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You mention the bus has just started to overheat. Did it ever overheat in the past?
I would start by checking to make sure both thermostats are workiing properly.
I would then make sure the fan is moving the air through the radiator properly. Make sure the radiator shroud is in place and the air it is moving is all going through the radiator. Any gaps will allow the fan to pull through the gaps rather than through the radiator.
Get an infrared laser thermometer so you know for sure what exactly the temps are. Check both sides of the block to make sure both sides are cooling the same amount. Check the radiator at the top and at the bottom. You need to have at least 20 degrees of differential. If you don't have at least 20 degrees difference your radiator is not cooling correctly.
Make sure your transmission is full up on fluid. Make sure the transmission is going fully into convertor lock up when you reach highway speed. Lack of fluid can cause the convertor to not lock up. Staying in convertor mode and not in lock up mode will cause a great increase in excess heat.
Check to make sure none of the hoses are collapsing as you reach cruising speed. The may appear to be fine at idle but the increase in volume when the engine is at WOT can cause old hoses to collapse. Collapsed hoses can greatly reduce the coolant flow.
Once you get all of the easy fixes done then you will need to start contemplating the hard fixes.
Let us know how things turn out.
Mark O.
Castle Rock, WA |
email Mark O.
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