2000 Expedition with 4.6 overheating and no heat

[tsciascia@aol.com]

Hello,

I have a 2000 Expedition 4.6 XLT with 133k.

This has only been driven occasionally over the last two years but with no issues.

I went to take it on a trip and about an hour out right out of the blue, it started running warm and then suddenly pegged the temp gauge. I immediately pulled over and shut it down.

There were no leaks anywhere and it was not low on fluid.

I towed it home and replaced what I thought was a no brainer, the thermostat and just for good measure, the fan clutch. I let it idle for about a half hour, topped it off and drove it maybe 4 miles with no issues. Got back in it after about 15 minutes of sitting and 2 miles down the road did the same, started getting warm and then suddenly pegged the gauge. I pulled over and shut it off but only within about 5 minutes, I turned the key on and it was at normal temperature. This continued to repeat itself so since the water pump was not lose or leaking i went to the next possible item and replaced the radiator.

After replacing the radiator, everything was great. I took off on my trip in 85 degree plus weather. Went about 200 miles then drove locally for a couple days without an issue. The temp gauge stayed dead centered the whole time.

Then coming home, I was so confident that the issue was solved that I took a mountain pass short cut. It was 95 degrees out, steep grades, lots of full throttle and not an issue. About 30 miles out of the pass after driving with no issues for about 300 miles, back onto level highway it started heating up again and then pegged the gauge. I pulled over and shut it off immediately. Again only after about 5 to 10 minutes, it was back down to normal. It did this three more time then the last time I was able to drive it the last 30 miles home w/o overheating, although driving w/o the a/c on and slowly in the right lane.

I also have no heater when I turn the Controlls to full heat front and back. Even if the a/c is on and I want to turn the temp down moving the knob to the red doesn’t do anything. Related??? I don’t know.

 

What else could it be? I am stumped after driving that far with the a/c on in 95-degree temps and pulling mountain passes then all of a sudden, the same thing.

 

Sorry for the long post but wanted to paint the complete picture.

 

Any help would be appreciated.

 

Thanks

Tony S.

 

[fuzzymoomoo]

There's probably a blockage in the heater core.

[tsciascia@aol.com]

It is the same, front and rear heat.

Do you think this will cause the overheating also?

 

Thanks for the reply.

Edited July 24, 2017 by tsciascia@aol.com

[fuzzymoomoo]

Yes. The heater core is part of the engine cooling system. If its clogged, it won't allow fresh coolant to cycle through the engine.

[fordtech1]

Unfortunately sounds like head gaskets. Most of the time after that happens, open the coolant bottle and smell the coolant. It will smell like exhaust. Have seen it a couple times. Not extremely common but does happen. I've put a set on for a 02 f150 same symptom. There's no heat because air is getting in coolant from combustion gases.

[tsciascia@aol.com]

Checked it out and no oil in water or water in oil. No moisture in the top of the oil fill cap and oil on dipstick is clean.

 

Thanks for the reply.

Tony S.

[tsciascia@aol.com]

With the heater on, I checked the lines going to and from the heater core in the back and are about the same temperature HOT!

[fordtech1]

The part that makes me think it's head gaskets still is because a engine doesn't over heat and cool down in a couple minutes. I truly think thats your issue. There test to check for combustion gases in coolant. The f150 I did had the same symptoms but no oil in coolant. The gasket can fail next to water jacket not oil port.

[tsciascia@aol.com]

Yea, the cooling down quickly is strange.

It is very odd, today I turned on the a/c full blast front and rear in about 85 degree outside temp and drove the heck out of it and the gauge never budged from normal.

[fordtech1]

Seriously after it happens, remove the cap slowly and smell the coolant. It most of the time really smells like exhaust fumes.

[tsciascia@aol.com]

Weve done that and there is nothing. But thanks!

[akirby]

Couldn't it also be a bad temp sensor? Another possibility is air in the cooling system causing a steam bubble which spikes the temp when it hits the sensor, then goes away when you shut off the vehicle.

[fordtech1]

Couldn't it also be a bad temp sensor? Another possibility is air in the cooling system causing a steam bubble which spikes the temp when it hits the sensor, then goes away when you shut off the vehicle.

Could be a temp sensor but the lack of heat when this happens indicates air in system or lack of coolant flow. Those engines have Degas bottles so they purge air by themselves. It's not like a Lincoln LS that is a bear to get burped at times.

[fordtech1]

One more thing. The Gage isn't very accurate. It basically goes cold, norm and hot. It could be on the verge of running hot and still show normal until it hits that threshold. A good way to see real time cylinder head temp is with a scan tool. That will give you temp the pcm is reading and see how much fluctuating it's really doing.

[tsciascia@aol.com]

Do you guys think there would still be air in it after a 300 mile run under extreme conditions and no overheating issue?

[fordtech1]

No there shouldn't be any air in it after that. Like I said earlier those purge themselves very well

[MKX1960]

Sounds like the only thing not replaced was the water pump. In a 60's -70's vehicle, that would be at the top of the suspect list.

[fordtech1]

Sounds like the only thing not replaced was the water pump. In a 60's -70's vehicle, that would be at the top of the suspect list.

I have never seen a 4.6/5.4 water pump fail as in the impeller spin on the shaft. Really only have seen a very few leak. However, it's possible.

[tsciascia@aol.com]

.

Edited July 25, 2017 by tsciascia@aol.com

[tsciascia@aol.com]

One more thing. The Gage isn't very accurate. It basically goes cold, norm and hot. It could be on the verge of running hot and still show normal until it hits that threshold. A good way to see real time cylinder head temp is with a scan tool. That will give you temp the pcm is reading and see how much fluctuating it's really doing.

I'm going to check it out with the scanner.

[tsciascia@aol.com]

I have never seen a 4.6/5.4 water pump fail as in the impeller spin on the shaft. Really only have seen a very few leak. However, it's possible.

My Same thoughts.

[tsciascia@aol.com]

Could be a temp sensor but the lack of heat when this happens indicates air in system or lack of coolant flow. Those engines have Degas bottles so they purge air by themselves. It's not like a Lincoln LS that is a bear to get burped at times.

I never have heat front or rear under any of these conditions.

[MY93SHO]

Here's what you need to rule out the head gaskets.

 

https://www.napaonline.com/en/p/BK_7001006

[RPF]

You can get a direct reading of the cylinder head temperature on a 2000 model by putting the cluster in HEC test mode. You will want to scroll to the degC reading. It will be in celsius.

[MKX1960]

I have never seen a 4.6/5.4 water pump fail as in the impeller spin on the shaft. Really only have seen a very few leak. However, it's possible.

I recall one car I had and thought it couldn't be the water pump because on Chrysler's, they would usually leak when they were about to go south. Turned out, the impeller was spinning free part of the time.