Overheating Problem with 2003 Explorer

[bclukey]

I have a 2003 Explorer 4.0L that has recently been overheating. The problem is strange because it doesn't happen all the time. I have replaced the thermostat and it didn't make a difference. I tried rotating the fan to check the fan clutch while it was cold, and I could turn it, but it wouldn't spin freely. After it came up to temperature, I could feel the top radiator hose getting warm when the t-stat opened. The bottom rad. hose was cool.

I drove this truck 200 miles on the interstate with the AC on max last weekend with no issue. I checked the water level in the tank before I came back and it had dropped about 1/4" from where it was when I left. I brought it back up 1/4" and didn't get 50 miles down the road and the temp. guage shot up to hot, the check guages light came on and you could hear the water boiling in the tank and coming out around the cap. I shut it off, let it cool, put more water in it to bring it back up to where I started and drove the remaining 150 miles with no issue. The problem is sporadic, and may happen in the first 5 minutes of driving, or I can make a long trip with no issue. It almost acts like something is closing off the coolant system occasionally and causing it to overheat. I also noticed what appears to be sand or scale in the bottom of the coolant tank. There is also a big fluctuation of liquid in the coolant tank. If I fill it to the max cold fill line, it will most likely overflow. If I leave the level at the seam in the middle of the tank it generally stays there unless one of the overheating incidents occur. Do you think the next step should be a radiator flush and fill? Any other suggestions?

 

[Ronin8002]

Do you know if the cooling system has ever been flushed?

I'd say a flush and refill should be the next step.

If that doesn't fix it then perhaps a radiator replacement.

 

[bclukey]

No, I don't know if it has ever been flushed. I bought it last fall, and it has 140k miles on it.

 

[Ronin8002]

By all means then try the radiator flush and fill. It may have never been done and should be relatively inexpensive.

 

[bclukey]

Is it possible that the vent hose from the top of the overflow tank to the radiator is plugged, or partially plugged? If so, will flushing the system clean that out as well?

 

[Ronin8002]

Could be. should be easy to check it by removing it completely and blowing through it or looking through it to see if there's a blockage.

I suspect though that if you have scale in the tank it's probably in the radiator too.

 

[jrford]

i'd change the fluid first make sure all the overflow hose is clear, good cap etc.

might be related or not, but someone another board had a similar problem. Turned out to be the bottom hose. Usually inside it there is a spring looking thing foot long, which prevents the hose from collapsing, which in fact cut the flow off. Well someone replaced the hose and didn't put the spring back in. Hose would close off sometime due to the vacuum. just a long shot.

 

[bclukey]

Thanks everyone. I'll try flushing the system and checking the hoses and rad. for plugs and see what happens. I'll definately be pulling off the bottom hose and see if the spring is in there while the system is empty.

 

[jrford]

I'll definately be pulling off the bottom hose and see if the spring is in there while the system is empty.

you don't have to pull the hose, usually when you squeeze it you can feel it. In that thread about half said they didn't have one??? . :scratch:. . .? i'll check mine at lunch. . .

 

[scottfab]

precisely the same problem

you don't have to pull the hose, usually when you squeeze it you can feel it. In that thread about half said they didn't have one??? . :scratch:. . .? i'll check mine at lunch. . .

My 2003 does not have one. My symptoms were precisely the same.
In my case I believe it was a combination of the belt slipping
AND loss of fluid. There was evidence of fluid leakage at the intake
manifold. I was being sucked in at cyl #1. It was slow so as to go
mostly unnoticed.
I replaced the head gasket on that side as well since I pulled the
head to inspect for damage. Probably did not need to go that deap.

 

[D Hook]

Thanks everyone. I'll try flushing the system and checking the hoses and rad. for plugs and see what happens. I'll definately be pulling off the bottom hose and see if the spring is in there while the system is empty.

Did you ever find the problem?

 

[bclukey]

Did you ever find the problem?

