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Finding Vacumn Leaks?

originalxj

NAXJA Forum User
Location
XXXX Naxja
OK so I have a heater that blows thru the defrost. I figured its a vacumn leak but how do I find it? And please don't respond, "dah just look around and look at the connections". Done that. Found nada. I'm looking for how to use a more logical or technical, well thought out approach. Possibly using one of those vacumn tools?
 
I've never tried this, but it has been previously posted to blow smoke (cigarette, cigar, etc) into lines and see where it comes out. Poster swore it worked good for him. Was he just blowing smoke?

Or if you had a little pump (like a cheap aquarium ais pump) to pressurize the lines, you could use soapy water to find leaks.
 
Well I'm not really sold on the smoke idea but the pressurization idea might have merit. I have an air compressor so thats not a problem.

Thanks. Has anyone used the vacumn tool?
 
Hallo. You can use a piece of rubber tube and stick that in your EAR.
Now you can searching for hissing sounds of vacuumleaks , isolated from the sounds of the engine.
You have to move and turn the vacuum tubes, especially the elbows. They are always the culprit.
This is not a yoke and watch out for moving engine parts!
This is a very cheap tool.

'92 XJ
 
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for YEARS, ive read that you can spray brake cleaner or anything else REALLY FLAMMABLE, around vacuum lines, and if you find a leak w/ the engine running, you'll be able to hear the engine rev up from the extra fuel....

ive never gotten it to work though... i usually just listen.
 
First off, what year model and engine?
 
First off, what year model and engine?

91' 4.0L 280K+ miles, runs great passes CA Smog II with no problem just a month ago. No hesitation or other signs of engine vacumn loss.

What I've tried -

Looking at everything except under/behind dash. I only listened there. I've listened under the hood, nothing. This is why I'm posting this question. There is no visable or audible signs of a leak. If it was that simple it would have been solved.

Thanks
 
that works with propane, but you have to disconnect the IAC first. actually it'll work with anything flammable like carb cleaner or whatever but propane won't pool up and is easy to target on a specific spot

x2 use one of the little propane torches you get form wallmart or lowes and run it along the lines with the propane on. The engine will rev when you fing the leak.
 
ooh, so you could just use a propane torch, but dont ignite it!
gotta remember that one!

You are right, to avoid ignition, better to use a small propane torch.
If you are a smoker, it's a habit to ignite things,especially with a lighter, it is one small move, you know.:flame::flame:
 
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You can use a mighty vac and see if it pulls a vacumm, also I one time didnt realize that I had a crack where the canister mounts to the bumper, and I didnt notice it till I took of the Jeep
 
You could hook up the vacuum pump (Mityvac) to the temp actuator to see if it works. So far, you don't really know if you have a leak, but if it works with a Mityvac, you probably do. Or the switch isn't turning the vacuum on?
 
You could hook up the vacuum pump (Mityvac) to the temp actuator to see if it works. So far, you don't really know if you have a leak, but if it works with a Mityvac, you probably do. Or the switch isn't turning the vacuum on?


OK now we're getting somewhere! What is this "switch" and where is it? And where is this "temp actuator".

Thanks. BTW nice weather your having in the Great Lake State. Here in NorCal its about 60 and not a cloud in the sky. But hey, our economies are about the same!
 
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