Anyone know the hose sizes for the thermostat housing to heater core and water pump to heater cores hoses? I’ve read the they are 5/8” & 3/4”. I’ve got a pin hole in one of them and figure I might as well replace both of them while I’m at it.
Heater hoses??
- Thread starter SQUATCH79
- Start date
The ends aren’t the same per hose, they are molded larger and smaller. You can buy proper molded hose at rockauto or parts stores.
I didn't have any trouble using standard hose.
Had to use a little lube to get them onto the heater barbs, nothing more than that.
Did have to fab the pipe into the water pump when that got changed (the threads for the original stayed in the old pump).
That pipe is only on models with A/C.
Had to use a little lube to get them onto the heater barbs, nothing more than that.
Did have to fab the pipe into the water pump when that got changed (the threads for the original stayed in the old pump).
That pipe is only on models with A/C.
They all have the pipe, it’s for the heater which all models have. I usually just buy a new one when I change the pump.
As for the sizes, the hoses are both 5/8 on one end and 3/4 on the other. They are different so you don’t get them mixed up.
My guess is if you were able to use standard hosing, you probably have the flow reversed through the heater core meaning you likely have the two 5/8 ends connected together and the 3/4 ends connected together. I always buy molded heater hoses specific to the YJ and they are a perfect fit. The one other benefit to molded hose is that they have the built in 90° YJ specific bends which is nice. Other than that doesn’t really matter.
Well near as I could tell the pipe was to clear the serpentine A/C idler, which a hose won't, I did try.
And I have seen them without it, all of them with no A/C, but maybe owners just put in a barb....
As for 3/4 to 5/8 an vice versa, so mines backwards, it works great.
I don't know why they would do that, except to sell dealer parts.
It’s to clear the upper idler which all of them have. The AC adds a lower idler on the timing cover…at least in every single belt diagram, online catalog, etc that I’ve ever seen.
You sure the ones you saw without the tube were 91+ 4.0 & 2.5? Older pumps like the 4.2 I believe had cast bulbs for the hoses to clamp to. Older CJ engines definitely did. All the MPFI engines though should have had the pipe.
And yeah at the end of the day probably doesn’t make a difference. The FSM shows the flow to be a certain way and the hoses make sure that happens but I’m sure it makes no heating difference. It’s also not that huge of a step from 5/8 to 3/4 so you may have gotten the hoses correct and just stretched the 5/8 over the 3/4 locations. End of the day it doesn’t matter, I only buy the molded hoses because they are easy and $10 each which is cheap compared to all the other garbage I’ve bought lol.