Running a little warm on the highway?
 

Ok, this is different but I have a good idea of what could be wrong. Just looking for confirmation. I have a 3 pass rad., new fan clutch (fan spaced back too), no thermostat being used.
I am on the highway doing 3K and 70 or so. The car gets up to 3/4s or so. I drop down to 30-40 in stop and go traffic and the temp goes down gradually to 1/4. This is strange that driving on the highway would make it run hotter. Is this because I am not running a t-stat and at that rpm the water isn't having sufficient time to cool down in the rad? Thanks.

I don't know if that is your problem or not, but that is what happens when you run a t-stat with a temp too low, or worse, none at all. There is no reason, other than an ECM chip, for a street driven car to have anything less than a 180 degree t-stat, and in most cases, they should have a 192.

:)

Take care,
~Chris

I will put it back in but why would it run hotter on the highway and cooler in traffic etc.? Thanks.

do you have that black peice of plastic that goes under the car that deflects air..that wil make a big diffrence

Because your engine is spinning faster on the highway. That means it's working harder, and generating more heat, and your water pump is spinning faster, not allowing the water to release the heat in the radiator. You were right on the money.