Heater hose diameter?

[jasonh]

Anyone know the ID of the 2 heater hoses? I heard they were different diameter. I need to bypass my leaking heater core and I can't pull the hoses off and leak coolant all over my parking lot, atleast in the daylight . Hopefully someone knows.

[85crownHPP]

if they are different I would guess one is 3/4" ID and the other is 5/8". I cant promise that though!

[jasonh]

Good guess! Thanks man I couldn't find a 3/4 to 5/8 adapter so I used a 3/4 and sanded down one end...seems to work ok. At least now I can figure out the erratic idle without clouds of white smoke in my face

[fatboy06]

i think i have the same problem, not to sure if it is the heater core or what.... whenever i run the defroster, the front windshield gets all steamed up, and i get clouds of waht appears to be white steam/smoke, is this the heater core? come to think of it, my idleing has been somnewhat eratic, i have a 89 marquis 5.0

[boXman]

That's a bad heater core. Have fun!!

[85crownHPP]

yep - its not gonna be pretty!

[Archangel]

Both heater core ports are 3/4", the water pump ones however are 5/8". The steel pipe under the upper intake plenum (for MPFI models) is also 5/8", it's the hose connecting it to the hetar core that makes the 5/8"-3/4" transition. When replacing the return hose and bypassing the steel line I just ran 5/8" hose all the way, getting on the heater core's port was kinda PITA, but nothing too bad.