Water temp and MPG

[PAExplorerXLT]

if you don't understand the connection between your engine's thermostat, coolant temp and heat, I don't think we can explain it to you.

I was just repeating what you said. "your heater core (huge job to replace by the way) has no effect on your engine temp. "

 

[Turdle]

The heater core does not have much effect on engine temp. It "may" help an overheating engine dissapate some heat, it extreme hot conditions, but will not cause an engine to run too cool in winter.

 

[PAExplorerXLT]

I have done the cardboard thing to block off the radiator so I decided to try it today. It is usually a pretty easy affair. Just drop it down in front of the radiator behind the grill. Not so with the Explorer. There are no openings.

 

[Jim_WY]

For some reason, the multiquote thing isn't working for me, so forgive me if I forget to acknowledge anyone or respond to all of the good tips I've gotten so far.

I just want to say thanks to everyone for helping.

OK, so it's gotten substantially colder here over the last few days, and now the engine stays even cooler (if I can believe the dash temp gauge).

It's about 7 degrees F here right at the moment, and the beast has been parked for a good 9 hours since I last drove it. So it ought to be about as cold as it needs to be.

I checked the coolant level in the overflow tank, and it was right at the cold-fill line. Then I fired it up, and immediately stepped out to check the fan. Sure enough, it's spinning. So now I'm thinking the fan clutch is bad or something is (mistakenly) applying power to the clutch to engage it.

It spun pretty much as was described for a "good" fan clutch on here, being able to spin it by hand, with the car off, and cold, but it stops almost immediately. So a bit of friction, but not so much that you can't spin it fairly easily.

Not sure how much that means, but the real point is that with the engine very cold, the fan is blowing.

With the fan blowing at all times, even if the thermostat is closed, is it likely that enough air is blown over the engine block to actually keep it from being able to warm up to proper operating temperature when it's cold outside?

I always figured that 95% of the cooling came from the radiator and if the thermostat was closed, it wouldn't really matter all that much if the fan was blowing or not. After all, if I was driving on the highway at 80 MPH, at this kind of temperature, there would be a LOT of air blowing over the engine even if the fan wasn't operating, and I'd sure as heck expect the engine to get up to proper operating temperature.

So, I figure the fan SHOULDN'T be running at this temperature, BUT I also question whether having it blowing should be able to prevent the engine from properly warming up. It seems to me that the main reason for having a fan clutch isn't to keep it from over-cooling the engine, but to save energy by disengaging it when it's not needed.

If that's true, then I may have both a bad thermostat AND a bad fan clutch (or problem that's applying power to the clutch when it shouldn't).

Does that sound like a reasonable assessment? Or am I underestimating the power of the radiator fan to cool the engine regardless of the thermostat?

 

[PAExplorerXLT]

Your observations and deductions make perfect sense. I have seen the fan stationary even for a good clutch. It always spins. May be not as fast but it spins. Mine certainly does. But as you said you get huge air flow when you start driving anyway. Does it warm up just idling?

 

[koda2000]

The fan will always appear to be spinning. The clutch allows it to slip when the engine is cold and increases engagement when the clutch spring gets warm/hot based on the air temp flowing through the radiator. The fan's job is to help cool the radiator when your not moving. It doesn't really cool the engine block.

It's clear to me that your thermostat is the problem. Overheating can be caused by a multitude of factors. Under-heating is pretty much always your thermostat. Period.

 

[DJRockit69]

I just change my thermostat tonight I'm just waiting on little bit silicon I used to cure all the way to see if that helped with my issue updates to follow

 

[SoNic67]

I have done the cardboard thing to block off the radiator so I decided to try it today. It is usually a pretty easy affair. Just drop it down in front of the radiator behind the grill. Not so with the Explorer. There are no openings.

You can push it UP from below. Then it will rest on something in there.

 

[Blacksheep Josh]

Should it please the jury, my '01 Tahoe was failing to reach normal engine temperatures and my interior heater performance was extremely lackluster. Compared to a few work Silverados we have with similar setups, I knew what I should be getting.

New thermostat did the trick.

Also, and this comes from a man who has worked for Oreillys, Autozone, and Advance, that most parts places will offer several temperature ratings and several pricing options. Never go with the cheapest part (it's cheap for a reason) and always go with OE temperature.

 

[DJRockit69]

Hey guys I changed out my thermostat and took my explorer for a drive after bleeding the system And the temp gauge I have before the thermostat goes up to 192 the thermostat opens and the gauge on the dash reads correctly till it opens then it drops down considerably and when it closes the process starts over is that right?

 

[Turdle]

Hey guys I changed out my thermostat and took my explorer for a drive after bleeding the system And the temp gauge I have before the thermostat goes up to 192 the thermostat opens and the gauge on the dash reads correctly till it opens then it drops down considerably and when it closes the process starts over is that right?

It will do that until the radiator gets warmed up, then it should get pretty stable.

