Air leak in 99 LTD

[agolfr]

Somewhere I have an air leak that becomes audible starting at speed over 30 MPH. I can't locate it. To the driver it seems to be in the rear, rear passenger says it in the front. I have inspected the door seals (all seems well) and applied a film of vaseline to them. Windows seem to be snug. Is there a technique shops use to find air leaks?

 

[CDW6212R]

You can use a piece of narrow paper to place in the door jamb. It shouldn't come out with the door shut.

From a couple of leaks that I have had, check around the side mirror housings, and the fender seals. A noise can be heard if the mirrors aren't sealed well to the doors.
Also, there is a noise deadening piece covering the back opening of each fender. Often times body shops will not reinstall them, and a noise appears from around the mirrors. LOL,
DonW

 

[Heavymentill]

This is my theory of finding a air leak. I took a cigarette and while someone else was driving went around all the seals . You could probably use insence if you don't smoke.

 

[MONMIX]

It is a hit and miss process.
CDW had great advise. Use a one dollar bill and shut it in the door. It should pull out real snug not easy.

Another way to track is down is by process of elimination.
Take some inch and a quarter masking tape and tape closed each gap one at a time as you drive around the block.
Mind you I DO NOT mean tape wile driving !!!!!!!!!!
Drive, stop, park, tape, drive.

 

[agolfr]

Thanks for your help. I think I'll try the masking tape.

 

[CDW6212R]

Good luck. Don't leave the tape on though, once you find the leak. I put some around my drivers mirror for a trip. It was hard to remove the glue two months later.
DonW

 

[MONMIX]

Oh yeah, thanks CDW !!!!!!!
yeah the tape is not to FIX the problem but to locate it

 

[Glacier991]

A shop should have an ultrasonic transmitter and a receiver. You turn on the sender/transmitter and place it in the car and shut all doors, then go around all the door seals with the receiver (sniffer) and try and find leakage. Works like a charm in finding leaks... see if any shops have one. I happened to find one on E-bay a few years ago at a very good price, so on a lark bid on it and won it. Cost me $50. The receiver is also good for finding vacuum leaks. (they emit ultrasonic frequencies). Can post pics if you are interested.

 

[MONMIX]

^^^ Now that is a toy I could use !!!!!!!!!!!!!!!
Does that tool have a real name ?

 

[Glacier991]

It is called an ultrasonic leak detector. They come just as a receiver, and some also come WITH a transmitter (VERY HANDY, and essential for finding door seal leaks). E-bay will have them from time to time, has a couple now in fact, one with a transmitter. I'll post some pics of mine tomorrow.

 

[MONMIX]

cool.
as you may imagine in my trade there is a thousand opportunities to use one !!!

 

[CDW6212R]

Cool, I'll add that to my wish list too.
Don

 

[Glacier991]

I promised you pics and the story. Here is my Leak Detector. I picked mine up off of E-Bay for about $75 ( I reported above it was $50 but on checking I see that with shipping the total cost was closer to $75). It is called an "Vacuum leak detector"... here is the label on the blowmold case...

The kit consists of a handheld ultrasonic "sniffer" (vacuum leaks emit frequencies in the ultrasonic range) this one was missing some extra tiny "snoots" to really hone in on leaks in manifolds etc (I have used this to roughly detect a manifold leak in my Merc Sable, just haven't chased it totally down yet... but it is great for tracking those pesky vacuum leaks.... anyway here is the hand unit...all you need to trace vacuum leaks.... (ok well some of the snoots would be nice but I can make some out of corks and brass tubing)

In addition there is a battery powered small ultrasonic emitter. To leak check car window/door seals you put the emitter in the car, turned on, and run the "sniffer" around all the seals. I have succcessfully narrowed a wind leak in my moon roof to a 2 inch area... Here are a couple pics of the whole setup

and

It works great for leak detection standing still. One thing often overlooked is that old soft seals can "open up" when the passenger cabin is pressurized by incoming air, creating a leak that won't show up when you are sitting still. A good idea is to run the cabin fan (or AC fan) on high as you leak check.

These show up on E-Bay from time to time. I think mine is a magic ace in the hole on occasion. A worthy addition to a tool kit.