Author Topic: Looking for a New Radiator for My 1977 K20  (Read 717 times)

Offline ehjorten

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Looking for a New Radiator for My 1977 K20
« on: April 28, 2020, 10:38:48 AM »
The radiator in my 1977 K20 350/TH350/NP203 is fairly worn and has some small leaks. I have talked to a local radiator shop that has been in business for over 40 years and they suggested I might want to find a replacement, because they could repair it, but likely the cost would be more.

Anyways, I am not sure where to find the best radiator for a decent price. The one that I have in it, must be the HD one. It is 4-row and measures about 28-1/4" W x 19" H x 2-1/2" D.  I am open to an aluminum radiator, but not one with the plastic tanks, and I want it to mount as stock with the stock rubber supports.

Also...where can it get the proper, new radiator supports? These ones are about 4-1/8" wide!
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline MIKE S

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Re: Looking for a New Radiator for My 1977 K20
« Reply #1 on: April 28, 2020, 04:59:49 PM »
Just my take on the plastic tank radiator. The original type radiators that are soldered seem to always develop leaks. When I used to work on them in the 80s and 90s on my farm I was constantly having them repaired. I have way less trouble on the plastic tank radiators. In the dealership were I work we rarely replace a radiator for a tank problem.My own 2001 Tahoe has 180000 miles on it and just now cracked the tank. If you are concerned about the plastic tanks i would put an all aluminum radiator with high fin count.

Offline ehjorten

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Re: Looking for a New Radiator for My 1977 K20
« Reply #2 on: April 29, 2020, 08:56:10 AM »
My experience and experience from guys I know...it seems the plastic tanks always crack way too early and there really is no practical way to repair a glass-filled nylon tank.  Some places can remove the old tank and replace it with a new tank and seal, but this isn't common.  These radiators are really just throw-aways.

I did find this: http://www.usradiator.com/radiators?find=chevrolet-truck-1977-23769&sid=dAyvN6AozW

Not cheap, but might be the ticket.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline bigben5054

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Re: Looking for a New Radiator for My 1977 K20
« Reply #3 on: April 29, 2020, 09:12:32 AM »
I was in a very similar position as you just a few weeks ago.  I have a 1979 K20 with a 3 core.  Previous owner also ditched the shroud and all the correct mounting hardware.  The radiator was just sitting on the metal support and the guy fabricated some terrible holders just to keep it from falling over.  In searching for a new radiator, I found that most online sources and auto stores carry the same thing - aluminum with plastic side tanks.  In fact, like so many aftermarket parts, I think they all came from the same foreign factory, but are given different names.  Someone pointed me to Champion Radiators, which was looking like a front runner for me until I found a guy (via Facebook marketplace) about 45 minutes from me parting out a 1980 truck.  For $75 I got a radiator, shroud, top plate, all the rubber holders and all the nuts and bolts.

Offline ehjorten

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Re: Looking for a New Radiator for My 1977 K20
« Reply #4 on: April 29, 2020, 10:37:19 AM »
Those Champion Radiators are a heck of a lot less than the US Radiators.  They are made in China, so there is the main reason.  I know lots of people want to say screw China over this Coronavirus stuff and buy American, but here is the reality...do you want to pay $600 for a radiator or $200?
« Last Edit: April 30, 2020, 09:11:28 AM by ehjorten »
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline Stewart G Griffin

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Re: Looking for a New Radiator for My 1977 K20
« Reply #5 on: April 29, 2020, 11:32:06 AM »
Sent PM, might have something you could work with.

Offline Stewart G Griffin

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Re: Looking for a New Radiator for My 1977 K20
« Reply #6 on: April 29, 2020, 09:39:19 PM »
ehjorten and others were concerned about the fitment of Champions----and rightly so.....

Inlet side


Pass side


As you can see, they don't quite fit or line up.   Also, at the bottom, the tanks DO  NOT  line up with the pads.   
With mine, it IS tight and snug, so i've relegated it to the weekend project/get to it when there's time projects;  i needed to get the truck running ASAP----THEN i could fine tune it when there was time, i figured.....
It may be difficult to see, but on the passenger/cap side, the pad IS touching the top of the core.  Yes, i know this is not the correct way to do it, but it is secure for now.

My other "complaint" is that, in my opinion, the inlet and outlets are a little too short.   You really have to be careful as far as getting the clamps on there properly.   There is not a lot of room for error.

Those are really minor complaints  in my opinion;  i think it's  a very good product.
« Last Edit: April 30, 2020, 09:34:23 AM by Stewart G Griffin »

Offline Mr Diesel

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Re: Looking for a New Radiator for My 1977 K20
« Reply #7 on: April 30, 2020, 01:37:24 PM »
Ehjorton,
I just recently purchased a new radiator the same size as yours. I went with aluminum and plastic tanks. I've had these styles on many of my vehicles for years with no real problems. The factory plastic/aluminum one on my Dodge Cummins lasted 20 years before cracking. In my opinion no radiator can be expected to last longer than that.
I did end up finding an all aluminum afterwards on Ebay for a good price and probably would have bought it otherwise. I'll see if I can find it again.
1976 C20 Crewcab, 6.2L/SM465
1982 K30 Crewcab , 427TD/TH400
1983 C30, 6.2L/TH400
1983 K30 Crewcab 454/700R4
1986 K10 350/400. 1989 K30 cab/chassis 454/SM465

Online VileZambonie

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Re: Looking for a New Radiator for My 1977 K20
« Reply #8 on: April 30, 2020, 06:02:18 PM »
If you go with that style radiator Stewart, you need to modify the mounting pad insulators.

Aluminum radiators with plastic tanks are more than fine. Make sure you flush the system and maintain it! Use premixed, not tap water mix, ground the core if possible, and enjoy a more modern trouble-free lighter weight radiator that is readily available. If you have a problem with it, you don't need to band-aid it. Most parts stores carry a lifetime warranty on them and have them same day for you.
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