VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 Radiator and Block Flushing

I've read the threads on flushing radiator and block with some interest. My 23 has overheated everytime I have driven more than a couple of blocks. I have not tried either the lye or muriatic approach yet but I did flush the block and radiator. First off, flow appeared to be good out of the block. Also I got no loose rust flowing out of the block. The radiator doesn't appear to be blocked because water seems to flow out at the same speed it goes in. If this were your project would you go with the muriatic acid treatment first or assume the radiator is blocked with grease and therefore try the lye route?

Dansker, short answer YES, do it! You have nothing to lose and a 23 to gain! I'm the guy that did the flush... and knock on wood, it cleaned up the motor but more importantly she doesn't overheat. I didn't get chunks or gobs to come out either but what I did get was a long, long stain of concrete down my driveway that looked like rust and old water. THAT was what was hidden inside the poor gal.

YES, do it and become a believer.

Jerry

All that cleaning is a positive effort to keep an engine from overheating. If you don't get positive results from that action I would switch over and start suspecting a headgasket or cracked head. A radiator shop can tell you if exhaust gasses are in your water.

Ray

I am going to be like Pollyanna and play the glad game and just assume the cleaning out will work. I think the engine was rebuilt just before it went into the car museum I bought it from. I'll take inspiration from Heavyhands and hope the treatment works. Just bought a gallon of Muriatic acid tonight. Maybe I'll have time this weekend to give it a try. BTW what do you think of our friend from Oz's previous suggestion of using a rust converter treatment? Thanks for the guidance.

You say that the radiator and block flow well and it over heats after a couple of blocks and the motor was rebuilt shortly before it went into a museum. OK it won't hurt to clean out the radiator and block but it seems to me for it to overheat after such a short distance says things like, "Tight engine", "Bad timing", "head problems". I once worked on a "27" that wouldn't run for more than 5 minutes before it overheated. Engine just far too tight on reassembly.Just something else to think about. Good luck.

Ray, I believe this overheating engine thing is a process of elimination. In my case, I had the radiator rebuilt (and it was full of junk and garbage, but she still ran hot. Next I pulled the water pump and basically replaced the seal and made sure it worked freely. And she still ran hot. I replaced all of the antifreeze of course when I pulled the radiator, and she still ran hot. Basically at this point I had no ideas left and she sat in my garage for awhile. Then we started talking about it on this site and so many people stepped forward and suggested the engine flush. Ever since then I have been driving it here and there and to this point and that place, with absolutely NO overflow, no overheating and so far no problems (ahhhhhhhhhh well there's that braking thing, ha, ha).

Jerry

Jerry
Re 'I replaced all of the antifreeze' get rid of it as its toxic, Many years ago my water pump had a small leak and after 6 weeks the 'annifreeze' had started to eat into my timing cover. I no expert in modern stuff but I was told that it must only be used in a sealed system.
Since the I just use a plain old rust inhibitor, not sure what you can get in the US but in Oz there are 2 brands available "BARS" and "NYLON"
Get rid of that anifreeze and make sure you don't spill it on your driveway as it eats concrete as well.
Chris

Hi Jerry,

I support Chris's comments. Modern Anti Freeze and Anti Corrosive additives are designed to work under pressure in a sealed cooling system, and when exposed to the air become corrosive. I have been running an over flow tank with a very low pressure sealed system for the last 20 years, but it was not until I put in a 28 water pump with modern GM inners a few years ago that I was able to use a modern additive. The original Chev water pump would occassionaly drip and spray coolant around the engine bay.

Hope that helps

Cheers

Ray

Dansker,

There could be a partial blockage in the block even though the flow is good. That is what I found in my '17 490 when I was doing a valve job. While the head was off I was checking the coolant passages in the block and found partial blockages around cylinders #1 and #2. The blockage of rust was so hard it had to be broken up with a small hammer and a long screwdriver. It took quite a bit of patience and time not to mention the back pain leaning over the fenders to get it all. All the bits and pieces were removed with a small telescoping magnetic pick up tool. With all the heavy rust gone the lower coolant inlet was blocked off and the block was filled with Evapo-rust and left to sit overnight. I did that process twice and thoroughly flushed with water afterwards. This was a couple years ago and have not had any overheating since. I installed a Motometer just to keep a better eye on it and even sitting in traffic at lights it still stays in the normal range.
Hope this was of help.

Cheers,
Gary

Gary,

Thanks for the advice. It is sounding more like I'm headed for a head removal if this attempt at acid flushing doesn't work.

