[TX3100Guy]

Originally Posted by dsraven

ok, as a journeyman heavy duty mechanic, I have seen my share of hard to find oil leaks. I have used the dye and several other methods of detection but here is what I would suggest to do after jacking it up and setting it on stands at the same angle it normally sits at when it is on the ground. this is going to assume you have already checked for an internal engine venting problem, the oil level is correct when hot, the oil grade is correct and not diluted, doesn't have a gassey odor like it is diluted, the fuel pump has been checked for any leakage at the vent hole and gasket, the water pump weap home is dry, all the hose clamps for coolant etc are tight and don't show signs of weaping, etc etc
-1- start the engine and warm it up to get the oil warm and as thin as it is gonna get
-2-let it sit for a bit to give any oil sitting in a seal lip or anything like that some time to finish finding its way out.
-3- if you have any loose paint or rust in the area scrape that off as sometimes it can hold the old moisture behind it. I use an old wood chisel for this and it works pretty well. wire brush the area if you can access it.
-4-check all the gaskets to ensure there isn't one that has a missing piece or has been overtightened and is squished out. look at the front crank seal as good as you can to see if there are any "clean" spots where the oil leak has washed away everything. also check the oil pan and front cover for wet spots that re-appear after wiping off. these can be caused from pin holes rusted through from the inside.
-5- spray copious amounts of brake cleaner on the area and blow it all dry starting at the top and working down from there. ensure to clean out any blind bolt holes etc. if you have any damp areas respray those. do the area around the crank pulley and any gasket surfaces as good as you can. keep an eye out for any spots that seem to re-wet themselves as those can be where the problem is.
-6-get some good lighting set up. personally I use a small LED penlight that is super bright and can fit into tight spots. have an inspection mirror handy and set yourself up to be able to crawl around under the truck. if you have a hoist, awesome. set it low enough so you can see up as far as possible on the engine
-7- start it up and let it run for a few minutes, long enough to show up any oil leaks, then shut it off and get under there with your light and mirror. if you find a leak keep working your way up until the wet spot dissappears and then check very carefully in that area.
-8- if still having trouble you can try sealing up the obvious leak spots, like the oil filler or vent cap and then apply a slight pressure with compressed air (and an air pressure regulator) through the dipstick tube. then recheck as above.
-9- I have used the dye as a last resort because I find once the dye is outta the leak it seems to spread all over along gasket surfaces and casting bumps and you spend more time cleaning the area and positioning the blacklight that you do actually looking. I mean, sometimes it is obvious, but for those hard to find leaks I always do the other way first.

if you have the engine jacked up be carefull starting it as sometimes the fan can interfere with the rad or hoses or wiring or a fuel line can get stretched etc.

This is an awesome check list of things to do. Honestly, I've already done some of them, but not all. I will be using this list to guide me in my search. Thank you very much!