1984 1/2 ton lwb overheating

[mikecb2014]

Hey guys, I'd appreciate some help.
I have an 84 c10 lwb with a 350. Engine is bored sixty over, stock heads worked heavy duty, edlebrock intake and carb, new water pump, new clutch fan, new radiator, currently no fan shroud or thermostat. The truck before was running about 170-185 moving but at a standstill it would climb clear past 220. Once it got that hot it took a good 15-20 min straight driving to cool down. If I stop again it would climb even more. Its a daily driver so I took out the thermostat just so I could drive it. I had tried new thermostats and put the new radiator in. It now runs about 140-150 moving but still overheats if sitting still long enough.
Any suggestions.

[timthescarrd]

Without a fan shroud, when sitting still, the fan is pulling air from all directions instead of just through the the radiator, generally this means that about 1/3 of the radiator space is not being cooled.  When driving, the movement of driving is pushing air through the radiator.  The fan shroud helps to direct the vacuum of air the fan is pulling to cover the entire surface of the radiator.  This may or may not be your issue, but definitely put a shroud on it.

[Jason S]

Howdy from Kansas and welcome to the site.

My $0.02:  I'd at least look into putting a fan shroud on it.  If the engine is a regular production 350 bored 60 over, there's not a whole lot of cylinder wall thickness to absorb heat. With a properly functioning cooling system (air bled out, no corrosion or obstructions), the absence of a thermostat can allow coolant to circulate too quickly through the radiator/engine block and not actually cool down the engine.

If you would, you might add some additional details like:
Is the overheating a recent occurrence or is this a new engine install?

You say it has a new radiator and several other new parts; Has all the air been evacuated from the cooling system?

Is the new radiator a stock replacement 3 or 4 row or something equivalent of sufficient size? 

I'm sure others will chime in soon.

[mikecb2014]

Its a newly rebuilt engine, had the same problem with the other engine and it was bored thirty over. Prior to the new radiator it had a fan shroud and still overheated.
The new radiator is a 3 core, the coolant system has been bled of air and is full. Also to note, even with a working thermostat, 180 then 160, it was overheating.
And thanks for the welcome.

[Jason S]

Additional questions to eliminate some possibilities:

When you say it's overheating, is it boiling over into the coolant reservoir or is it just showing hot on the gauge?

Are you using the factory temperature gauge?  If so, have you tried an aftermarket gauge to verify temperatures?

[mikecb2014]

Aftermarket temperature gauge, and if I let it keep heating up it will boil over into the reservoir, but it hasn't in a while cause I won't let it get that hot, avoiding traffic and such. Also without the thermostat it takes longer to heat up. Its okay to drive right now, but I don't like running without a thermostat.

[mikecb2014]

Also just to note on the shroud, it would have it one still except for my "direct fit" radiator from summit wasn't so direct fit and took some modification to fit. The fan rubs the shroud now so I have to get a new fan shroud.

[jetmech]

    You must get a shroud. A six blade fan may help and make sure it is for the correct rotation and new water pump is the correct rotation. Water pump/fan belt tight? Fan clutch working as it should? Bottom radiator hose could be collapsing at some point causing loss of circulation. Make sure you are not running lean.

[mikecb2014]

Still overheated with the shroud, working on getting a new one. Everything rotating and working correctly. I'll check the fuel air mixture. Hoses are new but I'll check and let ya know.

[roundhouse]

Gay a shroud that covers the rad and places the fan half in and half out of the shroud

Seal around the edges between the shroud and Rad with. Weatherstripping or something

Check your fan clutch
It should hold a piece or paper against the front of the rad at idle

If a piece of paper won't stay struck to the front of the rad  at idle.  It's not moving enough air

[mikecb2014]

Hoses are good, checked the fan clutch again, yes it works. New fan shroud should be here soon and we'll see if it works out better than the stock one

[Irish_Alley]

how did you check the clutch?