Exhaust coming into the cockpit..where did I go wrong?

[chrisreale]

I put on new heater flapper boxes, and while putting them on, I took all the piping off of the heat exchangers to clean up a bit. I put everything back on, and when the car was started, exhaust was coming through the dash heat vents. I assume my heat flapper boxes are not set up properly, so how do I set them up right? (meaning the defrost lever wires that hook up to the flapper boxes)

[HMeeder]

Well Chris,

Even if you had hooked up the boxes wrong, there is no good reason why exhaust should be making it in to the heat exchangers. Methinks you have a major exhaust leak. Have to be at the head maybe? Perhaps exhaust is blowing somehow into the exchanger along one of the down tubes.

Explore that first IMHO

[chrisreale]

Well, I just removed both heat exchangers. Is there a "first shot" method of putting them back on straight? I assume I should tighten the nuts in a certain pattern...???

[korijo]

Make sure you get 4 new copper gasket things, ya know the ones that are gonna be a PITA when puttin those shiny SS exchangers on.

Got your muff off, huh? We should blast it! Lemmeno when...

[Kevin Powers]

dress the tops of the he's with a big file, big enough to do both on one side at a time, take your time. blacken the top faces with a magic marker. when the black is gone they should be good to go. do not reuse copper o rings or nuts. trying to slip the he's up and not dropping the rings is a pain. put a small bead of high temp silicon on the flanges and the rings will stay on place. on a positive note, if you cleaned your he's it maybe off gassing of the cleaner. when you have a leak at the head and h.e. mating surface you can hear it and if you have to drop them again you should be able to see where the leak is via the black carbon mark. before you tear both off, which vent stinks? that's the side to investigate first as one h.e. heats that side of the car, just undo the rubber/paper tube that connects to lower firewall. as for putting them back on, bring them up evenly, cross tightening pattern. if you bind them and then over tighten, you may break a stud. believe me, that IS the worst case senerio. make sure you have the correct o rings, there are 2 types/sizes. oh, while the he is off look up at the exhaust port with a flashlight. if there is a big goober of carbon on the mating surface it may leak.

kevin