Radiator Fan

[bd]

That makes sense bd. I never thought about the fitting being changed out. That would explain why the coolant is circulating too fast thus the low temp. I know I would have never thought of the fitting. This problem is a real head scratcher for sure. I think several of us have learned a thing or two with this thread.

Coolant circulating too quickly generally has the opposite effect - overheating.  Diesels are particularly sensitive to this.  The coolant absorbs heat from the engine, but circulates through the radiator too quickly to transfer the heat to the surrounding air.  High volume water pumps are designed to increase coolant flow below ~3,000 RPM, but can cause cavitation above ~6,000 RPM.  Remove the thermostat or constrictor plate from an engine with high coolant flow and it might overheat.

Whether or not coolant bypassing the thermostat through the heater is the cause of the OP's powerplant running cold is yet to be determined.  It will be a relief if that simple.

[enaberif]

So beyond running cool, is the engine doing anything weird?

Nope it runs perfect otherwise! Its just really aggravating that its doing this because where I live the temperature can fluctuate enough that this could cause bigger issues.

[enaberif]

That makes sense bd. I never thought about the fitting being changed out. That would explain why the coolant is circulating too fast thus the low temp. I know I would have never thought of the fitting. This problem is a real head scratcher for sure. I think several of us have learned a thing or two with this thread.

Coolant circulating too quickly generally has the opposite effect - overheating.  Diesels are particularly sensitive to this.  The coolant absorbs heat from the engine, but circulates through the radiator too quickly to transfer the heat to the surrounding air.  High volume water pumps are designed to increase coolant flow below ~3,000 RPM, but can cause cavitation above ~6,000 RPM.  Remove the thermostat or constrictor plate from an engine with high coolant flow and it might overheat.

Whether or not coolant bypassing the thermostat through the heater is the cause of the OP's powerplant running cold is yet to be determined.  It will be a relief if that simple.

Well good news and uh weird news?

Pinching the heater hose still did not help. But placing a chunk of plywood in between the fan and radiator did.

So now I have discovered again that something is over cooling such as my fan or my water pump is being twerky...

Thoughts?

[philo_beddoe]

All this talk about fans, whats the most common size? 18 in. ?

Im putting these two together. Good?

[Stewart G Griffin]

All this talk about fans, whats the most common size? 18 in. ?

Im putting these two together. Good?

i measured the v-6 3-bladed fan off the 4.3 and it's 18".  The v-8 fan that came with my truck is about 20"+ a little bit.   

My opinion is that you'll generally be ok as long as you're not towing or hauling heavy----because will that 18" fan fit the stock shroud the way the stock fan did and provide maximum cooling?

Since we brought this thread back i have a few questions of my own:

1) What is the normal operating temp for a small block from the factory?
i believe i put a new 195 thermostat in the 4.3, but it won't go higher than 180 according to the gauge.  i "think" i would like to run a little hotter---maybe 195 to 200.

i am using the stock v-8 radiator (yes the hoses from a v-6 basically hook right up, more about this in my swap post) AND i don't have any fan.  Yes risky i know, but it's winter and i'm going to be installing an electric fan asap.

Heater works just fine.