Black box

[silversnake]

What is the black box that has a vacuum line connected to it. Located on Dri. Side wheel well? And What's it's purpose?

[JBFTech]

Without looking to verify, should be the vacuum reservoir for the hvac sys, to keep a supply of vacuum to the door actuators while under WOT.


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[fastblackmerc]

Without looking to verify, should be the vacuum reservoir for the hvac sys, to keep a supply of vacuum to the door actuators while under WOT.


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That's what it does!

Back in the 70's the vacuum reservoir looked like a big metal juice can.

[silversnake]

Without looking to verify, should be the vacuum reservoir for the hvac sys, to keep a supply of vacuum to the door actuators while under WOT.


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If there is a leak in the vacuum reservoir would it cause issues to the car?

[MyBlackBeasts]

If there is a leak in the vacuum reservoir would it cause issues to the car?

Yes, HVAC doors will not work correctly and can cause engine running & drivability issues.

[JBFTech]

If it's a large vacuum leak, it could eventually cause lean codes and idle issues, however, its a small vacuum line that doesn't pull much volume, so it may never cause any issues other than hvac defaulting to defrost on WOT, or at all times in some cases. I would repair it though, where does it leak?


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[silversnake]

Yes, HVAC doors will not work correctly and can cause engine running & drivability issues.

Thank you! That explains the hissing noise I was hearing from the drivers side engine compartment while driving, and car running like crap. I was checking all harness under hood and and loose or damaged vacuum lines when I discovered this line was not fully connect. I put a tie strap around it to prevent it from moving. Test drive the car and it feels great. Ill confirm the fix once I take it to work tommorrow.

[silversnake]

If it's a large vacuum leak, it could eventually cause lean codes and idle issues, however, its a small vacuum line that doesn't pull much volume, so it may never cause any issues other than hvac defaulting to defrost on WOT, or at all times in some cases. I would repair it though, where does it leak?


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Hose was partially on

[Vortech347]

Got any pics of said box. I have that exact symptom of going to defrost under load/full throttle

[RF Overlord]

Sorry, no pics, but it's the featureless black box sitting right on top of the fender liner...directly behind the washer fluid reservoir.

[silversnake]

^^^^^ what he said.. It's filled with vacuum

[fastblackmerc]

Got any pics of said box. I have that exact symptom of going to defrost under load/full throttle

The box is mounted on the top of the inner fender, inside the engine compartment, drivers side. It's about 6" x 6" x 2". There is one line running to it. You can't miss it.

Could also be the o-rings in the EATC.

As these cars get older the vacuum lines will start to dry out and crack. I check mine once a year.

[silversnake]

The box is mounted on the top of the inner fender, inside the engine compartment, drivers side. It's about 6" x 6" x 2". There is one line running to it. You can't miss it.

Could also be the o-rings in the EATC.

As these cars get older the vacuum lines will start to dry out and crack. I check mine once a year.

Where is the EATC? So I can also check for any cracks or worn out lines?

[Rockettman]

Got any pics of said box. I have that exact symptom of going to defrost under load/full throttle

Don't think that's a symtom of the "box".

[fastblackmerc]

Where is the EATC? So I can also check for any cracks or worn out lines?

EATC - Electronic Automatic Temperature Control - you probably look at and use everytime your diving your MM.

[tbone]

I was throwing a code on the fuel rail pressure sensor. Followed the line back to the intake where I noticed the rubber boot was getting a little flimsy from age. Put a little silicone on the metal intake tube and smooshed the rubber tube back on. Code is history. Vacuum leaks suck.

[GetMeMyStogie]

That's what it does!

Back in the 70's the vacuum reservoir looked like a big metal juice can.

In my 1980 Mark VI, it actually WAS a juice can! The original rusted out and started leaking, so I bought a can of V8 (what else?), emptied the contents through a single hole punched in the middle of the lid, popped a hose barb on it, spray painted it black and voilá - looked exactly like the OEM, for about a buck and a quarter. That is, $1.25 and a bit of scrounging in the garage.

[Pat]

That's funny mine's a purple box.........

http://www.mercurymarauder.net/gallery/data/21/DSC01758_117203.JPG

[marauder410]

yea vacumm leaks suck and sometime hard to find i got one on my rauder somewhere, every time i really WOT i hear a little whinning now like a supercharger whislte kinda lol.

ive had someone say you got a supercharger in this thing when i was giving them a whine because they were hearing thr whistle noise :lol:

[silversnake]

I keep hearing a buzzing sound Dri. Side engine compartment @ 40mph and above, then my car feels like its dragging like there is extra load on the engine , and at low speeds if I hit the gas I could hear a clunk sound which feels like something's loose (metal to metal contact sound)