DeWitts "Direct Fit" seems too thick to fit- what am I missing? - ZR-1 Net Registry Forums

billschroeder5842 · 02-25-2023

I need some advise please....I'm in the middle of the project so I'm putting this up on both CF and ZR1Net...

I'm installing (or trying to) a DeWitts "Direct fit " #32-1139090M in my '91 ZR1.

Removal of the old radiator (a stock style) was pretty straight forward. I'm putting back together and is simply is not. It looks like the radiator core is too thick from the stock (about 1/2 inch more) and the fan shroud that holds the electric fan it hitting up against the core. The fan shroud has these "Squarish Blisters" that protrude as some sort of mounting surface and hit the core, not allowing the fan shroud to close against the fan mounts. The gap at the junction point at top is about 1/2 to 3/4 of a inch and is uniform across the back, so everything seems to be aligned correctly albeit too wide.

So, did I miss something on installation, is this the correct radiator or is there some modification that I'm not aware of?

Any ideas are appreciated

Mikey · 02-25-2023

Call DeWitts. Their support is excellent. Engineering was at a show last week but should be back Monday.

secondchance · 02-25-2023

I seem to recall installation instruction sheet called for removal of about 1/2? of internal divider on the inside the fan shroud cover/fan housing.
Also, rubber cushion radiator sits on the bottom had to be trimmed.
Dewitt dual core is about 1/2? thicker than OEM radiator.

billschroeder5842 · 02-25-2023

Thanks Guys for the responses and ideas.

I've done a radiator swap before on my ZR1, so I had a good idea of what to expect and this radiator is not was was expected. I ordered a OEM "direct fit" meaning DIRECT OEM fit with zero alternations as I'm kind of a OE guy and don't race.
The radiator core (Dewitts knows this as they included shims) is too wide, the upper filler neck is too big for the hose, the lower petcock drain protrudes 1 1/2 inch and the reservoir inlet protrudes 3/4 more than stock all causing "snags" when installation--- I broke my shroud trying to make this work.

I'll call DeWitts on Monday and work a trade in for a correct one. If they don't have one, I''ll get my money back and order a Delco OEM.

Mikey · 02-25-2023

I'm pretty sure they'll make it right for you. Might have sent you the wrong part.
I got the wrong radiator a few months ago for my '64 and although it was technically my fault because they sent what I ordered, Dewitts listened to my explanation how it happened (their website can be confusing) and they happily exchanged for the one I needed. They even picked up the shipping for the exchange.

HAWAIIZR-1 · 02-26-2023

Sorry to hear and see this. They must have sent you the wrong radiator. Here are some photos when I installed mine. No issues and very easy. I still need to paint that white spacer and should have done that back then. It is a very good system and seals and fits very well. The instruction shows the only mod to trim the rubber a little. Best wishes to resolve it.

billschroeder5842 · 02-26-2023

Thanks again- I'm sure they will do the right thing. DeWitts has a great reputation. I did some researching and they have several "OE Styles" that have very similar stock numbers so the warehouse have easily picked a Hi perf model when I requested a OE one. This isn't the first time or the last (I'm sure) that a part arrived different. Funny, parts for my C5 Z06 seem to arrive (on par) just as expected. Maybe our cars ARE getting old!

Craig- thanks for the photo and mine arrived without any instructions or extra bolts. Just an FYI...

I have to keep reminding myself that "this is part of the fun!"

billschroeder5842 · 02-27-2023

I spoke to DeWitts and they are a stand up organization and will refund my money.

So, I'm going to have to "ride dirty" and go with a plan B radiator.

Any recommendation-- and part number-- of a radiator that fits/works? I'm calling the part houses and get different stories where some say a ZR1 radiator is different than other c4s and others say they are the same.

My current one I pulled out is (approximately) 23 1/2w x 17 1/2h x 1 5/16 core thickness hand I had no problem with cooling. No part numbers on the radiator to cross reference and the old invoice number show a generic C4 radiator.

The one that keeps coming up is a ACDelco 20681. Any thoughts?

https://shop.advanceautoparts.com/p/...E&gclsrc=aw.ds

https://www.oreillyauto.com/detail/c...radiator&pos=1

https://www.autozone.com/cooling-hea...81/1241676_0_0

Thanks!

Mikey · 02-27-2023

Truth be known, if ZR-1 radiator is same as an LT-1 car then it?s also the same as an S-10 pickup truck. GM assigned different part numbers and you can guess which one costs more..

Mystic ZR-1 · 02-28-2023

Did DeWitts agree that it was the wrong radiator?

FWIW: mine fit with no problems when following
the included instructions?

