...or maybe a hard HEAD story.

Well, whatever it is, I did it.

I got the notion I would do a "visual inspection" of the various small vacuum lines before "smoking" the intake system to discover further vacuum-system failures I might have overlooked.

First, I find a perished cap-connector on the line to the vacuum reservoir (known to some of us as "the cannonball"). Easy fix.

Then I observe the soft line running from the AIR pump to another unique "smog" device known as the "DECEL VALVE." This is where the trouble began.

The soft line at the AIR pump connector was pretty rotten. The end of the soft hose pretty much crumbled when I attempted to disconnect it from the AIR pump. I figured the other end of the soft hose would be pretty similar. Of course, it connected to the vacuum system via a T-connector buried under the labyrinth of the intake plenum and all the other vacuum lines and system lines that are found in that tight space.

When I tried to disconnect the soft line from the tee, it didn't want to give. I tried various methods. Just as I thought I had the tee braced sufficiently for me to free the soft line, I heard that sound...

SNAP!!!

oh no...

Yes.

I did it.

I snapped a hard vacuum up under the intake plenum.

I tried to free the hard line I had snapped. It was then that the other hard lines started snapping like an angry child playing with a box of uncooked spaghetti.

What have I done?

I managed to fish-out all the hard lines I destroyed. I gotta say, I'm feeling pretty down about right now. I pondered whether I should post this, because I know these sorts of things often elicit only derision on the internet. I've seen the remarks to the effect, "you're an idiot," "you should never be allowed to work on cars," "hit it with your purse," and on-and-on.

This sort of thing does make one question one's competence to attempt these sorts of jobs. I think I can fix it. But, I'm upset and perplexed, and not seeing a clear path to the solution at the moment.

Friendly advice would be welcome about now.

I've always looked at that "emissions hose routing" sticker on the underside of the hood with some trepidation. It really came home to roost in spades today.





I tried to label the broken bits as best I could as I was pulling the broken pieces out of the engine compartment. The experience was worse than this pic really shows, because some of those lines snapped (incomplete breaks) many times as I tried to free them. The sound of the relentless breaking was truly disturbing. Here is the carnage:

 

Get some 5/32 vacuum line and rebuild that mess

 

This should be the critter ya need. They also have it in 1/8, 3/16, and 1/4". Tends to be a little bit softer than the heat formed stuff GM used, but you can still heat it up a little, bend it, and hold it in shape until it cools.

DORMAN 47418 Tubing Dia.: 5/32"

 

Good idea to try to rebuild with "hard" line, or just soft-line the whole job?

 

Well, rubber will dry and crack, it's floppy so it's free to fall wherever it's not anchored. It also takes up more space than the semi-hard line. The hard line just gets brittle with age.

For my money, I'd repair any breaks that are visible with the hard line. But then I'm an OE kind of guy. If it's just a driver, go with whatever works.

 

What both Drew and Tuned said.

I prefer the hard plastic line myself. You can find various sizes of lines and various ends, hanging on cards in the PCV section at yer corner parts store. Unfortunately they don't usually have ends with every possible combination of nipple size, line size, and configuration (straight, 90°, etc.). But the size isn't really critical for most things, and usually you can come up with some sort of combo that's close enough to get the job done.

You can make nice neat factory-looking bends in it with a heat gun. To keep it from collapsing, put a piece of 12 ga stranded wire, or some of that steel cable you can get at HD and the like, inside it while heating and bending.

The rubber stuff absolutely will work fine where you can't find the other, at least as long as the 2 nipples at the ends are close enough to the same size that you can plug one size of rubber onto both of them. Otherwise you can maybe find one of those "universal" size adapter things and maybe make it work.

