Chalkboss

Excellent news! Please do post results. I am sure mine is a bit plugged- same symptoms as Dr. Bob above.

docmirror

I'm reluctant to post my method, surely it will get me ostracized, but that's life. Try this at your own peril, I make no guarantees, and will not be held responsible for the results should it fail.

Having a pool, and having very hard water at my house means a lot of scale on my tile in the pool. Every two years I'm out there with a bottle of muriatic acid, some rubber gloves and a green scrubber taking the scale off manually. When I bought a 968, it came with no radiator and I bought a used one without knowing anything about it. It was pretty clogged and the car would run really hot under all conditions.

Since I had options for a new radiator if needed, I decided to do some home brewed cleaning. I mixed a 50% solution of acid and distilled water, and tested the rubber seal to make sure it wasn't affected. I tested it on the side tank too and got some mild etching but no real damage. So, I laid the tank flat and poured the weakened solution into the radiator fill hole. The rest was pretty exciting! The solution started to boil pretty good and sent off some serious fumes as it etched away the scale deposits in the rad core. I let it get pretty hot and then poured the solution out in a bucket and rinsed with distilled water, and a bunch of crud came out. After drying, I filled it with the same solution again and let it sit for about 10 minutes. The rad got hot, and it boiled and smoked for a bit, then seemed to calm down as the scale was taken off the tubes. I rinsed it again, and mixed up another 50:50 batch and did it once more.

After that I cleared all the external fins with a pressure washer set on low and blow from the back to the front. It works great now even in the middle of summer. Remember, I make no promises, but it worked for me. Don't let it get too hot or you could have a geyser of hot acid on your hands.

Chalkboss

^^ I like this. Better living through chemistry. Having said this, I assume you neutralized that waste!

Bilal928S4

What about using CLR to remove scale?

VegasGnome

From a bottle of CLR. Check the middle column of the DO NOT USE CLR ON window.

jwillman

The radiator shop charged me $88 (I supplied the end tank seal) to pull the end tank flush and get back 30% flow and had it done in less than 2 days so I think for me it was well worth not having to deal with the noxious chemicals and removing and reattaching the end tank.

dr bob

CLR is a caustic product, vs the dilute acid solution that Doc Mirror used. I've dinked with the acid method, but used vinegar (weak acetic acid) vs Doc's diluted hydrochloric acid brew. Half an hour with the vigegar didn't do anything noticeable as far as the lime scale, but it did do some surface etching of the exposed aluminum.

Knowing I have the new radiator in the box here as fallback, I'm tempted to let a good local radiator shop take a crack at my original, if they can do it without trashing the stickers/labels. I drove to OC today in ~100º heat and saw the needle up near the last white line, a little warmer than what I'm used to. I did a coolant change a few weeks ago now, and upped the coolant dosage for a possible colder winter operation. That cost about 10º from 25% to 50% with no other changes, if anyone's paying attention.

Rob Edwards

Duly noted. But I have about 50 years' worth of radiator reserves here....

Roger's repro radiator stickers are ok, though not perfect. Maybe Jerry could take a shot at finding the magic gold foil, given his smashing success with the cowl cover stickers?

Roger's:

jwillman

I am listening!

I am also considering the 25/75 ratio. My luck we will have record cold weather in central Texas this year. Could always drain some out and increase ratio if the weather looked like it was going to get that cold.

dr bob

Jim/Rob--

Remember that the comparison is on a system that's just barely getting by in 100º+ temps. With a radiator that's flowing closer to design conditions, the temperature wouldn't change much. The thermostat would just open a little further to increase flow to the radiator. That's the theory anyway.

It's a little too toasty today to go swap radiators, so it may end up being a late-evening project soon as the weather cools some. I'm on standby for a power plant project that's in the middle of a performance dispute. I know that as soon as I disassemble something, the phone will ring and I'll be on a plane.

jwillman

So perhaps the better course of action is to reinstall the freshly flushed radiator with 50/50 and water wetter as I had before. That way I am apples to apples when I start looking at cooling performance changes before versus after.

docmirror

Yeah, CLR is about as feminine as you can get. If you're gonna go, go big. I tried to get H2So4 but for more than 4oz I needed to sign a bunch of stuff so I went with the comm avail HCl. Remember, if you go this route, dilute with distilled and not tap water, wear a face shield and have a hose handy(to spray your body when it goes off like a Roman candle).

I am not a chemist, and I don't play one on TV.

Jerry Feather

Hi Rob. Actually that idea is kind of in the "wings of my brain." In fact I just obtained a pretty nice spare tire cover with a very nice condition metalic sticker on it primarily for the purpose of replicating the sticker in some kind of foil to add to my Spare Tire Cover offering

When I had the vinyl stickers done for the Cowl Covers I asked the guy about doing the metalic ones and he said that he is not set up for that and that they are silk screened. I have a good friend in the Trophy business and have not yet talked to him to see if he can do these. I have seen him work in some kinds of foil, I think.

So, the radiator stickers should be no problem to add to the que, when I get back to it.

Chalkboss

If you dilute acid add acid to water- not the other way around. If you add water to acid you risk a violent reaction, depending on acid type and concentration. Read up on it if you have not worked with acids to avoid potentially serious injury.

dr bob

Most folks are less than prepared to do any serious acid cleaning. If you've been cleaning the pool tiles, you know about sacrificial clothes, rubber aprons, face shields over chemical goggles, and long-cuffed rubber chemical gloves. And plenty of ventilation. After that, it gets to logistics of how to mix, how to fill, when and how to drain, and what to do with the stuff you take out. You can't just pour it in the drain, the gutter or the lawn, at least not around here. In this case, dilution is the solution to polution, but it needs to be managed carefully before it hits the plumbing. Or just through the whole thing into the pool when it's done fizzing...