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  #1  
Old 08-29-2011, 01:47 PM
fmx4lif3 fmx4lif3 is offline
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Default engine running hot, really hot.

my ranger is a 2.3 with a 5spd and a flow master 40 muffler. i dont know what it could be i just changed the oil in her and everything. i just want to be able top drive it again.
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  #2  
Old 08-29-2011, 01:58 PM
DiabloBlanco DiabloBlanco is offline
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Default Re: engine running hot, really hot.

Check your coolant?
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  #3  
Old 08-29-2011, 02:18 PM
Mirage Mirage is offline
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Default Re: engine running hot, really hot.

I'm guessing you already checked the coolant level, if not do so. Then let it idle until you start seeing the temp rise. when it reaches or starts to pass the normal point on the gauge (I find every ones' normal point is different), jump out and check the temp at the radiator hoses. If they are both still cool, chances are you have a bad thermostat. If they are both hot, then I would suspect your water pump. (I just replaced a friends that was overheating. Found that the impeller blades in the pump were gone, just plain worn away. ) If one is hot and one is cool, then you have another problem and I'd take a look at your engine oil. Look for water in it. The oil will be milky looking, and that is bad, very possibly a blown head gasket.

Hope this helps.
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Old 08-29-2011, 02:25 PM
JGiddy JGiddy is offline
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Default Re: engine running hot, really hot.

and if your oil isn't milky, and your coolant isn't brown/murky, have a cooling system test done. the first time my truck overheated it was cause my heater core was cracked

Last edited by JGiddy; 08-29-2011 at 02:28 PM.
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  #5  
Old 08-30-2011, 04:39 AM
fmx4lif3 fmx4lif3 is offline
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Default Re: engine running hot, really hot.

my coolaant id brown murky looking. i need to change it.
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  #6  
Old 08-30-2011, 05:23 AM
sgtsandman sgtsandman is offline
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Default Re: engine running hot, really hot.

If your coolant is brown and murky, you have a head gasket leak and need to get it repaired. Then change your coolant and oil, not before.
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Old 08-30-2011, 07:03 AM
sheltonfilms sheltonfilms is offline
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Default Re: engine running hot, really hot.

Quote:
Originally Posted by sgtsandman View Post
If your coolant is brown and murky, you have a head gasket leak and need to get it repaired. Then change your coolant and oil, not before.
Not necessarily, could just be rust from corroded components from the system. Mine looked like some bad diarrhea and my impellers were gone on my water pump. I always pressure test after replacing something that uses a gasket such as the thermostat and water pump. Needle didn't move at all.
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Old 08-30-2011, 07:26 AM
FireRanger FireRanger is offline
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Default Re: engine running hot, really hot.

^^ x2

Engines overheat for a few reasons. You could have one, several, or all of these issues. We can't tell you which one it is. You have to diagnose it.

1) Low coolant level. The radiator should be full and the tank should be half full. Both with a 50/50 mix of antifreeze & water. When the engine reaches operating temperature, the thermostat will open and begin to circulate coolant through the radiator. You may see the level drop when this happens if the rest of the system was low. Just keep adding more until it levels off. Then put the cap back on.

2) Crappy coolant. If its full of contaminants and rust, it will not work efficiently. Flush and refill per #1.

3) Failing water pump. If the impeller vanes are rotted out, it will not be able to circulate the volume of water needed, especially above idle. This also usually leads to #2 due to the rusting out of the impeller.

4) Thermostat stuck closed. This is rare, usually they stick open. But if it sticks closed, coolant will never be allowed to reach the radiator. This will cause the engine to just keep getting hotter and hotter until pressure opens the radiator cap and blows off through the tank. Like I said, this is rare. You would notice this if the radiator and hoses never get hot.

5) Clogged radiator. This is a result of #2 which is a result of #3... Remove, replace, flush, and fill according to #1. Might want to check on #3 as well since the rust came from somewhere.

6) A leaking head gasket would cause the system to exceed normal operating pressure and blow off that pressure through the radiator cap and reserve tank. It isn't overheating in that case. It's the compression from the cylinders entering the cooling system. That said, it will obviously blow your coolant out through the cap and tank leaving you low on coolant. It is also introducing air, oil, and other shit into the system. Both of which will result in overheating eventually too.
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Last edited by FireRanger; 08-30-2011 at 11:46 AM.
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  #9  
Old 08-30-2011, 07:33 AM
sheltonfilms sheltonfilms is offline
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Default Re: engine running hot, really hot.

Quote:
Originally Posted by FireRanger View Post
4) With the thermostat closed, there is NO way to blow off pressure. Expensive components will crack and gaskets will probably jettison. Like I said, this is rare. You would notice this if the radiator and hoses never get hot.
The heater core inlet hose connects to the thermostat housing behind the thermostat so as long as your heater control valve is open pressure can be bleed off.
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Old 08-30-2011, 10:22 AM
FireRanger FireRanger is offline
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Default Re: engine running hot, really hot.