 

Hi W.E.G. ,

Here's my friendly advice ; Don't be so hard on yourself , our cars at 30+ years old are gonna have vacuum lines about as hard and brittle as a 90 year old's veins , and having them crumble with a mere touch is kinda par for the course . Like the others said , as long as everything gets the vacuum it's supposed to that's all that really matters . If it's a showcar sure , try to visually replicate the hard lines as best as possible , but if it's a daily driver street machine that your not concerned with original looks well then just plumb it back together with whichever material is the easiest for you to work with , and the various components won't be the wiser of whether their vacuum is being supplied by hard or soft lines

 

The last couple packages of the Dorman stuff I bought are a lot softer than they used to be. I'd expect it'd take a lot less heat to mold them, like hair dryer or maybe even boiling water.

Might try Weed-Eater line.

It's worse than that. I remember them being brittle when the cars were 10 years old or less. Started out splicing the breaks with stubby bits of rubber hose, and they'd just crack apart in another spot. Switched to the Dorman stuff, and life has been good.

 

Thanks for all the support!

The anxiety of just completely breaking everything I touched was a tough pill to swallow yesterday.

That suggestion to run some wire or weed-eater line in the hard-line stuff sounds like a top tip. I am pondering forming some coathanger to model the routing for hard-lines, then trying to mimic the coathanger model with the hard-line stuff.

My kid bottomed-out his girlfriend's Corolla in some parking lot stunt at the beach two states away this week. Sent me a blurry picture of dirt and/or pavement embedded in the undercarriage and some broke body fasteners. Somehow managed to not breach the cooling or hydraulics. So, I'm motivated to cobble-together something in a hurry so I can at least pull the Camaro out of the driveway so we can pull the Corolla in and get it on jack stands for inspection if they can just make it home via other than a flat-bed.

I think I'm diagramattically dyslexic when I look at routing-diagrams.

I get it that, at its simplest, all these accessories run off manifold vacuum. Please be patient with me when I ask this question: Looking at that diagram I posted below, where is the "master" source for the vacuum that drives all these devices?

It kind of looks like the master source for vacuum is at the rear of the intake manifold.
Three big pipes forking off that master, that feed-off into everything else?

I’m mainly concerned with the whether I’m mixed up somehow on whether a device is sending or receiving vacuum. Like they say, an extra set of eyes can really help sometimes.

Without sounding like I'm absolutely blithering here, tell me if this makes sense. I’m just trying to translate the hieroglyphics into English. Maybe you can tell I like lists.


• Main vacuum source is rear of intake manifold
• Three big fat lines send vacuum from intake manifold (one fat line runs to passenger side, one fat line runs to the driver side, and one fat line runs to the PCV valve)
• One big fat line on passenger side of motor sends vacuum directly to Idle Air Control and Decel Valve
• Decel Valve sends vacuum to AIR pump
• Decel Valve sends vacuum to “bellows” area of breather between air filter and throttle plate
• Decel Valve sends vacuum to the Crankcase Ventilation Valve
• Decel Valve sends vacuum into tee-fitting going to Fuel Pressure Regulator
• Idle Air Control sends vacuum into tee-fitting going to Fuel Pressure Regulator (why GM thought the Fuel Pressure Regulator needed to be fed from TWO sources escapes me)
• Vaccum Regulator Valve located near passenger firewall receives vacuum, from all the way on the other side of the car, from the large round fitting on top of the charcoal canister
• Vacuum Regulator Valve sends vacuum to Vacuum Switch and also to EGR valve
• Second big fat line sends inbound vacuum to charcoal canister. Charcoal canister has only one inbound vacuum line
• All other lines on charcoal canister are outbound vacuum (to canister purge solenoid and fuel tank and Vacuum Regulator Valve)
• I don’t know why GM gave the breather valves on the two valve covers different names. Driver side breather-valve is called PCV (positive crankcase ventilation), and passenger side breather valve is called CCV (crankcase ventilation?)
• I don’t know why GM felt it necessary to ventilate the passenger side valve cover through the always-enigmatic “Decel Valve”


I mean, just wow.

All these vacuum devices talking to each other at the same time. Impresses me as some sort of sorority tea party. All of them talking at once. Are any of them really listening?

