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Old 01-28-2009, 06:07   #1 (permalink)
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Smile Difference in mpg & reliability between a 4.6 & a 3.8 ?

Hey guys, I have decided to purchase a 97 t-bird for my daughter, so the hunt begins. I've found some low mileage cars with v-6 and v-8. I was thinking the cylinder head issues on the v-6's had been resolved by 97. Is that correct? I've read several owner reviews on both power plants. Of course opinions vary, but from what i can tell... the v8 seems to be a bit more reliable, but are a bit gas thirsty. Does anybody know what the difference in mpg is between the 3.8 & 4.6 ? Also, of the two engines, which engine would you guys rate the most reliable. Yes, i know the V8 is more fun to drive, but this car is for my daughter.... so reliability "trumps" performance... in this purchase. Much of her commuting will be to college on the interstate, about 30 miles each way. I'd appreciate your opinions, if it was your daughter... which powerplant would you choose ??
Thanks-a-bunch,
Mach
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Old 01-28-2009, 14:00   #2 (permalink)
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Re: Difference in mpg & reliability between a 4.6 & a 3.8 ?

The 4.6 has still to this day an intake manifold problem. the 3.8 has had the head
gasket problem resolved years ago. As far as gas mileage is concerned is how you drive it. I get better mileage from my 460 than my wife gets from her 3.8. If she drives my 460
i get better mileage from her 3.8. An engine is just as reliable as the next. You can get
lemon 3.8s and lemon 4.6s No engine is the same. Make a decision. When you buy the car you will know. To answer your question, if it was my daughter i wouldn't be too
worried about the motor. The motor will run till it quits. I'd be concernad about how much replacement parts will cost for the actual car and how avalable they are. Prime
example. If your thunderbird has tuned suspention and some do,the two front springs are $300.00 .If it is a regular suspention the springs cost $77.00 . You be the judge.
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Old 01-28-2009, 20:05   #3 (permalink)
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Re: Difference in mpg & reliability between a 4.6 & a 3.8 ?

Thanks, that is good info. From what i can see, there is less than 2 mpg difference between the 3.8 and the 4.6. I had a 3.8 v6 in a 94 sable. I suspected the head gasket was leaking. Rather than be honest with me, local ford dealer said... we charge $100.00 to evaluate your engine. If the head gasket is defective, you will not be liable for the $100. That sounded a bit shady to me, so I said, fine check the engine. the service manager came back and said, yep yours is leaking... we will cover it. I went back and talked with the mechanic... he said that all the 3.8's had bad head-gaskets. The service manager was using the $100. evaluation charge, to keep everyone with a 3.8 motor, from demanding a warranty repair. As far as the engine, i never had anymore trouble out of the 3.8, it seemed like a pretty stout motor. My brother had a 3.0 in his taurus, both engines made the same Hp, but the 3.8 had another 100 lbs of TQ. made a huge difference in performance; however, the 3.0 motor seemed to have much less repair issues. Unfortunately, the transmission in my car, was not as strong as the motor... I was under the impression that most of the head gasket issues had been fixed by 97, however... i still find forums where owners with 97 models, have failed head gaskets. I suspect, the ones that were not replaced under warrranty, may be the ones that are now failing, usually at or after the 100,000 mile mark. Best i remember, the head gasket job on a taurus / sable (front wheel drive) was about $2000.00 if not repaired under warranty. I wonder if the 3.8 head gasket failure, would be more than the 4.6 intake swap/repair? i agree, you can get good ones & bad ones regardless of which motor i choose... but I like to go with the one that has the best probability of success... lol
Thanks,
Mach
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Old 01-29-2009, 11:07   #4 (permalink)
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Re: Difference in mpg & reliability between a 4.6 & a 3.8 ?

The 97 taurus has a 3 lt. motor. Completely different motor from the second generation
3 and 3.8. Providing it is not a Duratec. They are all very good dependable motors if
looked after. The head gasket issue in the old 3.8 was Ford's fault. They got cheap
outsourced gaskets from a independent supplier. The gasket were garbage as everyone
found out. After Ford sent out a recall for some of the motors they started using their
own gaskets. Problem solved. The old 3.8 had 190 H.P. and 142 lbs. of torque. the old 3lt
had 152 H.P. and 113 lbs. of torque. If you cut the bottom out of the air box of the
older 3.8 and increase the timing one degree you will get approx. 202 H.P. Don't know about the torque but it will increase too. there is a special procedure to follow when
prepairing the 3.8 head before it is replaced with a new gasket. Not too many people
know about it when they replace gaskets in the back yard. The gasket will blow again if
not followed. One thing about the 97 bird with the 4.6 lt. is they seem front heavy and
subject to front plow when hard breaks are applied. No big deal. That is just what the car does. Good luck and hope you get a good one. They are beautiful cars.
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Old 01-29-2009, 11:14   #5 (permalink)
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Re: Difference in mpg & reliability between a 4.6 & a 3.8 ?

