[RoushRacing99]

Plastic intake cracked last year around the thermostat. Fixed it with JB weld last year and rolled with it. It held for about one year then going down the road the other day, it cracked off and starting spewing antifreeze. I stopped the car a couple times, dropped in enough antifreeze I thought to make it to my buddies and kept a real close eye on the gauge.

It made it til about a quarter mile from his house to get to normal operating temp. Then about a tenth of a mile from his house, it started bogging down and not hardly pulling itself. In his driveway it got barely over the normal temp reading and I shut it off.

Somebody said a lot of cars have a limp mode to protect the engine...is that what this was? Any other damage that could result?

[cliffyk]

Our cars do not have a failsafe cooling strategy as they have no cylinder head temperature sensor. Also, a problem with watching the temperature gauge is that when the coolant level falls the coolant temperature sensor (in the crossover on the intake manifold) is no longer immersed in coolant, and therefore it's output does no longer reflects the coolant temperature.

Hopefully no damage has been done, but "bogging down" with a known cooling problem is not good--you'll find out when you next start it up, if it turns over normally then you may be lucky...

[WickedSnake00]

Originally Posted by cliffyk Our cars do not have a failsafe cooling strategy as they have no cylinder head temperature sensor. Also, a problem with watching the temperature gauge is that when the coolant level falls the coolant temperature sensor (in the crossover on the intake manifold) is no longer immersed in coolant, and therefore it's output does no longer reflects the coolant temperature. Hopefully no damage has been done, but "bogging down" with a known cooling problem is not good--you'll find out when you next start it up, if it turns over normally then you may be lucky...

A New Edge era Mustang would not have this. While some vehicles do have this feature, especially diesels, this is not one of them.

As far as bogging down goes, I would be very concerned. Did it have enough coolant or did you low coolant light come on? If there was enough and your temps weren't high you might be lucky. If there wasn't, your in engine temps could be much higher than you thought, and you could be in some trouble.

[cliffyk]

Ford uses them a lot on the 4.6 2V; on the Crown Vic, E-Series, Expedition, Explorer, F-150, and others--even the 3.8L 6-banger has one--just not the GT or Cobra.

Go figure...

[WickedSnake00]

Originally Posted by cliffyk Ford uses them a lot on the 4.6 2V; on the Crown Vic, E-Series, Expedition, Explorer, F-150, and others--even the 3.8L 6-banger has one--just not the GT or Cobra. Go figure...

Well that makes 0 sense.

What are the critical parameters for it to enter limp mode? I know one of the more common is to set an RPM limit when certain sensors signals are lost, ie VSS, TPS, etc...

[cliffyk]

FMEM (Failure Mode Effects Management) mode is triggered by failure of any (of most of) the engine control system sensors. The PCM will substitute fixed values for the failed sensors' missing values to allow the engine to continue to run.

I do not have a list of the sensors involved, however it is all those that are inputs to the PCM's fueling and timing calculations. The hard-coded fixed values are as one would expect quite conservative, resulting in reduced performance. That being not the goal of the FMEM routines, but rather an effect of same.

Also it is more of a "keep the engine running" system, as opposed to a system to protect the engine from damage (though in some instances that is also an effect of FMEM).

[RoushRacing99]

So are you saying it has FMEM? It felt like a car that the battery cable was coming off of. It felt more like electrical dying than engine dying

It still had coolant in it, not much at all but some. It steamed out of the thermostat for just a second and then stopped when I shut it off. Plus the coolant temp gauge did read warm right as I got in his driveway so it had some coolant going over it.

okay well, filled it up with coolant and it started fine. I didn't run it very long and just let it idle a minute until it started leaking again just to see. I have some jb weld on it again just until I can get it back to my house. I'm going to bolt on a new Dorman intake. The thermostat housing is metal on them.



Worst case scenario, what's the damage?

[cliffyk]

Just to be clear, FMEM has nothing to do with protecting the engine from overheating if the coolant level is so low that the temperature sensor is not immersed in coolant. It is NOT a failsafe cooling strategy.

The Dorman intake is crap, it's a one-size fits all for all possible 4.6L 2Vs Ford ever installed in anything. It comes with two generator brackets (neither of which is like the OEM bracket), and multiple spacers for those and to make the thermostat housing fit properly. Also the runners are smaller in diameter than the PI manifold, and lower plenum has only perhaps 75% of the volume which could affect tip-in torque and other air-flow anticipation calculations done by the PCM.

