258 / 4.2L 5/8" x 3/4" heater hose

[jdcaples]

I didn't see anywhere else to put this.

Since my CJ decided to trash my left hand after I ignored warnings, I decided to focus on some research.

One of the things my CJ's PO did was to place a 3/4" x 5/8" plastic heater hose adapter from the water pump outlet to the heater core.

To accomplish this, he used a Dayco plastic reducer from any cheap auto parts supplier.

I've seen such a contraption on other engines and I've assisted drivers where the plastic had failed on the side of the road.

I also remember not seeing it on any of my father's vehicles. I do remember him huffing and puffing because the hose he wanted wasn't at the distributor's, so he had to tell customers to wait.

My dad hated hose adapters. I guess I inherited his loathing for additional points of failure, possibly because he saw too many such-equipped vehicles towed into his shop.

Anyway, while I'm gimp-handed, I decided to do some research because I remember him ordering hoses of different IDs on either side as a kid growing up around his shop.

I came across this:

View attachment 18337

which looks like "death to the Dayco plastic adaptor" as well as such stop-gap measures I recall from my childhood.

The heater core on my L6 is 3/4" while the outlet of my water pump is 5/8"

I think AC Delco part number 1804L aka 88907444 fits the bill. Am I right?

If I'm right, and if you, as I are bothered by a reducing adapter under your hood, this might be something in your future.

I'll order one as soon as I can turn a wrench again.

-Jon

PS: I did search for heater hose & 3/4 x 5/8 but all the threads I found were old. I didn't find reference to this particular solution in a thread less than 2.5 years old. Sorry if this is old news.

 

[RatDog8o8]

It's not only the water pump outlet, but the thermostat housing. Both are 3/4". I just learned this mixed logic recently while doing my engine re-do. I'm going to run with the plastic adaptors for now, but I have a pair that I'll be making from some copper........just in case the plastic fails.

Some of these little things (like the mixing of sizes) just defy logic.

 

[jdcaples]

On mine, the heater core is 3/4 as is either the thermostat housing or the water pump outlet (I forget) is 5/8ths.

So 3 out of four hose connection/end-points are 3/4" while one is 5/8ths.


I think the water pump is the 5/8ths.

-Jon

 

[RatDog8o8]

Yeah, I forgot to mention that on mine, both of the engine connections are 3/4"........while the core is 5/8". I learned this when running the 5/8" hose from the core to the water pump.......I was like......"Two sizes? Really?"

 

[jdcaples]

There are heater cores that are 5/8ths? My thermostat housing's definitely 3/4" so if I can find 5/8" all the way around, that'll be my preferred direction.

If I hadn't found a molded, purpose built hose, I'd have probably replaced the plastic with this:

View attachment 18338

since my gut trusts metal over plastic. I've seen one of these in person. It would require both hose clamps to be flush with the center ring of the adapter to avoid clamping force over the void of the hose, but it can be done.

-Jon

 

[PaRenegade]

Could it be there are multiple scenarios for different years. Mine has the water cooled intake so I have 6 ports, which I believe 4 of the 6 are 5/8" and the other two are 3/4". I know I pulled off two diff. size hoses but not sure off hand how they were. I do know that I bought new GY HighMiler hose in 5/8" and they fit on both the water pump and thermostat ports, plus the front intake port. I'd have to dbl. check the rest of the ports to be sure. But I have heard of this 5/8 to 3/4 issue.

 

[ThisGuyUKnow]

I always go with a metal adapter if I need one.... I am more curious about the story behind your hand injury.....

 

[jdcaples]

I always go with a metal adapter if I need one.... I am more curious about the story behind your hand injury.....

It's embarrassing and a long story.

Suffice it to say that I shouldn't have used the base of my thumb and palm as a hammer banging against the end of a short ratchet when there was a perfectly good 24 inch breaker bar not 15' away.

I tore some tissue and angered some nerves. I don't know how long it's been, but today's the first time picking up a wrench didn't feel like root canal below the wrist.

-Jon