Can anyone give me tips on how best to unclog/clean the inside of an original 74 radiator ? Which products could I use without endangering the insides of the radiator? As I live in Europe, brand names of products will probably not tell me much, so if you can, please use generic names (actual product inside the bottle). gert
a quick way is to get some hard water auto dishwasher detergent / remove t-stat / fill with water / run engine for about 30 min. drain / flush w/clean water / refill with 50/50 coolant and water...works wonders
You cannot clean out a radiator by flushing. It only takes about 3 open tubes to pass as much water as a 3/4 garden hose can dish out. The only is to unsolder the top half of the top tank and run a rod down through the tubes to clean them all out. This is the only way to be sure it is 100% cleaned out. A radiator shop can do this but they usually tell you the cores are too bad and need replacing. You can do it yourself but I understand it takes special flux that allows the solder to stick to the brass.
You may spend more to do this and end up with a radiator that has a leak soon from thin areas. Some cleaners could actually eat a hole through thin areas. If possible replace with a new unit. There are vendors here that still have them new. One possible cleaning agent you might try using is several flushes without any gaurrentees, of Lemon Juice about 25% or so. It is an organic acid that will act on some types of deposits and may help out. We use it here in the dishwasher (1/2 cup) before the rinse cycle, and makes the glassware crystal clean as well as the inside of the washer..
I wouldn't waste my time with it. Get a new radiator core (about $180) and have your old tanks soldered to it. It should be good for another 15-20 years. Trying to take the cheap route with a 30 year-old radiator produces less than optimum results, and since the coolng system is extremely important, there's no sense in skimping...
thanks for the feedback ! While looking for a replacement I will try to flush out all the brown liquid. Apparently in the bottom hose, there were some springs to give it shape, and those rusted into bits. This means I will certainly also need to dismantle the waterpump and check that one as well.
OK, I resisted replying this way, but... I took my radiator off, filled it with 50/50 muriatic acid and water ($1.50 per gallon) and let it sit for about 20 minutes. I tested it first on an "inconspicuous spot" to verify it did not eat into the brass. It didn't. (the radiator is OFF the engine, by the way). It bubbled for the entire time, eating away all the mineral deposits. I did this knowing that if I ruined the radiator, I would be forced to buy a new aluminum one, which is really what I needed. Anyway, the acid ate off about half of the white calcium/mineral buildup that was inside the radiator. I thought about doing it again to get the rest out, but I figured that some of it is actually sealing some of the cracks and pits, keeping it from leaking. Then I ran fresh water-hose water through it for about 15-20 minutes, both ways, to make sure it neutralized the acid before hooking it back up to the car. Anyway, it cleaned out most of the gunk (I had it physically reamed like Mavaholic said prior to this to clean out the big junk), the mineral deposits that accumulated over tha past 30 years. It now runs about 10 degrees cooler, and looks much better on the inside. AGAIN, BE SURE YOU CAN AFFORD A NEW RADIATOR BEFORE YOU TRY THIS!!! It worked for me for the short term. I would not "recommend" this, but am just stating what I tried in a moment of desperation/trial-and-error. But, if I ate a hole in the radiator, I could find $300 for a new one.
