Cleaning rust/scale out of radiator, OUT of truck...?

[K5_489]

Been searching for this one for a while, both here and on Google, without much luck. All the hits I was coming up with was something like "my radiator is full of crusty mud...how do I clean it?? I DON'T want to pull the radiator out!!!", and I'm the opposite - I don't want to put the radiator IN to clean it, lol.

I'm about ready to fire up my freshly built 489 for the initial break in, and I don't want to install a crusty radiator on it just to run some weak part store radiator flush through it sending rust and scale throughout my new motor.

The radiator that was on the truck before was one of those Chinese aluminum + dual fan combo eBay specials. Worked fine for normal street driving, but the fans didn't pull anything even remotely close to enough air to keep the stock 350 cool while running dirt trails all day. I pulled a good condition copper/brass 4 row out of my K20 parts truck, and want to install it with the new motor along with the factory clutch fan, but the PO of that truck ran plain tap water in it...thus the radiator has some rust and scale build up in it. I drove the truck for a bit before tearing it apart, so I know the radiator wasn't leaking, and it doesn't appear to be clogged based on looking at the core through the cap port.

I used muriatic acid on a Jeep radiator years ago, which seemed to pull a TON of crud out, but only ran that radiator for about a month after, so I don't know if it caused any long term damage, as I know hydrochloric/muriatic acid baths are used by electronics scrappers to melt solder for component recovery, though the boards are usually submerged for a few days.

I've read a lot of posts about using oxyalic acid, as that's what was in the old school radiator flushes before the EPA got involved, but same problem as I noted earlier - all the posts are about dumping this stuff in the radiator, and driving for a while.

Any good solutions for this without having to put the radiator in? I was thinking about rigging an electric water pump up to the radiator to cycle the cleaners through it, but not sure if heat is a needed part of all this too....

 

[TubeTruck]

yeah, you need to cycle the detergent through. If you don't have anything that can create a closed loop system try a radiator shop. See how much they charge to clean it.

 

[K5_489]

try a radiator shop. See how much they charge to clean it.

Tried that a few years ago for the '59, lol... they all said the same thing - "yeah...we don't do that any more...cheaper just to put a new one in" sure...just where do I find a NEW radiator for a '59 International medium duty truck that isn't a hacked in half plastic job from some other random vehicle?

Reality is that this K5 is likely going to end up with a new Ron Davis in it anyways, but I was just really hoping to get the new motor fired up this weekend. Not even all that concerned about getting shiny brass inside, just wanted the crusty stuff out, and not in the new block, lol.

 

[Snoots]

Find a shop that will do it for you or buy a new radiator.

Forget the DIY stuff for this job.

 

[TubeTruck]

Tried that a few years ago for the '59, lol... they all said the same thing - "yeah...we don't do that any more...cheaper just to put a new one in" sure...just where do I find a NEW radiator for a '59 International medium duty truck that isn't a hacked in half plastic job from some other random vehicle?

Reality is that this K5 is likely going to end up with a new Ron Davis in it anyways, but I was just really hoping to get the new motor fired up this weekend. Not even all that concerned about getting shiny brass inside, just wanted the crusty stuff out, and not in the new block, lol.

Cheap and easy? Roofing rubber (or something of the sort) and hose clamps. Block the lower radiator port and fill 3/4 of the way with detergent of your choice and hot water, cap off the top port, shake it like this , or get a buddy to help , rinse and repeat until you are satisfied Let us know how it turns out

 

[K5_489]

I was actually thinking about this some more during some down time at work....I know somewhere in the garage I have one of the Horror Fright's 12V utility water pump that's a poor knockoff of a Shur-Flo RV water pump, with garden hose connectors on it, that I scavenged out of a camper I rebuilt (didn't use it because it doesn't have the water pressure cutoff switch that proper RV pumps should have). Should be a simple affair to attach it to a couple PVC adapters that go from garden hose thread to a pipe adapter that matches the radiator hose outlets on the radiator, then connect to the radiator.

Stand the radiator up, fill with cleaning solution, connect the pump to my bench power supply, flip the switch, and do something else for an hour, or until the acids eat away the PVC adapters, lol. Empty radiator, refill with soda ash solution, flip switch, walk away for another hour, and repeat with fresh ash solution just in case.

 

[shiftpro]

I filled a rad with vinegar and let it sit a few days. A few hours of water running through it and I got a LOT of scale out of it. Now, I can't confirm if the vinegar had anything to do with it or it was just the gallons of water running through it. I certainly came out looking much better than before.

 

[legopnuematic]

A bike inner tube cut and each side clamped to an inlet/outlet is one way to close a radiator off. I would flush it reverse of standard flow to lessen the chance of crud making it farther in. Some old radiator hose and some pvc fittings you can make an adapter to hook a garden hose up to it to get some pressure

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[chengny]

Here's the cleaning process I use. It goes something like this:

I have used CLR and Bar Keepers Friend (the BKF needs to be mixed with hot water to get it into solution) to clean radiators several times with no ill effects.

I started doing this because the radiators were original - OEM with brass tanks and copper tubes. They were beautiful - had no leaks and the fins were all there. Looked great from the outside.

But inside was another story, the tube ends (where they are soldered to the tanks) were so fouled that flow was being restricted. The watersides of the tanks were encrusted with deposits as well (so the assumption was that the inner walls of the tubes were in similar condition).

There are no more radiator shops around here, so I decided to "boil" them out myself. Nothing to lose; otherwise they would have certainly just been junked.

