The V8 Owners Forum -

2

I'm never quite sure about those temperature guns - aren't they calibrated for a black surface?

Presumably the temperature gauge reads normally on both fuels?

I generally use a thermometer that is in contact with the thermostat housing to measure engine temps.

Chris.

Temperature guns are variable dependant on the make and model - same as any item out there. There are professional ones and cheepos.

Now using them is another story. Obviously different parts of the engine reflect different temperatures.

I use a specialist professional laser unit and ensure that the ambient surrounding light level is low - i.e. no bright sunlight. If you beam on the manifolds - off the scale, if you beam on the rocker covers - variable.

The place I find the most consistent is around the thermostat housing as this is reflective of the circulating temperature in the system. You can check as if you take a reading on the top hose and bottom hose you should see a variation.

The head gasket might have blown if the fan got stuck. I have a Disco 2 on a 2002 plate with a jammed fan and it killed the HG.

Solved the seized fan and used the dreaded "steel seal" and after two bottles and a new thermostat - perfect. Heater matrix is good, rad is good and temp is fine and the exhaust is back to being just that - no longer a plant waterer!

So, use the circ water a a guide, the rocker covers will not reflect the true temp in the same way as the exhaust would not either - basic logic.

Remember to check that piddly fan!