Does anyone have experience with finding the source of oil leaks with dye? Finished my engine rebuild and I have oil leaks near the valve covers. I have resealed them twice (the second time using pricey new valve covers. I also have a leak near the rear main (crank pulley). Unless I get better advise, I plan to try the dye technic and then pull the engine again. Yes I am a little discouraged. Any ideas?

 

Best approach is to clean the engine thoroughly drive it a short while and look to see if you can find the source. Not sure a dye will work with motor oil.

 

The crankshaft nose-bearing is a notorious leak spot. Not sure if you split the case and replaced yours during the rebuild. I replaced all of the seals that I could without splitting the case, and I have a very light weep coming from there.

The rear main seal is on the flywheel side. Rear, in our case, means toward the front of the car. New seal there should be enough unless it was nicked on installation.

No suggestions for the valve covers. I used to smear some oil on the gaskets, now I rub them in molykote (dc55) so that the rubber swells and they really seal. I haven't had any leaks with either method and I always reuse the gaskets at least once. You use a 3/8" torque wrench and torque the nuts correctly?

 

Dyes work very well with motor oil; one simply needs to use the correct one as its different from coolant dyes and others.

Its a well-proven method for finding stubborn and obscured leaks.

 

Do you have any suggestions on which type. Have a problem with a machine that is leaking and we cannot locate the leak. It is a bear to take apart due to its size. Spoke to the manufacturer and they said there is no dye that works with gear oil. Maybe motor oil is different.

 

Thanks

 

Thanks

 

Are your valve covers leaking? I had one leak after a valve adjustment, and used Curil-T on the gasket to seal the leak.

 

Thanks for your suggestions! Based on them and another thread ("curious oil leak") I now suspect the oil line soft plugs in the cam towers may be leaking as I had them replace by my machinists.
My plan is to add the UV dye to the motor oil then run the engine long enough to circulate the dye. Then unless I can find something obvious, I will pull the engine to fully inspect.

 

I am curious what dyes you might be using? I have worked with a lot of UV dyes and most of them will remove the paint off of anything as fast as brake fluid or aircraft stripper. How will that impact the seals and other materials and how do you flush it out of the system after you are done?

 

I got the dye from my favorite auto supply store. Can't give you the brand. The direction state that it may remain in place and came with a engine sticker that would notify future mechanics of its presence. Since I will be removing the engine the oil will be changed.