So I started this a year or better ago. Here is what I have.. Fix and add to it.
Every year when the weather turns cold there is a spike in certain technical posts:
Overheating. Dead battery. HVAC issues
Below I'll list the common causes, what to check and solutions
Overheating:
- Blocked radiator
- Blocked heater core
- Bad thermostat
- Low fluids
- Old in fluid - cracked head
- Radiator cap
- Expansion tank leak
- Leak of coolant
- Cracked head
- Collapsing lower hose
- Clutch fan failure
- Fan belt slipping
Dead Battery:
- Dirty terminals
- Corroded terminal connectors
- Corroded wires
- Dirty ground connections to body and engine
- Dirty connection to alternator
- Bad alternator
- Low acid level
- Contamination between terminals
- Accessories directly connected to battery
- Old and really cold outside
- Deep cycles
HVAC issues
Takes forever to heat up - missing or bad thermostat
Doesn't get warm enough - blend door is stuck - partially blocked heater core
No heat - blocked heater core - dead fan
Air only blows out the defrost vents - Vacuum leak.
There is only one fan speed - Fan speed resistor
No fan speeds or intermittent - Fan speed select switch - Melted wiring/connections
----------------update detail--------------
Overheating:
- Air in system- Improperly burped, leaking expansion tank, bad cap, cracked head, improper thermo, failed thermo, - air allows a pressure drop reducing the boiling point of the fluid. Enough air creates a vapor lock keeping the fluid from circulating. Air is a poorer heat conductor and can allow superheating of the engine if trapped near the cylinders.
- Blocked radiator - check that the external fins are clean and clear of mud and debris. You could see some cells by opening the radiator cap. There should be no corrosion or buildup. You could flush the system or remove the radiator and have a radiator shop flush it if you know it's blocked.
- Blocked heater core - by feeling or measuring the temp difference of the input and output to the heater core. They should be different especially if you hand the heater on high in the cabin. If they are the same temp flush the heater core. You could flush the entire system or unhook both ends on the heater core and just flush the core.
- Bad thermostat - thermostats can fail closed or fail to open enough to allow proper flow. Failed closed will overheat the engine and push excessive fluid into the overflow.
- Low fluids - low fluids eventually let air in the system. Air in the system does not allow constant or proper pressure that allows the fluid to boil.
- Old in fluid - cracked head -by opening the radiator you could visually inspect that there is no oil in the coolant. There is a test that directly measures oil and CO levels in the coolant.
- Radiator cap - inspect the cap. Any buildup replace the cap. The pressure of the system is set to be 18lbs. A cap that is week or too low rating allows more fluid to be pushed into the expansion tank. In some cases these fluid fills and spills out of the expansion allowing air in. The lower pressure also lowers the boiling point of the fluid.
- Expansion tank leak - inspect tank for cracks. Also check the hoses and connections. This leads to air in the system see above.
- Leak of coolant -coolant out = air in. See above. Look for drips or puddles under vehicle after it cools. The water pump has a designed weep hole that is first to fail. Check the radiator fins and near the lower hose connection. Cracked head(common head 0331) or freeze plugs(less likely)
- Cracked head - open radiator cap and look for constant stream of tiny bubbles. Perform a CO level test. Col plate a pressure test or leak down test at the radiator. An episode of excessive overheating can lead to cracking a head. The heads stamped 0331 are more prone to crack.
- Collapsing lower hose - inspect hose for bulging, squeeze when cold to ensure the spring exists. missing or eroded spring, high flo water pump.
Water pump failure- open radiator cap when cold start engine look for moving fluid esp once at temp. Inspect pump for leaks. Occasionally the fins erode completely. The shaft erodes allowing the find to free spin on the shaft.
- Clutch fan failure - when cold spin the fan hard. It should spin 2-5 times only. Less than 2 or more than 5 the clutch is bad.
- Fan belt slipping- visual inspection, verify tension or deflection and that the turnstones is not at min position.
Dead Battery:
- Dirty terminals - inspect and scuff to a shine.
- Corroded terminal connectors inspect and clean or replace
- Corroded wires - inspect, should have no corrosion, should be flexible, low resistance from end to end.
- Dirty ground connections to body and engine - inspect and scuff to a shine on all contact areas.
- Dirty connection to alternator - inspect and scuff to a shine.
- Bad alternator - battery voltage then running should be 14.4V - remove and have tested at parts store.
- Low acid level -on serviceable batteries, check . Take to battery dealer or service station to fill. Caution !!! You could add distilled water or battery acid carefully!!!! caution acid burns.
- Contamination between terminals -inspect and caution !!! With ppe carefully wipe clean and wipe with damp cloth!!! Caution acid burns
- Accessories directly connected to battery - visually inspect for additional wires to the battery or PDC terminals. Remove and connect properly. All circuits should run through a fuse and a relay. Additional circuits that are to run when the key is on or engine is running should have its relay switch to ign power so the relay can only come on when the key is on.
- Old and really cold outside - it happens, weak acid and old cells tend to fail when temps get cold out. Good batteries freeze below -76deg F but weak batteries can fail at 32deg F.
- Deep cycles - load test your battery at a parts store. Replace if CCA are below rated CCA- a deep cycle is when you allow your battery to be run down below 10.5-11V ~20% drop. An automotive battery usually can only take 3-5 deep cycles before failing
HVAC issues
Takes forever to heat up - missing or bad thermostat. If you start the engine from cold and start driving the engine should be at temp within 2 miles. No matter how cold it is out. Failed open or missing thermostat will take over 5 miles of driving to reach temp.the thermo should be 195 deg thermo.
Doesn't get warm enough - blend door is stuck - partially blocked heater core.
No heat - blocked heater core - dead fan- you should hear the fan. Even if the lower speed resistors are burnt the high speed is an oversize short. The speed switch and wiring is known to overheat and melt. Inspect and replace wiring or switch. You could direct power the fan to 12V and ground to verify it runs.
Air only blows out the defrost vents - Vacuum leak. Visually inspect all vac lines. Idling above 750 rpm is an indicator especially after resetting the PCM by disconnecting the battery. You could spray water, WD40 carb cleaner... Around the vac lines with the engine running and listen for the RPMs to change. When they do you found the leak.
There is only one fan speed - Fan speed resistor. High speed should always run if the wiring and speed switch hasn't melted. Remove resistor and inspect and measure with an ohm meter.
No fan speeds or intermittent - Fan speed select switch - Melted wiring/connections. Inspect.
Regards,
JPNinPA
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