What is wrong with the MIGHTY MERCURY?

October 5, 2007 11:35 AM

What is going on with my 1998 Mercury Sable?

I have a 1998 Mercury Sable with about 78,000 miles on it. Lately, and very, very randomly I have had a problem. Every once in a while (and only when it rains) I will back out of my parking place at work at 5:30pm and get to the stop sign when the battery light comes on and the steering locks up. The radio and air conditioner are still on and the engine is still running. After about a 45 seconds (long enough for me to curse and say "what is going on here.. rawr!") the light goes off and I can steer/drive again like normal. No other issues with the car. Less than 150 miles ago we had a full check up done on it with no issues. Any ideas as to what is going on? The car is running fine otherwise. This only happens about once every other week and ONLY when it rains (weird and probably not relevant). Thanks in advance for all the help :)

posted by ForeverDcember to travel & transportation (8 comments total)

I've owned so many Sables in my life (3 total) and they seem prone to inexplicable problems. In this instance, I'm thinking there's either a loose wire somewhere in the electrical system or a wire that's shorting out.

Can you reproduce the problem by spraying water on the car?
posted by drezdn at 11:58 AM on October 5, 2007

This sounds all kinds of stupid but when you think you have a problem with electrical (not electronic) equipment like solenoids, especially if it correlates with wet weather, honk the horn. Horns are driven by voice coils and the back EMF from the voice coil into the positive rail of the electrical system can give a spark across repulsive high-resistance deposits, thereby cleaning up corroded ones for a little while.

If honking the horn mitigates the problem it is diagnostic of corrosion somewhere.
posted by jet_silver at 12:23 PM on October 5, 2007

When you say the steering locks up, do you just mean that it's hard to turn the wheel?

It's possible that the wet weather is causing a belt to slip, which in turn means that the belt-driven alternator isn't turning fast enough (which causes your battery light to come on) and neither is your belt-driven power steering pump (which causes the steering to feel stiff).

If this is the case, it could be that a splash/rock guard under the chassis is loose/damaged/missing, which causes excess water to hit the belts, or your belts have worn down enough so that just a little moisture is causing them to slip.

IANAMAIGSACR i am not a mechanic and i generally suck at car repair
posted by spikeleemajortomdickandharryconnickjrmints at 12:47 PM on October 5, 2007

I agree with spikeleenanouanaceounaeonuaeocn. Replace your belt(s).
posted by banshee at 12:50 PM on October 5, 2007

When you say the steering locks up, do you just mean that it's hard to turn the wheel?


This means I cannot move the wheel at all, it will not budge. It feels like it is just locked.

Thanks for the suggestions so far... keep 'em coming!
posted by ForeverDcember at 1:00 PM on October 5, 2007

"... Less than 150 miles ago we had a full check up done on it with no issues. ..."

Sorry to say, but the free "full checkups" done by oil change places and similar service providers are basically "best faith" "visual inspections," not real diagnostics. If your fan belts were still on the car, and not squealing constantly, they passed.

spikeleemajortomdickandharryconnickjrmints is probably right, but it would also be good to have a real charging system diagnostic done, which most auto parts stores will have a machine to do, for free, at your request. It's quite possible you have a bad battery, and only a little less likely that your alternator is going out. Squealing noises when this happens can mean a loose or worn belt, a bad alternator bearing, or a battery with a cell shorted, reflecting a huge charging load to the alternator, temporarily stalling the alternator, by slipping the belt.
posted by paulsc at 3:22 PM on October 5, 2007

the battery light comes on and the steering locks up.

Without question, you have a situation with a slipping belt, and the weather is totally relevant.

If you've never driven a car without power steering, you wouldn't know that at rest it feels like the wheel can't turn at all without serious muscle (actually putting your back into it.) You quickly learn to let the car roll as you steer, instead of steering before moving.

There are four things running off your belt system: water pump, A/C, power steering pump and alternator. When the belt slips, all four items stop turning -- but only the power steering pump and alternator are immediately apparent, with the suddenly rock-hard steering and idiot light, while the water pump won't signal an idiot light until the temperature has risen to a dangerous level, and the A/C will keep blowing until the pressure has lowered somewhat (contrary to what you might think, the A/C compressor is not always engaged, it spends time freewheeling until the pressure needs to come back up.)

Since it happens when it rains, and always in the same spot, I'm going to go out on a limb and say that there are big puddles or somesuch in your parking lot, and so you're always splashing water on the belt when it's cold -- and the resulting reduction in friction (probably coupled with a loose, cold, and/or glazed belt) causes the slippage. Then, after half a minute (during which your engine is still turning but the belt is not -- or not much -- so the heat buildup dries the water out) the problem goes away.

I'd do this:

1. Change and tighten the belts.

2. See if the problem ever happens again (I doubt it will).

3. Consider the possibility that one of the four devices running off the belts is getting old and possibly seizing up, and the additional friction is significantly increasing the load on the belts (and so that much more friction is needed to keep the belt spinning off the crankshaft.)

Good luck!
posted by davejay at 10:03 PM on October 5, 2007

also what paulsc said, and by the way, all four items may not be on the same belt in your car -- perhaps your car has the power steering pump and alternator on one belt, isolated from the A/C and water pump.
posted by davejay at 10:04 PM on October 5, 2007