98 4.6 cooling issues
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98 4.6 cooling issues
I have a 98 F150 with a 4.6 with just over 200K miles. First issue I noticed was the gauge would not go to where it used to go. I have had 4 different thermostats ranging from 170 - 195 within the past 3 months... all of them from O'Reilly and they all generally read about the same. Changed BOTH the sender units (gauge and PCM) and still the same. About the only time it reads correctly is if I'm towing with the A/C on. The other issue I noticed was the gurgling from the heater core. I bought a vacuum servicing tool from eBay and tried it several times even with the front of the truck jacked up. Even bought coil springs to put in all the cooling lines so they would not collapse when I put it under vacuum. Just today I put a gutted thermostat in so I could have open flow from the top end. I'm not sure if it worked, I'm gonna let it cool to see if it did the trick. But if that doesn't work I'm out of ideas. A lil help please...
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If your saying your temp runs LOW all the time, then your thermostat is not working. If you saying it is running HOT quite often with a new thermostat, then you might have a bad water pump. There have been several posts on this site about the impellers rotting off or falling off on 16 year old motors with 200K miles. Taking the thermostat out will make the truck run very cool, and will take forever to get up to 150 degrees. You will probably get error codes due to running too cool and taking too long to warm up.
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Yes this is a bit of an odd one. I checked the thermostat I have now (Murray 195°) and it opens when it should, about 192°. But just for ****s and giggles I'm going to go get a motorcraft for the dealership tomorrow.
Update: Still hear gurgling in the heater core. Flow is not the issue. There were no leaks visibly nor any smells of coolant, and the level in the degas was always the same. So even if theye was an internal leak like head gaskets I would expect to see coolant level drop or oil/coolant mixture. None of that. Read around a lot of many vehicles being really difficult to get all the air out. Any Ford techs out there?
Update: Still hear gurgling in the heater core. Flow is not the issue. There were no leaks visibly nor any smells of coolant, and the level in the degas was always the same. So even if theye was an internal leak like head gaskets I would expect to see coolant level drop or oil/coolant mixture. None of that. Read around a lot of many vehicles being really difficult to get all the air out. Any Ford techs out there?
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So it seems there was a very small leak on one of the heater hoses (at the clamp on the return line going into the manifold ). The line seemed OK it just looked like a bad clamp, so I put a Toyota style spring clamp and no more leak there. I replaced the T-stat with a motorcraft 190°. Ran it a few times today. No leaks that I can tell. When a put a vacuum on it again it held vacuum steady for about 10 min. I still hear gurgling from the heater core. I will let it cool overnight and see if anything changes. Though it's not over heating I wonder if there is not enough flow from the pump to overcome the air pocket. The hoses going to the heater core go "up" to the core so if there is enough air it could be pretty difficult to get that air forced down back through the manifold.
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captain1997
1987 - 1996 F150 & Larger F-Series Trucks
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Oct 9, 2012 02:21 PM
