Overheating - 4.0l V6

[-Greg-]

Hello,

Me and my wife recently decided that we need an SUV with 3 row of seats, so went for 2004 Ford Explorer 4.0.
The car is great in every aspect - it is clean, never been in the accident, 93K miles. It is imported from Japan, has a message center, auto dimming rear view mirror, and climate control (with second row separate controls), but does not have the stability control that I have seen on many models when looking for one on the market, nor adjustable pedals.

The car had 2 issues when i was buying:
1. ABS light comes up after hard braking. ABS works (tested) but cruise control doesn't. I am sure this must be an easy fix, so this is OK at this stage.
2. Transmission might not engage in Drive or Reverse. If you apply some gas, it will still get engaged in a very rough manner. When engaged, transmission works great. This seems to be an issue of transmission valve body, but happens rarely + the previous owner bought reconditioned Valve body and included with the car.

So, happy with my purchase, me and my wife decided to go to the summer house. The road to this house is narrow, with lots of turns and all the time and in hilly area - for around 14 miles it is going up (never leveling). It took us around 40 minutes to get out of the city (covered less than 5 miles), with a very heavy stop-and-go traffic and on this hilly road (there was some traffic on the hillside as well, keeping average speed low, but constant, in between 20 to 30 mph.), after about 10 miles, I got the Check Engine light with a message on the Message Center that Coolant temperature is high. Coolant needle was getting in the red zone, so I stopped the car to check what's up. A/C was set at 74 degrees Auto for whole trip.

The water was boiling. I started slowly removing the plastic tank cap so gases did escape, but I did not lose coolant. The coolant in the tank is definitely just water so it does need replacing, but that's a different story. After gases escaped, I started the engine and the coolant level was back to normal. I continued drive to the house with no incidents. On the way back, after clearing traffic and getting really close to home, I got same situation. I stopped near the Pharmacy and bought distilled water and poured about 4 liters (about 1 gallon) in the plastic tank. No more problems until getting home.

This morning I added another 5 liters (about 1.3 gallons) of distilled water to the tank to top up, but no leaks anywhere. I left the car at home and took my other car to work, so I will check more this evening.

From what I've already checked:
Fan clutch must be fine - it has correct resistance when cool and increased resistance when hot.
Oil is good - It sits at the Max level, did not increase in volume after this incident, neither did decrease. It is 5W40 with Ford recommendation.
The engine pulls strong, with no rattle, not detonations or strange sounds...

Now I am very confused how to proceed. I did order new thermostat and a thermostat gasket already (I will get it tomorrow), also located new plastic tank cap (just in case mine is bad). This evening I will try to check on engine gasses getting in the cooling system to check if the gasket is cooked.

Sorry for a huge post, but I am really confused what might have gone wrong, so any suggestion will help. Is this the common issue on 4.0s? Is there a known cure? Shall I be worried?

Thank you,
Greg.

 

[-Greg-]

I tried to check further, but no luck .Gasket is good, no leaks. Thermostat opens exactly at 84c (183f). Car does not seem to overheat anymore. For a 20 mile trip in the city, 90 minutes total, Max coolant temp was 110 degree Celsius .That is 230f . That is measured by torque app. Temperature meter on the dashboard remained in the centre all the time.

Any ideas what can be wrong?

 

[kcblakely]

So ... you have an old car. With a lot of miles. It got hot and you added a gallon of water. Then you had to add almost a gallon and a 1/2 more. No apparent leaks. I'm gonna assume your T-stat is good

My theory: head gasket leak. It's either leaking into one of the cylinders and being burned out, or it's leaking onto the engine and evaporating. Bottom line is the coolant is going somewhere, and the fact that it was simple water in the system as opposed to antifreeze tells me it's an old, ongoing problem. If you don't see leaks and you have to keep adding coolant, then you have a head gasket leak.

Recommended way forward: replace the thermostat, fill the system with antifreeze (so it has color). Run the car in your driveway until it gets to operating temp, then run for another 20 minutes or so. Closely monitor temp gauge so it doesn't overheat. Look for leaks. If it starts to overheat, shut it off; don't let it boil over. If you found a leak, fix it. If you haven't found a leak, wait for the car to cool and then check coolant level. If it's low by more than 1/2 a quart or so, then you have a head gasket leak.

