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truckn'
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Discussion Starter #1
This question is for a friend of mine, she has a 85 6.9. I have replaced the thermostat, temp sensor, water pump and rinsed the radiator out several times. Each time it gets a little better but after awhile, around 30 min of running 60mph on the highway, it starts to get hot. The coolant hoses seem to have flow. And the fan is pretty much locked up on the motor. Am I missing something? :shrug:
 

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When you say starts to get hot, do you mean the gauge shows hotter than normal, or is coolant starting to boil out? A bad gauge can give a false reading, so a mechanical gauge may be in order even if temporary. What kind of pressure does this cooling system have? If it is building pressure you may have head gasket issues. Do the cores in the radiator look ok? Also the radiator hoses (lower esp.) could be collapsing at speed. Are you using a 50/50 coolant mixture? How about a serious exhaust restriction like a bad muffler?
 

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truckn'
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1,720 Posts
Discussion Starter #3
I was thinking it was the guage, and I'm probably gonna install a mechanical one. Didnt check the system pressure, that will be tomorrow I guess. I'm using 50/50 and 3 bottles of DCA. And the exhaust is pretty free flowing, straight pipes and glasspacks, all 6 months old. Thanks
 

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Good plan on the gauge. For what its worth, glasspacks are the most restrictive muffler you can have-they arent the cause of your overheating, but they do rob horsepower. Now we have the same number of posts again.
 

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truckn'
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Discussion Starter #5
I dont see how a glasspack is the most restrictive muffler, you can see clear through the thing? :shrug:
 

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Straight through, but what is the inside diameter. The small id is what kills the flow on a glasspack, thats why most people use turbo-style mufflers or flowmasters.
 

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truckn'
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Discussion Starter #7
10-4, maybe we'll go with really old school, no mufflers!!!!!!!!!!! The local police will love that! :Thumbup:
 
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