02-25-2023	#1
billschroeder5842 Join Date: Nov 2016 Location: Southlake, TX Posts: 599	DeWitts "Direct Fit" seems too thick to fit- what am I missing? I need some advise please....I'm in the middle of the project so I'm putting this up on both CF and ZR1Net... I'm installing (or trying to) a DeWitts "Direct fit " #32-1139090M in my '91 ZR1. Removal of the old radiator (a stock style) was pretty straight forward. I'm putting back together and is simply is not. It looks like the radiator core is too thick from the stock (about 1/2 inch more) and the fan shroud that holds the electric fan it hitting up against the core. The fan shroud has these "Squarish Blisters" that protrude as some sort of mounting surface and hit the core, not allowing the fan shroud to close against the fan mounts. The gap at the junction point at top is about 1/2 to 3/4 of a inch and is uniform across the back, so everything seems to be aligned correctly albeit too wide. So, did I miss something on installation, is this the correct radiator or is there some modification that I'm not aware of? Any ideas are appreciated __________________ Bill Schroeder Texas Proud! 1991 Corvette ZR1 #1388 2015 Challenger Scat Pack Shaker [SIGPIC][/SIGPIC] Last edited by billschroeder5842; 02-25-2023 at 02:06 PM.

02-25-2023	#2
Mikey Join Date: Jul 2020 Location: Nashville TN Posts: 351	Re: DeWitts "Direct Fit" seems too thick to fit- what am I missing? Call DeWitts. Their support is excellent. Engineering was at a show last week but should be back Monday.

02-25-2023	#5
Mikey Join Date: Jul 2020 Location: Nashville TN Posts: 351	Re: DeWitts "Direct Fit" seems too thick to fit- what am I missing? I'm pretty sure they'll make it right for you. Might have sent you the wrong part. I got the wrong radiator a few months ago for my '64 and although it was technically my fault because they sent what I ordered, Dewitts listened to my explanation how it happened (their website can be confusing) and they happily exchanged for the one I needed. They even picked up the shipping for the exchange.

02-26-2023	#7
billschroeder5842 Join Date: Nov 2016 Location: Southlake, TX Posts: 599	Re: DeWitts "Direct Fit" seems too thick to fit- what am I missing? Thanks again- I'm sure they will do the right thing. DeWitts has a great reputation. I did some researching and they have several "OE Styles" that have very similar stock numbers so the warehouse have easily picked a Hi perf model when I requested a OE one. This isn't the first time or the last (I'm sure) that a part arrived different. Funny, parts for my C5 Z06 seem to arrive (on par) just as expected. Maybe our cars ARE getting old! Craig- thanks for the photo and mine arrived without any instructions or extra bolts. Just an FYI... I have to keep reminding myself that "this is part of the fun!" __________________ Bill Schroeder Texas Proud! 1991 Corvette ZR1 #1388 2015 Challenger Scat Pack Shaker [SIGPIC][/SIGPIC] Last edited by billschroeder5842; 02-26-2023 at 12:18 PM.

02-27-2023	#8
billschroeder5842 Join Date: Nov 2016 Location: Southlake, TX Posts: 599	Re: DeWitts "Direct Fit" seems too thick to fit- what am I missing? I spoke to DeWitts and they are a stand up organization and will refund my money. So, I'm going to have to "ride dirty" and go with a plan B radiator. Any recommendation-- and part number-- of a radiator that fits/works? I'm calling the part houses and get different stories where some say a ZR1 radiator is different than other c4s and others say they are the same. My current one I pulled out is (approximately) 23 1/2w x 17 1/2h x 1 5/16 core thickness hand I had no problem with cooling. No part numbers on the radiator to cross reference and the old invoice number show a generic C4 radiator. The one that keeps coming up is a ACDelco 20681. Any thoughts? https://shop.advanceautoparts.com/p/...E&gclsrc=aw.ds https://www.oreillyauto.com/detail/c...radiator&pos=1 https://www.autozone.com/cooling-hea...81/1241676_0_0 Thanks! __________________ Bill Schroeder Texas Proud! 1991 Corvette ZR1 #1388 2015 Challenger Scat Pack Shaker [SIGPIC][/SIGPIC] Last edited by billschroeder5842; 02-27-2023 at 12:05 PM.

02-25-2023	#3
secondchance Join Date: Aug 2006 Location: McLean, VA Posts: 3,723	Re: DeWitts "Direct Fit" seems too thick to fit- what am I missing? I seem to recall installation instruction sheet called for removal of about 1/2? of internal divider on the inside the fan shroud cover/fan housing. Also, rubber cushion radiator sits on the bottom had to be trimmed. Dewitt dual core is about 1/2? thicker than OEM radiator.

02-28-2023	#10
Mystic ZR-1 Join Date: Jan 2010 Location: Mystic CT Posts: 2,627	Re: DeWitts "Direct Fit" seems too thick to fit- what am I missing? Did DeWitts agree that it was the wrong radiator? FWIW: mine fit with no problems when following the included instructions?