Anyone ever experience this: "Old Yella" runs great as I have been retired a little over 2 years now and the car has become a hobby to me as well as my daily driver. With the help of this site I have got the vehicle pretty much re-born. There is one thing that I haven't been able to remedy. The car's water temp guage reads right where Mercedessource states it should 99% of the time,(a picture of the guage reading is on this site or in one of the manuals) just around the 80 degree celsius mark. Well after driving for a while and usually after "letting the ponies loose" on the highway the needle on the guage gets a little erratic. First let me say that the motor does not act like one that is overheating. There is no excessive heat coming off it, no odor and no steam or smoke. However the needle will creep towards the 100% mark, hover there for a few seconds then jump back down to normal then bounce back up again. It might do that a couple of times and then right back to normal and stabilize. Then if I am driving the car on a long trip the cycle may start again. All the time the motor seems to be running fine. One time the needle pegged out into the red which prompted me to change the temperature sending unit. That hasn't happened since and I thought I had "slayed the dragon" but I still get the bouncing needle syndrome. Any ideas out there.
Thanks to all with input, Mike G.