1994 Radiator/colant problem (I think)

[innkeeper46]

Ok - first things first - my van has had 2 rads replaced and the latest one does not leak. However when I had the second one fixed they told me I have heater pumps. One in front and one in rear. They told me they might be cloged up and need either replaced or 'blown out'. Ok...sounds fine. However heres where it gets weird. Personally I think it is possessed LOL but.....

I have used that leak stop stuff called gunk or something like that from Wally Mart and for a time it works. No leaks......for a short time. Then all of the sudden water comes out the back right side. That may not be weird enough for ya so lets see if this will show ya how weird this van is. Today I took a trip about a 30 min drive and I topped off the rad with water and commensed driving. Soon after the van went hot - not nucular but HOT. Usually it cools down some but this time it did not. So we got to our destination and stopped to check and FILL rad. It was hot but not too bad and I filled it full. I figured the same thing would happen - you know over heat.....BUT NOOOOOOOOOOO lol.....not even past the right level of cool if that makes sence. Meaning the whole trip back was perfect. No leaks and not over heating. I have already forked over a bunch of money to get this fixed and now just new problems. Can someone tell me a profesional opinion? It runs very good for an old beast but this over heating is not good so any help would be great.

[alloro]

FYI, they're called heater cores not heater pumps. Basically they're a miniature radiator with coolant running through them. As air passes through the cores it is heated because of the hot coolant in them and you get heat. If they're clogged (or restricted) the coolant doesn't flow through them, so the air that passes through does not get heated and you have reduced or no heat. That why they need to be flushed out occasionally.

As far as your trip goes, it sounds like you have a sticky thermostat. First it was sticking closed so the van overheated. On the second leg of the trip, the t-stat was stuck open so the temperature stayed down below normal.

Your use of radiator sealer could've gummed up the t-stat and is making it stick.