Water

[joshuaA910]

Hi just got my first diesel car and I'm told it uses a common rail system which doesn't like water. If this is true what are the weaknesses besides the air box and what signs are there of damage if it happens? All I could find on Google is ads for some water watch system. Thanks for the help

 

[Old.Tony]

Two different things here.

The water watch device - and the reason for the common rail not liking water - is water in the fuel. Water compresses at a different rate to diesel, so when it's pressurised in a common rail system (up to 30,000psi, the world works differently at these extremes) the water basically can cut through metal like a knife through butter. Water will emulsify in diesel but won't dissolve - it will sit on the bottom of the tank and be the first thing picked up. Watch Watch will alert you to the presence of water in the fuel.

The other thing is the air box - this can be drowned. Two ways we've seen - bonnet deep in water without a snorkel (or a poorly fitted snorkel) or in a D22 through a puddle 300mm or deeper a little too fast - the water rushes up inside the guard, enters the air intake and it's all over. ALL of these can be rectified with a properly installed and sealed snorkel.

 

[nathand22]

Two different things here.

The other thing is the air box - this can be drowned.
puddle 300mm or deeper a little too fast - the water rushes up inside the guard, enters the air intake and it's all over. ALL of these can be rectified with a properly installed and sealed snorkel.

I witnessed a BRAND NEW BT50 do that exact thing down at Duea over the Xmas break, no snorkel, way too fast through a shallow but long river crossing with the water being sprayed meters over the roof and by the time he got to the other side the air box was full and it was puffing steam out the exhaust.
I tried to help by drying out the air box, removing the sopping wet air filter and spraying the MAFS, but once it started it was clear the water had gone through the engine and it was Stuffed.

 

[happy john]

I think the moral of the story is unless your using your rig as a grocery getter fit a snorkle as your first mod.