Replacing Vacuum Lines

[Freakzilla69]

I'd like to replace all the vacuum lines on my '98 GL this weekend.

I figure, they're all old, probably original, and if one is leaking (I've got 0171/0174 codes) chances are there will be more leaks in the future.

I was hoping to get the benefit of the cumulative knowledge here by asking for any tips on the replacement.

I've already replaced all the big hoses, I want to do the small ones now.

Questions:

1. Anyone know what size line I should use? Are the small ones all the same size?

2. How about the size of the connectors on each end? Are they all the same size?

I suppose if worst comes to worst I can take one off and run up to the parts store to size them but I was hoping someone here would know so I can just pick up the stuff on the way home. Any tips at all would be greatly appreciated.

[busboy4]

Hi

My van is a '96, but I have had all the semi-rigid lines out at once. They are somewhat "ganged" together on the '96 and you can maneuver them out of the engine compartment - did it when the cowl was off by the way. I see your biggest issue being the connections. The "main" vacuum accessory line on my van has one connection and two hoses coming off of it. There are also places along the lines where there are junctions allowing one line to pull from another. I am concerned that you will have difficulty re-engineering what is in there.

I wish you luck, but I would be careful. I don't think it is as simple as buying a bit of line and putting it in there. I could be wrong. But, I would advise you to pull it all out "in masse" first and then try and replicate what you see once the lines are out of the protective "sleeves". I think you may find it a bit more intricate than you might guess. Perhaps you can test the lines while out- I did that to some extent, and find a leak.

Good luck

[Freakzilla69]

I know what you mean, I'm looking at the vacuum diagram I found at the AZ web sight... I'm getting dizzy.

How do you test them when removed, blow through them? What if it's leaking at a connection?

Oh well, I guess I'll remove them and take it from there.

[busboy4]

Originally Posted by Freakzilla69

I know what you mean, I'm looking at the vacuum diagram I found at the AZ web sight... I'm getting dizzy.

How do you test them when removed, blow through them? What if it's leaking at a connection?

Oh well, I guess I'll remove them and take it from there.

As I recall, I did blow through them while they were out. I do have a hand vacuum pump but it was a little too cumbersome at that point. I plugged the ends with various bolts/screws first. The inter-connectivity of the lines will be obvious to you at that point.

Do you have anything to go on besides the 171/174? IMRC codes, evap canister, EGR or anything else to help direct your search? I am thinking that it would be hard to have a leak in one of the semi-rigid lines and not have other issues too. Off the top of my head, those lines all "power" other items.

Keep us posted.

Good luck

[busboy4]

One other thing:

I had a rather large hole in my vacuum line "powering" my A/C system. It was enough of a leak that all I had was defrost with no ability to change the setting. It did not however cause the van to run rough, nor did I have any lean codes. I guess to some degree I'm trying to steer you away from trying to replace all those lines, although I cannot say I have concrete evidence that doing so is the best bet.

[Winny_the_Pooh]

Not sure if this helps but here goes. I had to replace the vacuum line assembly on my 96 3.8L because I broke it when removing it for the lower intake gasket repair. I think it is all one assembly because of the molded boots. It cost around $130 from Ford.

[Freakzilla69]

Originally Posted by busboy4

As I recall, I did blow through them while they were out. I do have a hand vacuum pump but it was a little too cumbersome at that point. I plugged the ends with various bolts/screws first. The inter-connectivity of the lines will be obvious to you at that point.

Do you have anything to go on besides the 171/174? IMRC codes, evap canister, EGR or anything else to help direct your search? I am thinking that it would be hard to have a leak in one of the semi-rigid lines and not have other issues too. Off the top of my head, those lines all "power" other items.

Keep us posted.

Good luck

Yes, the next two posts after yours.

My A/C is stuck on defrost and I recenty changed the intake plenum and manifold gaskets.

I now have only one question.

Where does the vacuum hose for the a/c leave the engine compartment and go through the firewall?

It's not shown on any diagram.

[Freakzilla69]

I took your suggestion and removed all the vacuum lines and tested them and none leak.

However, I could blow through the line going from the vacuum reservoir through the firewall, I assume that is the A/C controller correct? I disconnected it and put a plug at the reservoir "T" connection.

I also made sure the line going to the IMRCs was disconnected and plugged at the split to each controller.

I'm still getting the 0171 and 0174 codes. Also, now and then I get a 0300(?) I cant remember the exact code but I think it was a general misfire.

I'm thinking it must be one of the controllers in the vacuum system.

Possibilities:

Fuel Pressure Regulator
IRMC Solenoid
Vacuum Reservoir
Brake Booster
Evap Purge Solenoid

I think I might just save up my pennies an take it to the dealership for a diagnosis and see if they can pinpoint the problem.

[Freakzilla69]

Where is the check valve on the '98 GL? I haven't checked the check valve, is it called something else?

[busboy4]

Originally Posted by Freakzilla69

Where is the check valve on the '98 GL? I haven't checked the check valve, is it called something else?

The one I was referring to should be on the A/C line between the vacuum reservoir and the firewall.

Have you very carefully checked your pcv lines? Particularly the rubber elbows for cracks/leaks?

[Freakzilla69]

Originally Posted by busboy4

The one I was referring to should be on the A/C line between the vacuum reservoir and the firewall.

You mean the little plastic part right at the connector? I blew through it one way but couldn't the other, I assume that's how it works to hold vacuum in the reservior right? Maybe it's on backwards, I'll check that too.

It's should allow air to go from the reservior to the engine and not the other way, correct?

Have you very carefully checked your pcv lines? Particularly the rubber elbows for cracks/leaks?

I replaced those when I changed the intake gaskets. I got rid of the elbow and just used a length of apropriatly sized hose. It goes from the top of the intake plenum to a "T" conector then to the PCV valve in one direction and to the EVAP Solenoid in the other.

I suppose it could be leaking at that T connector. Maybe one of those little hose clamps didn't get tightened. I'll check that... boy would I feel stupid if that was it.



BTW, I also replace the other large hose going from the plenum to the brake booster.

[Freakzilla69]

I just pulled off the line to the reservoir and I heard the hiss of the vacuum escaping so I guess it's not the check valve.

[Freakzilla69]

How long does it take the vacuum reservoir to fill (or empty I guess)? Would that take long enough to get the "mix too lean" codes?

I'm starting to think maybe it's not too much air but too little gas. I cleaned out the injectors as best I could when I replaced the intake gaskets. I used Sea Foam in a spray bottle. I also poured a can of it in the gas tank.

I replaced the fuel filter less than a year ago.

Fuel Pump maybe? Does the pump go out slowly or is it a work/doesn't work type thing? Would it get gas at all if it was bad?