Coolant Loss and temp gauge pegged

[Rog1010]

Have a 98 XLT 5.0 with 168K. Last couple months noticed coolant loss with no visible leaks and light smell of burned coolant. Nothing in oil. Nothing from exhaust either. Would top off radiator and vehicle would run great.

Driving home from work temp gauge pegged to hot with check gauge light on.
Pulled over and smelled strong odor of burned coolant. Overflow empty. Let cool, opened radiator and filled with water. Started vehicle, temp gauge was still pegged and moved slightly off when idled for 5 minutes. Drove vehicle for 5 minutes in neighborhood nothing changed. Temp gauge still pegged. Let cool and noticed smell and empty overflow and radiator. Vehicle never showed signs of complete overheat.

What can be done to troubleshoot where coolant loss is coming from as well as if headgasket needs replacement? thanks for your help. Roger

 

[swetrid]

It could be thermostat stuck or coolant leaks which are common on 5.0L are timing cover, water pump and thermostat housing.

 

[1998Exp]

I am presently finishing a coolant leak repair on my '98 Limited V8, so hopefully I can point you to something useful, based on this experience.
The simplest thing to do is pressure-test the system. This is done with the engine cold, by attaching a pump to the radiator and pumping the system up to the nominal pressure, usually around 15psi. Many auto supply stores rent those testers for free.
If the leak is external and as large as you described, you will certainly see it. The leak is not necessarily where you see the coolant dripping on the ground. Follow it back to the source, paying special attention to the radiator, hoses, water pump, and the front cover. Also check the overflow tube from the A/C (it will be around the bottom of the firewall, on the passenger side). Green fluid dripping from there indicates a bad heater core.

Not sure what to make of your 'burned coolant odor'. Do you mean that you can smell it in the exhaust? If not, it may be dripping on a hot surface, like the exhaust manifold or a catalytic converter. If you can't see any external leak, look and smell for signs of coolant in the oil. Also remove the plugs after you pressurized the system and look for signs of coolant on them.

 

[budwich]

well your temp gage problem is likely the result of a "well emptied system" that has air in it after "refilling" it. there are threads on how to "burp" the system "properly". As suggested, you have a "significant leak" that should be easy to find with a pressure tester and / or some observant eyes...