopes of finding something that shows it but no luck I’ve also searched realoem that shows multiple diagrams that don’t look anything like my exhaust shield setup.. Does anyone have a ‘75 thermal reactor exhaust winter/summer setup pic? Or anyone knows where the pre-heatied air hose originates at the exhaust manifold. Here’s a pic of my car so you can see it’s not the typical coned/tube exhaust shield. Thanks 77e8e45b7d0480bf7ffa8fce88ccf1bd.jpg

 

 

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I can’t help with a ‘75 U.S.-spec version, as that has the thermal reactor exhaust manifold, whereas my 49-state ‘76 does not have the thermal reactor.  The pre-heating hose (paper over a wire frame) on my ‘76 fits onto the nose of the cast aluminum heat shield (photos below).

 

The thermal reactor cars, instead of a cast aluminum heat shield, have a painted steel heat shield. But I can’t tell you where your car’s original pre-heating hose attached.  Certainly some other forum members have intact winter/summer pre-heating boxes on ‘75 or California-only ‘76 ‘02’s.

 

Regards,

 

Steve

 

 

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Edited by Conserv
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Awesome thanks for the replies, beautiful engine bay Conserv! Thanks for the pics I’ve seen the 49-state pre-heater setups but as you stated the thermal reactor heat shields are different.....Socalsean... I would guess so... all ‘75 model year are the same emissions and setup as ‘76 California cars from my knowledge... can you please post some pics of your summer/winter box? Thanks


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Eurotech,

 

My 49 state '75 has a different reactor/exhaust manifold than yours does as my air-pump connection is in the front of the manifold like Conserv's.  I read someplace that some are in front and some are in back but I don't know if that will impact the cold-air diverter routing.     The remnants of the hard "warm air" diverter vent pipe to the carburetor starts just below the manifold behind the engine.  I had an "extra heat shield" that must have held the flexible pipe.  

 

You missed the free give-away of my diverter on this site by about a month.

 

Scott

 

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Scott,
I was under the knowledge that all 1975 2002’s have the same emissions equipment from the factory(there were no 49 state or California versions...only one version/exact same emissions equipment) If you look at my pic a little more closely you’ll see it does have the connection to the air pump in the front like conserves... mine is missing the metal pipe,check valve, and rubber hose to the air pump...around the back of the cylinder head is supposed to be a metal pipe which connects to the egr filter under the intake manifold, from there it connects to the diverter valve and then into the intake manifold which I have some other questions about some of the other emissions equipment but I’ll save that for another post...... but the setup I have in question right now is how is my thermal reactor manifold heat shield supposed to connect to the Summer/winter box... I have all the connections and parts I bought off the classifieds for what looks to be the typical setup like Conserv posted of his engine bay... Scott is there any pics of your setup on your ‘75 that I can see please? Maybe my car has a different year heat shield?


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Buckeye, thanks I have seen that diagram, I’ve looked over my car and it does not appear such a bracket could even be installed with my style of heat shield, I have found a diagram picture online of what my exhaust manifold setup appears to be on my vehicle but it still doesn’t show my how the Summer/winter box preheat tube connection goes....42dfda20d0cbc7985fb5ea751d44e122.jpg


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23 minutes ago, Buckeye said:

I don't know much about 75 USA setup, but Studied the fuel preparation diagrams on Maximilian site and am going to guess that on the backside of exhaust manifold should a mounting surface for bracket #1 in the diagram below mount to. Just thoughts.

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The bracket (item #4 in diagram) attaches to two of the three studs where the thermal reactor bolts to the exhaust down pipe.

Then you can run a flex hose to the winter/summer diverter which attaches to the snorkel at the front of the car.

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Unless you absolutely have to keep that reactor manifold to meet state emission requirements, do yourself a favor, toss it in the neighbor's pool and fit a non-reactor manifold in its place--either a factory cast iron one or a header.  The former will allow you to fit the warm air intake; the latter won't.  

 

The reactor manifold is extremely heavy, and puts a real strain on those poor little studs that hold it to the head.  It also generates a LOT of heat in a confined space, and that can lead to cylinder head cracking and excessive under-hood temperatures.  

 

This was not one of BMW's better ideas; they used this instead of a catalytic converter to avoid having to specify unleaded gas.  Now that's a moot point as there is (almost) no leaded gas any more.  As an exhaust manifold, they make pretty good boat anchors.  

 

mike

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I don’t have to meet state emissions requirements but was wanting to keep the car complete and functioning as originally designed... I’ve been back and fourth in my head as to my decision on keeping the thermal reactor.... you do bring up very valid points that I have heard about, points I’ve been thinking very hard about for a while now....I agree with all the negative possibilities that can happen but can anyone chime in that has been running the thermal reactor for a long time(some California owners) if the reactor is checked and in proper working order, is it still highly likely for cylinder head damage? I know most will think I’m stupid for even thinking about it, it’s just I like the idea of having it function as it did had I bought it brand new.... opinions? Comments?


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