How to Improve LXi Engine Cooling Performance

[davidbrady]

The other day I was checking tightness of various cooling system clamps and fittings. To do this I needed to remove the under-radiator shrouding.

After tightening I pressurized the cold system to 16 psi for a few hours. Everything held leak free so I then went for a drive to thermal cycle the system and re-check for leaks. I left the shrouding off.

I took my usual 50 mile exercise route that I drive every 3 to 4 weeks. I know the route well and how the bus responds over the miles. I immediately noticed that the engine operating temperature was different. The bus normally quickly heats up to 190 deg F and over the course of the 50 miles the coolant routinely hits 200 deg F at which point the fan comes on. I can count on the fan cycling around a half dozen times.

This time was different. The coolant temps climbed more slowly. It seemed to take forever to hit 185 deg F. I managed to get it to the high 190's but the high speed fan never came on.

This led me to think that the radiator fan faces a high static pressure as it blows air into the engine compartment and with the shrouding removed the static pressure was greatly reduced. I need to do more testing to verify that the improved cooling performance is due to the under-radiator shroud removal and not to my tightening a few clamps, but my hunch is the former.

This led me to a trip to my local transit bus operator, Youngs, and the discovery of a piece of Blue Bird documentation that shows louvers in the under-radiator shrouding.

My LXi doesn't have louvers in this piece of shrouding. I'm going to experiment with adding louvers to improve the fan air flow leaving the engine compartment and to reduce the static pressure seen by the radiator fan.

It's early to say, but I'm fairly confident that adding louvers to the under-radiator shrouding is a simple way to significantly increase the cooling system performance in our LXi's. (and probably our LX's).