4.6L V6 intake leak

I have a '99 crown vic with the dreaded plastic intake manifold. The car has 55K miles and I've read many horror stories about the intake splitting open around 80K miles and spilling coolant all over while
leaving one stranded.
I can't afford to be stranded, so, I bought the factory upgrade kit for the intake manifold assembly that is supposed to eliminate this problem. The new part has an aluminum front runner that the alternator brace bolts to.
A friend installed the kit for me late last week and as soon as the car was started, there was evidence of coolant in the exhaust. We ran the car only long enough for the thermostat to open up.
After deciding that this was really coolant and not normal exhaust water vapor, whe shut it down and drained the coolant out. The car was clanking from the exhaust too, probably the catalytic converter getting excessively hot. My friend pulled it all apart the next day. We expected to see a defective intake gasket. However the gaskets look perfect. (Incidentally, the old gasket was in the process of failing too, with an area where the silicon bead separated from the gasket assembly and another area where it was way beyond its normal shape.)
We put a straight edge along the mating flange of the intake manifold and it's warped to beat hell. It's out 55 thou across 3 inches at the thermostat end. The opposite side has a hump in the center too.
I'd like some opinions about this sort of manifold warp on a brand new factory OEM part that has never been overheated...and in fact run only fifteen minutes. Is this within workable tolerances for the silicon intake gasket used? It seems like rubbish to me. My mechanic friend worked on cars for a living before they used plastics here, and he's never seen anything this bad! Maybe it's okay for plastics? Comments please!
Meanwhile, since we expected to find a bad gasket, my wife headed off to the Ford stealership to buy a new gasket set while he tore things down. They brought out the new set and it did not match the part in the "upgrade kit". The new part was XW7Z9439AA and though the part number matches the supplied part in the intake upgrade kit (F8AZ-9424-BAA), it is of a completely different design! She watched them open the bag, so we know the part number is right.
This new part differs in that all four intake runners are encircled by a single silicon bead rather than a bead of silicon around each. There molded grooves interconnecting all four intakes on one surface on the new gasket. There is also only a single bead between the four coolant passages and intake ports where the original design had two. The dealer explained that this was an "updated" gasket.
This has been a frustrating experience. I'd like to know if Ford not only has an issue with cracking manifolds but also intake flatness, intake manifold warp, quality control issues, intake gasket failures and similar. This is not an easy or fast repair and I can't keep asking for free help. It's got to be right.
So, if anyone here knows more about this problem on the 4.6Lmodular engine, please reply here. I found a reference or two on Google but not a lot.
Replies greatly appreciated!
Sign me
Fed Up!
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Why not go and talk to the parts people or service manager about this at the Ford dealer?
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I am talking with parts folks already. They ain't sure yet.
I want to know the whole story about this issue. I hoped I would get some of the inside info here in the Ford group. It helps to know the whole truth about a problem first.
Jeff wrote:

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when i installed a new engine in my t-bird i had an intake leak. after tearing it down we found they gave me the wrong gasket. after removing the intake and ripped out what i could of the gasket i took it all down to show it was the wrong part. you might try the same.
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ALOT of them failed. Our local Lincoln dealer warrantied them to 100K miles, unlimited time. I would give your local Ford and/or Lincoln dealer a call. There might be a recall or warranty you can take advantage of. I have installed probably 10 or so plastic intakes on the 96-97s. Most of them split up front near the alternator. All the intakes I got from Ford fit like a glove. GL
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Scott,
The police and taxi CV's are covered by Ford but the civilian "P74's" are not. In any case, I decided to replace this part before it catastrophically failed. It was cracked on the front mounting boss but not leaking yet. So, I'm out in the cold
as far as Ford fixing it free is concerned unless I persue redress in small claims court later. It has a stress fracture and there is evidence of seepage under the thermostat area of the intake assembly. The car was brought to the dealer by the previous owner for a"drivability" issues a year ago and they fixed it with a replacement Idle Air Control. I don't know if that was a correct diagnosis and repair or not.
Meanwhile, the replacement part has caused a coolent-to-intake runner leak. Otherwise, the workmanship was faulty and I doubt that. The torque specs and torque sequence were followed by the book. There is not much to do wrong in this department I think.
I'm intrigued that the intake gasket has been quietly redsigned too, while the part number is unchanged, i.e. no revision letter change. The new gasket design did not come in the intake upgrade kit, but was at the dealer in a 12/2002 packaged part.
What I really need to know is weather these plastic manifolds need to be flat. The old one was flat and the new one varies plenty when compared against a straight rule. The new one is leaking badly. There is no evidence of gasket damage on inspection after pulling the repair part.
Just curious.. since you've changed a few of these. Is the flat rate 3-1/4 hours for this repair treating mechanics fairly? I guess the 97's don't have the crash rail and hidden bolts... an extra twenty minutes.

