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Is it safe to use fluorescent dye in rotary engines to detect oil leaks? I searched but didn't find a clear answer.
I wiped off the old oil and road grunge as best I could, but still can't ID the leak source but it seems to be on the passenger (right) side of the engine. The rear turbo shaft seal has had a very slow, small external oil leak for about 23 years -- a drop at a time occasionally falls from the compressor housing down onto the motor mount heat shield and then gets onto the subframe and oil pan. Suddenly I'm now getting a bit more drippage. I've TENTATIVELY ruled out some of the usual suspects -- the MOP lines and O rings, oil pan gasket, turbo oil feed and return lines. Anyhow, before I start yanking ducts and hoses to get a better view of the turbos, etc., I thought of using a UV dye in the engine oil to locate the leaks.
Is is safe? Yes. Is it going to tell you anything you can't see already? Probably not.
Looks like the front shaft seal for the secondary turbo is going out. You can see oil/wetness where the inlet duct bolts to the turbo. That's my guess.
fwiw, I have found it helpful in identifying where leaks are coming from on my car. Needed to put some miles on it in order to see where the oil was coming from. I had thought one of my leaks was coming from the oil filter pedestal and was getting ready to remove that to 'fix'. The dye revealed that it was actually leaking from the plastic oil filler nick where it meets the block. Would have never thought to check that if it wasn't for the dye.
Thanks for the advice. I bought a dye kit and will report what I find.
The leak shown in my photo - from the rear turbo shaft seal - has been very slow. It has been there many years and has not been a problem worth fixing, but recently the amount of leaked oil running down onto the oil pan, subframe and garage floor increased. I haven't been able to tell if that old turbo leak just suddenly got worse or if there is a new leak. Without a lift, it's hard to get a good look at each possible leak source. I thought the pan gasket (replaced 20 years ago) or the OMP O rings (original) might be to blame, but after I cleaned off as much of the old oil and sludge as I could reach, they looked ok.
Other than a little smoke on cold starts or when first hitting boost, the exhaust looks clear. I suppose I should check the intake duct for excess oil accumulation as evidence of whether the turbo leak got worse.
Clean everything up well with brake cleaner, add the dye, and take it for a drive. There's not many places for oil to leak on that side of the engine, it's either the turbo oil feed (which I've NEVER seen leak), the turbo oil drains (which I have seen leak, esp. with original paper gaskets) and the turbos themselves.
Thanks Dale. That is pretty much the plan, although in such cramped quarters I always manage to ricochet brake cleaner back into my face. I've cleaned most everything already, but there are a few inches of pan gasket by the engine mount heat shield that I can't see, and I haven't had a chance to view the top side of the OMP or all of the ends of the turbo oil return lines yet.
For cleaning and degreasing, the POR15 Degreaser is the best that I have ever used. I jacked up the front of the car and sprayed that liberally on the underside of my engine and subframe. I scrubbed some areas with a nylon kitchen brush and agitated other areas with an old rag to try and scrub off as much gunk and oil as I could. Then hosed off. https://www.por15.com/POR-15-Cleaner-Degreaser
I've never heard of that stuff, but I see a local auto parts store sells it. I like that it is safe on plastic. The brake cleaners can damage plastic. Thanks for the recommendation.
Update: I still have not isolated the source of the increased oil leakage. I haven't been able to work on my car as much in the past month, but I have been under it a few times wiping off more of the old oil and sludge from various nooks and crannies. I also borrowed a flexible bore-scope to get a better look at things. I've ruled out the OMP and the oil lines to and from the turbos.
Two questions:
1. Is it true that the normal engine oil level is above the pan gasket, so that if the pan gasket is bad anywhere, there should be a continuous leak of oil whether the engine is run or not?
2. Would a bad pan gasket leak more oil if the car is driven vs. parked?
06-29-20, 04:44 PM
