Overheated Engine not starting

engines
mercury
sable

#1

Just finished driving through the Badlands and the got on the interstate driving at about 75mph. Everthing was fine for the the first 50 miles and then the car just lost power, steam was coming out under the hood and there’s no serious service within the next 100 miles or so. We pulled over, let the engine cool and added a couple gallons of water, started the car and went another 6 miles with the engine running very roughly, probaly missing some cylinders, and then it died again and did the overheating bit. This time there was no starting up again.



Car has since been towed home and this is what has been done so far.



Oil was clean, nothing white or foamy in it. Never blew any smoke much less white smoke. Transmission fluid looks good and does not smell burnt.



New Crankshaft sensor, new timing chain and sprockets. Replace fuel filter.



Prior to the trip: changed fuel injectors because we where trying to stop a slight hesitancey when going up a hill. Cleaned air filter and changed oil. checked all fluids.



Engine is a 3.0 V6 OHV (not a DOHV)



Problem: The engine turns but never starts. Took spark plug out and put on block and they where firing. You can smell gas as though it was flooded. While we where putting on the timing chain we never got a good reading on compression in the cylinders but it was pretty hard to turn the crankshaft when there should have been compression. My son noticed that the shop rag that was over the intake manifold would bulg upward as though gasses where being pushed through the intake (I’m pretty sure that isn’t good either)


#2

Let me see if I’ve got this straight: You were driving on the highway, and after the first 50 miles it simply lost power with no warning? Had it been overheating before this happened? What did your temperature gauge tell you?

So you pulled over and found there was no coolant in the engine, correct? Could you see a leak anywhere? What was the temperature gauge doing when you tried driving it again? Did it indicate an overheat condition at this point?

More information about the initial failures would be helpful, but based on what I’ve read I think that a coolant leak sprung itself while you were driving, and the engine overheated and died. THEN you drove it another six miles with only water (which boils too soon to effectively cool the engine), during which it was running very rough and clearly not heathily, and possibly continuously overheated this entire time.

Barring some miracle, I’m guessing this engine is history. A compression check needs to be done to determine the extent of any damage.


#3

It hadn’t overheated for about a year, after we replaced the water pump. Since that time it hadn’t overheated until this moment.

Temerature guage was maxed and maxed the second time also but showed normal when we first took off.

Other than the overflow we couldn’t see any leaks.

Question: What is it about the overheating that causes the engine to be no good. It is it because the headgaskets are shot? Would replacing the headgasket(s) solve anything?

I bought a compression tester and ran it on cylinder 1 and got about 100psi but when we tried to do the same thing by manually turning the crankshaft we got zilch. Not sure if I really know what I’m doing with a compression tester.


#4

Do a compression test on all cylinders and write back. Don’t manually crank the engine when doing the test. Unplug the coil or disable the fuel pump and crank the engine over with the starter.


#5

Okay…it’s possible that the thermostat never opened, that can also cause an overheating condition.

When an engine overheats, the cylinder head often warps and/or cracks, and in the process the head gasket is usually ruined. Additionally, the pistons can swell up and scuff the cylinder walls to hell and gone. You can also have preignition (hot spots on pistons that ignite fuel prematurely, and can melt holes right through a piston) and/or detonation (fuel combusting prematurely from excessive heat, can severely damage pistons and bearings if ignored).

I can say that 100psi is too low a reading, and may be one sign that severe damage has already happened. You won’t be able to do a compression test by hand; you have to crank it over like you’re trying to start it. Remove all of the spark plugs, disable the fuel injection and crank the engine over a few times until the pressure gauge stops increasing. A healthy engine should show a minimum of ~140psi on all cylinders, with no more than a 10% difference between cylinders. I’d bet that all cylinders will show less compression than that.

Post back with your compression test results.


#6

Ran the compression test per instructions. Practically had to be a gymnist to get the back three cylinders.

Cylinder - PSI
1 - 80 PSI
2 - 45 PSI
3 - 130 PSI
4 - 60 PSI
5 - 15 PSI
6 - 40 PSI


#7

If your test results are accurate, start looking for either another car or another used motor at a salvage yard. Try to find a Ford Taurus or Merc Sable 3.0l of the same year. If you don’t get the same motor of the same year you may have to change other things like the computer controls etc.


#8

And next time, stop the car before the temperature gauge maxes out.


#9

That’s the wierd part. The temp guage pegged like a timing belt had broken. One minute fine the next maxed.

Before we left we had the cooling system flushed for the 3rd time in 1 year because the heater core was plugged. Replaced the thermostat twice (once because we thought it was the overheating problem from a year ago and again after changing the water pump). The water pump was replaced as the last resort bucause it had never squeeked so we didn’t consider it bad until all else was done. When we took the pump out it had no fins, so that it was turning but not moving any water.

Regarding another engine. Does cartalk have references for companies with rebuilt engines?


#10

Coolant goes low, so coolant temperature sensor doesn’t see hot coolant. Head overheats and head temperature sensor is tripped. Because of this, the PCM sends a command to the gauge cluster to set the temperature gauge to maximum.


#11

thanks for your help. this will be good information to bring to my wife so she understands why this might have happened.

PS. In looking throughout the internet it would appear that the 96-97 Merc/Sable has had a history of this problem.

Thanks again, You folks where a great help!