Odd rattling noise

[AJ/FormS]

Altho,
if you hook the heater core up backwards, it tends to make funny noises when you rev it up, and it can do this for months,as the trapped air has no place to go. I guess that might be why on some models the hoses are coded by sizing. But I wouldn't call this a rattle, even tho it is a very odd sound. More like a waterfall in a small creek. Oh,I know; a gurgle! or a trickle.

 

[BudW]

Speaking of heater hose sizes.

From starting when (not sure, mid ’50’s or before?) to 1970, Chrysler used the same size heater hoses on cars (5/8” on both sides).
In ’71, Chrysler went to 5/8” and 1/2” heater hoses, and did so until ’79.
1980, Chrysler went back to using 5/8” hoses on both heater hoses.

I’ve been wondering why they made that change (curious to know).

It is not hard to change it either way. The heater hose fitting on intake is different as well as the heater core itself.
BudW