Hello y'all I got a 88 ford f150 with a 4.9 I bought the truck and it was running 190*f the truck sat for a couple months I went to drive it and it started running 210*f thought it might of been the thermostat. Pulled the housing off and there wasn't one in there so I put one in and was still running 210*f so I changed the water pump and its still running 210*f any ideas what it might be. Has dual electric fans on it just to note and they are working thanks y'all

 

210°F would be about close to right. That's what my 302 will run with a 192°F Motorcraft t-stat. They aren't going to stay dead on at 192°F. If your only running electric fans, this holds true. You will need to move to a HIGH quality lower t-stat, such as Mishimoto. Their design and structure is the same as Motorcraft. No crap like Mr. Gasket and Stant. The next 2 t-stats I will be installing in my '92, 300 and my '95, 351.

 

Thanks bud its strange when I got the truck it was running 190° without a t-stat now that there is one in there its 210° its got a 160° t-stat in it

 

It really doesn't matter if your T-Stat is opening at 160/ 180 or 195, once the truck is up to operating temp usually around 210, then it's there. If you were reading lower temps before, you may have to consider at what time of year you were looking at it or if you're going by the gauge in the cluster, that's NOT very accurate. You may want to put a temp gun on your heads and get an accurate reading, When was the last time the system was flushed and new coolant put in? There are alot of factors, but 210 isn't running hot.
My 95 F250 barely gets over the 1/4 mark on the dummy gauge but the heat will blow you out.

 

It was reading 190 3 months ago I also have a aftermarket temp gage in it. I just put all new coolant in when I did the water pump and thermostat.