Using Leak Detection Dye

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I'm trying to track down and confirm a potential rear main seal leak. I bought a 1 oz bottle of Tracer Products LeakFinder leak detection dye for oil-based systems (Link) and added it to the engine oil. After cleaning the area really good with engine degreaser, letting it dry, and taking the car for a drive, I can see the area starting to darken as if some oil is seeping. However, when shining a UV LED flashlight that I bought from Amazon (Link) on the area, I don't see it glow fluorescent yellow/green as expected. Shining the light in the empty bottle doesn't glow either. I don't need some kind of special light, do I?
 

barlowc

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What do the directions for LeakFinder say?
"Scan the system with a fluorescent leak inspection lamp. Leak glows bright fluorescent yellow-green."

I initially wondered if the dye just hasn't made its way through the system yet. But I'd think that when I shine the light on the remnants of fluid in the bottle, I'd get some glow.
 
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"Scan the system with a fluorescent leak inspection lamp. Leak glows bright fluorescent yellow-green."

I initially wondered if the dye just hasn't made its way through the system yet. But I'd think that when I shine the light on the remnants of fluid in the bottle, I'd get some glow.
Look at the contents of the bottle with your LED light in a dark room.

You can get a cheap incandescent UV light bulb at Home Depot and screw it into a work light.
 

barlowc

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A 12 LED light is too weak. Use a 100 LED light, and use it after dark.
The UV light needs to be the correct wavelength for the dye. The manufacturer of the dye can tell you what you need.

David
I picked up the leak dye manufacturer's kit containing a UV leak detector and protective glasses. No difference. Their light contains 9 LED bulbs whereas the one I'd already bought has 12. At this point in time, I have to suspect that either a) the dye is defective, or b) the dye has not mixed and made its way though the engine yet. I'm going to drive the car some more and continue to examine the area where there are signs of a suspected leak.
 
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I picked up the leak dye manufacturer's kit containing a UV leak detector and protective glasses. No difference. Their light contains 9 LED bulbs whereas the one I'd already bought has 12. At this point in time, I have to suspect that either a) the dye is defective, or b) the dye has not mixed and made its way though the engine yet. I'm going to drive the car some more and continue to examine the area where there are signs of a suspected leak.

Just because it comes as a kit, doesn't mean it's good. 12 LED's isn't enough.
 
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I think you're using leak dye that really isn't very good. I've been using Bright Solutions 4-in-1 dye for a long while now.


This is what it looks like with the lights on the far side of the garage on:
20220927_143732_resized_annotated.jpg


The above image was illuminated with a 2-cell, AAA penlight that has one UV LED. IIRC, the penlight came with an AC leak detection dye kit. It's plenty "bright" enough.
20220927_144010_resized.jpg
 
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Your dye is defective if you can't see any trace of it under your uv light. No matter what size uv light you have, a bit of residual dye in that bottle should fluoresce like crazy even in broad daylight.
 
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