1999 Honda Odyssey weird temp readings!?
 

I have a problem with my Odyssey (1999 3.5 v tec) when ever you are driving and come to a stop the temperature rises almost to the H on the temp gauge. This happens almost every time you come to a stop... not so much at short stops unless you have been driving for maybe 15-20 minutes the temp will go down if you start moving or rev it a little.. I also think it is warming up faster than before. The temp rises and falls rapidly that why I was thinking maybe the sensor is going bad, but more likely it is a problem with the water pump or water pump clutch. Have any of you had a problem like this? and if i need to replace the water pump or clutch how much would i expect to pay for it?

Go the easy route first. Try replacing the thermostst. If it is sticking, or old it can cause some of those problems. If that doesn't work, then look into putting a new water pump in.

I am afraid you have a blown head gasket and it is blown on the inside so you will not see a leak on the outside of the block.Take it to a garage and tell them what is going on before you do anything else.Also check the level of your anti-freeze.