You can get the FRPP PI manifold online for $190 (Summit and others)--if you can possibly wait for several days do that instead--Summit will ship it (to 32086 anyway) via 2nd day for $15, and next day for $25, plus $12 handling charge.

Thats $217 total for 2nd day, and $227 for next day.

[WickedSnake00]

Originally Posted by cliffyk FMEM (Failure Mode Effects Management) mode is triggered by failure of any (of most of) the engine control system sensors. The PCM will substitute fixed values for the failed sensors' missing values to allow the engine to continue to run. I do not have a list of the sensors involved, however it is all those that are inputs to the PCM's fueling and timing calculations. The hard-coded fixed values are as one would expect quite conservative, resulting in reduced performance. That being not the goal of the FMEM routines, but rather an effect of same. Also it is more of a "keep the engine running" system, as opposed to a system to protect the engine from damage (though in some instances that is also an effect of FMEM).

Ah, this isn't quite the type of "limp" system I was thinking of, more of a fail safe. I'm much more heavily involved on the diesel side of things. I was just wondering about Ford's system versus what we impliment where I work, as well as how extensive it is. Seems to be two completely different animals.

[RoushRacing99]

okay so if it didn't go into limp mode, what exactly was it doing, predetonating?
Because I would assume had that been the case, it would have continued running when I turned the ignition off

It felt like something more electrical. It was just too erratic feeling. The only thing I ever felt that was similar was driving with a battery cable coming off.

My problem with not buying the dorman is the FRPP is all plastic again and it will eventually crack again

[cliffyk]

Yeah, it's a "if at all possible keep the engine running to get the customer home and not get them real pissed off" sort of system--NOT a preserve the engine thing though in most situations it does that too. The major missing element the the failsafe cooling protection.

I don't know what Ford's thinking was as to leaving the failsafe cooling off the Mustangs?

This is not a problem for a geezer like me as I would never drive a car with a blown cooling system another inch past where I knew it had an issue. I guess it can be a problem for those that have never dealt with overheated and seized engines, and think they can go "just a few more miles"...

[nathanielwilliam]

my heater line blew the other day and my car over heated and is spraying antifreeze out by the thermostat as well. it is parked for now.

Is there a gasket between the metal thermostat housing and the plastic intake?

I was hoping for just needing a gasket, but i've found another intake on craigslist.

going to pull my baby apart in the next few days to know for sure

[cliffyk]

Originally Posted by nathanielwilliam my heater line blew the other day and my car over heated and is spraying antifreeze out by the thermostat as well. it is parked for now. Is there a gasket between the metal thermostat housing and the plastic intake? I was hoping for just needing a gasket, but i've found another intake on craigslist. going to pull my baby apart in the next few days to know for sure

That's what happened to mine a few weeks ago. There is no gasket, but rather a rectangular section "O-ring" that sits in a groove in the manifold.

In my case the inner wall of the rear most port's groove, on the t-stat side, was completely disintegrated--the rest of the plastic seemed solid however. I cleaned it up with Purple Power and hot water, and degreased it all, then stuck it back together with J-B Weld.

J-B Weld needs to cure properly to be effective, I bolted it all up and let it sit for 4 hours before remounting the manifold on the engine. After getting it back on the engine and torqued down I let it sit another 15 hours before refilling the radiator and starting it up--it's been fine for 7 weeks and 1500 miles or so now, but at the very first sign of any leaking I will order an FRPP PI intake manifold. Summit will ship one via 2nd day service for $216.

[RoushRacing99]

Well, thanks for your help guys. I think the ol' girls fine... it still had enough coolant to have a reading and to steam out the thermostat when I stopped it but I am going to start it and run it today(with a lil jb weld that has set for about 40 something hours) to get it home and 6 gallons of coolant in the backseat just in case

[04GTAMPA]

Remember, heat will melt your pistons in a second and scuff your walls. If the temp raises above 220, stop and let it cool before you keep going. Don't rev past 2500 rpm. I hope you make it.

[RoushRacing99]

Well it was still leaking with jb weld that had cured for 40 hours or so. Intake must have just cracked more. I'm just going to work on it there. Change the plugs this weekend and do a compression test and go ahead and get the intake off and put the new one on when I get it this week.