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Old 10-21-2019, 03:29 PM   #9
fdryer
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Join Date: Jan 2006
Location: NYC
Posts: 43,262
 

2003 L-Series 3.0L Sedan
Default Re: Lw300 NIGHTMARE PLEASE HELP (OVERHEATING)

Teejoka813, are there any histories of maintenance done to this car? At 192k miles, the first major milestone at 100k miles; replacing the timing belt, water pump, idler pulleys and serpentine (accessory) drive belt. Timing belt, water pump and idler pulleys are a must to continue long term engine life with well worn parts. Coming up to 200k miles, repeat again. Water pumps have a limited life with access requiring many things removed so they're all replaced at recommended intervals (every 100k miles). Ignoring this can result in catastrophic engine damage if the water pump bearings fail and/or timing belt lets go at any time while driving. As a diyer, you should be able to perform this procedure. Many threads with snapshots from members sharing info makes this procedure less stressful from members showing imagination to replace one time use tools with either hardware store nuts, bolts, fender washers or vice grips to hold the four camshafts in place when timing marks are aligned prior to replacing the timing belt.

If you aren't aware, most engines with electric fans are temperature controlled. The coolant sensor relays temperature info to the engine computer (ecm). As shown from pierrot, the fan(s) don't turn on until a programmed temperature is detected. Three speeds are available depending on ambient temps, ac use and engine loads in local or highway traffic. Hot and humid weather with ac use can have high speed fans running in local stop and go traffic. For everyday driving, low and medium fan speeds. Smart electronics knowing the engine is hot will run cooling fans for a few minutes if the engine is shut down to force airflow thru the ac condenser coil and radiator (all vehicles with ac have two radiators - ac condenser coil in front of the engine radiator) then automatically shut down without concern of draining the battery. After engine shutdown with fan cooling has been around awhile when electric fans replaced older belt driven fans as electronics slowly took over many functions. The engine computer have programs like timed fan cooling if coolant is above a certain temperature and the engine is shut down. Heat soaking occurs under tight engine compartments so fan running automatically occurs to move air thru to dissipate heat. Whether driving or shut down, the cooling system temperature is always monitored to cycle fan operation as needed. When ac runs, the ac condenser coil gets hot. In grin of the radiator, all airflow begins in front of the condenser coil to flow into the radiator hence fan cooling when ac is used, to ensure both systems are adequately cooled to prevent overheating both systems. Ac use starts with low cooling fans then switches to medium or high speed as a combination of ac pressures and coolant temps rise. All speeds automatically controlled.

If you can ensure your new radiator isn't leaking, it's difficult to determine if the water pump is leaking other than a massive bearing failure in the pump to release coolant, flowing from the bottom of the timing cover.

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