Mach. Most of the 4.6's with a possible manifold problem are on a " double secret silent
recall ". the dealer won't say a thing untill you rattle his chain if you get a bad one.
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Old 01-29-2009, 12:07   #6 (permalink)
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cool Re: Difference in mpg & reliability between a 4.6 & a 3.8 ?

More great info... I wonder what the limitations are on the 4.6 intake recall. Is there a limitation, like it has to fail within 10yrs or 100,000 miles, before FORD will step up and fix it? I'm a fan of the 4.6 motors. I have had (2) crown vic's, both with the 4.6... and i never had a failure with either. A friend of mine has a heritage edition F-150, that has over $220,000 miles on his 4.6 It runs like a top, and the motor still doesn't smoke. Amazing performance considering it has a 1/4 million miles on it. My F-250 has a 5.4, and so far... the engine has been super reliable. I was surprised that Edmunds rated the gas mileage between the 4.6 and 3.8, within 2 mpg of each other. The only t-birds I can afford will be 80,000 to 100,000 mile birds. I'm thinking the 4.6 might have a better shot at hitting the 200,000 mile mark, than the 3.8? but thats just a guess.... What's the highest mileage anyone has put on a 3.8, without a mechanical failure?

Thanks,
Guys...
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Old 01-30-2009, 08:21   #7 (permalink)
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Re: Difference in mpg & reliability between a 4.6 & a 3.8 ?

My wifes 3.8 has 558.966 K.M. on it. I think that is 365.966.5 miles. 80 oil pressure
cold, 60 lbs. hot run, 40 hot idle. She had 129.000 km on it when she bought it. I
wouldn't be doing her transmission this spring if she had checked the oil every week
like i TOLD her. How long does it take to check oil ? It was leaking at the pan. I don't thing the manifold recall times out. There were only a few engine runs that had a problem
but the manifold is subject to cracking over time. Her 3.8 is on the hyway every day.
120 mile round trip 5 days a week. Her engine gets an oil change every 30 days
whether it needs it or not. An under hood inspection every 2 weeks and an under car
inspection every month. I cannot afford to have her brake down on the hyway at 40 below zerro. That doesn't make her 100 % safe but it sure helps. Every vehical is subject
to a suprize.
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Old 01-30-2009, 22:02   #8 (permalink)
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Exclamation Re: Difference in mpg & reliability between a 4.6 & a 3.8 ?

Quote:
Originally Posted by chipset View Post
The 97 taurus has a 3 lt. motor. Completely different motor from the second generation
3 and 3.8. Providing it is not a Duratec. They are all very good dependable motors if
looked after. The head gasket issue in the old 3.8 was Ford's fault. They got cheap
outsourced gaskets from a independent supplier. The gasket were garbage as everyone
found out. After Ford sent out a recall for some of the motors they started using their
own gaskets. Problem solved. The old 3.8 had 190 H.P. and 142 lbs. of torque. the old 3lt
had 152 H.P. and 113 lbs. of torque
. If you cut the bottom out of the air box of the
older 3.8 and increase the timing one degree you will get approx. 202 H.P. Don't know about the torque but it will increase too. there is a special procedure to follow when
prepairing the 3.8 head before it is replaced with a new gasket. Not too many people
know about it when they replace gaskets in the back yard. The gasket will blow again if
not followed. One thing about the 97 bird with the 4.6 lt. is they seem front heavy and
subject to front plow when hard breaks are applied. No big deal. That is just what the car does. Good luck and hope you get a good one. They are beautiful cars.
3.0L's were 140 hp and 160 lb-ft of torque originally, non-SC 3.8L's were 140 hp and 215 lb-ft of torque (Before the split port manifold design was developed, then 200 hp and 230 lb-ft of torque).
SC's were 230 hp and 330 lb-ft of torque.
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Old 01-31-2009, 13:50   #9 (permalink)
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Re: Difference in mpg & reliability between a 4.6 & a 3.8 ?

Tbird. Was wondering where you got your H.P. information from. My info comes from
the Ford rebuild manual that the dealer uses. Is there another source ? A factory
Super Coupe is 195 H.P. and 215 lbs. of torque.
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Old 01-31-2009, 14:08   #10 (permalink)
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cool Re: Difference in mpg & reliability between a 4.6 & a 3.8 ?

Quote:
Originally Posted by chipset View Post
Tbird. Was wondering where you got your H.P. information from. My info comes from
the Ford rebuild manual that the dealer uses. Is there another source ? A factory
Super Coupe is 195 H.P. and 215 lbs. of torque.
Some were from the original brochures of the time (I have a few left) and a few were from memory (did look on wikipedia for one).
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