Tom’s response to a friend with car problems
A friend of Tom’s was on vacation and called in worried about his car’s overheating problem that had developed on the way to Lake Quinault in Washington. The car was continuing to drive but the temperature gauge was starting to rise higher than normal. The car didn’t seem to be losing coolant, but he was obviously worried about the classic scenario of a breakdown in the middle of the desert with steam pouring out of the hood. Since the coolant looked good he called Tom to see what he should do.
Tom’s Response-
“If you don’t already have AAA Plus then get it! If there is no local shop and you must continue to drive here are some things you should know…
First check and make sure the radiator is full. You need to look in the radiator; do not trust the over-flow bottle it can be full and the radiator empty. When the vehicle is cool remove the radiator cap and inspect the coolant level. Do not attempt to open the radiator cap when the vehicle is over heating or even at normal operating temperature unless you know what you are doing. If the radiator is low or empty the cause of the loss will need to be determined and corrected. If the radiator is full then here is a “101 primer” on overheating without coolant loss:
“Probably the most common cause of over-heating is low or weak coolant, but if you’ve ruled that out then there are several other possibilities. Over-Heating without coolant loss could be caused by a defective thermostat, plugged radiator, electric fan not cycling, compromised head gasket, temperature gauge problem or a loose water pump impellor. Older vehicles had an external belt that ran the water pump and if it was loose or missing the water pump would not be driven properly. The timing belt runs the water pump on your vehicle so that will not apply here. Here is a bit of info on each possible cause for your car:
- Radiator plugged: Usually restricted radiators will cause problems and heat-up on hot days, uphill or under heavy loads, then the engine cools when the load or temperature drops. This can come on suddenly, but it’s usually a gradual problem that gets noticed when the ambient temperature climbs or the car pulls a long uphill grade on hot day. The temperature gauge usually moves slowly up or down when this is the problem.
- Electric fan not cycling: Your fan is not needed as much when you’re moving at freeway speeds or on cool days, it is needed more for around town, extended idling, stop and go traffic or pulling step grades. It is normal for the temperature gauge to climb at stops or slow traffic, then drop when the car gets moving faster or when the fan kicks on. Listen for the sound of your radiator cooling fan operation… The Fan is thermostatically controlled and usually comes on somewhere over half gauge then switches off somewhere under or about half gauge.
- Thermostat problem: Thermostats can stick open, closed, partially open-or-closed, can be erratic, or work just fine then act up before returning to “normal”. Once a thermostat has overheated it’s damaged and needs to be replaced, no matter what initially caused the overheating.
- Head Gasket failure: Cracks or leaks in head gaskets (or heads or blocks) can cause some of the most difficult problems to diagnose. They don’t always just “blow”. The failures do eventually get worse and become obvious but it can take time in some cases. The head gasket should separate coolant, oil, and compression gasses from each other and keep all of them from escaping to the external world. There can be many types of failures- external leaks, oil and coolant mixing, compression gasses and coolant bridging together, compression between cylinders, and more. When the barrier between compression and water fails, funny things can happen; for instance when compression gasses push into the cooling system it can stop the circulation of coolant and cause over-heating. (Not all breaches of combustion gasses into cooling system will cause this kind of coolant loss, though). This form of breach is the worst to diagnose because it can be really intermittent and troublesome before it is diagnosed or “blows”. The gauge may behave erratically but will not move instantaneously up and down unless the temp sensor is not submerged in coolant. I’ve seen this type of failure behave normally for days or weeks and then go back to over-heating. Eventually the head gasket gets compromised enough to consistently lose coolant, cause ignition miss, steam out the tail pipe, or hydraulically lock the motor etc.
- Temperature Gauge: If the gauge is moving wildly, really fast up and down, or erratically then there may be an “indicated” problem as opposed to a “real” problem. Your sending unit, gauge, or wiring can be causing the gauge to read wrong. Sometimes the gauge can indicate normal or cold when the engine is actually overheating. Common sense and being familiar with your vehicles normal operating behaviors can be a savior when the gauge is not working or not being monitored. Unusual Smells, engine pre-ignition (ping), visible heat, smoking, or power loss can all be tip offs something is wrong but yet the gauge may seem perfectly happy… Sadly the warning system may not work when there is no coolant. The temp sensor needs to be submerged to operate properly. One test is to run the heater and if no hot air is produced then either there is no coolant or no circulation. Steve said you knew the “run the heater to try to scrub of heat trick” the heater core is like a small radiator and it can remove some heat from an overheating vehicle when there is coolant and it can circulate…..
- Water Pump Impellor: I don’t often see this form of failure on Hondas, but in VW and some others the water pump impellor can spin on the shaft without moving coolant. Water pumps are not really pumps… they just sort of encourage the coolant to move with a bit of a push. If the impellor quits spinning even though its shaft is turning…. No push, and therefore no coolant circulation.
General ramblings and comments:
- Removing a thermostat can mask an overheating problem caused by a compromised head gasket for some period of time.
- Leaving the radiator cap loose can also keep the pressures from a failing head gasket from stopping circulation or over pressurizing the system to the point it blows things like the radiator up. Don’t forget that if the cap is off or loose, coolant will evaporate and you’ll need to replenish it often.
- If you idle the car with the hood open, the radiator cap off, and with the coolant full to the brim, and if you see bubbles raising from the depths of the radiator, that can be a sign of combustion gasses from a compromised head gasket (or cracked head or block) entering the cooling system and exiting the radiator.
It’s generally better and safer to rent a car than to try to proactively fix everything that could go wrong on an older vehicle. I counsel clients to rent cars for short vacations (7 days or less) when their vehicle is high mileage, challenged, or if there will be a lot of miles or extremes. You could easily spend $2000 on repairs before leaving yet still have something go south and ruin your trip. On the other hand, you know a rental will make the trip, it will probably be more comfortable, it will get better mileage, and all those trip-miles will be on the rental (not your car) when you return. In situations like these a rental is not a waste of money, it is prudent insurance to protect your vacation.
If you go on your trip without getting the problem resolved and you end up trying to nurse the car back; do it early in the morning or at late at night when the temperature is lower and you won’t get stuck in stop and go traffic.”
Some advice anyone can use
Incidentally, Tom’s advice about “renting a car for vacation” would have been unchanged. You can spend thousands prepping a high mileage vehicle for a trip and it can still break down! When the odometer is 200k even a psychic mechanic might not anticipate all the potential problems. People think spending $200 on a rental is a waste, but compare that to a breakdown 1000 miles away from home and 100 miles away from a shop. Do you really want Goober’s fillin’ station to do that head gasket job while you’re waiting? How much is a real carefree vacation worth? A rental will get there for sure and usually with better mileage and accommodations than ol’ Betty. And realize, if you do have any problems on the trip they become the rental company’s problem.
How did it all come out?
As it happened, things worked out OK. The friend made the return trip safely and brought the vehicle into our shop when he got back. The problem turned out to be a compromised head gasket, which as Tom pointed out can be one of the most difficult possibilities to diagnose when the gasket has not completely failed but is on the verge of failure. Two valuable lessons from this experience…
- Get your vehicle checked BEFORE a big trip, with plenty of lead time to FIX any problems and TEST any repairs
- Consider getting a rental for that next big trip when your vehicle has high mileage or a list of problems!