I have only done this with the radiator out of the truck and lying flat (outside and on a wooden picnic table). Radiator cap is on and the small connection to the expansion tank is capped

Pour a whole quart of CLR into the radiator and top off with city water. I use ZEP brand - it has a higher concentration of acid (hydrochloric & sulfamic) than the big name brand. If using Bar Keepers Friend (oxalic acid) mix half a can of powder into warm water and stir until you have a solution that can be poured.

Let it sit for hours. When you want to check the progress, dump the acid/water out (save it in a bucket - it still has plenty of life). Using a garden hose at full flow, flush the waterside out. Go in both directions. Lift and shake a couple of times. When no more deposits are getting flushed out, pour the acid back into the radiator. It helps if you filter the re-used solution through a piece of window screen or similar.

With several applications (dump and flush with clean water between) the deposits will be gone and the copper and brass will be a golden color.

When satisfied that you have clean surfaces and will get good heat transfer/coolant flow, do a final long flush to get any remaining acid out. If it makes you feel better, you can use a solution of baking soda/water to neutralize.

 

[shiftpro]

Here's the cleaning process I use. It goes something like this:

I have used CLR and Bar Keepers Friend (the BKF needs to be mixed with hot water to get it into solution) to clean radiators several times with no ill effects.

I started doing this because the radiators were original - OEM with brass tanks and copper tubes. They were beautiful - had no leaks and the fins were all there. Looked great from the outside.

But inside was another story, the tube ends (where they are soldered to the tanks) were so fouled that flow was being restricted. The watersides of the tanks were encrusted with deposits as well (so the assumption was that the inner walls of the tubes were in similar condition).

There are no more radiator shops around here, so I decided to "boil" them out myself. Nothing to lose; otherwise they would have certainly just been junked.

I have only done this with the radiator out of the truck and lying flat (outside and on a wooden picnic table). Radiator cap is on and the small connection to the expansion tank is capped

Pour a whole quart of CLR into the radiator and top off with city water. I use ZEP brand - it has a higher concentration of acid (hydrochloric & sulfamic) than the big name brand. If using Bar Keepers Friend (oxalic acid) mix half a can of powder into warm water and stir until you have a solution that can be poured.

Let it sit for hours. When you want to check the progress, dump the acid/water out (save it in a bucket - it still has plenty of life). Using a garden hose at full flow, flush the waterside out. Go in both directions. Lift and shake a couple of times. When no more deposits are getting flushed out, pour the acid back into the radiator. It helps if you filter the re-used solution through a piece of window screen or similar.

With several applications (dump and flush with clean water between) the deposits will be gone and the copper and brass will be a golden color.

When satisfied that you have clean surfaces and will get good heat transfer/coolant flow, do a final long flush to get any remaining acid out. If it makes you feel better, you can use a solution of baking soda/water to neutralize.

This is amazing info, thanks!

 

[bucket]

@Vbb199 You seen this thread yet?

 

[73c20jim]

I been messing with cars and trucks since 1962 and I still don't remember which way the water flows in the radiator.

Top to bottom
OR
bottom to top.

Help an old man.

 

[bucket]

I been messing with cars and trucks since 1962 and I still don't remember which way the water flows in the radiator.

Top to bottom
OR
bottom to top.

Help an old man.

Top to bottom

 

[Vbb199]

@Vbb199 You seen this thread yet?

Apologies for no replies....

Ive been doing heads on my DD all weekend...

I planned on taking it to the local rad shop and having them repair my bbc rad and flush it and boil it and all

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[K5_489]

So I said the heck with it, and did the flush before reading more replies here (I live in the sticks, with my only internet access on my cell phone, and less than stellar cell phone signal).

Used a gallon of Zep CLR dumped in the radiator, filled the rest of the way with tap water, and used that old 12V water pump to circulate the water. Capped off the heater core connection, and used a pair of PVC plumbing fittings to go from the big hose connections to 1/2" NPT hose barbs (glue on male on one end in 1.25" and 1.5" sizes, female NPT threaded on the other end), and connected to the water pump with an old garden hose cut up to fit.

First used the garden hose to flush and back flush several times, flushing quite a bit of loose stuff out. Then let the CLR circulate for an hour, followed by a neutralizing flush of soda ash mixed with water. Ended up getting several cups of what looked like beach sand after the CLR flush, which I'm assuming was calcium from the often salt softened tap water out here. Some flaky rust looking stuff came with it, but not nearly as much as I had expected to see. Maybe I just needed to let it circulate longer..I don't know.

But I will say that I doubt I'll ever use the Zep CLR again...holy sudsing action! Probably beneficial as a cleaning agent, but it was a real pain to work with, as I had to stand over the radiator for a good 30 minutes, slowly pouring more mix in as the suds went down. I know hydrochloric will bubble and fizz a bit due to the chemical reactions, but this was like I dumped a bunch of Dawn dish soap down the hole. I know I didn't get nearly this much fizz when I did that Jeep radiator years back, and I used a much higher concentration of acid on a much nastier radiator.

Still though, all told, I'm glad I went through this, given the amount of crap I pulled out. Thought about it for a while, and figured if it works, great! If it eventually causes the radiator to fail...well, either I buy a new radiator now, or then..either way, I'm in the same boat. If it doesn't get all the crap out...well, it's still less crap in my new motor than it would have been had I not done anything. And buying a new radiator....given the amount of pure garbage on the market, short of dropping big money right now (and my budget has already been blown clear out of the water on this project...so far, I'm in it at least 10 times as deep as I originally planned, and my project fund is completely decimated for a while, lol), I figured I'd be taking more of a gamble on a new parts store radiator holding together.

The attached picture is of the silt haul in the bottom of a 5 gallon bucket.

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