The car, it is hot in the wrong place
February 3, 2011 9:42 PM   Subscribe

My temp gauge suddenly went to the max and the heater died. I was a couple miles from home (downhill) so I limped home. No water leaking from anywhere. I assume this is coincidence (??), but I very recently had the serpentine belt replaced. In recent days, the car's been a bit stumbly at low RPMs, maybe a bit more in the last couple days. It's a 2000 Crown Victoria (police model), 4.6 V-8. Water pump? Thermostat? Thanks for any thoughts you have to share.
posted by ambient2 to Travel & Transportation (10 answers total)
Not sure on that vehicle but I'd check:

1 - did they route the belt properly and use the right belt? Is the belt running over the pulley and tensioner that drives the water pump? I THINK on some cars (not all) its possible to accidentally reverse the serpentine routing and essentially your water pump turns in the wrong direction then and doesnt pump coolant.

2- themostat? maybe broken in closed position? If new coolant was added recently that can remove the old goop that was letting a bad thermo still open and close and then it sticks closed... you can check it yourself if you can remove the thermostat and put it in some boiling water to see if it opens (use an old pan for that!) - or if they are cheap just replace it and see...

3. Radiator fan disconnected/not working (if it's electric) - though I assume you are in cold weather in US right now so that would seem unlikely unless it was hot outside.
posted by clanger at 10:08 PM on February 3, 2011

P.S. I didn't lose coolant.
posted by ambient2 at 10:18 PM on February 3, 2011

1. You drove your car after it maxed out on the temp. gauge? Did you let it cool down first?
If not, you may have damaged your engine (head, head gasket,block). It could be damaged anyway. Is there oil in your coolant? Coolant in your oil?

2. Is it still overheating? If yes, there are a few things to think about:

a. coolant - You say it has lost none. Check it when the engine
is cold.
b. thermostat - If your car overheated to the max, replace it.
Spend a little more for a dealer part. It protects your
whole engine and may run you $15 more.
c. water pump - If your heater died at the same time as the overheating,
this points to a lack of circulation of coolant as the common
element. The impellers of water pumps sometimes give up
by loosening on the drive shaft. It doesn't have to leak.
Take the radiator cap off. Check to see if coolant is moving
through the radiator after the engine is warmed up. If it is
not moving, the pump is out or the thermostat isn't
d. belt - If it was improperly installed it could disintegrate. I oncehad
a pulley out of alignment and a new belt died the next day
after installation. Is the belt there and is it turning the
water pump?
e. radiator - As mentioned by charger above, the fan may not be turning
on. You may notice the temp. rising when at a traffic light,
but not on the highway as the higher speed drives plenty of
air through the radiator. This doesn't happen when the car
is idling if the fan isn't operating. The temp. sending unit may be at fault, or it could
be the switch in the radiator, if your car has one.
posted by noonknight at 11:14 PM on February 3, 2011

Everyone here is saying good stuff. Did your engine cool off as you coasted downhill
home? Did the temperature needle ever peg?

Check the belt tension. You'll need a little thingy to do so, from NAPA. If you don't
have calibrated fingers, then if the belt doesn't seem really very tight then it's too loose,
and it might be slipping on the water pump. If they're new, and they're not put on tight
enough, then they quickly loosen to something barely functional.

Get an ODB II code scan, and see what it says. You can buy cheap devices that will do this
down at your local auto parts store, or from Amazon.

Heater Died? That's weird. Sounds like a thermostat failure, suddenly closing and staying

After the engine cools off, start it again and let it idle. If the gauge shows hotter than
normal while it is idling (might take 20 or 30 or 40 minutes, depending on how dog damn
cold it is there right now) then you have some kind of problem you have to address.

Check the charging voltage on the battery while it is idling. If it doesn't come up to
14.5 or so, I would again be suspicious of the belt (not turning the alternator, or water

Squeeze the upper radiator hose and constrict it, and see if you can feel any turbulence
when the water is rushing past the constriction.

Stumbly in low RPM? Might be hypervigilance now that you are paying close attention, but
a "stuck at hot" coolant sensor would run the engine too lean, and it would stumble.

Don't trust it again until you figure it out.
posted by the Real Dan at 11:51 PM on February 3, 2011 [2 favorites]

You are probably right about this being a coincidence. Probably the water pump bearings are bad and the water pump pulley isn't turning freely. This is causing a little belt slippage, which explains why you're getting the "stumble" at low rpms. It also explains why you're not getting heat. This could have contributed to any extraordinary wear on the belt that you had replaced. If your mechanic had been circumspect when replacing your belt, he would have checked to ensure that all pulleys turned smoothly.

In any case, if you decide to drive your car back to the shop to get it diagnosed or repaired, drive safely. Also, keep a close eye on the temp gauge and don't even think about letting it get to maximum hotness again.

I wish you lived in my neighborhood. I'd tell you get online and order a new water pump, and would help you install it in exchange for a case of medium-good beer.
posted by L'oeuvre Child at 12:57 AM on February 4, 2011

My money is on "poorly installed belt failing to drive water pump properly."
posted by From Bklyn at 12:58 AM on February 4, 2011 [1 favorite]

Define "stumbly"? Odd performance at low rpms can possibly be indicative of a problem with the head gasket and compression. Is the exhaust giving off excessive water?
posted by dougrayrankin at 2:55 AM on February 4, 2011

It is possible that your thermostat "froze", meaning that it got stuck in the closed position (how it starts off when the motor is cold, to allow for the motor to reach operating temp more quickly) which would not allow coolant from the radiator to return to the motor. if this happpened the motor would surely overheat.

The 4.6L ford modular motor is a strong, reliable design, but no overhead valve design engine takes kindly to overheating. I sincerely hope that by continuing to drive it while it was overheating you did not blow a head gasket. If you did, then be prepared for a very expensive repair bill. Depending on the mileage on your car it is possible that your waterpump went, or that whoever installed the new serpentine belt routed it incorrectly, but if the belt was put on wrong you would notice it immediately temp wise. The important thing to do right now is ensure the overheating did no permanent damage, so take it to your mechanic and have them check it out.

For future reference, get a AAA membership and if something like this happens again (on any car you may have) pull over and call for a tow. Good luck, and let us know how it turns out.
posted by chosemerveilleux at 3:54 AM on February 4, 2011

Thermostat. Classic symptoms to a common problem.
posted by Slap*Happy at 12:23 PM on February 4, 2011

I would say its the thermostat.
posted by chugg at 12:39 PM on February 4, 2011

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