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Discussion Starter #1
Hi, from begging my English is not good, I will try. When I run hard my bronco 302 5.0l, automatic, the coolant run out to expansion tank, and out of system. The motor is without thermostat, and the temperature is very low, the bronco run cold recently turn on. The compression of piston are passenger side front to rear 130-150-150-133 from driver side front to rear 140-140-140-130. Some one have any idea what this happen.
I bought the bronco 3 week ago, the last owner say he change water pump, radiator is new, the temperature is low because no have thermostat. If some need additional info ask me a question and I try to answer...
Thank for your help. NOEL
 

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I stall a proper tstat and verify the Guage is working correctly.
 

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I understand the gauge is right because I can touch the radiator and hose without any damage, or I can't see any part hot like boiler....
 

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Hi, that is a good try, thank you. For info, I verify the oil and no have refrigerant or coolant and coolant is without oil, no coffee in my engine...
 

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Discussion Starter #6
Hi, I try to find some diagram for serpentine belt, but I found many different, someone help me with the correct diagram. Ford Bronco 1989 5.0l 302 engine. Power steering, ac, tensioner, alternators, everything in the engine.. Thank in advanced.
 

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imdabes
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You need a thermostat.

The thermostat acts aas a restriction point in the system and increases pressure, even when its wide open. The head rate on the water pump is the same, and if you give it a wider path to flow through the pressure will decrease.

Running with no thermostat isn't good for our trucks, and pretty much messes everything up.
 

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Previous owner may have installed the wrong water pump, rotation is backward which is forcing coolant through the system the wrong way. Had this happen to a friend, bought the wrong water pump (pump was for serpentine belt installation, engine was set up for multi-belt) which was turning the water pump backwards and puking coolant out through the radiator. Installed the correct water pump and fixed the problem.
 

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imdabes
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Low pressure isn't his problem. The coolant is blowing out of the cap, which he says is holding 13psi. That means he already has too much coolant system pressure. Adding a t'stat is certainly good, but it won't help his truck's problem.

Yeah, did the second part of my post not come through? My phone was acting weird while typing that. I don't know what the head rate is on the water pump or if the computer can adjust it, but I'd imagine since its belt driven its fixed at whatever the rpm is, but without the tstat impeding the flow out of the block its possible it could produce more than 13psi.

That tstat is a pretty important piece of the system.

I'm just guessing though, but the pressure should be way above 13 anyway before the tstat, then the impedence in flow at the tstat helps regulate the pressure too.

Overheating will increase pressure too, how jot is it running?
 
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