packy

well, just had both heads on my 1999 4L v6 ranger, both were cracked between the valves. runs great, but have noticed one thing, the temp gauge fluctuates, not a lot, but every now and then, will move 1/2 way up the scale, then quickly back down just under 1/2 way, coolant is full, does this sound like a bad sensor?

Johnny Mullet

I bet there is an air pocket in the cooling system. Remove the rad cap while cold, turn the heat on hot in the vent position, and let it run till it warms up. When it's warm, rev the engine a few times to force any air out.

packy

I turned out being a bad temp sensor, replaced sensor, fixed problem