
COOLING SYSTEM
□
Thermostat seal -- Worn, missing, improper installation
□
Water pump -- Impeller loose or damaged, drive belt loose or missing, worn pulley
□
Aerated coolant -- Low coolant level, excessive agitation of deaeration tank coolant,
water pump seal failure, exhaust gas leakage (cracked cylinder head or block,
damaged seals or gaskets, etc.), incorrect bleed line installation
□
Pressurization loss -- Defective pressure cap/relief valve or seat, debris trapped
between seats, internal or external leaks anywhere in the system
□
High restriction -- Radiator plugging (solder bloom), silicate dropout, dirt, debris, etc.
collapsed hose(s), foreign objects in the system (shop towels, plugs, etc.)
□
Core Coolant Flow Capacity - Core coolant
fl
ow capacity is often described as “free
fl
ow." This term is used to indicate gravity
fl
ow rate through the core and should equal
or exceed the coolant
fl
ow rate given on the performance curve. The design of the
radiator inlet and outlet tanks
must
also offer low restriction to coolant
fl
ow.
□
Coolant loss -- Internal and external
4. Check for inadequate heat transfer capabilities. The following are possible causes of
inadequate heat transfer capabilities:
□
Radiator selection -- Core selection inadequate for application
□
Incorrect coolant mixture -- Over/under concentration of antifreeze or inhibitors,
corrosive water, incorrect antifreeze or inhibitors
□
Contamination -- Oil or other material depositing on heat transfer surfaces
5. Check for insuf
fi
cient air
fl
ow. The following are possible causes of insuf
fi
cient air
fl
ow:
□
High restriction -- Plugged core, damaged or bent
fi
ns, shutters not opening correctly,
addition of bug screens, winterfronts, noise panels, small air in or air out openings, etc.
□
Fan/Drives -- Lose or worn belts and pulleys, improper drive engagement, fan installed
backwards or damaged, insuf
fi
cient fan speed (drive ratio), etc.
□
Shroud -- Damaged or missing, not completely sealed
□
Fan positioning - Excessive fan tip to shroud clearance, incorrect fan placement in
shroud, insuf
fi
cient fan to core distance, insuf
fi
cient fan to engine distance
6. Check for inadequate heat transfer capabilities. The following are possible causes of
inadequate heat transfer capabilities:
□
Incorrect fan/radiator match -- Severest operating conditions not correctly identi
fi
ed.
□
Core degradation -- Tube/
fi
n separation, oil
fi
lm, debris, contamination, etc.
□
Air recirculation -- Radiator baf
fl
es damaged or missing, fan shroud and seal damaged
or missing, wind conditions, etc.
7. Also check the following:
□
Increased heat rejection or engine horsepower upgrade
□
Engine, installation, or cooling system modi
fi
ed
7-54
All information subject to change without notice.
(Rev. 03/06)
7SA250 0603
Copyright © 2006 DETROIT DIESEL CORPORATION