Replacing head gaskets is a non-trivial job, but it's not impossible and you can do it if you have the space and the tools. There are several threads in the forum on how to do it. I've done it myself. happy to answer any questions.

 

[-Greg-]

I really do not think there is anything wrong with the head gasket. The power is there, no rattle, no detonations, no CO2 in the cooling system.

I drove the car form more than 100 miles in the city traffic during the weekend and no drama whatsoever. Everything is great. No water lost in the system, no overheating.

I am still sure that it will overheat if I go to the mountains. Are there any common issues with overheating for these vehicles? I am really tempted to go sightseeing and overheating on a paved road does not sound like it will be able to handle off-roading in mountains

 

[kcblakely]

OK, fair enough. Just cuz I'm curious: Why would there be CO2 in the cooling system, and how do you know it's not there?

Like I said tho: the cooling system is pretty straightforward. If the coolant is there and it's circulating, then the car will stay cool, and vice-versa. If the coolant isn't there, then you have to find out where it's going; coolant doesn't just go away. It either goes outside the engine or inside the engine. A very common fault on old cars with lots of miles - like yours - is a head gasket leak. Just sayin'....

 

[-Greg-]

Well, 150,000 km is 93,000 miles, that does not seem much to me. I really hope that these cars can do better than Nissan Micra

I took the car to the garage and they did the test with blue fluid. It did not turn yellow. During the test, Car kept running for 10 minutes without any problems. According to the garage, it is either thermostat or fan clutch, but they cannot say for sure. In Tbilisi these cars are very rare, we have more Mercedes GLs that Explorers so these guys don't know much about common problems or what to look at. The water pump seems good, no noise or leaks. Fan clutch is something I really cannot judge. This is the first car for me with such device . It takes around 90 second from cold start for the fan to reduce speed and it has consistent resistance when engine is hot (does not seem to lose it anyway). I did assume it is ok just by the info or in the internet. I will have more time on next weekend to find out more and post an update.

Car overheated on Thursday. Nobody drove the car on Friday. During Saturday I drove about 45 miles and on Sunday morning I added about 0.6 litres of distilled water. We drove about 60 miles on Sunday (heavy traffic), and car did not lose any water.

I could not locate new thermostat here so ordered it from the USA together with expansion tank cap, spark plugs and wires. Delivery will take about 2 weeks, so I am wondering if there is anything else I need to order )

Edit:
New
One more thing - I just realized that my car does not have any fans on A/C radiator. Is this how it should be or its just some part missing? I have never seen any car without a A/C radiator fan

 

[Phil02]

I had a problem with my 02 getting hot and found a crack in the radiator tank under the trim panels. I did not have time to replace it my self so I took it to a shop and they also found a crack on one of the pipes on the heater valve. I had them replace that as well and have had no more problems.

 

[-Greg-]

Hello once again. I drove about 500 KM without any problem in the city, but one drive through mountains and same thing happened. I am really confused now.

I will take the car to check on CO2 in the cooling system (maybe the garage did something wrong?) and ask them to take out and clean the radiator + change the thermostat. This is the most awkward overheating problem I have ever had on any car

 

[kcblakely]

So ... are you or are you not losing coolant? When you have these overheating issues, do you find afterwards that you have to add coolant?

Assuming you haven't allowed the car to boil over and spew coolant all over the place, if you are losing coolant then you have a leak. It's either leaking out (such that you might see it) or it's leaking "in" and going in the oil or being burned out thru the exhaust.

If you are *not* losing coolant, then you don't have enough circulation; either your water pump is not pumping or you have an obstruction. The former would be pretty obvious very quickly, so the latter is more likely.

re: your question about "fan on the AC radiator": The radiator is specifically the heat exchanger associated with engine cooling. By "AC radiator", I assume you're referring to the AC evaporator, which is a heat exchanger attached to the front of the radiator. In my experience, the AC evaporator does *not* have its own fan; it gets cooling the same way the radiator does, and with the same main fan.

