.

 .

After soaking and rinsing my radiator with 100% distilled white vinegar at least 5 times letting it soak for at least a 1/2 day at a time,  I observed some demineralization but not enough. I could look down into some tubes and see that they were still clogged. I could still see crud at the tops of the tubes as I looked further down the upper tank in either direction from the cap hole.

 .

 So I considered whether I should get a new radiator or take mine to the shop to get it hot tanked or rodded.

 .

It’s tempting to shop for a new radiator especially since there are some much more efficient designs out there that are still stock looking, but sometimes you need to hold back from spending cash.

For financial reasons as well as taking a step by step approach, I took my 3 row 26 inch radiator to a radiator shop called “Howard Ave.” in San Carlos, California, an easy drive in the morning before going to work.

.

Turns out to be the kind of place I would patronize especially when they understand muscle cars and Vanishing Point, the 1971 movie. They frequently perform work on antique and rare pieces as well as run of the mill daily drivers. Plus, they are easily understandable over the phone.

 .

For $88 dollars they hot tanked the radiator, made some minor repairs, put a new coat of paint and provided me some copper screen to use as an upper hose filter.

 .

Talking to the guys about what could be giving me woes made me glad I did not buy a new radiator (at least until I need to rebuild the engine).

 .

.

.

The guys, Rick and Bill, told me a couple of things about the engine blocks cast in the 60’s and early 70’s that I wasn’t aware of.  One, the casting material tended to release metal flakes which build up into crud and; two,  the water pump is positioned high in relation to the engine cooling passages which promote crud build up in the block that is not easy to flush out, that is, unless you pop the freeze plugs and blow out the crud from there.

 .

They said that the crud in my radiator is the residue from the cooling passages in the engine that made it to the radiator and it was likely a long term process. After the hot tanking, they said the radiator flowed much better even though it may seem okay before hot tanking. They managed  to get about 50% better flow after tanking and back flushing.

.

They run a flow test by standing the radiator upright and filling the radiator from the bottom, waiting until the water comes out the input then releasing the bottom to let the water flow out. The distance the water shoots out forms the benchmark and is measurable.

.

I’ve read some people suggest that the water flowing fully (taking up the whole orifice) is an indication that the flow is good, but my radiator, even with the clogged passages was able to do this. So I’m theorizing that that indication in itself is not an adequate indication for a performance engine.

For a fragile radiator, heating up the upper tank to do rodding is not as desirable as it could damage the core, and fragile or thinned tubes could be damaged by rodding. This wasn’t the case for my radiator as it had plenty of strength for rodding but if good results can be had by hot tanking, it is much less risky and easier.

.

Considering that I most likely have some weird leprosy-like condition in the engine block waiting for an engine rebuild to solve, I was glad I didn’t buy a 500-700 dollar radiator just to get clogged up by the fallout. (I sure would like to get one of those 4 row high efficiency radiators though – some other time). Also, I just became aware that my radiator yoke, the crossmember is for a 22 unch radiator and someone drilled wide to fit a 26 radiator. It’s cool, I’m not trying to create a show car.

 .

.

What they suggested to clear out the block without popping the freeze plugs, is what one did with his old Mustang that had cooling system leprosy: he made some high speed runs (150 mph) with an upper hose filter plus no thermostat and flushed his cooling system after each run to resolve his overheating problem. Whether he actually did 150mph or not, well… I get the idea.

This little education highlights a very important and unheralded aspect of engine rebuilding, renovation and  resolving cooling problems especially since we’re often dealing with over 40 year old technology or old blocks. Some additional attention can be given to your old muscle car’s long term maintenance if its stuck in a shop for a while, especially if the freeze plugs are ever easily accessible and you suspect a cooling problem or not, you pop them off and flush out your block of crud that is likely building up on your old Mopar.

 .

For the next engine rebuild, I’ll be giving careful attention to the cooling passages and any new technology that can offset the flaking of the old cast iron. Is that one reason they used more nickel in some blocks now and before?

 .

Anyway, I hope the hot-tanked radiator will get the engine to run cooler.

 .

In the meantime, if you see me driving around town at 5000 rpm or more, you’ll know why –  “Yes sir, officer, I’m treating leprosy.”