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very easy once you do a few. One thing I can think of off hand is dont bother to remove the fuel lines, just pull the rail and lay it over to the drivers side. I would guess it could be done in an hour if you were in a hurry, had air tools, and have done a few before. It probably took me an hour and a half or 2 but I get paid by the hour(when I did them alot). That 3.25 hours is treating the mechanic just fine. The dealer loved it when we brought them in. Be carefull tightening it down. What you are trying to due is squish the silicon part of the gasket which doesnt take much. Also be carefull not to damage the silicon part of the gasket when installing and clean the surface of the head well. I remeber using an old gasket on one when I forgot to order them along with the intake. They seams to last forever. I would grab a straight edge and take it back to the parts room and see if they have another to compair it to. I hate to say it but you might have damaged it when installing. Again, I would not expect it to be perfect. Sounds like you need another one so take a straight edge with you to the parts room. You might have a problem with your O2 sensors now since they got hit with coolant. If you dont get an O2 code I wouldnt worry about it much though. Keep in mind I am assuming yours is the same or very similar to the '97. Also check *very* closely around the t-stat area and the brass heater hose connection. You might have cracked the intake at the t-stat when you installed it. It needs those bolts with the cuped washers on the '97. Just be very carefull and look closely at it when you go back with it. Tighten the bolts slowly and in a sequence suck as, all loose, all a little tighter, all snug, then all at whatever the book says.(Ill guess 20 ft lbs tops.) when tightening them you can fill the silicon squish and then the bolt will al of a sudden get harder to turn meaning the silicon has been crushed enough, stop there. Be carefull its plastic. :) you might want to wait on the t-stat bolts and fill the engine with coolant through the t-stat hole. Make sure the t-stat is in there correctly. If it is crooked it will break the intake for sure. Also, you should blow the coolant out of the plug holes when done, if you dont it will likely miss when it warms up, then you will have to do it anyway. GL
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have to come off before any real work starts on this model."
===You dont touch all that stuff on the 96 and 97.....Sounds like they built it kinda like the truck, with the engine under the dash? Are you sure about this? I've looked under the hood of the newer CV's didnt notice a big change. I know some of the rear bolts are kinda hard to get to but not *that* hard. Aren't the coils up front, one on each side? Are you fighting the EGR tube? It can be bent up a little to alow the intake to come out. Oh, one more thing. You said it was steaming out the tailpipe. No leak outside of the engine? I dont remember ever seeing a failed CV plastic intake that leaked on the inside. That seams VERY odd now that I think of it. Your failure was between a coolant runner and an intake runner. I've never seen that happen on a '95 and up CV that I can remember. Hmmmm
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I guess to keep the vehicle length down, some of the engine is tucked down under the windshield wiper pan and air cowl. You can't reach anything towards the back of the engine without removing all this stuff. They have a new "crash rail" which is a heavy steel stamping that bolts through the intake through the second right head mounting bolt to the right rear. This gem also bolts with a stud through another bracket mounted to the back of the engine. The hardware for this bracket faces the firewall. It's kind of a Hodini act to get that loose and out of the way.
Yes, the egr tube is tight to the manifold. The shop manual actually says to remove it, but it didn't seem necessary. The front of the manifold clears things by being lifted 1/2 inch or so and then brought frontward. There is about an 1-1/4" of space to play with between the manifold and the egr tube.
I looked again with bright light. The black sooty deposits in the left rear corner intake port have a pretty translucent amber color to them. It's as though the coolant washed away carbon but left varnish behind. The other intake ports have mostly a gritty black appearance. Anyway, I suspect this is where the leak was but I can't be sure.
I suppose the crash rail bolt going through all this got enough binding from other junk attached to effect the torque reading. The leak is under the crash rail assembly I think. Interesting! We set all bolts in shop manual sequence to the 20 foot pounds a read from the wrench. All bolts felt equally tight whe removing them later too.
I had read of a lot of intake failures on the 4.3L engine and on many GM's but not on the 4.6L. That is why I posted here... I didn't find anything on a Google search. That is why I went with a ford purchase. I had read many articles of GM engines sucking coolant into the engines causing major internal damage. I think it was the smaller ones at question. The only ones I found on Fords refered to the external leak except on the 4.2L Ford there were some unhappy truck owners with intake-fuel system leaks. Their sysmptoms were idendical to mine. One site described the Loud banging and clanging from the catalytic converteres and showed the gasket failure on thier 4.2L engine.
Should know more today. Do you have any comment on the pictures of the two different type intake gaskets? They both have the same Ford part number. The left on is the original construction with one ring per intake. The new one has visibly more silicon and a single bead of silicon circles all four intakes..
It interesting that the gasket design was beefed up though and yet the revision letter was not touched. So two different parts are in their system with the identical part number.

