Don't lose your cool over a cooling system

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TRUE. HEAT is not rhe lricnd

I t'l your diesel enginc. But a prohIcm u ith r our cooling systent i: rtt, reason to Iose your cool. espeei:rll.r when you can analyze problcms on the basis of symptoms and take cor rective action promptly. And when you can take avoidancc action bclirrc the oroblem starts.

The cooling \_vstcnr srnrplv dissipates engine heat to the atn'rospherc by means of the radiator. Coolint system oroblems usuallv occur with one of two symptoms slow' warm up or overheating.

Slow u'armup is most often caused by a thcrnrostat str-lck in the opcn position or one that opens at a temperature lower than specific-d. This situation pernrits water to flori' betrveen the radiator and engine even when the enginc is cold. The opening temperaturc of a thermostat can be checked by suspending the thermostat on a string in a pot of water (an electric hot pot works best). Also suspend a thermometer and begin heating the water. The opening tempcrilturc i\ determined when the thermostat lnlls off the string. The thermostat should be fully opened by 200 F.

Overheating. which is much nrorc common. is also morc dif'ficult to solvc. Houcvcr. don't lose 1'our cc'rcll Your conrnlt)n scnsc is Your bcst tool.

I1' thc- cnginc coolant tempcrature gaugc indicute\ an overheating condition. first shut off the engine and check thc fan belt tension. Undcrtensioned fan belts can slip on pulle;'s rcducing \\'ater pump speed and. therefore. $'ater flow through the engine.

width arc ad.justed properll uhcn thcv can be dc-prcssccl r: to rl".

of a failing cooling system ways to analYze problems take corrective action promptly. stay calm and cool.

Fan belt tcnsion can be checked by hand. Belts of r,:" u'idth are properly adjusted whcn thev can bc depressed t'/rr, L'!". Belts of rr,'tt,. -7+ and 7s"

Next. chcck thc uatcr outlct hosc which is located betuccn thc thcrnltr stat housing and radiator. lf it fccls cool and thc gauge indicatcs the thermostat is stirck closed or is Icrv sluggish, replacc thc thcrmostat or e hce k tht' ()pcninil t'hltrltt lcri:tit: ar previously outlincd. If the water outlet hosc is warm or hot. check the entire front ol' thc radiator. The radiator should f'eel warnr or hot on the top gcttinl progressively cooler as you reach the bottom. Cold or cool areas indicate restriction in water flow through thc radiator.

A * arm fceling whe n testing a \\ \lcn) u ith durl thermortrlr e ltn in dicate one stuck thermostat. Tentpcraturc check thermostilts uhcn questions arise.

The entire radiator cxtcrior should also be fiee of forc-ign debris. It therc is a build up of foreign dcbris. dircct air pressure (do not cxcce cl -10 psi ) through thc radiator oppositc to normal air t'lou,.

The next logical stcp would bc to let the enginc- cool and thcn chcck the watcr lcvcl. Carcf'ullr.' rcntove the radi:rtor eup ltnd lill il ne.er.lrrr. The radiator cap or nrorc spccifically the /l'lt'u';t'ltrrtt 1() /)u:qr 71)