I've spent some time on the net today looking at various options for unclogging a possibly clogged heater core in my 98 Volvo. The driver's side gets cold air and the passenger side gets hot air, so I'm expecting it to be a partially clogged core. It is cold here in Minnesota now, so I was looking for relatively easy options that included reduced risk of frostbitten hands.
I figured I'd share a couple ideas other than what has already been mentioned.
One idea is to swap the hoses on the heater core. That will use the pump to do the dirty work for you. The crud will still be in the system, but not blocking the core. A full flush is probably recommended at some point after doing this, but might be an easy way to get you up and running quickly. The recommendation (from others) is to swap the hoses and run for several minutes with the heat on high and then swap the hoses back.
The other plan is a product called RMI-25. You can google it to find one of the online places to purchase it. Apparently local shops don't carry it. Goes for about $10/8 oz bottle.
This is a product that you can add to the coolant and it will slowly unclog and open up the narrow passages in the system (radiator, heater core, pump, engine block). It somehow keeps the junk in suspension and will supposedly end up migrating it to the overflow tank, where you can remove it if you want. From the pictures, it will look like a slimy material.
Benefits of that approach is that you don't have to mess with the hoses, antifreeze spillage, etc. Might take a couple weeks to complete the unclogging, according to what I've read.
I ordered a couple bottles today and I'm going to try this approach.
This product can also be used as preventative maintenance once or twice a year to keep the system clean.
Even though it keeps the junk in suspension, I'm still planning on having the system emptied and refilled when time allows. And if this stuff works, I'll probably start using it for preventative maintenance.
I don't have any stock in the company. I don't even know who makes it.
Prestone makes a Super Radiator Flush and Super Radiator Cleaner. The Flush involves emptying the system, putting the stuff in, and letting it run for 10 minutes and then emptying and refilling again. The Cleaner is the same process, but you leave it in for 3 to 6 hours of driving (can be intermittent) before flushing it out.
I figure the RMI-25 is the same idea as the Super Radiator Cleaner, yet you can leave it in there indefinitely and don't have to go through the flushing procedure right away if you don't want, so that's what I'm going with for now.
David
