I just installed a new water pump-Flow Kooler Aluminum Water Pump, 351W (5.8L)-and it was so good at cooling, that it caused my thermostat not to open which caused the engine to overheat. Replaced the thermostat three times before me and a bunch of other mechanics sorted it out. Don't know if it is a problem, but the engine runs just above "C" the whole time without a thermostat. The car runs fine as it is now, but wanted to if I should be concerned

 

The job of a thermostat is to PREVENT the radiator from cooling too much.
Water pumps move water, radiators cool water.

How does it overheat if it's so good at cooling?
Please clarify the confusing statement.

 

I think this is a case of having the thermostat in the wrong way!! If the temp
sensor part isn't facing into the hot side of the housing it will not open or open
too late. Leaving it out is not good since a too cool motor will never get hot
enough to burn off the water and combustion byproducts in the motor oil and
it will also not be able to burn off the carbon as well. Get a full flow thermostat
from Summit if you drive hard and stick with the stock temp rating especially if
you have a computer controlled engine or it will be stuck in warm up mode for
too long and that will cause the computer to add extra fuel and your mpg will
drop big time. That is the reason you should always go to the stop in your errands
that is the farthest away from your house first, that way the motor can get up
to temp and do the aforementioned things.

 

Don't rely on the gauge in the dash either
Get a real temp gauge.

 

Ok, I will try. Installed a new water pump and new thermostat because there was radiator fluid dishcarge underneath my water pump from time to time and figured it was time to install a new one. While at it, I had the thermostat replaced. I had a repair shop. I bought the parts. When I first drove the Bronco everything was fine. About 20mins of driving the temp gauge would soar rapidly to "H" and then race back to "C". When it went to "H", the car ran rough and ther was some gurgling sounds coming from the engine. Figured I would try replacing the collant tempaert\ature sending unit. Bought it at the dealership and spoke with the guy who said that I had bought the wrong thermostat since I bought one for 160 degree and should have bought one for 195 degrees. So, I replaced the sending unit and replaced the thermostat. What happend was the car ran fine for a short period of time and then the temp would race back to "H" and would stay ther and not cool off like it did before. I then took the Brnco back to original repair shop sicne I was out of ideas. They replaced the thermostat agin and it did the same. So, the took the thermostat out and now it just runds right abocve "C". AT least ti doesn't overheat.

 

Could be an air bubble in the system, bad clucth
on the fan clogged heater core?
Can you guess I've been there well Ihave with my
full size.

 

Its probubly what blue said or just plain ole bad thermistat. I've seen this many times. (new stat being bad) One thing I can tell you, its not that the rad is cooling too much.

 

I don't think anyone made the assumption that the rad is cooling too much.
The problem started with the installation of the new pump?

My guess would be air pocket also.
Is this the correct pump for the installation?

 

Are you sure the temp pellet is facing the correct direction? If the heat is hitting the
wrong side it will make the needle go to HOT then it conducts the heat through the
metal and it opens the thermostat then it cools off enough and it closes up some
and the process starts all over!! Make sure you have the right temp(180-195*)
and test it in a pot on the stove with a thermometer. You should see it open.
I always clip the little valve deal off the plate and drill a hole in the plate of the
thermostat to be certain there is always a bit of flow, Of course it does lead to an
extended warm up period but in FLA that isn't really a problem for 9 months out of the
year. The bronco usually don't have a air bubble problem but facing the rad up higher
than the motor and running it at temp and checking the radiator level through the
fill neck( take off cap before getting hot) will make sure it isn't air. I always run the
coolant to water ratio at 70/30 or at least 60/40, which is more water then coolant
since water cools better then antifreeze/coolant. I wouldn't use that water wetter
or any other heat transfer fluid chemical since water is already a good conductor of
heat and I have only seen trouble in cars that ran that stuff.

 

sounds to me that the cooling system isnt burped, " About 20mins of driving the temp gauge would soar rapidly to "H" and then race back to "C". " and " and there was some gurgling sounds coming from the engine" when ya change a water pump or thermostat or any part in the cooling system, and you've drained the system down under the thermostat, your going to have to burp the system. add enough coolent so you can see it in the radiator, pref half or a lil less. as the engine warms up, the air in the block will push the coolant up towards the filler neck. If its too full, it will puke it out. watch the temp gauge and the thermostat will open and the level will drop, you'll see vapor excape the filler neck, add more anti freeze, but leave a some room again, as the engine needs to cycle again. the thermostat will open again and flow on a regular rate. now you can top it off, put the cap on and fill the catch can to 1/2 full. from here it will give & take for what the cooling system needs. On the thermostat, the spring goes toward the block, leaving the flat part pointing towards you. If you look at the flat disk you'll see a small hole in it, (some do) keep the hole facing up, and make sure that the thermostat is seated in the groove, if not you could bust the water neck when tightening it down. what ever ya do dont take the cap off if the engine is hot, if it does have a air bubble in it when you take the cap off if could blow back at ya. water boils at a higer temp under pressure. in the end what the gauge should show is, on start up, moves up into the normal range. ( C \ normal / H ) once the thermostat opens the needle should drop back a lil, then move back up. my dealings with Ford gauges. hope this info helps. Keep Em' Twistin'! Bob B.

 

That is correct. The problem started with the new water pump. I have been driving around w/o the thermostat. I can tell that I witnessed the three thermostats being uninstalled and all three were installed correctly. Also, I just triple checked that the water pump functions and it does with a vengence. I revved the engine up and the radiator fluid churned like a vortex in the radiator.

 

if you put in a thermostat, just make sure you burp the system, once the system is full and the thermostat is open, it will look the same as it does now with out the thermostat. you'll see it flow from the vaines into the side tank.
Keep Em' Twistin Bob B.

 

Here is oem more info that may be helpful for you and me.

WHen I was having diffuiculty with the thermistat in, when it warmed up, the top radiator hose was collapse and motioned like it was trying to suck air. The top hose was much coller than the bottom. It appears the bottom end was clogged and the top was absent of any fluid hence it would not cool since ther wasn't any circulation. COuld it be the bottom hose has a split in it and it blocks the hose whenever the fluid gets hot?

 

For what you just explained, & for what I've seen, thats typical of a low coolent level. the water pump is tryin to pump something that isnt there. It could be that your radiator is plugged and not holding enough coolent. but how you've explained how the gauge reads and how the upper hose acts, that to me is just a typical non burped system. she's got a slug of air trapped in her. casue when you take out the stat it can free flow. thus your not at normal operating temp. It's up to you, but there's only two things left to change, and thats the lower hose & the radiator. if you do elect to change those two things and it still acts the same, then its air in the system. ok quick question, how's the heat / defrost? does it stay consintant or does it go cool to warm & back cool again? If you have the defrost on and you feel it go cool then you with out a doute have air in the system. keep us posted
Keep Em' Twistin Bob B.

 

Heat and defrost work just fine. Zero issues there. I will go ahead and replace the lower hose and see what happens.