Heater hose size?

[WP29P4A]

Just finished replacing the cooling system on my son's 87 GMC. The heater hose that goes from the firewall to the radiator was old and fit kinda lose. The problem we are having is a 3/4' hose fits lose and won't tighten enough to not leak. (even with good quality clamps) The 5/8' hose is to tight to get on the radiator. Is there a special size between 5/8 and 3/4?

Has anyone else had to deal with this issue?

 

[Jimbarry]

On mine, the bigger hose went to the radiator.

 

[Bextreme04]

Just finished replacing the cooling system on my son's 87 GMC. The heater hose that goes from the firewall to the radiator was old and fit kinda lose. The problem we are having is a 3/4' hose fits lose and won't tighten enough to not leak. (even with good quality clamps) The 5/8' hose is to tight to get on the radiator. Is there a special size between 5/8 and 3/4?

Has anyone else had to deal with this issue?

Pics? Is it a replacement plastic tanked radiator? You should have one 5/8" hose and one 3/4" hose. On a TBI motor I think the feed for the radiator comes off the back of the intake manifold and the return goes to the water pump, not the radiator. Although squares can have it done either way. Did you get actual replacement heater hose? Sometimes old hose will be stretched out and therefore fit loose... sometimes you are using the wrong kind of replacement hose and it isn't the right ID even though it says its the same "size".

 

[WP29P4A]

The original hose was loose fitting on the old radiator, all the sizes have remained the same. On his truck one hose goes from the back of the intake manifold to the firewall (heater core) the other goes directly from the heater core (firewall) to the passenger side radiator tank along with the trans cooler lines and the lower radiator hose.

The 3/4" hose fits the same at radiator and heater core, easy to slip on, not sloppy loose. You don't have to work it to get it to slip on. So we had the loose hose issue with all the old parts before we started, and after replacing everything with the same sizes we still have a hose that fits loose.

I measured the hoses because what you said about ID makes sense. Hose says 3/4" on it and measures out at 3/4" looks correct.

 

[WP29P4A]

On mine, the bigger hose went to the radiator.

Yep, thats what we have too, 3/4" goes to radiator and 5/8 goes to intake manifold.

 

[Jimbarry]

Yep, thats what we have too, 3/4" goes to radiator and 5/8 goes to intake manifold.

On mine the 5/8 goes to the intake then to the right-side fitting on the heater core. The 3/4 goes to radiator.

 

[AuroraGirl]

not the same engine or the same year or the same etc etc but my big hose goes to water pump and the small one goes to intake.
my heater core is side to side tho not up and down, but the hose diameter is pretty standard across makes..

 

[AuroraGirl]

h,,,

 

[WP29P4A]

I may see another issue, what KINd of hose are you using? Heater hose? Or some other type of hose?
And your clamps are not ones you want to use. nope. nada. also your radiator hose appears... strange

What picture are you looking at?

 

[Wolverine]

started separate thread

 

[Scott91370]

More than likely 5/8"

 

[Bextreme04]

They do have 11/16" heater hose