COOLING SYSTEM a  hose  doing  its  job,  replacement  should  be  made.    Clamps should be inspected to ensure they are strong enough to hold a tight connection. TRANSMISSION OIL COOLER On  some  trucks  equipped  with  automatic  or  semi-automatic transmissions, the transmission oil is circulated through an oil cooler or heat exchanger.  The function of this unit is to control transmission  temperature  and  thereby  keep  oil  in  the  proper temperature  range  for  its  most  efficient  lubrication.    This  is accomplished   by   using   engine   heat   to   bring   transmission temperature up or by using the cooling system to dissipate any excessive   heat   generated   within   the   transmission.   Leakage due to corrosion or an improper sealing will cause contamination between the cooling system and transmission. FAN AND ACCESSORY BELT ADJUSTMENT Fan and Accessory Drive Belts New   belts   have   a   break-in   period   and   lose   tension   during groove seating. NOTE  -  New  belt  Initial  Installation  tension  Is  higher  than the   re-tension   value   applied   to   a   used   belt   (run   five minutes  or  longer).    This  Is  done  to  minimize  number  of belt   adjustments   and   prevent   belt   operation   under   low tension during break-in period. Belt  tension  checks  must  be  performed  using  a  Belt  Tension Gauge, such as a Howard KRIKIT Gauge, tool  number  7401- 0071.  This tool is available from: Howard Manufacturing Company 59996 South Crocker Little Town, Colorado 80120 Phone (303) 794-2510 NOTE - Use of the KRIKIT Gauge Is restricted to SAE 3/8, 1/2  and  11/16  Inch  belts.    Check  tension  on  the  midpoint range of the longest span of belt. New  belts  should  be  checked  at  483  km  (300  miles)  or  10 hours, then checked again after 2 414 km (1, 500 miles) or 50 hours.    The  second  service  adjustment  of  belts  establishes tension stabilization. Before adjusting belt tension, check the tension several times. Use an average of the readings. Belt   tension   checks   must   be   made   at   midpoint   between pulleys at the longest belt span.  Refer to Belt Tension Chart. The  9.0  liter  fan  and  water  pump  drive  belts  have  an  idler pulley with spring tension.  No adjustment is needed. In   multi-belt   drives,   the   belt   tension   readings   taken   on   the same span  may  vary  considerably  between  belts.    When  this occurs, average  readings  to  establish  applied  tension,  except in the application of the DT/DTI 466 engines’   power   steering   pump   (Vickers),   where   the   values stated are for each belt. Belt Tension Chart Tension Condition Belt Tension New Belt Installation 423-444 N•m (95-100 lb-ft)* Re-tension New Truck upon delivery After 10 hours (or 300 miles) 356-378 N•m After 50 hours (or 1, 500 miles) (80-85 Ib-ft)- - At intervals of 200 hours (or 6, 000 miles) Minimum Permissible Tension 267 N•m (60 Ib-ft) *DT/DTI 466 Engine Power Steering (Vickers) Pump New Belt - 356 N•m (80 lb-ft) per belt Re-tension - 222 N•m (50 Ib-ft) per belt Minimum Permissible Tension - 222 N•m (50 Ib-ft) per belt EFFECTS OF COOLING SYSTEM NEGLECT A   neglected   cooling   system   can   lead   to   inefficient   engine operation,  either  directly  or  indirectly.    Most  of  the  problems may  be  traced  to  overheating;  however,  an  engine  that  is running too cold can be just as troublesome. Overheating may lead to troubles such as the following: 1. Burned valves. 2. Pinging or knocking. 3. Vapor lock. 4. Poor lubrication-increased engine wear. 5. Sticking valves and valve lifters. 6. Short spark plug life. 7. Engine hot spots. 8. Need for higher octane fuel. Overcooling often results in the following: 1. Excessive fuel consumption. 2. Sludge formation in crankcase. 3. Corrosive acids found in crankcase. COOLING SYSTEM MAINTENANCE COOLING SYSTEM INHIBITORS Systems With Coolant Filters When   the   vehicle   is   manufactured,   the   coolant   filter   is equipped with precharge filter element which is larger in  size than  the  normal  service  element.    The  precharge  element contains a sufficient amount of chemical to CTS-4181 Page 7