Welcome to the Forum.
A ton of terrific information and an abundance of super folks , who like to help.
There are a few Not-So-Nice People, who , for some reason, feel the need to spill their Venom.
Like at any public event or gathering. You know, the Types who write all that weird stuff,
on the Public Bathroom Stall Walls.
There is a couple of terrific features you need learn, right now.
First, if you place mouse over a posters Name, that box to left of their post. Let your Mouse Symbol just sit there.
A pop window will have Follow, Ignore or Conversation. Clikc the Ignore and you will never see that screwballs Drivel, ever again.
I had no idea who you were apologizing 'to' because I had already put that individual in my "Ignore the Feces Tossing Monkey" List.
2nd Awesomely, Terrific Feature is at the top right of every page.
Little magnifying Glass Symbol to the left of the work SEARCH
Fastgest way to find Answers is to go fetch them form threads other people have discussed, rather than waiting for someone to answer your new thrad.
FOrums members to tend Ebb and Flow. Your Issue may very well have been solved, by a forum Member who has not visited in Months. He will not see your post but your problem is one he already provided the solution. Go get that solution. It;s like Gold just waiting for you to fetch.
Rgarding yoru problem,
Remove the hoses from your heater core. Back flush the heater core with a graden hose but be aware to keep pressure low. Coolling systems are normaly less than 20 PSI, House water presure tends be 65 - 100 psi, city, rural etc.
See hwo it flows through the heater core adn look for Gunk.
If any gunk comes out, then the entire engine needs to be cleaned up.
Best way is coolant flush, couple of tiem,s to get teh easiest gunk out, then add RMI-25 to bust loose the caked on gunk, then fluch a few more times.
Idea is to ensure coolant ahs a freef lwoing pathway through the entire cooling system and no GUnk staling the heat of the coolant and keeping it fromm transfering to your heaqter core itself.
Once that is all good, then we can start looking at thermostats and other things.
let us know and, most imporatn
once you find the solution, post the experience, the path you took and the actual solution that fixed yoour issue.
It may help another, own the road.
again, Welcome to the forum and do not let the few jerks, run you off.