I just did the heater core in my 92 S19 Blazer. I dreaded doing it for two
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.
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.
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
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.
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?
The 4.3 has a block drain on the driver's side, dead in the middle of the
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
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.
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
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
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