Another one bites the dust

"MM54" (mm54mk2) 08/13/2017 at 16:42 • Filed to: WHY IS EVERYTHING SO RUSTY

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The intake manifold on the modular 4.6 is known for failing and leaking coolant (sometimes spectacularly). About a year and a half ago, my Crown Vic started leaking a little down the back of the block. In December, it started getting worse until recently when I noticed coolant just about everywhere it could be on top of the engine, and had to refill it almost daily.

Removed: Alternator, throttle body, plenum, ignition coils, fuel rails/injectors, emissions stuff, entire wiper/cowl assembly (for access), 15 years of dirt and corrosion, some more stuff I’m surely forgetting

So most of yesterday was spent replacing that manifold. It’s possible my leak was just the gaskets, but considering the reputation of this manifold to fail, I wasn’t about to find out otherwise. Being a (relatively) modern car, there is a lot of stuff in need of removal, as can be seen above, to get the intake off.

I have a 2-car garage, so why not work in the driveway as far from the toolbox as possible?

Once I finally got everything apart (mainly challenged by the fact that every bolt was rusty and stuck to some degree - including one of the wiper/cowl bolts that I ended up having to drill out) I found that the head surface near the water port that was the first to leak had been eroded away some. Nothing that a little RTV shouldn’t handle, though.

That bracket on the right was incredibly inconvenient, and of course refused to come off where it’s bolted to the back of the engine. At least it came loose a little.

My alternator had been on the fritz as well, so I took advantage of the opportunity to replace it while everything else was apart. I also replaced a ground strap on the back of the engine that has been broken as long as I’ve had the car, since it was actually accessible at this point.

Blurry picture courtesy of the setting sun and a 5-year-old phone.

After much reassembly and letting it set overnight, it seems to be good to go. Filled the coolant back up and went for a drive, no obvious leaks (yet...) and seems to be running pretty well. As a thank-you, the car left me a business-card-sized present when I closed the door.

Yes, that’s rust. I don’t have rocker panels behind the trim anymore, and the pinch welds are rapidly disappearing. Weirdly, the frame is in good shape. The coming winter will probably be this car’s last.

Honeybunchesofgoats > MM54 08/13/2017 at 16:48

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That manifold problem was the only non-wear issue I had on my Town Car in 200k miles.

MM54 > Honeybunchesofgoats 08/13/2017 at 16:51

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I’ve had about the same experience with this police interceptor. Other than catching up on a decade of deferred maintenance when I got it, it’s been good to me. At 194k miles now, this really needed done. The only time it’s left me stuck was when the shift linkage rusted off the side of the trans - and I was able to zip tie it enough to get home. I’m going to be really sad when it has to go away (it’s seriously rotten underneath).

Alfalfa > MM54 08/13/2017 at 16:55

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MM54 > Alfalfa 08/13/2017 at 16:58

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I wish I had more than one star to give this

Alfalfa > MM54 08/13/2017 at 17:02

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My MN12 Thunderbird developed a slow coolant leak a few months before I got rid of it, never bothered to look into it. Now I wonder if this was the cause.

LongbowMkII > Alfalfa 08/13/2017 at 17:06

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Then the floorboard falls off.

MM54 > LongbowMkII 08/13/2017 at 17:20

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That’s a possibility.

*sweeps rust off driveway*

Urambo Tauro > MM54 08/13/2017 at 17:29

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So where exactly do these ones leak, anyway? I had one of the earlier 4.6s with the plastic coolant crossover, which cracked right at the T-stat housing. But your old one there was one of the later ones with the aluminum crossover, right?

MM54 > Urambo Tauro 08/13/2017 at 17:54

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Yes, the aluminum crossover ones are much more resilient for sure, but tend to fail where the aluminum meets the plastic I believe. Mine was originally leaking from the driver’s side rear where the unused water port is blocked off, but by the time I replaced it there was also a leak near the thermostat and possible the passenger’s side front water port.