cooling question?

[gregamorton]

guys I have put a new aluminum radiator on my 78 and a new 195 thermostat. I also added a new locking radiator cap as recommended by a friend to keep pressure right in cooling system. My problem is that my gauge shows to move between 1/2 and 3/4 all the time. I hate not knowing for sure and am wondering if yall think this is a gauge issue or the sending unit on the block? Water pump is good and tight and no noises any where.

[fordman]

what thermostat was in it before. and were did the gauge read before?

[gregamorton]

195 also and it moved from 1/2 to overheating. the radiator was clogged up and was going to cost a fortune to rott out and fix. Now going down the road it does not ping like it was doing before so I assume its not to warm. every time I checked the water in the top of the radiator it was 150-160.

[FreakysFords]

Could well be the sending unit or the gauge, but a couple things.

A) did you flush the cooling system, or just replace the radiator and thermostat and refill?
B) have you verified your base timing?

If you've got a thermocouple and a multimeter for it, driver it till you see it start to hit the worry line, stop and check the temp at the t-stat housing. It's going to show a little less than the internal temp, but will put you in the ball park. The other easy option is a "laser thermometer" used the same way (one thing to think about with these things is that it's not really reading where the laser dot is, depending on how close to the test point you are, so check it with the dot on the area to test, then move the dot away, moving the "eye" inline with the area to test. The temp reading change will tell you when you're there)

[gregamorton]

yea flushed all old junk out and the timing is right on factory. just need to get my lmc book out and check on a sending unit. Also need new bulbs for the dash for night. Half of them are out.

[BobbyFord]

Also, if you had water in it before and now have coolant mix, the temps will be higher. What pressure cap did you have on it before and what pressure cap is on it now? Just because the engine is running hotter does not mean it's overheating.
Here is a good article from Century Performance Center on cooling systems:
http://www.centuryperformance.com/cooli ... g-136.html

[gregamorton]

it was a 13lb cap and I got a new red fliptop 13lb cap.

[Skifu]

195 also and it moved from 1/2 to overheating. the radiator was clogged up and was going to cost a fortune to rott out and fix. Now going down the road it does not ping like it was doing before so I assume its not to warm. every time I checked the water in the top of the radiator it was 150-160.

Its not as bad as you think,I rodded mine out myself,Get a small flat screwdriver,and bend the tabs up,slip off the plastic end tank,and rod it out with an old dipstick,afterwards,pressure wash each tube by holding the wash gun right over each hole,replace end tank by bending back the tabs when closing it up,also use silicone to seal it back up.there was a double handful of trash,stop leak,and what looked like mud in the bottom of my radiator,it helped a lot,but Its still running a little hotter than Id like.Thermal clutch fans are a joke,it free spins when at idle,when it needs cooling air the most,and dont kick in untill the motor is good and hot,Ive got a 195 t-stat.,now Ive got to replace the radiator.

[Dragon]

Yep I have been arguing clutch fans for that very reason.

[Skifu]

What is a good alternative to a clutch fan,? does anyone know where to get a bigger radiator? Im thinking about a electric fan.

[Dragon]

I have a Hayden 16 inch that more than keeps my 390 cool on the hottest day here in the Desert. You don't need a bigger radiator except for looks We over cool so much with our big radiators that my electric can would not turn on in the winter. The water coming in was 190 degrees and going out was 52 degrees without the fan running. So to get the engine to warm up I had to cover half my radiator to make it get warm.

Even a flex fan is better than a clutch fan. At least then some air is moving through the engine compartment at all times. Most flex fans rob less power than a clutch. They move more air at an idle than a clutch and less when you are moving forward.

http://www.summitracing.com/search/Part ... d=flex+fan I have used 418 on a street 390 and the engine stayed cool.

http://www.summitracing.com/parts/FLX-396/ I use a Hayden 16" that looks like this and has an electric thermostat so it runs anytime the engine is above 180. No sense in it running of the thermostat is not open.

[Skifu]

Im just about at the end of the cooling system rabbit hole,This is how I ended up where Im at now.

1st, driver side radiator tank had a small split in plastic tank,removed tank,rodded out rad.patched end tank with epoxy mil,inside,and out,helped,but still had small leak,dont believe the hype,epoxy mil 2 part epoxy dont always work like advertised.still running a little hot.

2nd,got universal all aluminum radiator from Summit,changed to new water pump,195 t-stat,and new thermal clutch fan,didnt have a t-stat in with old radiator,like this when I got it. I did reinstall the factory shroud.still getting hot at long traffic lights,

3rd, I had a 10 inch electric push fan in the box,so I said what the hell,and put it in front of the new rad,and this seems to be what put it over the top,it seems to be staying put right at the first mark over 190,according to my gauge.I still havent been at a long light in midday heat,but well see what happens,I hope its good to go.
let us know what yours is doing.

[ForingaMex]

gregamorton wrote:
...on my 78...

Skifu wrote:
Get a small flat screwdriver,and bend the tabs up,slip off the plastic end tank...

78s don't have plastic tank that can be removed by bending some tabs. At least not the ones I've seen. They are soldered on.

[Dragon]

He is talking a 95 not a 78 or even a bumpside so his post was irrelevant.

[fordman]

the newer aluminum core radiators are crossflow types from some manufactures and those would have plastic tanks on them. and they are suppose to be built to bolt into our trucks but i haven't seen one yet so i couldn't comment on how good they are for our trucks.