I hope whoever decided where to put the heater core...

[jonathon]

..dies a slow, and painful death

Did mine today in my Suburban, took 5 hours. No mess at least and the clip on the defrost was just fine(maybe they changed for '91?).

Observations from me:

NO WAY could you not drop the inner fender. With as much of that black sh!t they sprayed around the AC box, it takes a fair amount of time to scrape it off to even get to the lower nut closest to the fender.

The clips GM used to secure the fender are ghey. All the ones on the rear of the fender broke on me, I said fock it and didn't put them back on. I figure with the remaining bolts, plus those two 9/16's ones that secure it to the firewall, and the battery tray would hold it just fine. I saved the bolts in case I ever got adventurous and decided to do it again.

Disconnect the heater core well in advance of doing it. Most parts places should sell a 5/8's to 3/4's hose adapter, thats what I used. I disconnected mine almost a month ago and there was still a tiny bit of coolant in it.

Removing the passenger seat makes it easier to get to stuff.

I am convinced the funny focker who designed the location for the GM heater core must've been on acid or something.

 

[4X4HIGH]

I've replaced my heater core in my 89 blazer with A/C in about an hour. I did get to the one "hidden" bolt without removing my inner fender well by using a 1/4" drive socket with a swivel and extension.

 

[abig84]

heck, these are the easiest trucks ever to do a heatercore on, try doing one in like a 97 town car or a newer body s10, youll spend 12 hours. i did one on my suburban the very first time in like 2 hours. my k5 with no a/c like a hour

 

[thatK30guy]

I take it your rig has A/C?

Trucks with the non-A/C heater boxes are much, much easier to get the cores out of.

 

[4X4HIGH]

I'm doing an engine swap for a guy in 2 weeks on a 94 GMC Sierra 4WD and he also wants me to do his heater core. Those are supposed to take about 5-6 hours to do. Maybe since i'll have the engine out it will make things a little easier. Oh well, doesn't matter to me since it's all extra money anyways.

 

[jonathon]

I've replaced my heater core in my 89 blazer in about an hour. I did get to the one "hidden" bolt without removing my inner fender well by using a 1/4" drive socket with a swivel and extension.

My Ranger took me all of 20 minutes, same as my grandpa's F250 But on those, it's just a plastic box with a few bolts holding it in.

I didn't have a 1/4" drive socket set big enough to get into there(sure it would've worked since these nuts weren't all that tight), but someone went crazy with the black stuff(it took me a bit just to find the nuts). I removed a ton that wasn't directly sealing the box to the firewall. Think that'll effect it any?

I take it your rig has A/C?

Trucks with the non-A/C heater boxes are much, much easier to get the cores out of.

Yep, it has AC.. looking at my K5 I don't think I'd have an issue(and there's not nearly the amount of sealer around the box). I am grateful that my AC does work though.. blows cold as ice and it's still the original R-12. Original owner took good care of it.