 

PCV Valve = the thing that plugs into a grommet in the DS VC and has vacuum applied to it
CCV Air In = just a tube that plugs into a grommet in the PS VC and gets fresh air from in front of the TB (no vacuum) but behind the MAF, so that the air that goes through the system gets metered by the MAF
Vac Reg Valve = EGR solenoid valve

It's ABSOLUTELY CRITICAL that the system is COMPLETELY closed at ALL points behind the MAF, thereby not allowing ANY air to get into the intake tract ANYWHERE BEHIND the MAF without ALREADY having gone THROUGH the MAF to get there. Reason being, if any air can get into the engine from ANYWHERE OTHER THAN having passed through the MAF at some point on its way in, the MAF won't have any idea that it's there; and consequently, the ECM won't have any way to know to put in fuel for that air. You'll see lots of posts on these forums about 85 - 89 cars with weird idle problems and the like, that seemed to miraculously appear after someone installed "breathers", or "cleaned up the engine bay", or otherwise did something stoooopid that violated the fundamentals of the design because they thought they were smarter than the factory, and then couldn't figure out (or were unwilling to confront the fact) that their "improvements" had fornicated the car.

That diagram is really quite simple. First, divide it into systems (PCV/CCV, AIR, fuel tank venting & purge, etc.) as much as possible; then observe that the factory used a T to supply control vac both to the canister and to run the EGR. Once you get to that point it's not so scary anymore, pretty simple even actually.

The "source" of vacuum is the intake manifold, behind the throttle blades.

 

To continue:

Main vacuum source connections are the rear of the manifold (goes primarily to the fuel tank vent system), and the rear of the TB behind the throttle blades which is effectively also from the manifold (goes to PCV and the AIR Decel Valve)

Fat line coming from front of TB / bellows behind MAF and going to CCV & Decel Valve is fresh MAF-metered air at atmospheric pressure; no vacuum

Idle Air Control is not on this diagram anywhere

A small-diameter source of vacuum, for control purposes, comes off the back of the TB and feeds the FPR, AIR Mgmt Valve, and Decel Valve

Another small-diameter vacuum source comes off of the back of the TB and goes to the Vac Reg Valve (EGR solenoid valve) and to the canister for its control

The "Restrictor" in front of the canister limits the amount (flow rate) of vacuum reaching the canister, and is bypassed (i.e. full flow of the large hose is available) when the Purge Solenoid is activated

The Vac Sw allows vacuum to bleed off of the EGR line, thereby deactivating the EGR

The line to the fuel tank is the tank vent

The Tank Pressure Control Valve lets pressure in the tank, containing fuel vapors of course, bleed off into the intake (no fuel vapors into the atmosphere at large) when called for

Capisci?

 

Thank you sofakingdom for the detailed run-down.
I pulled a few quotes from your remarks, and commented.
Please let me know if I’ve got anything still garbled.

Understood.
One valve cover receives metered air, and actually applies vacuum to the valve cover.
Other valve cover has simply a vent that is protected from incoming contaminants due to placement downstream from intake filter elements.

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Makes sense.
Can’t put the EGR solenoid right on top of the EGR, or would cook it to death

.

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Understood.
“Un-metered air is the devil.

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Undertstood.
Working on my sub-diagrams for clarity today.

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Undertstood.
Because of the proximity to the Idle Air Control valve, I was describing those lines as going into the IAC. I understand now that those lines are actually inserted in a fitting behind the throttle body, and not into the IAC. Please correct me if I have over-simplified this description of the vacuum connections going into the connector right behind the throttle body.

 

Looks like you got it.

 

Thanks.

I got the scraps of what I tore out of there all tape-labeled for comparison when I re-create the system.

I was going to write a big description - and I might yet.

But the short version is, it looks like the big fat line fro the back of the manifold feeds into a dual-output port on the backside of the throttle body. The various sublines branch-out from there in two main sub-line routes.

Now I just gotta finess some new lines into the old connectors. Some of those connectors pretty ordinary 90-degree, or Tee. Others not so much run-of-the mill. Might try to get a few spares before I ruin the only ones I have.