Fluorescent oil dye is neat stuff

chris snell

Administrator
Callsign: NW5W
Staff member
I have been fighting a persistent oil leak on my 300Tdi lately. I wasn't sure exactly where it was coming from but it was leaking down the back of the motor and dripping onto the exhaust. I suspected a rear main seal leak initially but quickly ruled that out after inspecting the access hole on the bottom of the bell housing. I next considered a head gasket. I asked my friends for advice and one of them told me to get some flourescent oil dye.

Last week, I bought some Tracer Products Dye-Light leak detection dye, along with a little 396nm UV flashlight. I did an oil change and added two bottles of the dye (double strength) and drove the truck for a few days of lunch runs and kiddo football practice trips. I went out there tonight and this is what I found:

It looks like I have a leaky rocker cover gasket. The leak was so slight back there that I couldn't even really see it during the day. I assume that when the motor is hot and under pressure, it weeps out back there at a pretty good rate. I'm going to replace it tomorrow and do a valve adjustment while I'm at it.

41E3B41C-3CF8-4840-8C6D-4C739D2F081A.jpeg
 

SouthTexasRover

Member
Callsign: KF5AAM
looks like a crime scene photo.
I used fluorescent dye on my father in laws car to find a leak in his AC told him to drive around for a few days so we can see the leak and then completely forgot about it and to this day I still haven’t fixed his leak.....

 

Z.G

Well-known member

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
So I used a bottle of this stuff about a year ago, but it took a lot of very careful looking to find any of the dye. I think it was because I had multiple leaks here and there, so the oil wasn't heavy enough in any one spot to allow for the dye to work. In my case, it didn't allow me to see where the oil was coming from. Once I got the lights turned off, and figured out what I was looking at, the dye was very dim here and there, with no spot being a place that could be a leak. For instance, one of the places where I could see the dye, was on the frame.
 

bearskinrug

Well-known member
So I used a bottle of this stuff about a year ago, but it took a lot of very careful looking to find any of the dye. I think it was because I had multiple leaks here and there, so the oil wasn't heavy enough in any one spot to allow for the dye to work. In my case, it didn't allow me to see where the oil was coming from. Once I got the lights turned off, and figured out what I was looking at, the dye was very dim here and there, with no spot being a place that could be a leak. For instance, one of the places where I could see the dye, was on the frame.
I tried some of this to better pinpoint a coolant leak on my D1 once but when I looked with the black light everything lit up. It was like a murder scene, didn’t help me much.
 
Top