My mistake, I misunderstood your words "goes on at 200 degrees go off at 185 degrees". I construed that to mean the fan actually came on at 200 degrees, and actually shut off at 185 degrees. What you meant to say was "The fan is supposed to come on at 200 degrees and shut off at 185 degrees". So you're using the dash gauge for your readings. Ok, not test gauge quality. How many rows of tubes in your radiator? What is the radiator frontal area? Do you know what the max BTU heat transfer rate is supposed to be? Do you want me to reverse engineer this for you?

 

This sounds like a water flow problem to me. Either wrong impeller rotation, head gaskets on the wrong sides, or -?-. You didn't answer Mixer's question on whether this is happening while driving, idling in the garage, or what? If this is in the garage, definitely a water flow problem. Try leaving the radiator cap off, and watching for flow.

 

As an aside, you can actually overheat an engine by removing the thermostat altogether, because the coolant doen't spend enough time in residence in the radiator core to transfer heat fast enough, and will eventually become thermally saturated with only convection for cooling.

 

OK it has a 180 degree thermostat-- Ron Francis intake fan probe goes on at 200 degrees off at 185 degrees-- 4 row aluminum radiator--16" fan and shroud-- AC condenser in front of rad.-- I took it out Monday morning for 1 st road test, temp was a nice cool 55 degrees-- was going 50-55 miles and hour for 10 miles gauge was going up to 180 degrees still driving I thought good temp nice cool air flowing gauge going up 190-200 FAN came on-- OK good watching if it will come down pulled over into park driving slow temp going up -fan still running doing nothing to bring temp down--pulled out on main road to go 45-50 MPH watching it close going to 240 so before I could pull over turn it off the LOWER rad hose blew -- so that did that-- got it home washed it up--put NEW 180 degree thermostat in --all new clamps ---my bottom rad. hose looks like a L but does not have a spring in ---I used 50-50 concentrated anti-freeze--I am now using the green and I will mix it myself with distilled water which I am going to fill it up and try again---either thermostat stuck or air pocket or shroud is to big and fan to small--- NOW from what I remember it is was a clockwise rotation pump-- can not tell with it installed ?

------- So hopefully I explained what I got and what happened to all of you that are helping and giving me advise--- this is the first rest-o-rod I had that I ever used a shroud like this one always just used fan and worked -------
?

 

That's odd that the lower hose blew because that's (supposedly) the suction side of the coolant pump, and would have the lowest Δt and Δp . Apparently your radiator and expansion reservoir caps aren't working/relieving either. The symptoms you describe now lead to thermal saturation. Did you change the coolant pump for your build? Another thing to consider is air pockets in the cooling system (the pump could be air bound). The truest way to eliminate air pockets is how you fill the system - fill it from the bottom up, the lowest point. Usually the radiator drain. Use a hand or drill pump with the radiator top tank cap removed.
Edit: Fill until there is no air space around the neck and it overflows onto the coolant recovery reservoir, and then one-third full.

Edit: That spring in the bottom radiator hose is to keep it from collapsing under the coolant pump suction (very low Δp).

 

----------------- I can not find a LOWER hose with a SPRING in--tried NAPA--Auto-Zone-- still looking --------------

 

The universal corrugated hoses have steel springs in them.

 

A picture of the lower hose set up might help. Respectfully, At this point, I suggest you go back thru this thread, read every word, answer every question that has been asked of you.
What is the build level on that engine?
Is it a new rebuild or has it been in any service before?
Have you used an infrared thermometer to view temperatures at various locations of the assembly?
Is the radiator heating up at the top first?
Are you absolutely certain the water pump rotation is correct?

 

If you look at the older cars that had shrouds on them, these shrouds were deeper and had the edges tapered to the fan to improve fan efficiency. So as stated above, the aluminum shroud does direct air through the fan, not around it. The large taper just allowed the air to flow faster as air like other elements follow the path of least resistance.

Later!
Mr. Ed

 

ENGINE-- complete rebuild--was a 93 Mustanf GT 42K engine I converted over to a carb engine
Know engine temp by water dash gauge-- it does work goes to 200 fan comes on
Heating top of rad first-- UNKNOW
Pump rotation when I order it was to be a clockwise rotation--

 

Too many unanswered questions here, but due to the facts that the lower hose blew off, and the cooling system has reached thermal saturation and it heating the radiator top tank by convection, I am going to speculate that the coolant pump is discharging through the suction side. In essence, reverse flowing. Unless this engine was from a starboard side marine application it would be standard SAE left hand (counter-clockwise rotation, looking at the flywheel). I believe therein lies your rub.

 

I have been reading through this post and tend to agree with Mixerman. I would certainly check the flow at the radiator with the cap off and observe the flow through the radiator. I would also check the air flow in front of the radiator with a piece of paper to make sure air is being moved at all areas of the front of the core, not just the area where the fan is situated in relation to the total are of the core.

 

Exactly. That is why a deep conical shaped shroud is the most desirable. It will draw air from the far corners as well.

 

I would like to note that standard rotation and reverse rotation water pumps have different pulley bolt patterns. The cover doesn't really matter for flow. From factory Ford put reverse rotation pumps on normal covers in the Mustangs. Only the trucks got the proper reverse rotation timing cover.

 

Tried it this morning at idle fan went on at 200 degrees got it down to 185 BUT no heat in cab and it was on HIGH and another problem I was not happy with was went out to grill see how fan was pulling put paper up to the grill did not suck fast to grill-- Put it up against AC condenser not even a little pull in--- but inside engine bay area blowing lots of air back towards firewall---