A few days ago I stopped at a store & when I started to drive again, I noticed that my engine was overheating. Just as I noticed it & was getting ready to pull off the road to stop I noticed the temp. was rapidly decreasing, so I continued to drive. This happened a couple times, so I thought it was only happening when I slowed down or stopped & started driving again, but then the next day I noticed it doing the same thing while continually driving around 55 MPH. What would cause it to rapidly over-heat & then rapidly cool down while driving a steady speed, over & over again? Would it more than likely be the water pump or possibly be something more serious, like a cracked head? Btw, I havent noticed any fluid leaking anywhere either.
Engine repeatedly overheats & cools down, over & over again while driving on 1990 Chevrolet 2500 Pickup
by 1973HESSIAN in Petersburg, WV on September 20, 2010
ANSWER by Visitor on October 20, 2010
Had same problem with my 89 2500. Turned out to be a head gasket. Needs to be checked quick before antifreeze wipes out piston rings.
ANSWER by Visitor on December 04, 2010
FIrst and foremost, check the radiator fluid level. A low level will cause that exact problem