94 Concorde 3.5 L over-heating problem. Zoomed to top of scale veryfast.

I had been night driving about 30 minutes when I looked down and
noticed the temp gauge had red-lined all the way to the top, without
me even noticing it. It couldn't have been more than two minutes till
it had topped out. Then the check engine light came on. I was driving
in an area where I didn't want to stop so I kept on for the next mile
or so until I got the car into the driveway, when it shut itself down,
with a terrible rattly sound.

This is a rural area so I consider myself lucky to have gotten it
home.

I opened the hood and noticed steam, though not sure exactly where
from. As it was late, I just left the car to sit overnight. Next day I
checked the oil (down about 3/4 quart, seemed typical) and 'low/no'
coolant in the reservoir. I started it just to see if it would turn
over, which it did just fine. I topped the oil off and added as much
water as the reservoir could take..about 6-7 quarts went in..it takes
12 quarts total).

It started fine, ran up to regular temp at idle and per the hose heat
test, the thermostat seemed to be working ok. I have brought it up to
running temp twice since then (about 20 minutes, once driving, once
idling) and it seems to be running normal as could be. No engine noise
at all.

My question is what might have made it spike like that and would the
next thing be to replace the thermostat/gasket?

Could it have been a sensor of some sort?

The car has seen very limited local use throughout its life, but has
been driven moreso during the past year. Its just hit 40,000.

Thanks

Brian

 

its possible your water pump impeller is loose on the shaft. has it ever
been replaced? its turned by the timing belt. if its never been done, i bet
your car is due for both to be changed.

 

Low on coolant.

I'd find the coolant leak first.

If it's leaking coolant.

 

My first guess would be the same as aarcuda's. You ran low on
coolant. Keep an eye on the temp gauge and the water level. If the
water level drops find out where it is going.. Leaky hose, leaky
water pump, leaky radiator.

Steve B.

 

Believe it or not, my wife even had a 3.5 water pump seize up, but the
timing belt continued sliding on the WP pulley without even making any
screeching sounds. Took a bit of diagnosis to figure out why it was
overheating for no apparent reason, until I caught a whiff of burning
rubber smell coming from the timing case cover. When I got it apart, the
back side of the timing belt was badly glazed from the friction and the
belt was obviously not reusable, but it wasn't shredded. I wouldn't have
thought it possible.

 

yeah mine was doing that as well at the end. heard a nasty noise coming
from it. dead giveaway.

 

Thanks for responding.

I was wondering about how thermostats typically 'go out' though.

Is it all at once or do they just not work all the time? I will
probably put a new one in as its a very cheap part and easy to do, but
I won't really feel too confident about driving it without knowing the
old one was the issue.

I will do the boil test on it I suppose.

Regarding the loss of coolant. Could that have been cause by the boil
over/steam I witnessed when I opened the hood? The temp gauge hasn't
read hot until that one, and so far only, time.



Brian

 

When was the coolant last checked before the incident happened?

 

When you said yes, which were you saying yes to?

It probably hadn't been checked for a couple months.

I've since driven it quite a bit more, probably a good 30 minutes
freeway speed, then a 30 minute cool off time, then back 30 minutes.
The needle functioned perfectly, no overheating.

I can't be sure how much coolant was in there when the incident
happened.

I bought the thermostat as it was only $7, but I'm now thinking about
not putting it in yet...because it may have just been low on
coolant......and it somehow went off. Someone looked at the engine and
claimed it was so clean he didn't suspect any burst hoses or leaks.

Brian

 

That's a poor maintenance practice.
You'd have a much better direction to go if you checked it regularly and
knew that it was full just X days ago.

The O-ring that seals the water pump to the right side timing belt cover
and the identical o-ring that seals the timing cover to the engine block
were a known failure point, as were water pumps themselves up until
(IIRC) 1997 when they and the timing belt were superceded with the late
model items.
I find it hard to believe that a failed thermostat caused the 50%+
coolant loss unless you totally didn't see the warning gauges/indicators
and kept driving and driving, in which case, I hope more drastic damage
didn't occur.