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1988 7.3 Air Conditioner Vacuum Tank Mess

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Ray Cecil

1988 7.3 Air Conditioner Vacuum Tank Mess

Hey. I've been having to wait a long time for my air to switch from defrost to the dash vents. So, I figured I'd investigate.

I could hear a vacuum leak once I shut off the engine. So I knew we had a leak somewhere.

I did the old smoke technique with a cigar and quickly found the leak here....

But wait...what the....something doesn't look right...at first I thought this was part of the box, and upon closer inspection I found this....

Yup, that's a vacuum tank. It's designed to fit right onto the side of the blower box. First I've ever seen this style. I'm used to the coffee can or black plastic ball....

So I cleaned it up and attempted a 3M gasket....which failed miserably.

So....I kept the 3M on there, and applied some weatherstripping adhesive around it. It's currently setting up.

However....I plugged the hose that was going to this tank. Everything in the dash worked much better and quicker.

Why do I need this vacuum tank again???

1988 F250 Supercab Longbed 7.3 IDI, C6, 1356, GEARVENDORS, 4.10 Sterling with autolocker

1986 F150 302, C6, 9" 2.75, Wood Flatbed

85lebaront2

Re: 1988 7.3 Air Conditioner Vacuum Tank Mess

Administrator

Ray, probably not on a Diesel, you should have a mechanical vacuum pump so it just pumps faster as the engine speeds up, just like my two Diesel GM cars.

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

Gary Lewis

Re: 1988 7.3 Air Conditioner Vacuum Tank Mess

Administrator

As Bill said you may not need a reservoir on a diesel. The gas engines use manifold vacuum and a reservoir is needed to keep things in the right mode when you accelerate hard and the vacuum goes away. But with your vacuum pump I don't see the need.

And if you do need one you can just use one of the old juice cans or the ball reservoirs.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

grumpin

Re: 1988 7.3 Air Conditioner Vacuum Tank Mess

My first thought was its there because it is a diesel.

I thought the vacuum pump on the 7.3 IDI I used to own was lacking.

Dane
1986 F250HD SC XLT Lariat 4x4 460 C6-Sold
1992 Bronco XLT 4x4 351W E4OD
1998 GMC Sierra SLE K1500 350 4L60E
Arizona

Ray Cecil

Re: 1988 7.3 Air Conditioner Vacuum Tank Mess

In reply to this post by 85lebaront2

Unless Ford just liked putting parts into a truck for no reason at all....I'm inclined to keep it.

I noticed awhile back when I first start the truck, it took about 30 seconds for the vacuum to build enough for my brake booster to function well. That's when I started noticing the damper door delay as well.

Plugging that vacuum line solved the damper door slowness. But I did not test the brake vacuum boosting. I'll do that later and see if it's improved.

I stuck it back on last night and am letting the adhesive cure really well before I pull vacuum on it.

I have a few other components under the hood on this truck I'm not sure what they do. I'll post some more pics in my other thread. We can keep this one focused on diesel vacuum components for the internet searches.

BTW I was at an autozone recently, and the guy in line before me was working on a 86 bullnose. They searched on the autozone computer and pulled up this forum for reference on a fuel related issue. I kinda chuckled.

1988 F250 Supercab Longbed 7.3 IDI, C6, 1356, GEARVENDORS, 4.10 Sterling with autolocker

1986 F150 302, C6, 9" 2.75, Wood Flatbed

Ray Cecil

Re: 1988 7.3 Air Conditioner Vacuum Tank Mess

In reply to this post by grumpin

grumpin wrote

My first thought was its there because it is a diesel.

I thought the vacuum pump on the 7.3 IDI I used to own was lacking.

Yes, I feel the vacuum pump is lacking. It's good enough for hvac. So, I'll probably be doing hydroboost in the near future.

1988 F250 Supercab Longbed 7.3 IDI, C6, 1356, GEARVENDORS, 4.10 Sterling with autolocker

1986 F150 302, C6, 9" 2.75, Wood Flatbed

Gary Lewis

Re: 1988 7.3 Air Conditioner Vacuum Tank Mess

Administrator

In reply to this post by Ray Cecil

That HVAC plenum was used on both gas and diesel trucks, so the vacuum reservoir was needed for the gassers. I am using the one from the 1990 truck I put on Big Blue. It is nice, but I’m not sure it is a requirement on a diesel.

As for the website, I’m glad it is helping others. 👍

Gary, AKA "Gary fellow": Profile