1998 Ford Explorer Temp Gauge Acting Goofy

For reasons I can’t figure, the Temp gauge on the wife’s Explorer is shooting from normal to high in just seconds. Then, it drops back to normal. When I looked at it this afternoon, I noted 2 things.

  1. There was no sign of a coolant leak or overheating.

  2. There wasn’t ANY coolant in the tank!!!

The truck has evidently been running fine while this is going on.

Unfortunately, this may be an indication of a breached head gasket, and if it has been breached for more than a short period of time, it could spell a quick death for the main bearings in your engine.

Check the dipstick in order to see the level and the appearance of the motor oil.
If the oil looks like a chocolate milkshake, that indicates the presence of coolant in the oil, and that is a very bad sign.

Please report back to us on your findings, but even if the oil appears normal, I suggest that you have a compression test and a leak-down test performed in order to check for a bad head gasket. Also, your mechanic can use his emissions “sniffer” to check for the presence of exhaust gases in the coolant.

If it turns out that you do have a bad head gasket, then you have to decide whether the overall condition of this 13 year old vehicle warrants spending the $$ for the needed repairs.

This type of gauge behavior is typical of a seriously low coolant level. You are losing coolant somewhere. First thing to do is fill it with coolant and check for any obvious leaks. If you find none, the next thing to do is drive the truck while vigilantly monitoring the temp gauge. Do not allow it to overheat! Monitor your coolant level and don’t let it get low. Next, get the truck to a repair shop for a cooling system check, including pressure check (in fact, the previous test drive should probably be driving to the repair shop). Have any leaks that are found repaired and hope for the best from there. Operating the truck with the coolant so low is very bad for the engine, so hopefully you will get lucky and not subject it to the worst possible damages such as head gasket or cylinder head damage.

CRAP!! It’s been so long (30+ years) since I had to deal with head gasket, I forgot all about that!!

Checked the oil cold and hot, twice each. Other than being in need of an oil change, it looked normal. I drove it 8 miles to our old house, and 8 miles back. The coolant tank was empty at the end of each drive. Those trips are when I checked the oil hot.

Truck is no parked until we can get it to the shop. She’s talking to a pro mechanic friend about looking at it in the next couple of days.

Overall, the vehicle’s condition is real good.

Turns out, there is some sort of housing on top of the engine. A by-pass hose runs from it to the pump. I dunno what it’s for.

Anyway, this crummy plastic housing was cracked, and that’s what caused all of the coolant to leak out. It’ll be fixed next Wednesday. Cost–$600 for the part, and $100 for the labor.

MY GOD…WHAT? 600 for the part? 700 total? Are talking about the plastic coolant tank with the rad cap? THATS NUTZ JEEZ go to a salvage yard and buy it for 20 bucks…and install it yourself…for free

ALSO…you still havent eliminated the specter of Head gasket failure…whenev you run an engine very low on coolant…this is a distinct possibility…and it would NOT be accompanied by any Fanfare…like a boiling over rad…or steam shooting out…bec there is no coolant to fuel that fire… Savvy? So you could still have majorly overheated a cyl head and warped it… Anywho…just repair and refill the rad and make sure to BURP the system and see what you get…thats all you can do at this point… Hope your head gasket is OK

Here we are, 6 years later.

The fix back then took care of the issue then.

However, the gauge is acting goofy in the same manner now. Just started yesterday. This time, there is no loss of coolant, and the engine is running just fine.

While sitting in stopped traffic, the needle would jump up to hot, and the check gauge light would sometimes come on for a couple of seconds. The needle would then fall back to the mid-point. This would happen quite often.

When traffic would move, and I would start to accelerate, the needle would head back up, but not as far, and then settle down again.

On the freeway, everything was hunky-dory. The needle would stay where it is supposed to be.