This "might be" a solution.. If you can take both lines off the heatercore from the engine side, use compressed air to lightly blow it clear of most any liquid, get a couple of hoses about 2-3' in length and attach to core lines thru firewall. Get a large pot of almost boiling water and add some "Lime Away" from the hardware store to this mix.
With a funnel and safety in mind, pour hot mix down to fill up core. Let stand for a while (maybe til it cools enough to not burn yourself, and then let one line down to a bucket or.. and see what comes out. Repeat if necessary..
And or flush with clear water.
This will bubble and foam while its' eating the corrosion and build up inside the core. So, watch out for painted surfaces..(I never had paint around an engine that nice to worry about anywho..)
NOW, I say "might" because if ones core is severely corroded, this might cause leakage. That solution could be to compress the core with the hoses/lines and listen for 'hissing' under the dash.. And if there is, Don't get mad at me:wink: Just what I've done before.
One needs to COMPLETELY FLUSH the system after, due to chemical properties unforeseen that could eat your radiator if its' incompatible with the "Lime Away"..
I'm going to try and get a big pot of boiling water and fill up a drum to soak this 4.1 bare block and bare heads with a pelletized rust remover that one can use for household apps like rust on walls or driveways..
Heck, if they say, use to dissolve in the back of a toilet tank rust, then it should knock out the rust in the oil galleys and such that one can't get to.
ANOHER thing.. Did you 'burp' the system after you changed the T-stat?
If there are air pockets around the sensor, you will have a false reading until that water can flow around the sensor end.
Sometimes one needs to push down on the upper radiator hoses to make sure that the highest point will be near an air bleed of some sort.
Sorry for the long post. It's helped me out many times before.
E
