What is Oppo's favorite method of finding vacuum leaks?

"Decay buys too many beaters" (decay)
10/11/2016 at 16:12 • Filed to: None

I’ve been playing around with the !!!error: Indecipherable SUB-paragraph formatting!!! over the last few weeks.

While the misfire went away with a replacement coil pack the car is running real lean on throttle and throwing bank 1 lean codes. I’ve already checked fuel pressure, and cleaned the MAF (furthermore, disconnecting the MAF still makes it run lean) so I’m down to either o2 sensors or a vacuum leak. I tried to hook up a party smoke machine to a vacuum line but didn’t really get me anywhere as I do not believe it puts out enough pressure to fill up all the voids. I bought a cheap smoke tester off ebay ( !!!error: Indecipherable SUB-paragraph formatting!!! , actually looks like a decent design and I don’t think I could do the same for cheaper) but I’m still waiting for it to come in. So anybody have any other good ideas I could do to check for gross leaks in the meantime?

DISCUSSION (30)

Frank Grimes > Decay buys too many beaters
10/11/2016 at 16:14

propane or

SidewaysOnDirt still misses Bowie > Decay buys too many beaters
10/11/2016 at 16:16

Spray starter fluid at your hoses until you hear the revs change.

not for canada - australian in disguise > Decay buys too many beaters
10/11/2016 at 16:16

i usually look for holes in my vacuum cleaner

petebmwm > Decay buys too many beaters
10/11/2016 at 16:18

smoke test

HammerheadFistpunch > Frank Grimes
10/11/2016 at 16:18

Yeah, I was going to say propane

Decay buys too many beaters > petebmwm
10/11/2016 at 16:19

Real machine? or a contraption like the one I bought?

Decay buys too many beaters > not for canada - australian in disguise
10/11/2016 at 16:20

Kinja'd!!!

Decay buys too many beaters > SidewaysOnDirt still misses Bowie
10/11/2016 at 16:22

Doesn’t work on the jag, I’ve tried, only place left is right over the exhaust manifold and no thanks on that.

Party-vi > Decay buys too many beaters
10/11/2016 at 16:25

USE FLEX SEAL ON THE ENTIRE ENGINE! WOW! NO MORE LEAKS!

Decay buys too many beaters > Frank Grimes
10/11/2016 at 16:26

Hadn’t heard of using propane, but makes sense. Worth a shot

Decay buys too many beaters > Party-vi
10/11/2016 at 16:27

Kinja'd!!!

crowmolly > Decay buys too many beaters
10/11/2016 at 16:27

Method 1: Hook a vacuum line up to an air compressor to pressurize the system (maybe 20 psi?) and listen for hissing.

Method 2:

Kinja'd!!!

iSureWilll > Decay buys too many beaters
10/11/2016 at 16:28

I’ve always used brake cleaner but tend to not spray towards hot things like exhaust manifolds. If the hoses are cheap, you could just try replacing a bunch of the vacuum lines and see if it helps, but you could have a leak around the intake manifold or something where replacing hoses wouldn’t help.

As others have said, smoke machine would probably be your best bet.

Or pick up vaping :)

Decay buys too many beaters > crowmolly
10/11/2016 at 16:31

I was under the impression that much positive pressure in the vac system would break things? That’s why all the real smoke testers are regulated to less than 1.5 psi.

Decay buys too many beaters > iSureWilll
10/11/2016 at 16:33

Can’t vape, I drive a Subaru but have self respect :(

crowmolly > Decay buys too many beaters
10/11/2016 at 16:34

Start low, maybe 5 and then work your way up? I’ve never had an issue at a higher pressure but that doesn’t mean you won’t. As long as you hear a hiss.

petebmwm > Decay buys too many beaters
10/11/2016 at 16:49

i’ve always used a real machine, mainly because i have access to one...the party machine should work, it fills untill it leaks, you just might mot be seeing it if its not a lot...