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Fix Daily wrote:

Just did a google search on "ford", "Manifold", "4.6", "failure" and came up with over 1000 hits. Blue oval news had a few good tips on this too.
BOB
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No so, ALL 4.6 V8's, built within certain build periods, are covered by the recall up to seven years/100K. Contact your dealer to see if yours qualifies for the free fix. Ford didn't change anything, secretly or otherwise. The deficiency was caused by the manifold manufacture when they made a changed that did not meet Fords specs.
mike hunt
fix daily wrote:

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Take your vehicle to a dealer. The warranty on the intake has been extended to 7yr/100K WOF.
mike hunt
Fix daily wrote:

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this is a perfect example of the old addage, if it aint broke, don't fix it.
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also, the 99 4.6 did not come with a plastic intake, it has an aluminium intake. plus the V6 is a 3.8. the 4.6 is a V8
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To all the advice of if it ain't broke don't fix it. and it's already aluminum and ask for the dealer to fix free and all that... Read the original posts. Do a bit more thorough googling and you will find out that it is really not really related to where it was manufacured or which Ford 4.6L car it was in. It is a serious design fault in the cars. Only the TSB relates these erroneous thoughts. There is a class action in progress for this very defect across the entire 4.6L product line. Thunderbirds, Mustangs, CV's, Towncars. Take your pick. Every owner of this engine has a ticking time bomb.
I've looked for hours. Ford dodges the issues in their TSB's by hinting the problem is related to fleet, police and taxi use from a single assembly plant. Yep, they are important customers who network more than retail consumers.
Other analysis (look more on google) suggests that stress and shock repeatedly transfered throught he serpentine belt to the alternator which is cantalevered only at the bottom by a pair of bolts, and supported to the plastic manifold at the top suggests that this is an accident waiting to happen. My manifold already shows stress cracks on the right front mechanical support boss where 1/2 of the alternator belt stress is immediately and repeatedly placed.
It's a good thing this CV doesn't explode when parked at the side of the highway and stuck from behind at high speed. Except if you look further, there are some pretty specatular reports of this too, because of it's rear seat mounted gasoline tank. Where do you want to be diasabled with a car lacking any coolant. It's a pretty sudden and dramatic if not disabling failure mode. Parked at the side of the interstate just after the acceleration ramp is my least fav spot!
Many many folks report this manifold catastrophically failing while out of town immediately after accelerating to enter an interstate. Some report it failed right after a drag race against a rice box. Entering a highway at full throttle causes additional stress on the belts and tugs very hard on the ill supported alternator.
Most here have noticed that even a squeaking tired alternator belt stops protesting during acceleration. Think about this. Acceleration repeatedly stresses the plastic manifold which eventually fails if the car is owned long enough. The top of the alternator is readily pushed 1/8" or more with a small screw driver if it's not bolted to the manifold. This suggests that the plastic manifold is being relied upon for some serious mechanical support.
This is a design error. Ford has corrected it by swapping the alternator support runner for one fabricated from aluminum. It has little to do with the temperatures involved and has everything to do with stress fractures resulting from repeated physical movement and stress opon this plastic component. It is an unsuitable use of plastic materials in the basic design.
Since I am ill, and cannot afford to become stranded in mid-winter with a car that has no coolant and therefor no heat, I chose have the defect corrected in advance of a catastrophic failure. "If in ain't broke, don't fix it?" Think a few days beyond tomorrow. Imagine walking home five or ten miles in sub freezing temperatures, especially when walking back from the mailbox is a serious effort.
Thanks to Scott for all your help and advice. The rest of you folks, look more on google if you own the 4.6L and you will find that this part will fail... not if but when.
I think my new intake seal issue may be caused by mechanical interference of the '98 and newer "crash rail" upsetting the torque sequence. I'll soon know. This crash rail makes plug changes an expensive or time consuming task. I guess most owners never notice during their typical three years and 30,000 miles of ownership.
D'oh. could be worse. It could be GM 3.x liter series.
Falcoon wrote:

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