sbc overheating. 650hp rated aluminum radiator

Oops....typo, the correct temp is 257,...NOT 227 !!!

4TTRUK

 

I see no mention of what pressure radiator cap is being used...."220" degrees, with a 15 lb cap is well withing acceptable "limits".

Using a 50 / 50 mix, water / antifreeze, a 15 lb pressure cooling system will boil at 227 degrees. Each 1 psi will raise the boil point by 3 degrees, so in this case, the real boil point would be 257 degrees. 3 degrees X 15 lb = 45. Add that to the 212 degree boil point, and it becomes 257 degrees.

With those pressures and temperatures, car mfg stopped using "real" numbers on the temp gauges, because the buying public thought there was a problem.

When installing temp senders, the "bulb" must be as "submerged" in the coolant as possible; Using more than one thread adapter moves the bulb farther away from the coolant flow, and result in low readings. <I learned that, the hard way...>

Happy Roddin'
4TTRUK

 

i have no idea what pressure cap is on the radiator. cap has no identification on it.

 

Ya know, I saw where the sensor is located, and thats just wrong in my opinion. It needs to be in the intake. I didnt read every post, cuz to me there kinda rodundant, so mine may be as well.

I also dont know, but if it where me, I would put a candy thermometer in the radiator, and compare your guage to the candy thermometer.

My gut is saying its where your sensor is located. Thats gotta be the hottest part right before the water goes through the radiator.

The electric fan switch should be in the front bank of the left head, and the guage should be in the intake near the water neck. Exception is the LT1 engine.

 

huh? The water pump is after the radiator, the water is as cool as it will get right there.

 

Yes, I had to move my temp pickup from the heads to the water pump when I swapped out the aluminum heads and went to the old camel humps with no hole for a stat. My temp readings are about 5 degrees lower at the water pump than they were at the heads before.

 

Ya I was just seein who knew that.........

well I guess thats my Blond moment.... WTH was I thinkin????

I have never seen a sensor in the water pump...It cant be accurate, and I also remember a few years ago, that style guage was plagued with fault....

I still say the candy Thermo might clear up, if it is really runnin that hot.

 

You can probably get by with using larger guage wires (14ga.) instead of complicating things with a relay. The wires I can see in the photo are pretty small. Also is the sender indeed that diameter or is it in a bushing? What is in the threaded bung next to the leaking thermostat housing? Can you put the sender there? You also have no overflow tank to catch the overflow as it heats and returns it to the radiator as it cools. Without it you will be fighting air in the cooling system and it will never work to it's potential.

~Alden

 

Vacuum advance should go to manifold va***.will cool down engine.Jimmie King

 

I see u have messed with everything coolant wise, but never anything mentioned anbout your va***e advance.

Next, how much room exactly do you have between the pump and radiator? Have you tried bolting up a fan directly to the water pump?

 

so youve heard of the guages....? they are always forsale at the kyana swap meet

 

Well I am not ignorant, although I expected alotta razzing from my one post. haha... We all have ones we would like to have back.

I will say though, I had the same problem in my Mustang, which I drag race. I put a bigger radiator in it. Problem solved. SHe runs 180 all day. no matter what the temp.

I have the same problem in my 40 GMC truck, I am gonna et a bigger radiator.

I never trust a guage with out double checking it, especially electric ones. The one you posted looked the same as the one at GoodGuys, that was faulty. They had a rash of bad ones. Thats why I suggested double checing it with a candy thermo.... SImple no cost check. ( just dont put it back in your wifes drawer) I made mine go away with all the cookie trays.

I havent said much on this post, although, I will say. My timing is set all in at 2500 in my 351 and she runs cool. SO to me timing may elevate cylinder temp, but not much for coolant temp if the system is adequit. And vacuum? I go with what ever the 40 street rod performs best with.

 

If it runs cool while dragging the weight of the truck, under load, when the engine makes the most heat then the radiator is ample. If it only runs hot at a dead stop, when the engine makes minimal heat then it's improper air flow thru that radiator

 

If you have a mechanical temp guage of known accuracy, put it in, and see what readings you get...That'll resolve any question re; mismatched or inaccurate electric temp guage readings....

Definitely put the sender <mechanical or electric> close to the t'stat, in the manifold, before it goes to the radiator.

4TTRUK

 

Click here: Griffin Radiator - Radiator Tips

 

Nobody has mentioned what sort of shrouding there is around the radiator. What is there to stop the hot air blowing out the back of the rad simply going back round front and through the rad again.

I had a buddy with a Nova race car, overheated all the time. He had a flip front on it, with nothing but the rad stood upright in the middle, no sheet metal, nothing.

