1978 C3 L48w/AC - Radiator Help
Thread Starter
4th Gear
Joined: Jun 2024
Posts: 4
Likes: 0
1978 C3 L48w/AC - Radiator Help
Hoping for some help...I have a 1978 C3, L48 Automatic with AC and need a new radiator. While trying to find a replacement (Brass not AL, I have my reasons) I see 2 versions, a 2-5/8" core and which says its for an L82 OR L48 w/AC, the other a 2"core is for an L48 w/o AC. This car came with factory air, the radiator end tanks measure 2-1/2" so the core has to be 2". Suppliers I call tell me the car must have aftermarket AC and that the correct radiator is the 2-5/8" thick core if it has AC. I have most every GM service and assembly manual including the dealer parts books for this, including a 1978 GM spec's sheet and it lists the radiator for the L48 with AC as 1.9" thick core, matching whats in the car. The leaking radiator looks to be original, has radiator code MK and I see no signs where anyone has messed with either it or the AC condenser in front of it.
I'm convinced the radiator I need should have a 2" core.....please chime in and let me know if im missing anything obvious
Thanks,
Bjw
I'm convinced the radiator I need should have a 2" core.....please chime in and let me know if im missing anything obvious
Thanks,
Bjw
Racer
Joined: Jun 2018
Posts: 282
Likes: 139
From: NH
Hoping for some help...I have a 1978 C3, L48 Automatic with AC and need a new radiator. While trying to find a replacement (Brass not AL, I have my reasons) I see 2 versions, a 2-5/8" core and which says its for an L82 OR L48 w/AC, the other a 2"core is for an L48 w/o AC. This car came with factory air, the radiator end tanks measure 2-1/2" so the core has to be 2". Suppliers I call tell me the car must have aftermarket AC and that the correct radiator is the 2-5/8" thick core if it has AC. I have most every GM service and assembly manual including the dealer parts books for this, including a 1978 GM spec's sheet and it lists the radiator for the L48 with AC as 1.9" thick core, matching whats in the car. The leaking radiator looks to be original, has radiator code MK and I see no signs where anyone has messed with either it or the AC condenser in front of it.
Le Mans Master
Joined: Sep 2002
Posts: 5,236
Likes: 898
From: Myrtle Beach SC
Hope this helps!
Thread Starter
4th Gear
Joined: Jun 2024
Posts: 4
Likes: 0
Thanks to both of you !!
Does anyone know if the stock MK was a 3 or 4 row ?? I see lots of conflicting posts on this.
Mine is leaking every fluid known to man, except for wiper fluid (wooohooo !!). Radiator is the worst followed by transmission and brake fluid. Oil pan gasket needs replacing as well but the absolute worst is the clock has stopped working.......so now I'm motivated to get this going
Does anyone know if the stock MK was a 3 or 4 row ?? I see lots of conflicting posts on this.
Mine is leaking every fluid known to man, except for wiper fluid (wooohooo !!). Radiator is the worst followed by transmission and brake fluid. Oil pan gasket needs replacing as well but the absolute worst is the clock has stopped working.......so now I'm motivated to get this going
Le Mans Master
Joined: Sep 2002
Posts: 5,236
Likes: 898
From: Myrtle Beach SC
That's what motivated me to do an engine compartment refurb...took everything out and took the engine down to block, replacing gaskets, paint, etc. Had masks for the carb, EGR, etc (they were removed along with timing chain cover, fan clutch, balancer. I posted it in a discussion thread but it goes back probably ten years or so.
Race Director
Joined: Feb 2001
Posts: 11,350
Likes: 2,102
From: Grapevine Tx
2018 C3 of Year Finalist
2016 C3 of the Year Finalist
Why not put the heavy duty one in for better cooling?
Also, you should easily tell whether it has factory air or and aftermarket add on.
Also, you should easily tell whether it has factory air or and aftermarket add on.
Race Director
Joined: May 2006
Posts: 18,755
Likes: 2,589
Thanks to both of you !!
Does anyone know if the stock MK was a 3 or 4 row ?? I see lots of conflicting posts on this.
Mine is leaking every fluid known to man, except for wiper fluid (wooohooo !!). Radiator is the worst followed by transmission and brake fluid. Oil pan gasket needs replacing as well but the absolute worst is the clock has stopped working.......so now I'm motivated to get this going
Does anyone know if the stock MK was a 3 or 4 row ?? I see lots of conflicting posts on this.
Mine is leaking every fluid known to man, except for wiper fluid (wooohooo !!). Radiator is the worst followed by transmission and brake fluid. Oil pan gasket needs replacing as well but the absolute worst is the clock has stopped working.......so now I'm motivated to get this going
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Thread Starter
4th Gear
Joined: Jun 2024
Posts: 4
Likes: 0
Thats a job taking it down to the block, not sure I have that much motivation. I need to get it drivable then decide how much further I want to go. Driving it again maybe enough to spark.
Appreciate the comments !!
Thanks for the suggestion, the engine never had any cooling issues so think I'll stick with the standard duty radiator. Looking at all the doc's I have the AC looks factory to me.
I seem to think its a 3 row but I wish I could find a definitive statement in a GM document but alas.....or, pull it out and cut in half...HA !!
I will certainly check the lower supports, that lower area does have lots of surface rust, so far nothing looks too bad but i can't see everything....yet.
Thanks again all for the comments !!
Appreciate the comments !!
Thanks for the suggestion, the engine never had any cooling issues so think I'll stick with the standard duty radiator. Looking at all the doc's I have the AC looks factory to me.
I seem to think its a 3 row but I wish I could find a definitive statement in a GM document but alas.....or, pull it out and cut in half...HA !!
I will certainly check the lower supports, that lower area does have lots of surface rust, so far nothing looks too bad but i can't see everything....yet.
Thanks again all for the comments !!
Last edited by bas78c3; Jun 22, 2024 at 06:56 PM.
Thread Starter
4th Gear
Joined: Jun 2024
Posts: 4
Likes: 0