Impossible to overheat a Mark 8?

D

dsinclair

Registered
I wasn't aware of this handy little feature - called the "Fail-Safe Cooling Strategy". I shutter to think I would ever push an engine that far - but I guess it's nice to know if someone else ever drives my Mark 8 - that it's smarter than them:

Fail-Safe Cooling Strategy

The fail-safe cooling strategy is activated by the PCM only in the event that an overheating condition has been identified. This strategy provides engine temperature control when the cylinder head temperature exceeds certain limits. The cylinder head temperature is measured by the cylinder head temperature (CHT) sensor.

A cooling system failure such as low coolant or coolant loss could cause an overheating condition. As a result, damage to major engine components could occur. Along with a CHT sensor, a special cooling strategy is used to prevent damage by allowing air cooling of the engine. The vehicle can be safely driven for a short time with some loss of performance.

Engine temperature is controlled by varying and alternating the number of disabled fuel injectors. This allows all cylinders to cool down. When the fuel injectors are disabled, their respective cylinders work as air pumps, and this air is used to cool down cylinders. The more fuel injectors that are disabled, the cooler the engine runs, but the engine has less power.

Before the fail-safe cooling strategy is activated, the instrument cluster engine coolant temperature gauge is within the hot zone and a temperature warning light comes on. If the overheating continues, the strategy begins to disable the fuel injectors, a DTC is stored in the PCM memory, and a malfunction indicator light (MIL) (either CHECK ENGINE or SERVICE ENGINE SOON), comes on. If the overheating condition continues further and a critical temperature is reached, all of the fuel injectors are turned off and the engine is disabled.
 
RE: Impossible to overheat a Mark 8?

Where did this info originate? I heard that the NorthStar engine system would allow 50 miles of driving with no coolant, but I did not know about this.
 
RE: Impossible to overheat a Mark 8?

I lifted it right out of the Ford Technical Service Information for the 1998 Mark VIII.

I guess you learn sumpthin' every day...
 
RE: Impossible to overheat a Mark 8?

What sensors / computers have to be operating properly for this to work? Are we told when they malfunction?
 
RE: Impossible to overheat a Mark 8?

you'll get a "check coolant temp" message, your temp gauge will max out, and the check engine light will probably come on if the engine ever gets close to that hot.
 
RE: Impossible to overheat a Mark 8?

I would hope that no one would ever let their engine get that hot! If the temp gauge goes past 1/2 on mine I worry!
 
RE: Impossible to overheat a Mark 8?

Once the Gen2's Gauge is in Normal operating temp. it never moves a dime.

Great Tip Dave. Thanks.
 
RE: Impossible to overheat a Mark 8?

No problem.

I guess if I'm ever stuck in the toughest part of the city - and take a slug in the radiator - AND my gun jams - I'm still be able to drive outta there.
 
RE: Impossible to overheat a Mark 8?

Trust me, that is not the case with the first Gen's. One overheat and say goodbye to the head gaskets.

'98 Pristine Pearlescent LSC
'93 V-10 Twin Turbo Money Pit (The MonsterMark)
'93 Collecting Dust
Bryan
 
RE: Impossible to overheat a Mark 8?

I have not had my 1st gen remotely close to over heating, but my 94 SC came real close and actually shut itself off and did not let it start until it had cooled off. Do you know if the 1st gen's at least have the shut off as a fail safe?
 
RE: Impossible to overheat a Mark 8?

I would hope not. I don't know about anyone else, but abrubtly shutting down an overheated engine goes against my grain. My preference is to allow the engine to run at a high idle(without load), giving the cooling system a chance to remove the excess heat as quickly as possible, rather than killing the ignition which IMHO just lets the engine cook in the overheated condition. Of course after allowing the engine temperature to drop, shut the engine down and identify and correct the problem which resulted in overheating.
 
RE: Impossible to overheat a Mark 8?

True - but if there's no coolant - or it's not flowing - you might as well shut it down and say a prayer to the Gods of Aluminum for salvation.
 
RE: Impossible to overheat a Mark 8?

Way back when I was driving the pearl car from Denver to Casper. I was going up and down the hills in between those two cities. It was about 95 degrees outside. I remember having to turn the a/c off many times to keep it from overheating. That was the only time ever had a problem with that car overheating.
 
RE: Impossible to overheat a Mark 8?

I'm going to fly you to my house to fix mine. I ALWAYS have problems with the cooling system.
 
RE: Impossible to overheat a Mark 8?

I don't know about that injector shutdown, but on a 1st gen, no way. It will survive an overheat, but it depends on how bad it overheated. My situation the thermostat stuck in the closed position, the temp guage never budged (no coolant to measure). The only way I knew it was hot it was losing power, and when I was against the curb (just happened to have the windows down) I heard that clacking sound that usually indicates an overheated engine. I pulled over and as soon as I came to a stop the engine shut itself off. I attempted to restart it, my heart sank as the the starter just rolled but no start. I let it sit for 10 minutes and she fired right up, and I promptly shut her down. I went to the nearest auto parts store, had my wife bring my tool box. Corrected the problem fired her up and she's been running fine ever since. So I guess I just did not let mine get hot enough (thankfully), and I know what an overheated engine sounds like. Cool feature though.
 
RE: Impossible to overheat a Mark 8?

You are the luckiest man alive. This is the first time I have heard someone sesriously overheating an all alum engine and not loosing a head gasket. YOu must be living right.
 
RE: Impossible to overheat a Mark 8?

My '94 maxed out the gauge twice, to the point where the message center warned me, but it never shut down or anything. First time i was stuck on a snowbank, and the snow stopped the fan and blew the fuse. Second time was an air bubble in the system. Never blew the head gasket, and that sucker had a lot of miles on it when that happened.
 
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