 

[Mbrooks420]

If you keep overheating the car you will blow a head gasket, or crack or warp the heads. Check the thermostat housing for leaks. These leak on the motor and don’t always show an obvious leak.

I suggest buying a pressure tester and checking the system, and to not drive it until it’s sorted out.

 

[allmyEXes]

Did you say if your radiator clutch fan is good or not ?

 

[Mbrooks420]

Yes, he mentioned the fan clutch checked out.

 

[allmyEXes]

the dreaded mystery leak...
I agree with Mbrooks420 about getting a tester and pressure testing the system but also I would get a high intensity flashlight and look around the right front, passenger side U.S.A. of the engine for some dried up leak residue usually rust colored. I started out with a cracked radiator tank, JB welded it. Then t-stat housing started leaking. Replaced that. The radiator started leaking at the bottom of the tank on the passenger side. Most of the liquid was evaporating because I was using 100% water.

 

[-Greg-]

If I drive in the city, no matter how tough the traffic is, there is no overheating or lost coolant. If I go to the mountains, the car overheats and the the leak is from the plastic tank cap - because the pressure is too high. After the first overheating, I have torque app running all the time to check the coolant temperature and do not let the coolant go over 110 degrees (230f). That is before the temperature gauge reaches red zone.

The fan clutch seems to work well. It takes around 90 seconds on a cold start to reduce rpm and keeps constant resistance when the car is hot. Thermostat housing is also good - no leaks. Thermostat gasket or the thermostat might not be closing well enough, because the pipe get a little warm when the temperature rises, but at 88 degrees (190f) the pipe gets hot fast - I assume that that is when thermostat opens.

In any other case, I would have assumed water pump issue or the head gasket, but there is no noise from the water pump and the CO2 test came clean. Today I will take the car to a different garage for CO2 test. If it turns out to be OK once again, I am actually stuck.

On this Saturday I will change the thermostat take out the radiator to clean it and check if the fluid flow is OK. I have no idea how to check the water pump - on previous cars (BMW, Audi and some VWs) bad water pump meant noisy operation or leaking. I never had a case when there is no noise or leaks but the pump is damaged...

PS Thank you for the info about the A/C evaporator. I am used to see another fan on that and though mine simply had it removed.

 

[allmyEXes]

I have seen an impeller on a water pump free spin when it got hot and also have seen one deteriorated away before, but it doesn't happen often. However the water pump would have to be removed to see it. BUT neither of these were on a 4.0 SOHC Ford engine

 

[allmyEXes]

how many feet above sea level are the Mountains ?
link to a guy having overheating problems in the mountains
Need advice! Coolant boiling in high altitude - Toyota 4Runner Forum - Largest 4Runner Forum

 

[-Greg-]

how many feet above sea level are the Mountains ?

Lowest point of Tbilisi is about 350 meters (1100 feet), highest is 800 meters (2600 feet). With this car I get somewhere at the mid point (around 1100 meters (3600 feet), at this point coolant is at 230f, so I stopped and went back). Tallest point is about 1400 meters (4700 feet). Roads are really good, with smooth asphalt. Median speed - about 40-45 km/h (24-28mph), with highs closer to 80km/h (50mph). Sometimes there is too much traffic, lowering median speed to as low as 10mph.

This is the route: Google Maps
In total, it is around 20 miles, but you start at 1360 feet, in about 15 miles you cross 4700 feet and get at the final point at 4500 feet.

 

[allmyEXes]

The altitude doesn't seem to be super extreme...

 

[-Greg-]

The altitude doesn't seem to be super extreme...

I have been there with every car I had, including 1.2 Nissan Micra. The roads are good, no off-roading, not even dirt roads. The problem is how you gain elevation - it is constant upwards drive, so unless the cooling system works well, overheating is not surprising. I am just trying to figure out what is wrong with it
With the older BMW at some point I had to manually limit gearbox to lower gears to let the pump do its work, but higher rpms definately did not help in case of Explorer.

 

[donalds]

Hayden severe duty fan clutch

Someone may have mentioned this already