Likely Heater Core Failure - ZR-1 Net Registry Forums

HIZNHRZ · 09-20-2015

I've owned my current 1991 ZR-1 for just short of 20 years. It currently has almost 18K miles and I've maintained it since it had ~2K. It had less than 7K miles for the first 15 years. The balance of mileage has been added in the last 5 to 6 years. As of today, I've got antifreeze smelling vapor condensing on the windshield and antifreeze in the passenger plastic foot wells. I'm thinking it's time for a heater core.

I would like to get some input from someone who has installed a heater core in their ZR-1. Specifically:

1) Did you remove the dash or were you able to get to everything by removing the glove box and lower passenger-side panel ? I think there are a couple of bolts that will be tough to get to without removing the dash. I'm planning on using an inspection camera in order to get a socket on them.

2) Is the OE heater core still available and if not, is there one aftermarket manufacturer known to be "high quality" and form, fit, and functionally interchangable ?

3) Any other words of wisdom or suggestions ?

The damage is done but the cooling fluid was changed every 3 to 4 years with the proper antifreeze and distilled water. In the winter the car was garaged in spaces heated enough to take the chill off and in the summer, air conditioned enough to dry the air and keep the temperature below 85 F. Any thoughts on why this heater core might have crapped out ?

secondchance · 09-20-2015

What makes you think it has failed? Is it leaking coolant into passenger side footwell?
I have never replaced late C4 heater core but when Paul Farrance had his replaced Dan (Y-me), I believe, removed the dash pad to do the work.

Dynomite · 09-20-2015

Quote:

Originally Posted by secondchance

What makes you think it has failed? Is it leaking coolant into passenger side footwell?
I have never replaced late C4 heater core but when Paul Farrance had his replaced Dan (Y-me), I believe, removed the dash pad to do the work.

Everything I read says you have to go in from the Dash and it is NOT fun. Take plenty photos for us if you do it.

Removed Heater Core

secondchance · 09-20-2015

But then, may be not necessary to pull the dash pad.
http://www.c4vetteregistry.com/vrfor...at-bad/406397/

HIZNHRZ · 09-20-2015

Quote:

Originally Posted by secondchance

But then, may be not necessary to pull the dash pad.

Thanks. I saw that thread and a few others. Looks like it can be done but either way it does not look like a fun job.

Fortunately I have those carpeted plastic "boots" that lined the footwells but yes, I had coolant in the passenger footwell. The defroster was also blowing vapor that smelled like coolant onto the windshied.

Anyone have any thoughts on aluminum vs copper heater core?

HIZNHRZ · 09-20-2015

Quote:

Originally Posted by Dynomite

Everything I read says you have to go in from the Dash and it is NOT fun. Take plenty photos for us if you do it.

I'll do my best ! Need to get it done. In the Washington area, this is the best time of the year to enjoy the car!

GOLDCYLON · 09-21-2015

Having been there and done that its easier with the dash off on the 90-93 MYs. Best suggestion I can offer is to remove the targa top and pull the passenger seat to allow you to lay on your back and get some room to do the job.

I wont kid you its a complete PITA and a labor intensive job. I have not done this on the 94-95 ZR-1 since I havent owned one yet but the passenger airbag just adds to the complexity however its a simple unplug and move out of the way process.

Take a lot of pictures for reference along the way. If you do pull the dash be mindful of the weak area along the window on the passenger side which is very thin and can be brittle. It is best to have another person hold the drivers side of the dash while you negoitate this side out of the car.

Use this as an oppourtunity to clean the vents or consider a dash leather wrap upgrade opportunity

. Repair the foamy felts that surround the AC vents. I used to joke about the heater core being GM part 000000000001A and then the GM guys designed the rest of the C4 around it. Some GM Engineer is still prob laughing his AZZ off. GC

WVZR-1 · 09-21-2015

I don't know that I wouldn't consider a repair VS. the replacement of with the current product offerings. Not in your neighborhood but in years past (many) I used this shop in Landover for some unusual repairs. SMITTY'S WELDING AND RADIATOR if the management and employee staff is the same might be worth contacting OR perhaps there's shops in your area that might come with recommendations. SMITTY'S wasn't close but I sent all that I had to them and if they mentioned a fix/repair possible it was always done VS. the purchase.

A bypass of the heater core for the season? Maybe

New I'd maybe consider SPECTRA - a very long time ago this was a Canadian Corp that did engine oil pans and higher quality than most radiators etc. I used their products for many years. I'm quite sure the company has certainly evolved and possibly "consumed" with maybe the cost-cutting adventures. Who knows? They do seem to offer or at least I was able to get a cross-reference using some tools to what was/is their product. A 94494 would be their part # if they still offer it.

GOLDCYLON · 09-21-2015

I would not EVER consider a repair on the Heater Core. Other than bypass a OEM quality factory replacement is the only way forward IMHO.

Could it be done? Yes as WV states but I personally would never do it.

QB93Z · 09-21-2015

Hi Scott, I am busy with rehab'ing a rental property, but if you let me know when you are going to work on it, I will try to come down to your area and help. Nelson has experience pulling the dash pad and I am sure he would be glad to help as well.

