High eot after repair

[Fredsvt]

Is what I read a long time ago true, that in the 6.0 in the Ford application, the cooler takes out roughly 700 degrees of EGT?

 

It's no wonder the coolant doesn't completely boil out of the thing, even when under 16psi. Maybe that's why the gold elc coolant crusts up so much in the 6.0?

 

It almost seems as if they should have put coolant to it with hoses/pipes as large as the rad hoses, rather than through such small diameter hoses.

[GregH]

And doesn't it seem like an odd design choice to feed the EGR cooler with preheated coolant from the oil cooler... Seems as if the cooling would be more effective if it got it's own flow from the water pump.

 

I read something about up to a 700 degree drop across the cooler too, Fred.

 

I usually explain the chain of failures to customers using an engine (or components - depends on what's in my stall) as a visual aid and tell them for the coolant to keep from boiling when in the presence of exhaust that can be up to 1200 degrees, the coolant must move fast. Since it gets a feed from an oil cooler that gets restricted over time, the flow will slow down, and once it goes slowly enough a steam bubble forms at the rear of the cooler. Since steam does not conduct heat as well as liquid, the metal there overheats, expands beyond design limits, and cracks any joints in the area.

[rlchv70]

Also remember that hot gas contains fewer molecules. If you have higher EGR temps, that means higher intake manifold temps. That means fewer molecules are being sucked into the cylinder. Fewer air molecules means that the fuel molecules have less oxygen atoms to grab onto when they burn. That results in more unburned/partially burned particles - soot.