heater core with ac and speedo questions


New Member
Apr 11, 2005
So as I am on my way to Bellingham to catch the ferry, my car turns into a steam mobile. Not a great amount, just enough to smell of antifreeze and almost make it impossible to see....:eek:
So now I am in Kodiak, AK and could use some defrost w/o steam, and have a heater core on the way....
Did a seach of this forum and figured out that an ac car is more involved than a non ac, but couldn't determine the best way to swap with all of the ac/non ac tips going back and forth. So, if you have swapped an ac heater core, how'd you do it? Any thing to look out for? I should mention that the ac works perfectly, and I hope to keep it.
Also, would a radaitior stop leak fix this? :shrug: I don't really want to do this, as its a brand new radaitior....but.....
Next, my speedo went poof.... I guess all those interstate miles on a 30 year old plastic gear weren't good for it.
I pulled the cable from the c-4 and its gone....$h!t....just had this c-4 rebuilt!!! :bang: Where'd it go??????? I don't want my tranny dying because of a plastic gear...:nonono:
Anyone who can, please advise on what gear{part #} I need for a bone stock replacement..please (78,302,13"tires,C-4)
Please advise if you can, and thanx...........mike78
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IMO, on the heater core, plan on pulling the dash out. It CAN be done with just loosening it, pulling it back, and working around it, BUT 1) It's a HUGE pain in the rump that way, and 2) 30 year old plastic dashes and stress from pulling...not a good mix. You'll need to recover the refrigerant, as it is a Federal offense to vent it to the atmosphere (and it's the right thing to do). Might be able to have a shop evac it for you, don't know your situation up there. Split the expansion valve from under the hood, MUCH easier than trying to disconnect the lines from it. Splitting it is the Ford service method, anyway.

Gear will depend on the axle ratio, but they're usually white in 77/78. You might try ther calculator on the org website http://www.mustangii.org/tech/speedo/ but I've found in my experience, it's usually about one tooth off.
Did it have the clip on it when it went in? That's the piece I'd be worried about. I would think the plastic gear will just lay in the extension housing, but if the metal clip gets picked up, it could get ugly. Might try fishing around with a magnet stick to see if you can pick up the clip.

It's been a while since I messed with a C4, you might be able to pull the extension housing and see what's floating around in it while it's in the car.