Air was coming out the back of the rad and simply getting ****ed back round through the fan, getting hotter all the time. When he was moving along it was okay as plenty of fresh air was forced into the loop, but at slow speed or stop the temp went through the roof.

You need to get the hot air out of the engine bay, not just blow air though the rad.

Or it can actually blow back through the outer areas of the rad, if the engine bay is pressuring up with air. Try driving around slow with the hood off for a little ways, see if there is any change. If it runs cooler then it is an airflow issue. Air flow out of the engine bay.



Of course if you do have all the full sheet metal sealing the rad all around then I'm talking shyte.

 

Most radiator caps will have a marking on them,...usually looks like this example; 14#. If yours has no markings,..get a new one that IS marked, so you are working with a known fact; I would begin with a 15 lb cap.

Each lb will raise the boiling point of a 50 / 50 mix by 3 degrees.

Happy Roddin' 4TTRUK

 

I'd spend the money to install a short water pump with a clutch fan and a shroud then go down the road

 

inorder for this to happen on the 51 chevy truck 3100 series is near impossible in my eyes. the two inner fenders meet to the sides of the radiator. from top to bottom. top front edge to about half way down the hood latch covers. the only way hot air can go back to the front is when the hot air comes out the radiator to go down and back infront of the fan.....which i guess is possible????but with the fan blowing towards the engine i dont see how the hot air can move forwards.

my new infrared themometer should be here any day now. i had a good excuse to buy one this way i can see what temp the radiator really is and see if any cylinders are dead

 

i would post pics of the fan setup but....GRILL is in the way. no good way to take a picture.

 

The short water pump idea is a good one....I didn't think of that...

 

after being mentioned again....i looked this up. i would do this but...i think the water pump currently on the engine is the short water pump? the long neck ones on autozone look way different to me. anyone else agree?

 

That is a long water pump! If you go to a short you are probably gonna have to get shims for your pulley, if you can even use the same pulley! You can always make a fan shroud to fit in just about any where, its been covered here many times! I'm not saying its easy but it could be done!

 

Some interesting reading here on heat transfer in a radiator:

http://www.arrowheadradiator.com/14...apability_in_high-performance_automobiles.htm

....for those with an inquiring mind.

 

finally got some numbers for you guys. the infrared themometer came in the mail today so the first thing i did in this freakin 105degree heat was go striaght outside to my none ac garage and fired up the chevy. the results are.....










inlet temp 199
outlet temp 165
core temp of rad...175
temp unit temp at water pump 210.
rad stat temp 199
when the thermo stat opened up i noticed the overflow puked a little water/steam. not hardly even noticable but i did see it.
this was with me in the truck every now and then reving the engine up to get the truck to warm up faster.

the temp guage read 225.

should i move the temp unit? seems like its reading accurate or pretty close.


things i still need to do....
buy a radiator cap that has a measured # on it preferred 15#
install a over flow catch bin.....ive got one just need to install.
possibly a shroud to block downward airflow going foward back thru radiator.
get a better ground on the sending unit. better grounds everywhere


also a buddy at work sold me a 12" fan i can possibly fit behind the radiator. the only thing is i wont be able to install in the center of the radiator due to the thickness of the fan but i will be able to make it a pull type. the fan has no markings nothing. he said he paid like $70 or so for it. just dont need it. sold his car before installed.

would 12" be good enough for my size radiator? can i leave the push fan on or should i remove?

thanks

 

Get a Lincoln Mark 8 fan and put a short water pump on it.. My 40 Willys ran hot in traffic with a 3000m cfm fan ( anyway thats what they advertised it as). I'm talking 220 - 240 hot but was fine on the highway. I took out the Ram Jet motor and put in a tunnel rammed 350 with a Big Muther Thumper Comp cam. While breaking in the cam I ran the motor at 2000 rpm in the garage with the Mark 8 fan, water only, and no thermostat and it never got over 185 and actually got down to 175 when the fan kicked on. These fans are cheap at the junk yard. I paid 15 dollars each for two of them. The only catch is they require a relay because they use a lot of amperage when running and a lot more when starting.

 

yea im not running a relay on my fan and my fan is also running all the time. would not running a relay cause the fan to run slower?

 

Can you relocate the temp gage sender to near the thermostat?

Interesting that the temp at the pump is so high.

 

yeah...temp at the water pump makes no sense to me at all.the only thing i could think its because the temp unit is br*** and it holds more heat????? the thermometer ive got is damn accurate also. really surprises me since i only paid $20 for it.