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Fluctuating temperature gauge

(1992 Ford E-150)
in Nokomis, FL on November 07, 2010
My van has had the tempurature gauge fluctuating for about 2 months. It goes from middle to high (not in the red) back down and up again constantly. The engine light came on. I check the water and had a water leak. The temperature gauge was replaced about 300 miles ago. The van overheated and had to be towed. New radiator was put in. Gauge still fluctuates - no one knows why - but this time it is in the testing stage and doesn't have any coolant. The engine got so hot there is no grease on it and the radiator was in pieces. After all the money, it still does the same thing. A tiny bit of water came out of the exhaust pipe. Is the engine shot? What can I do. It has 134,000 miles. Thank you
Displaying 1 answers & 1 comments
Popular Answer
on November 07, 2010

Wow, sounds like a pretty serious situation you have been the very least frustrating.

I have to admit I'm not sure I follow the whole story, but let me give you some opinion:

The termpature gauge fluctuation usually makes me think of a faulty thermostat. You did not mention that you have replaced that. If you have not, it is likely sticking closed intermittently too long causing the overheating situation.

The temperature gauge is not usually at fault. Sure, they can fail, but usually it's a situation where they don't work at all. The sending unit for the cooling system can send erratic signals, but again - usually way off when faulty.

The check engine light may or may not be related to the overheating. Code 116 would indicate the Engine Coolant Temperature (ECT) sensor went out of range - meaning over 250 degrees Farenheit. That's pretty hot for any engine! If the engine got that hot, you don't really know what the internal parts have done. The 5.0L V8 is a tried and true engine for over 30 years (engine family even longer), and are not known specifically for head or head gasket failures. However, at severe temperature extremes, anything can happen.

Water out of your exhaust pipe, however, is more likely condensation than coolant. You will know if you have coolant in your exhaust -- the smell of your exhaust will be kind of sweet smelling. And, you may smell some exhaust in your coolant reservoir.

My suggestion from here would be to fill the cooling system up to it's proper level, start and run the engine. Verify there are no leaks. Pressure test the cooling system to make sure there are no leaks. Replace the thermstat if you haven't already, and make sure to purge the air out of the cooling system afterwards.

If you continue to have severe fluctuation and overheating, check for the odors I have mentioned. Pull some spark plugs to inspect them for coolant residue. Change your engine oil and filter, and monitor the new oil level -- see if it rises after running a while, and turns milky from coolant intermix.

Much information - I know -- but you can get to the bottom of your issues, to be sure. Make sure you get good help and support from a good mechanic if you are not already.

Good luck!
on November 08, 2010
Thank you! Yes, the thermostat was replaced recently (4 months?) by a neighborhood mechanic. it seemed fine after that and I can't remember why it was replaced because I've had to replace many, many parts on this particular van. The fluxuation is a recent problem, before and now, after the new radiator. I appreciate your comments. I hope they help whoever is going to work on it. THANKS!!!!!
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