But it would be bleeding off to itself wouldn't it? The heater core water inlet and outlet are both "behind" the thermostat (I think?). So its a closed loop with nowhere new for pressure to go. Although, that is probably the weakest portion of the cooling system behind the thermostat so one of those hoses, connections, valves, or the core would be one of the first things to fail due to the pressure.

If the the heater core's discharge goes to the other side of the thermostat, that would indeed provide a path for pressure relief. But if that was the case, it seems to me that would defeat the purpose of the thermostat to begin with?
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  #11  
Old 08-30-2011, 10:45 AM
sheltonfilms sheltonfilms is offline
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Default Re: engine running hot, really hot.

Its kinda hard to say what is behind and whats in front of a thermostat. I guess it depends on what is the midpoint in the system that is equal distance from the thermostat both ways. Sorry, just getting a little technical....lol

The heater core outlet hose goes back into the water pump at the same location as the lower radiator hose. So I guess you could say that it goes from the high pressure side to the lower pressure side of the cooling system.

As for defeating the purpose of a thermostat:

The heater core lines are about 5/8" in diameter. So they are pretty restrictive compared to the cross area of radiator hoses, water pump ports, and water jackets (cumulative cross area). Plus if you didn't have it this way I pretty sure you would have pulses of heat through your vents as the thermostat opens and closes.
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Old 08-30-2011, 11:02 AM
FireRanger FireRanger is offline
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Default Re: engine running hot, really hot.

Yep. The water pump is circulating coolant in a closed loop with the thermostat shut too. And that does flow water through the heater core as well. But so long as the thermostat is shut, nothing is going passed it. It is all on the closed side of the thermostat. if it is stuck shut, something is going to pop. Hopefully something cheap...

There is no "low pressure" side of the cooling system the way it is designed. The water pump is not creating pressure (other the small amount needed to flow water. The real pressure here is due to expansion from heat. That pressure is equal throughout the system. Normal operating temperature brings the pressure up to about 12-14 psi. In an overheating situation, the pressure would rise with temperature and eventually open the radiator cap 14+ or whatever the number is.

As opposed to, for example, the A/C. In that case it is closed loop but it has a compressor, expansion valves, and adiabatic cooling that reduce pressure on the "low side".
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  #13  
Old 08-30-2011, 11:28 AM
sheltonfilms sheltonfilms is offline
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Default Re: engine running hot, really hot.

I drew a (kinda shitty) diagram.

With the heater core circuit the thermostat IS being bypassed. And this happens at all times, because of the way the 4 port heater valve works. Either coolant flow to the heater core or it bypasses it and goes straight to the waterpump inlet.

Pressure wasn't a good classification. I should have used cold (more like warm) and hot side. Red color is hot and blue is warm. Notice that the return line from the heater core circuit is both because of either going to the heater core or bypassing it.
Attached Images
File Type: jpg waterpump.jpg (17.4 KB, 19 views)
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  #14  
Old 08-30-2011, 11:44 AM
FireRanger FireRanger is offline
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Default Re: engine running hot, really hot.

That prize winning work of art is missing the closed re-circulation. When the stat is closed, water is returned directly to the pump (by passages made for that, not just the heater circuit).

Guess what we've both totally overlooked making the heater circuit totally moot. You're going to smack yourself and say duh, I just did. There is no valve on the radiator circuit's discharge. It's open to the water pump inlet. Which means it is open to the entire system at all times. Which means pressure in there is equal regardless of thermostat, heater hoses, etc.

I had to draw my own picture (on paper and not as artistic...) showing the closed recirculation path in addition to the radiator's discharge. Then it jumped off the page and hit me. Duh.

I modified my previous post to say

4) Thermostat stuck closed. This is rare, usually they stick open. But if it sticks closed, heated coolant will never be allowed to reach the radiator. This will cause the engine to just keep getting hotter and hotter until pressure opens the radiator cap and blows off through the tank. Like I said, this is rare. You would notice this if the radiator and hoses never get hot.
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Last edited by FireRanger; 08-30-2011 at 11:47 AM.
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  #15  
Old 08-30-2011, 11:50 AM
sheltonfilms sheltonfilms is offline
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Default Re: engine running hot, really hot.

Can I see your drawing?....lol

I think on the 2.5 there may not be closed re circulation in the block. The reason I saw this is because all the 4 bangers have a 4 port heater valve (which redirects the coolant). And the V6's I've seen have a two port (simple valve that stops coolant). So I'm thinking v6's have the recirc built in but the lima blocks don't. This is just an assumption.
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