overheating 350 w/6 cyl radiator

[63 & 64 Bowties]

my 64 c-10 has a 350, stick, and the original 6 cylinder radiator. It's been doing a fair job till the temps starting climbing over 90. That's when it starting getting up around 190 and I'm getting a little antifreeze release out the burp tube when I shut it off.
I bought a bigger radiator that I was going to put in, but my buddy says that a 165 thermostat ought to cure the problem. Anyone try this?

[PrerunnerRob]

You might be able to get away with a 165 tstat, but you might want to check what the design temp for the engine is. If it were up to me, I would run the bigger radiator, that way you aren't putting a band aid over a larger problem.

[wild one]

I had the same issues with my truck, I finally installed a coolant catch can to retain any " burped " coolant. My truck still runs around around 190 - 200 degrees on a 90 plus day, but no longer over heats. Oh, and I run a 180 degree thermostat.

[63 & 64 Bowties]

thanks for the come-back. both of you being in CA, you've got to be the ones who know about hot temps. another problem i have is no shroud. i've been laying off doing anything about the shroud, waiting to decide "new rad, or old rad that fits just right." i want to weld up my own shroud out of some thin stainless i have in the shop. might involve some tricky bends, but i'm gonna give it a shot.

[Fred T]

If you're overheating at speed, a different t-stat won't help. If the t-stat is working right and there is enough cooling from the radiator, the coolant temp will not exceed the temp rating of the t-stat.

First thing to do is check your gauge. Take off the cap and warm up the engine. With the engine warm and coolant flowing, put a thermometer in the radiator.

Best solution is more colling surface, the bigger radiator. Another solution is one of the coolant additives that change the surface tension of the water, letting it make better contact with the radiator, improving the cooling. But since you have the radiator, put it in.

Fan shrouds only make a difference when the fan is pulling air through the radiator. That's only at low speed. So if the engine is running at normal temp at speed, then warms up in low speed driving, a shroud might help.

[Tomsriv]

In addition, a 160 degree thermostat won't really make it run that much cooler. What it does is let the water run through the engine quicker but the problem is that it does not soak as much heat up when it is going through quickly. The temp will read 160, but the cylinders will still be warm. I like to run a 180 deg because its a good compromise. A three row radiator should do the job if you have no AC and don't tow a trailer. If you want extra insurance go with a 4 row. Also, a good clutch fan is always a good investment and is quiet and fuel efficient compared to a fixed or a flex fan.

[63 & 64 Bowties]

yea, makes sense. it is overheating at high speeds. guess i better plan on putting in the new radiator. i was just trying to keep the old one which fits right. guess i better start fabbing up some supports for that new one.
thanks for the come backs.

[rickf]

Running at 190 was mentioned as a concern, that's actually a perfectly fine temp to run at. The stock thermostat (for 71 at least) is 192. With anti-freeze and a 13 PSI (or so) cap, boiling point is up around 250.

The temp rating on a thermostat is simiply the temp at which is opens. If your cooling system can't cool to the rating of the thermostat, then putting in a colder thermostat will not make the engine run cooler.

What FredT says is spot-on, but one thing to add is relative volume. The greater cooling surface is needed, but also the increased volume it holds helps. The 350 holds more water than the 230/250/292, and it just pumps through the small radiator too fast for it to keep up. The larger volume in the big radiator lets the water stay in the radiator longer, the greater surface area removes more heat.

But you already decided to put in the larger radiator, so I guess I'm preaching to the choir.

[joehalford01]

it looks like u have this fixed but i wanted to point out that without a shroud your fan is only cooling the surface area that is directly in front of it. so even though you have a small radiator, you were cooling even less of the water then the radiator was capable of without a shroud. Fans and shrouds go hand in hand and are for low speed cooling, your right on for going bigger if you are overheating at speed. also, my truck has a 327 and runs like a pig any lower then 180 degrees. 165 degree thermostats are baloney, if you have an efficient cooling system then 180 or 190 degree's is where it should run.

[ClassicAutoResto]

Royal Purple makes a coolant additive that my father uses in his dually. He hauls FEMA campers all over the south and midwest,swears by the stuff, and never runs hot. Even if you change out radiators, might be a good thing to add. Jerry

[63 & 64 Bowties]

thanks for the responses. I think I'll forget that 160 thermostat. I'm installing an aluminum 2 core cross-flow radiator from Summit Racing (part # SUM-380328) and sticking with the 180 thermo. And I like the idea of the coolant additive. I've never used one, but if you think about it; fuel additives get used up every tank full, oil additives get drained out every oil change, but coolant additives keep on working until you have another repair.
thanks again.