Can someone help me find an upper radiator hose?

[derotoreut]

I'm doing my first LS swap into my '70 K10 and for the life of me can I find an upper radiator hose that will work. I've seen what a couple of guys have done, but it doesn't seem to fit my application. I even took a piece of flexible air intake preheater hose, molded it to shape and took it into NAPA to try to match something up. No luck.

My swap is a Gen III 5.3L LM7. I'm using a radiator made by Northern that has upper and lower radiator hoses on passenger side. The lower radiator hose connection is 1-3/4". I was able to use Gates 20687 for the lower. The upper hose connection is my problem, it's 1-1/2". I've seen where guys have used the Gates 21439 for the upper, but this hose is 1-1/4" and just does not line up. Does anyone have any ideas on something that might be close?

For the upper I'd be going from 1-1/2" at radiator to 1-1/4" at engine. I could always use a 1-1/2" hose with reducer if need be. I had someone give me some numbers off an upper hose that they used, but I can't seem to get these numbers back to a useful part number. The numbers are 80GN25 and 1451.

Hose has 80GN25 Made In USA


Hose also has 1451 number on it


My 5.3L LM7 with Northern radiator

[mongocanfly]

Could you have a 1-1/4" nipple welded on the radiator?...would that help find a hose that fits?
I've also used a coupling sleeve and 2 pieces of hose to make the connection...may be a better option

[derotoreut]

Originally Posted by mongocanfly

Could you have a 1-1/4" nipple welded on the radiator?...would that help find a hose that fits?
I've also used a coupling sleeve and 2 pieces of hose to make the connection...may be a better option

I'd rather not weld a 1-1/4" connector on the radiator if I don't have to. I thought about using a coupling if I could find two hose pieces that would work. So far I can only do it with three hose pieces and I don't want that many connections. There must be a better way. Someone must have something close. I'm hoping someone did something similar that would work. Thanks for the comments.

[truckdude239]

I used the stock hose from the 2004 swap just cut it down shorter but not sure what size my outlets were using a cold case ls swap radiator

[mongocanfly]

I understand...and I wouldnt want 3 pieces either...looking at your picture it doesnt look like it would be hard to 2 piece it though...the only LS swap I've done that I could use a off the shelf hose was my C30s top hose...the bottom is 2 pcs....the IH both top and bottom are 2pc...oreillys let me in the back and I just kept looking till I found what I could make work..the IH bottom hose is 2-90s joined..that one was easy..the top was more difficult to do...I used the middle section out of 2 hoses to get what I needed..
Good luck on your search though

[kipps]

Have you asked the radiator manufacturer? If they're building a radiator for LS swaps into 67-72 trucks, they should have a pretty good idea what hoses are needed.

[derotoreut]

Originally Posted by truckdude239

I used the stock hose from the 2004 swap just cut it down shorter but not sure what size my outlets were using a cold case ls swap radiator

Dave, what was your swap? 2004 Silverado, or something else?

[derotoreut]

Originally Posted by kipps

Have you asked the radiator manufacturer? If they're building a radiator for LS swaps into 67-72 trucks, they should have a pretty good idea what hoses are needed.

The radiator is made by Northern, but Pacific Fabrication buys it unfinished. They complete it by welding the upper and lower connections, steam port, overflow and mounting brackets on. When I asked them (Pacific Fab) what to use, they only gave me the first two pictures in this thread with the numbers on them. That is no help to me.

[verdell]

Ran into the same issue with the Northern radiator in my '60. Ended up joining 2 pieces with hopes of finding a better solution later and never did bother it again. What I have works well but it's ugly as crap. I think what I did was just found two pieces that looked close enough and made them work.

[87chevy.com]

https://www.youtube.com/watch?v=VXLjXUWMsT4

Part number on the hose

[derotoreut]

Originally Posted by 87chevy.com

https://www.youtube.com/watch?v=VXLjXUWMsT4

Part number on the hose

Thank you. I'll check it out and keep you posted.

[First c10]

I bought silicone adapters from www.siliconeintakes.com. I also bought stainless stall piping from them and built my upper hose/pipe.

[72MARIO]

I used 1996 jeep grand cherokee 4.0 hoses for both upper and lower on my 2005 LQ4 swap. my rad is a RnD rad with outlets on passenger side. A little trimming and they fit perfect

[bigmoe]

Originally Posted by 72MARIO

I used 1996 jeep grand cherokee 4.0 hoses for both upper and lower on my 2005 LQ4 swap. my rad is a RnD rad with outlets on passenger side. A little trimming and they fit perfect

The Cherokee upper hose is a Gates 21970. 1 1/2" x 1 1/4". I picked one up for less than $20 to try on my Gen IV 5.3 with an RND rad with passenger side outlet and it worked pretty well. I cut about 3 1/2" off the engine end.

[truckdude239]

Originally Posted by derotoreut

Dave, what was your swap? 2004 Silverado, or something else?

2004 Silverado 4.8

[derotoreut]

So I tried the Jeep hose and it was close, but not the best. I could've probably made it work, but I think I found the way I'm going to go. I bought two 45-degree, 1-1/2" elbows. I put a small section of 1-1/2" stainless tubing inside. This seems to fit the best of anything I've tried so far. I would either have to put a 1-1/2" to 1-1/4" reducing adapter on the engine side, or go to a reducing elbow.