Cooling system issue

[Emanresu]

Hi guys. I'm looking for some advice or suggestions on an issue I'm having.

My car is a 2001 Mitsubishi Pajero LWB 3.5 V6, 6G74 SOHC engine.

Some background, the car was burning a bit of oil so I did a semi rebuild over a couple of weekends. The mileage was high, almost 200k. I honed the bores, fitted new piston rings, connecting rod bearings and valve stem oil seals. Also fitted a new thermostat as the old one didn't look great, did the timing belt, tensioner and idler when I was in that far too. When I had the engine split, I cleaned and measured the head and block and am sure they are flat. Also fitted a new viscous fan clutch as the old one wasn't great.

Now the problem. When the car is started for the first time, the temperature hand rises to the top. If you hold the throttle for a minute or go for a short drive, it will come back down to normal and stay there, no overheating in traffic etc or no signs of overheating in the engine, i.e. Not spitting out coolant or anything. This only happens the first time you start the car. When you're driving it's fine. I changed the gauge temperature sensor just in case but the problem is still there.

This problem wasn't there before I did the work so it's obviously related to something I've done. At first I suspected I done something wrong with the head gasket but there's no big pressure in the system, no oil in water or vice versa. I thought it could be something to do with air in the system but I followed the correct procedure for bleeding. Open both bleeder screws, fill radiator, when coolant comes out of first screw then tighten and keep filling, when coolant comes out of second screw tighten, them fill radiator and process is complete.

I can't figure it out at all so would like to hear some suggestions.

Thanks

[E-bmw]

From what you say you have done my only thought would be stat.

Did you fit it the right way round?

Is it one with a small (typically 2mm) bleed hole in one edge? If so the hole should be at the top to prevent air locks at the stat itself.

[GreenV8S]

Emanresu said:

When the car is started for the first time, the temperature hand rises to the top.

Does it also do that when the engine is cold? If so, that would make me suspect an electrical problem rather than a cooling system problem.

[stevieturbo]

Given the engine or coolant cannot possibly warm up so fast that the gauge would rise to the top upon starting, clearly it is an electrical/wiring issue of some sort

[Emanresu]

Finally got around to doing some proper fault finding on this thing yesterday. There was a small resistor on the back of the clocks that had a dry solder joint. Touched it up and it's good as new.