Hi,
Sometimes the flow through the radiator appears to be good but the core could still be 70% blocked.The water passes through the 30% clean core too quickly to cool properly.
The easy test is to feel the inlet pipe and outlet pipe on the radiator.There should be a noticable difference or you can use one of those infa red temp sensor guns.
If there is little difference there is your problem.
Cheers
Rusted

Rusted,

Another great diagnostic idea. I didn't have a chance to even try the acid flush this weekend due to adverse weather (typical for the Great Northwest) and other activities. I promise to update you all after I have had a chance to work on the old girl. Just hoping that it is not a cracked head or blown head gasket. I've had a couple of sleepless nights since those posts came in. I don't think the engine rebuild was too tight as I was able to turn the flywheel by hand when I was adjusting the clutch springs. Am I wrong about that?

So here's to thinking simple and positive thoughts about my cooling system!

Ray, thank you for the advice on the anti freeze. I have come to accept everything you guys tell me - to be the gospel. Now, I just need a fellow yank to tell me what we have available up here in the USA. So fellow yankees what do I use if not anti freeze? If you tell me just plain water, I'm gonna back flip. I'm sure there is something we are supposed to use and I sure didn't know that anti freeze was corrosive.

Thanks Ray and Chris,
Jerry

There are several options to help protect the cooling systems in our old Chevys.

Water is an excellent heat transfer agent. Tap water can contain dissolved solids which will build up on the cooler surfaces (like radiator passages) and reduce heat transfer. Distilled or De-ionized water does not have those dissolved solids so is much better. Unfortunately rust is formed when ferrous metals (cast iron, steel) are exposed to oxygen and water, like in an engine cooling system. So some method of inhibiting this reaction is needed.

Soluble oils have been used for many decades. They work by coating surfaces with the oil film to prevent water and oxygen reaching the ferrous metal. The fact that they coat the surfaces reduces the heat transfer at that surface. The amount of reduction is proportional to the thickness of the coating. They are also promoted as water pump lubricants. Automotive water pumps are designed to use water as the lubricant with or without other additives.

Supplemental cooling system additives such as Nalcool products are used in heavy duty equipment with and without antifreeze to provide protection to cooling systems. They are available from heavy equipment and over the road dealers. Heavy equipment cooling systems are more like our old Chevys than modern cars and light duty trucks. The additives are also used in water based industrial cooling systems. They do not build up on the surface like soluble oils.

Currently produced antifreeze contains ethylene glycol and an inhibitor package [Common additives include tolytriazole, sodium silicate, disodium phosphate, sodium molybdate, sodium borate, and dextrin (hydroxyethyl starch)]. They are primarily formulated to protect the cast iron engine parts as well as aluminum engine and radiator parts. In order to passivate (render the surface non-corrosive) the metal the additives convert the surface metalurgy to a form that is resistant to both corrosion and erosion. This conversion and the dulling of painted surfaces that some consider to be corrosion. Extended exposure to oxygen and moisture can exceed the protection capabilities and then normal corrosion processes with occur. With aluminum many salts will affect the protective anodizing coating accelerating the oxidation of the base metal.

I spent many years researching and developing coolants and cooling system inhibitor packages for a major company. So what do I use in my old Chevys? De-ionized water that I get from the dispenser at a large food store. Or rain water that I collect. I either add a heavy duty cooling system additive or 33-50% antifreeze. Because freezing weather is not normal even in the winter here is SE Texas water is okay for all but a few mornings per year. Draining the inhibited water is an option if extended freezing weather is anticipated.

Your choice is up to you. Hopefully I have provided some information to aid in that decision.

And so, Chipper, it sounds like a 50% modern antifreeze mix is OK? If just distilled water and "A heavy duty system additive" what additive are you using?

I use Dow Cooling System Conditioner which I developed some 30 years ago. Still have some sample bottles on the shelf. It is similar to Nalcool 2000 or 3000 and several other similar brands of heavy duty coolant inhibitors. It provides all that is needed to protect these old Chevy cooling systems. Will not work well with systems with a bunch of aluminum components.

Chipper, you are amazing!

Jerry

Having spent nearly 10 years researching, developing and technical servicing antifreeze and coolants, it amazes me how much bad information still circulates (pun intended). It try to educate people so they will understand what is happening and not just regurgitating the misinformation that they hear.

I'd take the top of the radiator tank as well, I just had this problem with our 63 Valiant it SEEMED to flow well, but until I took the tank apart couldn't tell that the flutes were all restricted with hard gunge. I had flushed it twice with good brand radiator flush but it just couldn't dissolve the build up. RAY