I have developed an oil leak on my port 550hp 8V92TI. It is coming out from under the rear outboard side of the blower. I removed the airbox and the airbox has oil residue in it and the blower gears also have a slight oil residue on them. My question is do I have bad seals on the blower? Can a layman repair them or do I need a new reconditioned blower? I am pretty mechanically inclined but am NOT a diesel mechanic, should I opt to have a DDC mechanic come down and look at it or just try and do it myself.
I (with help from friends) have replaced both heads, injectors, water pumps, turbos, done tune ups, changed oil, and such. I am not so sure I want to get into governor timing, blower gear tolerances, and such. Any opinons are greatly appreciated. I am not even sure I can get the blower off without taking the whole front of the motor apart, cooling system included.
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Thread: 8V92 Blower leak
05-25-2004 12:12 AM #1DaveP3 Guest
8V92 Blower leak
05-25-2004 01:31 AM #2Genesis Guest
.... is not a big deal. It looks bad, but it isn't really.
You have to disconnect the governor linkages to the racks, and the intake plumbing. The blower comes off with the governor attached.
Do you have a DD shop manual for your motor? If not, you need one. If you do, then the procedure is detailed in it.
Its time consuming but not all that difficult.
05-25-2004 12:43 PM #3DaveP3 Guest
Thanks for the info. I have the shop manuals for V92 Series Engines and it doesn't really go into replacing seals and or gear rotor set up and only gives genaralities on removal and re-installation. I guess I probably need to go get some shop technical manuals rather than service manuals. If you think it can be done without a shop or factory tech I'll give it a try. Should I just replace the blower with a rebuilt on or try and do the rebuild myself?
05-25-2004 02:36 PM #4Genesis Guest
I'd probably exchange the blower, or pull it and take it somewhere to have it rebuilt.
While its apart you may as well have it gone through completely. They're not really very complicated, but since it has to come apart to get to the seals.....
05-25-2004 05:06 PM #5Genesis Guest
... just so you know, blower oil leaks are extremely bad news on Detroits.
If the seals fail entirely you WILL get a runaway. If your engine doesn't have airdoors (many V92 series engines do not) there is no way to shut down the motor if this happens!
If this happens in gear, its bad, as the engine will run away with lots of black smoke until the oil is all consumed, and it seizes. This will totally destroy the engine, and can cause secondary damage (fires, etc), depending on exactly what quits working in what order.
If it happens OUT of gear, its far worse - the engine will reach unholy RPMs very quickly and pieces will exit at very high velocity. The latter can cause death or serious injury to anyone in the area, or even sink the boat (consider how much damage a flywheel coming off can do; it'd go through the bottom like a hot knife through butter)
05-25-2004 05:38 PM #6DaveP3 Guest
Thanks Genesis. The last thing I need is a bomb going off in my engine room. I was afraid of the runaway thing and haven't used the boat since finding the leak. I think you are probably right and I am going to go to Johnson and Towers tomorrow and pick up a reconditioned blower. Better safe than sorry. At least since my engines are of the really old variety I do have the emergency air door shut offs.
I have only experiences one runaway DD in my life. On my grandfather's old Rybovitch, a 650hp 12V71TI must have ingested a seal because it started burning lube oil. When it got to 2300 under load we shut down the other motor and managed to keep the bad one from detonating. I remember stuffing rags, sheets, and finally discharging a halon extinguisher into the air breathers. definitely NOT something I ever want to experience again. One thing to be 18yrs old and be crazy enough to be there with the engine but not at age 48 :lol
Thanks again, I think we can handle the job ourselves, J&T has a blower so we are going to have at it tomorrow and see what happens. The service manager at says we ought to be able to do it in a day. They expect their techs to be able to do it in like five hours by themselves. So we shall see,,
05-26-2004 02:01 AM #7pirate1960 Guest
Dave, don't get a rebuild. Get YOURS rebuilt. You know what your blower has gone through. Down here in South Louisiana, you could end up with a rebuid from a crew boat with 10,000,000 hours on it. I stamp my initials somewhere and get my stuff rebuilt. You will be better off.
05-26-2004 03:02 AM #8Genesis Guest
Pull .vs. replace
I can pull a blower in about 4 hours.
REPLACING it takes longer, because you need to do a full tune-up. The tune-up alone takes me about six hours, but I'm ANAL about the rack and injector timing - a lot of people are nowhere near as careful, and the result is an engine that is out of balance at idle at best.
I would figure on two man-days to remove and replace, including the tune-up.
Superchargers are pretty simple things, really, but the tolerances are pretty tight, and when they get sloppy the rotors will hit. The damage this does is immediately obvious on inspection; all you gotta do is look. If your rotors are clean I'd probably have my existing blower resealed; if not, I'd do the core swap for a rebuilt one.
05-26-2004 03:04 PM #9DaveP3 Guest
Thanks for the info about everything. We have the old blower off and it appears that the seals are the problem. The rotors and gears appear OK but I am not real sure how to test them for clearance and what the proper clearance is. They do have some play in them, the engine in question has almost 3000 hours on it since I bought it and I have no idea how many hours were on it before (I rebuilt it before installation). A local shop wants $1500 to disassemble, reseal and reassemble. They will give me no guarentee on anything other than the seals. They will sell me a rebuilt blower with a three year guarentee for $2250. I also found one of the airbox bolt holes stripped of all threads. I don't think I want to get into rethreading the blower bolt holes and maybe will go with the rebuilt blower with the guarentee. Plus there is a time factor here, i have plans to go on a cruise to the Upper Chesapeake this weekend with friends and the shop won't have my blower done till late Friday or maybe Monday if anything comes up. They have the rebuilt unit there and I can just take it with me. So I think after we grab a bite I'm off to the shop. I have Penn Detroit Diesel scheduled to come down Friday and tune up both engines. I plan to watch so that I can do the next one. Thanks again for all the insight.