[v8volvo]

Adding an aftermarket temperature gauge would be an option if you cannot or don't want to fix the stock gauge. Aftermarket gauges are also typically more accurate than the original gauge which is designed to restrict its movement around normal operating temperature and as a result can prevent the operator from being warned of a problem until after it has already become serious.

However, repairing the stock gauge will not be difficult if you would prefer to use it rather than adding another gauge. It is a simple system with only three possible areas that could cause it to not function:
1) the sending unit on the engine
2) the gauge or the instrument cluster
3) the electrical wiring between the sending unit and the cluster

There are simple diagnostic procedures you can do that will pinpoint which of these three areas the problem is in. Once you know where the problem is you will then be able to make a repair. There is no point in attempting repairs such as reflowing the solder in the cluster circuit board if you don't yet know whether that is the cause of the issue.

We can walk you through the troubleshooting process step by step. But before anyone here donates their time and knowledge to help you with this, you will need to be agree to follow the steps exactly in the order and technique that is described, and then report your results back here in a clear way so we can guide you along.

If you want to do that and are prepared to go about it in a way that will not waste other forum members' time, then start a new thread focused on the topic of your temperature gauge, and folks will assist you there.