No, not yet. I haven't had a chance to spend much time on it. I had a pressure test done on the coolant system, which checked out. The tech. suggested that I replace the cap on the coolant tank, which I did, but it didn't fix the problem. I think the next step is to have the system flushed. The issue is really strange. I can start the truck, go a half-mile down the road and the temperature guage shoots up to hot and the check guages light comes on. If I pull over and rev the engine a couple of times, the guage goes right back down and usually I don't have any issue after that. I normally just go on short trips with it, but lately this seems to be the pattern every time I drive it.

 

[jgarr]

Bclukey - did you ever find the root cause of your Explorer overheat problem?

 

[blueoval9erlifer]

I would pull the new thermostat out and check it to make sure it opens up and closes properly.

Are you having to add a lot of fluid?? Or has it ever been really low to where you could have gotten air in the system?

 

[bclukey]

I ended up taking it to a local mechanic. First they checked the intake manifold, as some of the Ford engines are notorious for cracking on the intake. That was not it. After seeing the amount of water in the oil, it was determined to most likely be a head gasket or cracked head. The 4.0L in the 2003 Explorer has to be completely pulled out to replace head gaskets or heads, so I opted to get a used engine with 70k miles on it and a warranty, and currently the mechanic is putting it in. Hopefully the end of my problems.

 

[Eb 60]

2003 Explorer 4.0L that has recently been overheating

I have a 2003 Explorer 4.0L that has recently been overheating. The problem is strange because it suddenly happened, I even don't look to the temperature gave when I heard a strange noise while driving, I thought it's an AC fan noise. After about 10 miles I stopped to check, I found that it's boiling and some mud and a little oil is comes out with the vapor and water. I drove this truck 200 miles on the interstate with the AC on max last weekend with no issue. I checked the water level in the tank before I came back and it had dropped about 1/4" from where it was when I left. I brought it back up 1/4" and didn't get 50 miles down the road and the temp. gauge shot up to hot, and you could hear the water boiling in the tank and coming out around the cap. I shut it off, let it cool, put more water in it to bring it back up to where I started and drove the remaining 150 miles with no issue. The problem is sporadic, and may happen in the first 5 minutes of driving, or I can make a long trip with no issue. It almost acts like something is closing off the coolant system occasionally and causing it to overheat. There is also a big fluctuation of liquid in the coolant tank. could it be possible that leaving the car for about 48 houres without use may make the t.stat stuck, and this is the cause of the overheat? Do you think the next step should be a radiator flush and fill? Any other suggestions?

 

[bclukey]

The issues you are having sounds almost exactly the same as what I dealt with. I replaced the overflow tank cap, checked the fan clutch, did a pressure test on the coolant system, checked to make sure the coolant hoses weren't collapsing and restricting flow and probably several other things before I finally took it to a mechanic. They pulled the intake manifold and checked it for cracking. When it was determined to be ok, they concluded that it was either a cracked head or blown head gasket because there was water in the oil. I was also getting an engine code of a misfire in one of the cylinders, which I am sure was due to water getting in the cylinder. The issue with a 2003 Explorer is the only way to change a head gasket is to pull the engine out. I opted to replace the engine with a used one that had a warranty. Hopefully you have better luck than I did.

 

[Eb 60]

The issues you are having sounds almost exactly the same as what I dealt with. I replaced the overflow tank cap, checked the fan clutch, did a pressure test on the coolant system, checked to make sure the coolant hoses weren't collapsing and restricting flow and probably several other things before I finally took it to a mechanic. They pulled the intake manifold and checked it for cracking. When it was determined to be ok, they concluded that it was either a cracked head or blown head gasket because there was water in the oil. I was also getting an engine code of a misfire in one of the cylinders, which I am sure was due to water getting in the cylinder. The issue with a 2003 Explorer is the only way to change a head gasket is to pull the engine out. I opted to replace the engine with a used one that had a warranty. Hopefully you have better luck than I did.

actually I checked the oil, there is no water there, the oil I realized with boiled water and mud that come out

 

[scottfab]

The issue with a 2003 Explorer is the only way to change a head gasket is to pull the engine out.

Sorry, not true. I've replace both head gaskets on mine. Cost was $50 gaskets from Rockauto.com. That and a few bloody knuckles.
The root cause of my intermittent overheating and slow loss of coolant turned out to be the water pump!! ($29 and easy to replace) I suspect due to wear it was cavitating at times.