Once your truck cools off, recheck the coolant level in the radiator. Do not rely on the level in the reservoir, you must check the level in the radiator. Sometimes these things are a bugger to get all the air out-

 

[DJRockit69]

Yea I know from past experience lol but I do know When I was bleeding the system I had two huge air bubbles came out and my heat is 100% better also to the air temp is about 8 degrees out right now

 

[DJRockit69]

Ok I will do that hopefully it will I bleed the system and two good size are bubbles cames out also it's 8 degrees outside right now so it's cold lol

 

[koda2000]

The thermostat for the 5.0L has a "rattle valve" that is supposed to be positioned at/near 12:00. There's a slight recess in the thermostat gooseneck to accommodate it. It's purpose is to let air out more easily. I've never had a problem bleeding a 5.0L, but I sure have on the SOHC.

Good tip from Turdle. Always check the coolant level in the radiator (when cool). Too many things can cause the overflow tank to not give you a true reading. Even with no issues it can take days for the overflow to completely fill the radiator.

 

[PAExplorerXLT]

Is there a special bleed valve. Some engines do and some others are supposed to bleed themselves.

 

[DJRockit69]

Crap I didn't think I did that. I have an aftermarket thermostat housing due to the factory one cracking on me I just checked my radatior coolant level and it didn't need any fluid

 

[koda2000]

Crap I didn't think I did that. I have an aftermarket thermostat housing due to the factory one cracking on me I just checked my radatior coolant level and it didn't need any fluid

it's not the end of the world if you didn't put the rattle valve in the right place. the air will come out eventually. I wouldn't worry about it. some people force the thermostat open enough to insert an aspirin in it. this allows the air to escape and then the aspirin dissolves.

 

[Jim_WY]

First, I've now changed the thermostat again. Different brand than the first one, but they were/are both 198 degree F units.

Your observations and deductions make perfect sense. I have seen the fan stationary even for a good clutch. It always spins. May be not as fast but it spins. Mine certainly does. But as you said you get huge air flow when you start driving anyway. Does it warm up just idling?

It really doesn't warm up much when idling. It always used to. I could fire it up on a cold day, just let it sit and warm up, and the temp gauge would be at the middle fairly fast.

As things are now, if I just start it and let it idle, the gauge comes up to right around the line at the "C". Then, when I drive it, it warms up a bit more, and with this latest (put in today) thermostat, the highest I ever saw the gauge go was maybe a hair over what is shown in that photo we've been plagiarizing in this thread.

The fan will always appear to be spinning. The clutch allows it to slip when the engine is cold and increases engagement when the clutch spring gets warm/hot based on the air temp flowing through the radiator. The fan's job is to help cool the radiator when your not moving. It doesn't really cool the engine block.

It's clear to me that your thermostat is the problem. Overheating can be caused by a multitude of factors. Under-heating is pretty much always your thermostat. Period.

I appreciate both of you guys' information about the fan. I suspect mine is working just fine, then. The fan moves fairly easily when pushed by hand when the engine is cold. It probably just spins somewhat when I first start the car because of the bit of drag it does have at that temperature.

I've had to replace the thermostats in every car I've ever owned (Well, OK, not the VW Bug, but...)

And the symptoms were usually a lot like what I'm seeing with this vehicle. And putting in a new thermostat has always fixed the problem immediately, and positively. So that's why I changed this one right off.

But now, I've put in the 2nd thermostat in as many weeks, and neither one seems to be making any significant difference.

But I need to let this one run for a while, make sure the system is properly burped and fully topped off, etc., but so far, today, it seems just like it was at first, and after putting in the first new thermostat a few weeks ago.

So I bought a new temperature sensor/sender for the thermostat housing. I'll put it on if things continue to act strange. Maybe the thermostats have all been just fine, but the sensor is lying to me. And I'll check the wiring and connectors for the temperature sensor, too, in case it's just a broken (intermittent) wire or a crummy connector.

It was almost up to freezing today, and the sun was shining, so I took that opportunity to swap in the new new thermostat. But it's supposed to snow and get colder in the next couple of days, so I'll have more opportunity to observe the cold weather behavior.

I did, indeed, have the first thermostat installed correctly (wax pellet in, pointy end out - and bleeder valve thing at 12 O'Clock) for what that's worth.

I'll let you all know what happens, and if I swap in the new temperature sensor, too.

Thanks again, everyone.

 

[2TimingTom]

Changed the thermostat today (finally) and now the ScanGauge reads 190 (188-193 or so as it fluctuates).

Needle points more toward the middle now as well.

No word on MPG as I barely drive it. Should improve though.

 

[DJRockit69]

so it turns out my gauge on my dash isnt reading right or something alone those lines I got a scanner and everything is reading and working correctly proper water temp and all that Jazz. now Im wondering why the gauge o my dash isnt working right considering I replaced the thermostat and the temp sending unit. Im wondering if it has something to do with the v6 to v8 swap I did. Now the parts explorer I got was a early 96 just mine is so is it possible that I have some wiring pins that arent lining up right or could the gauge failing?