Cleaning GU engine

Don't spray a diesel when hot! The injector pump has such fine tolerences that the diferences in temperature can damage it. Big Dollars!

Cheers Mackie

You NEVER repeat NEVER hose any engine when hot. Firstly you risk cracking components especially the exhaust manifold and turbo parts as they rapidly cool down from the hosing as the hot metal can't contract fast enough so it cracks just like hot disc brake rotors do when you enter deep water. Secondly the condensation created is more likely to find it's way into the electrical components you are worried about protecting than if you just gave them a surface spray with normal pressure water. I agree with the other reply, just use a good detergent eg Truckwash, CT18 or similar and if using high pressure water keep the actual jet away from anything electrical. You are not likely to do any harm from just normal splash water. This same principal applies if you need to top up your cooling system. You never fill a hot engine, especially an overheated engine with large quantities of "cold" coolant. You either wait for it to cool down sufficiently to safely add the coolant or you hose the outside of the radiator down while the engine is running to cool it slowly and safely. You then, while the engine is idling, SLOWLY (and I mean trickle) add the coolant allowing time for the cooling system to circulate it throughout the engine until it is topped up. If you add too much coolant too fast to an overheated (red hot, paint burning off and smell of burnt oil) you will almost certainly hear a large "crack" and if you do it's all over red rover cause you have most likely cracked the block or at very least the head and then you will be walking or getting towed.

I do agree with the above advice, but I chuckle when I think of all of those years we drove rally cars for hours on end at 7000 rpm then drove flatout into creek crossings. The engines were so hot that you could read by the exhaust pipe glow when you lifted the bonnet!

Interestingly we never had a problem.