98 318 with 100k miles, new thermostat 195, new coolant, all flushed core is open flushes nice, blend door good, low temp guage, all hoses ahot except bottom rad hose, burped system drove for several dys now, all full luke warm heat, even blocked entire rad with cardboard, still low temp guage and luke warm heatr

 

Did you bother to review any of the existing "No Heat" or "Heat Doesn't Work" threads? Either way, it still sounds like a blockage, which could be in the block or even the heater core hoses. What about the truck's temperature gauge? Does it show the truck warms to 195º.

 

as said above low temp guage, and yes i have read several diff forums, known problem with these trucks it seems with no apparent fixes, nothing plugged been all flushed as said above, and nowhere near overheating, as result of a plugged system, all hoses are pretty hot except bottom rad hose

 

Plugged system isn't necessarily going to cause overheating. OK, so you have little heat and a low engine temp. Assuming you've checked all of the hoses for blockage (especially the ones to/from the heater core) I suggest pulling the thermostat and testing it in a pot of boiling water to see if it is properly opening. For all you know, the thermostat opened on initial use and failed open -- yes, that's possible.

 

well i thought of that have changed several thermostats, all same result, and all hoses are clear, used garden hose on them both ways and the heater core is open also flows well both ways, temp guage has 130 and 210 and its about middle ways, heat is warm at best, i just figyred id address the low guage 1st as that may be all the problem, others ive had run up next to 200, so this 1 is def low, truck has 100k mioes, runs awesome plenty power, just runs cool

 

OK, this is a real head scratcher. Are you running a 50/50 mix?

 

yes it is, i been under the hood for a week, even put cardboard in front of rad, i can take cap off while running and its just luke warm water, but thermostat is working cause when cold it has to run forever b4 coolant gets warm in rad, so it clearly is shutting and opening, its just as if its cooling too much, i have no idea, these trucks need a electric fan, has to get 190-200 b4 any fan

 

Is this a Dakota or a Ram?

 

That's right where mine runs with a verified functional thermostat -- rated 195 degrees, opens at 197, tested three times. The gauge sat right at the same spot on the old thermostat, tested once, opened at 194. You just can't trust the darn gauge.

A pretty good approximation of coolant temperature can be had by measuring the temperature of the coolant under the filler neck while the thermostat is open, assuming that you've got no blockage in the radiator. Add 30 degrees F to that reading and you'll be pretty close to top hose temperature.

 

If the hoses are all hot, 'cept the lower radiator hose, and the blend door is working as it should, then you either still have a pretty big air bubble in the heater core, or, the core is plugged up. It will still flow coolant, and both hoses will get hot, but, not enough of the core is going to be exposed to hot coolant, to warm the air sufficiently to keep YOU warm.