I bought a replacement heater core for my car. The box came with no instructions or pictures, it just said what it was and what car it was for. On my old heater core, both little tubes are the same size and had a 5/8 hose going to them. The new core has a 3/4 hose side and a 5/8 hose side. Does it matter which is which. Is there a wrong way to put in a heater core? Is one side only for incoming and one side only for outgoing? Thanks, I'd like to get this stupid thing finished today.
Heater Core You need to return the core to the store and get the correct one. If your original had the same size hoses, the new one needs to be the same. You will not find a heater hose with two different sized ends. There is a correct way to install the core. It's easier to do the job correctly the first time, than do the job over.
I don't know about a '76, but I know that a '73 heater core for a 225 is supposed to have a small and a large diameter tube.
My 1964 Wildcat's have a 5/8 nipple on one end and a 3/4 nipple on the other. Can't remember which is on which (and it is late here), but there indeed two sizes of nipples on the same heater core. Don't know if this helps, but maybe you call sell it to a '64 guy. :laugh:
Funny you should mention it.....I'm dealing with my heater core this weekend too. ou: Usually the smaller port is the outgoing but, if the one that came out was original then I would take it back and get the right one.
On all the Buicks I've seen, one hose is 5/8", the other is 3/4". The 5/8" hose comes off the intake manifold, via the heater control valve. The 3/4" line comes off the water pump. Check your hose sizes carefully.
65 401 has the 3/4 5/8 set-up. There have been guys with air lock issues and no heat with some Buicks, so I wouldn't change your original set-up. Be very carefull with the tubes as they have a tendancy to crack at the weld if you horse them into the openings, Good luck
I bought the right heater core. So there is a specific inlet and outlet side? How do you recognize them if they are the same size? What happens if I hook the wrong hose up to the wrong tube? The box I bought had no documentation. NAPA has ordered me a different one that fits, but it won't be here for a few days.
I bought the right heater core. So there is a specific inlet and outlet side? How do you recognize them if they are the same size? What happens if I hook the wrong hose up to the wrong tube? The box I bought had no documentation. NAPA has ordered me a different one that fits, but it won't be here for a few days. I really appreciate the help so far.
Here's the deal. If they are the same then it makes NO difference at all. If they are different, then the small end is always OUT GOING. Think about it. If your core has a smaller output then it's designed to keep the water in the core from flowing out to fast, not by much but just a little. If you happen to get it in backwards, don't worry, it aint gonna blow up your car. Your heater may just take longer to get hot because the water may be flowing in too slow and out too fast. Water pump>into heater core or control valve>big tube Heater core output>small tube> to engine return
I don't know if 78ParkAvenue has solved his problem yet, but I feel obligated to chime in here, if only for future reference. The issue here is what size nipples are on the motor? Every Buick motor I have played with has a 3/4" nipple at the water pump and a 5/8th inch nipple in the intake (as Larry described.) Maybe the nipple in the intake has been changed? Either way, the hoses need to match the motor, and the heater core has to match the hoses.
