If any of you caught the high speed heat up thread in the engine section, you might know about my valiant heating up to 200 degrees on the freeway but never getting over 180 when driving around town. I decided that this was a good situation to try redline's water wetter which claims to bring engine temps down 20%. since the temp in my car would start heating up the second I got over 65mph for any length of time. (I drove 100 miles like this) I had a good base to start with. I drained all the coolant out of the radiator. and then flushed out the block and heater cor with about 15 gallons of water. I then filled the radiator with one bottle of water wetter and topped it off with water. took her out on the freeway after I hit operating temp and got on her, hard. she still broke a sweat getting up to 190 max. no matter how fast I was going. I am going to try again tommorow in the midday sun and see if it'll make more of a difference. but so far so good.

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64' Valiant Signet 5.9, 64' Dart 170 moredoor 3.7, 67' A100 3.7, 00' Dakota SLT 4.7

How much antifreeze did you have in the radiator before? I browsed through your previous post and you said "no danger of freezing" but I didn't know if that meant zero antifreeze..... if you went from part antifreeze + water to all water + wetter, the loss of antifreeze may explain temp drops more then the wetter itself.

I'm 1 hour east of you in San Joaquin county. Hotter then SF on any day. My duster, on the freeway even in the altamont mountains on a 100 deg day won't go past 190 (according to dakota digital gauge, sensor mounted in thermostat housing) with 40-50% G05 antifreeze + distilled water combo.

For point of reference, I run the a/c radiator (without a/c), 180 deg thermostat, but everything otherwise engine cooling is stock. Engine compartment tends to run hotter due to the headers. 3.23 rear gear w/stock built 904.

I would still look into the radiator, and open up block drain to make sure its not plugged up.

I had persistent "high-speed" heating issues with my '64 Valiant too...

225 slant, 4-speed, 13" radials, Holley single barrel, etc.

Driving around town was fine, never went over the center of the gauge.

Get it on the Interstate ( commute to work is 20 miles), and as the speed went above 5o MPH, so did the engine temps... in fact, the faster I drove, the hotter she'd get... long grades made it heat even more. I could observe a rise in engine temp just by turning the headlights on ( additional alternator load)...

Replaced stat with a new 180 Stant, replaced water pump, tuned-it up, checked the timing, etc.

Finally started talking to some radiator people, and they suggested that the radiator core was probably getting crudded-up.

One guy peeked inside the filler, and immediately noticed all the "solder bloom" at the tops of the tubes, and suggested that I needed a recore.

A recore was going to run about $250 ( that I didn't have), so I went looking for an alternative... somebody here suggested trying a radiator from a Volare or Aspen, so I ordered one of those for $149 bucks, had to drill some new mounting holes through the rad flange, and make-up some elbows out of 1-1/4" copper pipe to reconcile the radiator outlets with the engine.

That change alone has solved my overheating problems... I will notice the temp climb a little on long hills, but now it never passes the center of the gauge. Previously, it would go all the way over to the "H" mark if I didn't slow-down and let it cool off...

The radiator guys tell me that the stock rad ( 2-row core) was "barely adequate" for the six, and when they started to clog-up, the cars would overheat very quickly. Had the same experience with Falcons, back in the day... they too had small radiators.


If you 've already got a clean radiator and still are experiencing overheating at high speeds, then perhaps things like "Water Wetter" might be in order...

I have my OEM rad stored in the garage; some day I will have it re-cored...

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De Soto Frank

If the core is just cruded up but otherwise OK it is often effective to take off the top tank and rod-out the tubes. With a little practice and a suitable soldering torch you can even do it yourself.

My experience with do-it-yourself radiator repairs ( aside from re-soldering tank straps) has been as miserably unsucessful as my attempts at HO-scale railroading...

I'm either too darn clumsy or just have bad luck...

My last attempts at "rodding" a radiator core was on a Falcon radiator, and I wound-up tearing the walls of the tubes right out...

When I took that rad to the shop for a re-core, the radiator man offered me a little consolation: he said that the old core was so thin and rotted, that it was no surprise to him that I shredded the tubes...

At any rate, the Volare rad is doing the job for now...

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De Soto Frank