Dave the car guy , still here > crowmolly
10/11/2016 at 16:55

Propane works well. I used to have a GM shop tool by Kent-Moore that was for propane enrichment during tuning carbs but I used it more for searching out leaks than its real purpose. Sold it years ago before most ended up on ebay for dirt cheap prices.

SantaRita > Decay buys too many beaters
10/11/2016 at 17:02

i’ve used a cigar to smoke test before successfully on a turbo passat.

hook a hose to the take off on the manifold and start puffing into it.

I’ve used the maf cleaner/starting fluid methods as well but smoke test was my most conclusive because that stuff sprays a wide mist.

good luck.

Frank Grimes > HammerheadFistpunch
10/11/2016 at 17:26

usually i just look at all the hoses and if they are shabby replace them. Its cheap enough.

HammerheadFistpunch > Frank Grimes
10/11/2016 at 17:29

True nuff , unless its one of those stupid OE shaped hoses that go to a special fitting.

Die-Trying > Party-vi
10/11/2016 at 17:40

if flex seal can turn a screen door into a floor for an airboat, vacuum leaks dont stand a chance.............

V8Demon - Prefers Autos for drag racing. Fite me! > Decay buys too many beaters
10/11/2016 at 17:44

the car is running real lean on throttle and throwing bank 1 lean codes. I’ve already checked fuel pressure, and cleaned the MAF (furthermore, disconnecting the MAF still makes it run lean) so I’m down to either o2 sensors or a vacuum leak.

1. DO you have a tester that will show OBD II real time data such as the O2 sensor switching?

2. Do you have one of these????

Kinja'd!!!

If not; get one. It’s been masterful with a couple of nagging issues with my old OBD-I car. Smooth idle,good power. Problem with cold start. Found the vacuum was consistently a bit low. Found my issue and the problem went away. I’ve had a couple of head scratchers that were vacuum related since that were made much easier by my vacuum tester.

Check out the following link: http://www.secondchancegarage.com/public/186.cfm

Decay buys too many beaters > V8Demon - Prefers Autos for drag racing. Fite me!
10/11/2016 at 17:49

Yes, have one of the OBD2 android dongles that works pretty well for diagnosis, but do not have a vacuum gauge. Thanks for the tip and link!

Rykilla303 > crowmolly
10/11/2016 at 18:05

propane for the win. use soldering torch, open valve, wave around and listen for RPM increase.

Land_Yacht_225 > Decay buys too many beaters
10/11/2016 at 18:29

Attempt other, non vacuum related repairs on the engine, break many brittle vacuum lines in the process, replace said broken lines with rubber hose and clamp bridged new vacuum lines, have brand new vacuum lines.

Dr. Zoidberg - RIP Oppo > Decay buys too many beaters
10/11/2016 at 18:54

I turn up the idle screw on the carburetor and go back to not finding the leaks.

Frank Grimes > HammerheadFistpunch
10/11/2016 at 22:32

theres always that. also those hard plastic one that are like shrinked onto some plastic nubbin fitting.

AMGtech - now with more recalls! > Decay buys too many beaters
10/11/2016 at 22:45

I worked with a jaguar master tech once upon a time. I seem to remember him telling me there were issues with the crankcase breather system that would set faults. We used to do a lot of throttle valves at the rover shop (LR3 with jag ajv8), but I can’t for the life of me remember why.

gmporschenut also a fan of hondas > Decay buys too many beaters
10/12/2016 at 23:34

Not sure about diagnosing, O2 sensors. As they vary voltage maybe try unplugging the wire and see if it runs even leaner? I’m not sure I’ve never had to fix an 02 sensor.

Kinja'd!!!

As for hose leaks I’ve had some experience with this. With the engine running, pinch the hose ends and listen for any changes in rpms or sound. If anything does make a change put a hose clamp on it. (non marring one is better)

Kinja'd!!!

Also would look into replacing any hoses that look cracked.

If its running lean, so its getting more air than it should, I would check any hoses after the MAF