Heater core - DONE!

I just did the heater core in my 92 S19 Blazer. I dreaded doing it for two months now.
I'm not sure why I waited so long. It was done in about an hour and a half.
Very easy. I didn't have to take apart most of the stuff the instructions on the other websites gave me.
They said to disconnect part of the dash, and remove the ECM. Neither one was in my way.
Thanks for everyone's suggestions and help.
Lannie
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two
half.
Good job man! I might be digging into the dash on my wife's 98' Sonoma pretty shortly as she's gurgling a bit.............
Doc

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""Doc"" wrote

Uh oh! Sounds like the beginning of the dreaded mud in the Dexcool cooling system....though I'm sure you have been keeping an eye on that.
Have you changed up the rad cap to the revised one? If not, you might want to start there.
You might also want to remove both heater hoses at the engine and back flush just the heater core with a garden hose.
Ian
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Ian,
I have been putting off service on the wife's truck <not like me at all eh? he he he he he>. It's a 98' w/ 29,500 miles and I was planning on waiting till she hit 30k to do the coolant, AT, diff., etc. Guess I'll have to jump the gun by a few hundred miles. We got the truck used so I don't know if it has the revised rad cap or not. Do you have a P/N for that one? I have checked the condition of the coils in the rad via the filler neck and all looks pretty clean to me, and there isn't any of the Dex Mud on the cap like you see on some.
She only gurgles on mid-to-full throttle acceleration within the first 10 minutes of being started up. Sound like a typical Dex problem? We've been running the A/C quite a bit lately and I thought it might just be leftover condensate that gathers after the truck is shut off and runs off when it's fired back up <wishfull thinking eh?>.
Looks like next weekend I'll be drenching my garage floor with the "orange stuff."
Doc
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""Doc"" wrote

The bulletin lists this number GM P/N 15075565, but I did think that there was supposed to be a Stant cap that had a different design. I can't remember that web site that has been posted around here for a quite awhile, but I believe it had that number.
Ian
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Thanks bud, I'm gunna have at it this next weekend. Haven't done this on a 4.3L before as this is the 1st six cylinder truck I've owned. Any suggestions as to how to get all the old stuff out? On my older SBC's I just drain the rad and pop the Knock Sensor out to get most of it out. Do ya hafta yank the freeze plugs on the 4.3's to get all the ol' shit out?
Doc

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The 4.3 has a block drain on the driver's side, dead in the middle of the motor, IIRC.
Been a little while since I put my motor in <89>, but I'll be putitng a new tranny in this week and will let you know if the above statement isn't accurate.

have
a
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""Doc"" wrote

a
Don't be pulling any freeze plugs....(grin). Unless you want to just yank the motor right out of there. The 4.3 has drain plugs just like your small block.
Since you have probably kept your antifreeze level up, you may not find a lot of crap in your engine. The main thing is to make sure the rad cap is working properly so that it will draw what coolant it needs out of the overflow tank, and make sure the hose from the overflow tank to the rad is not plugged in any way. Then don't be afraid to overfill the overflow tank a bit.
Ian
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on
Do
Roger..........
Gunna backflush the system this weekend, change t-stat and rad cap.
Doc

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LS, Please share more of what you did (to avoid dash-ripping, etc)!
I have a 96 GMC Sonoma that I think needs a heater core... It gurgles often. And when shut off for about an hour and restarted it mists the windshield (drys off with the defrost ok). There is also a slight smell of antifreez in the cab. There's also a green antifreeze color coating on the underside of my AC pump. Seems possible I could also have a mild leak in the manifold, but I'm not seeing any mixing (vasalene in the oil cap).
Doc - does the diagnosis sound correct? Heater core? Manifold probably OK for a while? Did you do your heater core you mentioned in this post?
I'm also rebuilding an 87 S-10 Ext 4x4 - may need to replace a heater core on it too - so shortcuts to not having to rip the dash would be most appreciated (I'd even consider cutting the firewall from outside on that one.
Thanks, Elliott
LS wrote:

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