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Discussion Starter #1
What are issues that 4.6's commonly have? The 3.8L SCs I'm coming from blow headgaskets like no tomorrow.

Do the 4.6L's have any chronic problems?

I think that the 4.6's are a much tougher motor than the 3.8 since they stand up to Police Interceptor, Ambulance and truck use, but please correct me if I am wrong.

If left alone (IE no power-adders) how long do 4.6's typically last, and at what RPM should my maximum shift point be to prevent motor death?

I've lost several motors to headgaskets now, and I lost my SC to a snapped crankshaft.
Are there any failures that these tend to suffer from? The OHC heads look pretty easy to change if the headgaskets went, so thats not that big of a deal, but what should I be aware of?

Sorry for the redundancy.
Also, can a tbird with 175k still make a run down the 1/4, or handle an occasional autoX if the car isn't pushed hard the rest of the time, and will going WOT off of stoplights or during freeway merges hurt a 4.6L with as many miles as the one I'm buying has? (not my questions, my girlfriend's convinced that if there is a way for it to blow up, it'll blow up on me if I do anything besides grandma-style driving.)

Also, if you know someone that's good at breaking curses or can remove the hex or whatever from me that's given me such bad luck with cars, I'd appreciate it. :p



Thanks,
ghost
 

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Actually, if you keep fresh oil in them and keep them maintained they seem to last forever. I have bought two cars with 4.6's that have failed... one is my '95 T-bird that had blown head gasket(s) and the other is a '93 Town Car with a failed oil pump. I think these are the two most common causes of failure with the 4.6.
As far as replacing the head gaskets in a 4.6, unless you are wanting to rebuild the motor with forged internals ($$$), it is almost more cost effective to find a used PI motor because the 4.6 is so expensive to rebuild.
Sorry, I can't help with your streak of bad luck. The best I can tell you is to stay away from bowties. :tongue:
 

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See my signature. . . . .I am not really easy on the these motors from the throttle standpoint. The RPM's in the 4.6 MN12's are more limited by the Torque Converter than the motor, so there is no problem there. I have read about people "regularly" doing 6000 RPM shifts with modified TC and chipped vehicles, but I don't know how often is "regularly" . Like tinman_72 said: maintenance is the key with these motors, and they will last for what seems like forever. I have yet to have one fail on me.

I personally love the durability of the 4.6 and if I can get away with it I will never buy something with a different motor! :D (some people say I'm biased?)
 

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I'm Cynical, I say replace the girlfriend and get another bird:) My 94 4.6 has 150k on it, bad O2 sensors, still passes smog 3 years in a row. Just keep going and going. Mine leaks oil, and runs rough, but its never left me stranded nor never not started. its been a very good motor for me.
 

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the 93-95 4.6L engines do have a problem with valve stem seals, and burning oil.

But if you keep the oil up they will run pretty much forever.

They are pretty ping sensitive motors, so keep an eye out for any detonation, and take care of it before it beats up the bearings.
 

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mine is at 187-188k right now. only mobil1 since i own it at about 155k and autocrossing twice, with first time doing 4 lap and second time doing 6 lap. 1/4 miles past about 10 or 11 times, redline once or twice per week. still holding right now. have a tiny bit sign or valve stem seal smoking problem but not bad at all.

my house's angle drive way may contribute to the valve seal maybe the front one because everyday day i warm up the car for 15-20 minutes before i drove it.

still running strong. the tranny is the weak point for now.
 

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Discussion Starter #7
thanks much!
 

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Both of our 4.6s are still alive and kicking. The Birds is at 170k, and is doing just fine. The transmission that sits behind it is hosed though. My Cougar's is at 95k, and still feels like new. I had my transmission built up, so I'm not worried about reliablity on that car.
 

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Ya my oil level on my 95 was about a quart low every month but other than that the motor ran really strong.Overheated about 3 times in california heat and when i finnally pulled it there was no damage what so ever.The motor ran as strong from the day i bought it till the day i pulled it and swaped the PI.

The only problem i feel that these NPI motors have is the lack of power.
 

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I have 2 4.6 cars, a 94 cougar with 210K miles, and a 94 crown vic with 260K miles. Both motors burn oil from worn out valve seals, but otherwise have no problems and still have plenty of power. Don't hesitate to beat on the car. Just keep oil in it and it will run for a very long time.

Mike
 

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My 97 4.6 has never been apart, except for the intake manifold being replaced with a PI one. With 300,000+ miles on it, it does burn some oil, pan gasket seeps a bit...but it runs like a champ and I "regularly" rev it to 6500 when playing around. Yes, I know this is a bit much, but I know the consequences and no I don't have a stock torque converter, lol. :)
 

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Good thread!!

5,600 on my rebuilt motor :D
 

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My 97 4.6 just hit 95xxx miles and does not burn oil at all .

Why do the valve seals ware out ?

I thought That the 96 and 97 did not have that problem .
 

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The 96/97s arent as bad as the pre 95 ones, but it does still happen. The reason the valve seals start leaking so bad on the old 4.6s is that the valve guides on the older style heads are too short, and over time they wear out. Once the guides are worn, the valve actually starts to wobble a bit while it is being lifted, and this can very quickly wipe out even new valve seals, so the ones with 200K miles on them don't hold up and start leaking oil down the valve. The 96+ NPI heads have longer valve guides, so they don't wear out as quickly, but it will happen eventually.

Mike
 

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Nice info Mike ,

Thanks
 

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I've only seen 2 of these engines blown up.

One was a Town Car with a leaky intake. Same intake they recalled. The gasket leaked into the front cylinder and caused a hydraulic lock. They bent a rod or something. Just replaced that one with a used '02 Crown Vic motor.

The other was an early Crown Vic with the aluminum intake. Some kid was driving to school from Seattle and the oil light came on. Then the motor started missing and clattering. He siezed a cam. The oil wasn't on the stick and hadn't been changed or checked in 20,000 miles. One used head fixed that one right up.
 

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icantdrive55 said:
The oil wasn't on the stick and hadn't been changed or checked in 20,000 miles. One used head fixed that one right up.
Now if that isn't a testament to how un-killable the 4.6 is, I don't know what is. You don't change the oil or even check it for 20K miles, run it dry to the point where the cam seizes in the head, and you don't even need to replace the whole engine, just one head! That's an awesome story.
 

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I've killed the same 4.6l twice..lol..I think it was just a dud... 1st time: threw a timing chain which ripped through the valve cover, bent valves, dinged up pistons, metal shaving all throughout the engine... but..lol.. I still drove it home (2miles) just to see how tough a ford is.. well it made it home, started back up once then was dead.. so I got it rebuilt top to bottom.. 2nd time: 20k miles on the rebuilt motor.. sheared off the key that holds the timing gear on the crankshaft, spun the gear 1/4 of a turn, bent valves, dinged cylinders.. but..lol.. it once again got me home (1.5miles) before she rolled over and died... they say a cat has 9 lives.. i've burned up 3 of those lives.. 2 motors, and a "totalled out" wreck... and after thinking heavily wether or not I should let my cat eat a snake (cobra motor). I've decide the explorer motor is the logical route for me.. as of right now.. she's out infront of the house with her chin up so high and proud (since there's no motor in it..lol) waiting to chow down on an explorer motor.
 
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