Any common spots for a vacuum leak on the driver's side of the engine?

[zwoobah]

I replaced the plugs & wires this past weekend, and noticed what sounds like a vacuum leak from the driver's side area of the engine. I've also noticed my brake pedal getting a little spongy, and my idle has gotten lumpy - both point to a vacuum leak. Any common spots to check? I'm planning to spray a little ether on the connections with the engine running, but didn't know if there was one particular spot I should focus on. Thanks!

 

[Tbars4]

sounds like you have dry hoses and while you were changing parts you probably leaned on one and it cracked...i would check with the vacuum line at the brake booster first, and then i would check from your charcoal canister to the engine....either one of those with a crack in it would do that...what i usually do is start replacing hard hoses that might be ready to crack with new ones...this is the time of year to do it...you can get 6' of hose for like five bucks...

 

[Glacier991]

At the back of the driver's side head is what is called the "Octopus"... many hoses connect there. Check that first. Also check the vacuum modulator on the auto trans... prone to break a diaphragm and leak....

 

[zwoobah]

Thanks guys. I will start relacing all the vacuum hose this weekend.
Glacier, is the octupus a 3-connector metal fitting? I was looking at that when I first heard the leak - mine looks pretty rusty. It's not the auto trans vacuum modulator since my truck is a 5-spd.

 

[mikeinri]

The "octopus" is also commonly referred to as the "tree" on this forum. Lots of postings here about this issue. It is located at the rear of the engine, on top, on the driver's side. One line does go to the brake booster.

Besides the hard vaccuum lines, there are numerous rubber connectors to connect the hard lines to the tree fittings. I believe these are dealer parts, and it is common for them to stretch over time and not seal completely on the tree fittings.

Hope this helps.

Mike

 

[Tony H]

If you did the wires correctly and unclamped them as they went around the back of the engine you probably knocked a vacuum line off that tree.

It's on the upper Intake Manifold all the way back by the Firewall. there are , like 5 lines and one plugged off section going to it.

Follow the hose on the PCV valve then look up a little higher

 

[shamaal]

Another Navajo!
Picture of tree below. Common spot for leaks is the grommet on the brake booster. I got mine gooped up; someday I'll replace the grommet. Other than that follow th lines from the vacuum manifold (octopus). on the drivers side is the fuel purge switch. Check back if other questions.

 

[zwoobah]

Ok, I checked into the vacuum leak at the tree. If I spray ether in the area the idle speeds up, so this is definitely the source of the leak. The small vacuum line closest to the firewall is snapped completely off whatever it's supposed to be attached to. I probably broke it while clipping the wires to the back of the driver's side head, and now I can't find the other end. Where's it supposed to go?

And here's a pic of the truck, before and after new wheels. Put a set of 2000 Explorer Limited wheels on it today, and will be selling the old 15" Navajo wheels. Went with the 16" Limiteds because they came with good 16" tires...which will allow me to swap the new 16" Yokohama Geolandar AT+IIs off my girlfriend's truck before it goes back at the end of it's lease

Also figured out why the 4x4 isn't working...the auto hubs are packed full of nice fresh bearing grease...d'oh. Gotta get those cleaned out and working, then finish replacing the brake lines and the truck will be back on the road.

 

[shamaal]

Looking Good! I'd post mine but the clear coats worn off and it looks like crap.

The small lines go through the channel along the firewall.
One goes to the vacuum switch that goes to the vacuum reservoir (just aft of accumulator in pic below) The item labeled switch is the A/C pressure switch. You want the three tubed switch.

The other goes to an extender that goes to the bimetallic switch on rear of air filter box on the passenger side.

Replacement tubing and connectors can be gotten at O'Reilly's. First thing to do would be to cap off the leak at the tree. The end of a bic pen fits nicely.
The two vacuum tubes feed the outside air damper and the hot/cold air intake mixer. The car will run well without them, but not with a leak at the tree.

 

[UKExploder]

Since the brake pedal is spongy as well, I'd check the line to the brake booster 1st, then check the others. Spongy brakes can mean that line may soon burst & the brakes not work properly. not good news!

 

[zwoobah]

OK, did some more work on it tonight. The good news is that I fixed the problem. The bad news is that there are 3 connections on the vacuum manifold that don't connect to anything at the moment. This includes both of the connections that face directly toward the firewall, and the connection circled in this pic:

The smaller one facing the firewall is supposed to go to the bitmetallic switch on the airbox, as shamall suggested. I don't know what the bigger one facing the firewall or the small one circled in the pic go to. Any ideas? They're all blocked off at the moment, so the truck will run. Thanks!

 

[shamaal]

You should have a sticker next to your hood latch to looks like the one below. In addition there is a line that goes from the vacuum manifold to the three port vacuum switch as shown in my previous pic. That looks like the one you are missing. Also one port is capped off unless you have an automatic transmission.

 

[Tony H]

One on my car is just capped off, maybe you broke the cap off or it slid totally off when clipping te wires behind the engine. If you don't see a hose that fell back by the firewall you might want to just plug the open nipple.