One of the water temp gauges on my old 311 seems to "bounce"- the needle sort of hops up and down erratically. Boat is not getting hot or anything and I am getting plenty of H20 through the pump, block and exhaust. Is this a sender issue or am I seeing the beginning of the end of my temp gauge?

Make sure all the connections are tight.

make SURE all is ok ..... Steam pockets can make it jump around ....

I have the same issue with my starbord water temp guage. Replaced the sending unit but didn't make a difference. Checked all connections, seem okay. Figure the guage is wearing out. I just keep an eye on oil pressure. If motor gets too warm, oil pressure will drop.

My left engine temp cycles from about 165-180 and then cools back down. The right stays pretty consant near 160 degrees. Oil pressure is stable, don't know if it's a thermastat issue or w/in normal operation. Anyone have a similar indication?

My 91 292 acts identical to Bikini situation. Spoke with mechanic at Chesapeake (former Full-Tilt) and he says the original VDO gauges have this issue. If your gauges are original, may be time to look at an upgrade. I am going to a new set of Gaffrig in the off season.

Treads- this is the same advice my mechanic gave me on the issue. His position is that VDO needs to GO . . . . .