C4 Heater Core Replacement



C4 Heater Core Replacement

Postby bytor » February 3rd, 2015, 10:20 pm

Next project on deck for my 87 vette is the dreaded heater core replacement. I have no leaks but smell coolant when running the heater and notice the windows fog up slightly. Telltale sign of a very small leak in the heater core. I checked behind the carpet on the passenger side and no signs of a leak either.

I plan of doing a vacuum leak down test on the core in the car to verify the suspicion. Just like the C3 corvettes, the heater core was put in a jig and the rest of the car was built around it, it would seem. The shop manual has you removing the dash pad and other goodies before you can access the core cover. Here's an old mag article covering the process.

c4heater01.jpg

c4heater02.jpg

c4heater03.jpg

c4heater04.jpg


There seems to be an alternate method thats considered shorter.

-Remove passenger seat
-Remove lower dash panel (the one with the courtesy light)
-Remove connector to temp door motor
-Remove ECM ( held in by two 10mm screws, remove them and slide the ECM down and out of the way. You can disconnect it and remove it entirely)
-Disconnect rod from connector at door motor arm.
-Remove the door motor
-Remove the tubular angle brace
-Disconnect small duct-work
-Remove all the screws holding plastic cover
-Wrestle cover off
-Remove the old core and re core and put it all back together.

This method seems doable except for the 2 upper core cover screws look like a PITA to remove and reinstall.
100_0099.jpg



What method have other C4 owners here on the forum used to replace the heater core and what words of wisdom would you pass along?

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Re: C4 Heater Core Replacement

Postby bytor » February 4th, 2015, 1:55 pm

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Re: C4 Heater Core Replacement

Postby Indycars » February 4th, 2015, 3:24 pm


I can already hear some choice words coming out of you garage!!! :D

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Re: C4 Heater Core Replacement

Postby grumpyvette » February 4th, 2015, 3:35 pm

Ive only had to do that job ONCE and it was on a friends 1987 vette, and while I remember it took all weekend I also don,t remember it being all that difficult, it was more of a P.I.T.A. getting the new one installed and the dash re-assembled than it was to get the heater core out as I remember it but it was 15 or so years ago.
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: C4 Heater Core Replacement

Postby bytor » February 4th, 2015, 9:10 pm

Put the MightyVac on the core while still in the car and pulled about 15 inHg of vacuum and sure enough, drops about 1 inHg per minute. Very small leak. Fun weekend ahead for sure.
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Re: C4 Heater Core Replacement

Postby Indycars » February 5th, 2015, 8:22 am


Good luck, wish I was there to hand you tools!

You should do a time lapse with a GoPro!

Rick
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- Need a Dynamic Compression Ratio Calculator: viewtopic.php?f=99&t=4458
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Re: C4 Heater Core Replacement

Postby bytor » February 5th, 2015, 10:25 am

Indycars wrote:
Good luck, wish I was there to hand you tools!

You should do a time lapse with a GoPro!



You guys don't want to see me do Yoga and stand on my head, I got a feeling I will be doing a lot of that. I will get some progression pic's up though..
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Re: C4 Heater Core Replacement

Postby grumpyvette » February 5th, 2015, 11:09 am

Id strongly suggest removing the pass seat and getting several low heat LED shop lights

http://www.harborfreight.com/rechargeab ... 94668.html
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: C4 Heater Core Replacement

Postby bytor » February 8th, 2015, 4:42 pm

I successfully replaced the heater core without removing the dash pad. It wasn't a horrible task if you just take your time.
The challenging part was removing the brace tube, getting to the upper bolt was a practice in patience.
IMG_2404.JPG


I most deferentially had a very small leak in the core. I had coolant on the hush panel. I believe I caught it before it made a mess on the carpet.
IMG_2391.JPG


You have to remove the ECM to access the heater core cover. It would seem the ECM was replaced with a reman unit based on the sticker on the ECM.
IMG_2403.JPG


I took a peek inside while I had it out. Couldn't resist.
IMG_2394.JPG


I discovered another problem while putting things back together. The darn heater control valve vacuum canister wont hold a vacuum and operate the valve.
hcv1.jpg

download.jpg




I found a way to repair it withoug having yo buy the whole pipe.
http://www.corvetteforum.com/forums/c4-tech-performance/2172122-heater-control-valve-solution-85-87-corvette.html
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