I have a coolant system pressure tester that you can borrow if you want to try and verify a heater core leak.

Jim
443-244-1347

09-20-2015	#1
HIZNHRZ Join Date: Apr 2004 Location: Germantown, MD Posts: 738	Likely Heater Core Failure I've owned my current 1991 ZR-1 for just short of 20 years. It currently has almost 18K miles and I've maintained it since it had ~2K. It had less than 7K miles for the first 15 years. The balance of mileage has been added in the last 5 to 6 years. As of today, I've got antifreeze smelling vapor condensing on the windshield and antifreeze in the passenger plastic foot wells. I'm thinking it's time for a heater core. I would like to get some input from someone who has installed a heater core in their ZR-1. Specifically: 1) Did you remove the dash or were you able to get to everything by removing the glove box and lower passenger-side panel ? I think there are a couple of bolts that will be tough to get to without removing the dash. I'm planning on using an inspection camera in order to get a socket on them. 2) Is the OE heater core still available and if not, is there one aftermarket manufacturer known to be "high quality" and form, fit, and functionally interchangable ? 3) Any other words of wisdom or suggestions ? The damage is done but the cooling fluid was changed every 3 to 4 years with the proper antifreeze and distilled water. In the winter the car was garaged in spaces heated enough to take the chill off and in the summer, air conditioned enough to dry the air and keep the temperature below 85 F. Any thoughts on why this heater core might have crapped out ?

09-20-2015	#2
secondchance Join Date: Aug 2006 Location: McLean, VA Posts: 3,705	Re: Likely Heater Core Failure What makes you think it has failed? Is it leaking coolant into passenger side footwell? I have never replaced late C4 heater core but when Paul Farrance had his replaced Dan (Y-me), I believe, removed the dash pad to do the work.

09-20-2015	#4
secondchance Join Date: Aug 2006 Location: McLean, VA Posts: 3,705	Re: Likely Heater Core Failure But then, may be not necessary to pull the dash pad. http://www.c4vetteregistry.com/vrfor...at-bad/406397/

09-21-2015	#7
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,153	Re: Likely Heater Core Failure Having been there and done that its easier with the dash off on the 90-93 MYs. Best suggestion I can offer is to remove the targa top and pull the passenger seat to allow you to lay on your back and get some room to do the job. I wont kid you its a complete PITA and a labor intensive job. I have not done this on the 94-95 ZR-1 since I havent owned one yet but the passenger airbag just adds to the complexity however its a simple unplug and move out of the way process. Take a lot of pictures for reference along the way. If you do pull the dash be mindful of the weak area along the window on the passenger side which is very thin and can be brittle. It is best to have another person hold the drivers side of the dash while you negoitate this side out of the car. Use this as an oppourtunity to clean the vents or consider a dash leather wrap upgrade opportunity . Repair the foamy felts that surround the AC vents. I used to joke about the heater core being GM part 000000000001A and then the GM guys designed the rest of the C4 around it. Some GM Engineer is still prob laughing his AZZ off. GC __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V Last edited by GOLDCYLON; 09-21-2015 at 01:54 PM.

09-21-2015	#8
WVZR-1 Join Date: Oct 2004 Posts: 1,889	Re: Likely Heater Core Failure I don't know that I wouldn't consider a repair VS. the replacement of with the current product offerings. Not in your neighborhood but in years past (many) I used this shop in Landover for some unusual repairs. SMITTY'S WELDING AND RADIATOR if the management and employee staff is the same might be worth contacting OR perhaps there's shops in your area that might come with recommendations. SMITTY'S wasn't close but I sent all that I had to them and if they mentioned a fix/repair possible it was always done VS. the purchase. A bypass of the heater core for the season? Maybe New I'd maybe consider SPECTRA - a very long time ago this was a Canadian Corp that did engine oil pans and higher quality than most radiators etc. I used their products for many years. I'm quite sure the company has certainly evolved and possibly "consumed" with maybe the cost-cutting adventures. Who knows? They do seem to offer or at least I was able to get a cross-reference using some tools to what was/is their product. A 94494 would be their part # if they still offer it. Last edited by WVZR-1; 09-21-2015 at 11:17 AM.

09-21-2015	#9
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,153	Re: Likely Heater Core Failure I would not EVER consider a repair on the Heater Core. Other than bypass a OEM quality factory replacement is the only way forward IMHO. Could it be done? Yes as WV states but I personally would never do it. __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V

09-21-2015	#10
QB93Z Join Date: May 2007 Location: Westminster, Maryland Posts: 3,687	Re: Likely Heater Core Failure Hi Scott, I am busy with rehab'ing a rental property, but if you let me know when you are going to work on it, I will try to come down to your area and help. Nelson has experience pulling the dash pad and I am sure he would be glad to help as well. I have a coolant system pressure tester that you can borrow if you want to try and verify a heater core leak. Jim 443-244-1347 __________________ If it isn't fun, you aren't doing it right! 1990 Black ZR-1 - sold 1993 Quasar Blue ZR-1 1994 Competition Yellow ZR-1 1995 Dark Purple ZR-1 Maryland State Coordinator WAZOO Member