Front seal blew out, again

Bruce Herrington

Bruce Herrington

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Just had the stbd BW tranny coupled to a 454 Crusader replaced 3 weeks ago. After less than 8 hours and only 20 miles at cruise speed, it blew out again.

What would cause this to happen so soon after being rebuilt? Tranny shop do poor job? Or, did mechanic not align shaft properly?
 
Just to clarify, are you talking the engine side or the coupler side? Is the fluid clean? It could also have been a defective part.
 
Engine side. Fluid pours out when engine is running. Even if tranny is in neutral.
 
Then I'd say defective part, Improper installation, or shaft that is pitted or has a grove in it and it should have been replaced during the rebuild.
 
It could also be a blocked or clogged filter screen on the input side of the oil pump causing a build up of pressure and it will blow out the seal. A rare condition but I have seen it happen.
 
Or possibly a slightly bent engine crankshaft? Does the crank pulley appear to be very steady when running or have a little runout? That may not be a good indictator for what is happening at the flywheel/output/tranny end, but might offer a clue.
 
Last year I had both of my BW 5000 rebuilt I know one transmission had about 1100 hrs and the the other one had some work done to it before we bought the boat. The shop installed a sleeve on the input shaft on both transmissions where the seals had worn a slight groove,they also up graded the seals because it is common for the the seals to blow out because of to much pressure in the casing,the seal up grade has something like shark teeth that clamp to the outside of the casing to help stop them from blowing out. BW supplied the seals, also is the vent on the transmission clear,when your shop did the repairs did they replace the vents. I hope this helps
 
Thanks, everyone. I'll make sure the mechanic/tranny shop knows to check the items you have mentioned.
 
Bruce was this engine/Transmission in use for some time? Mated and working for some time?

I'm suspicious about why there had to be a Repair in the first place.
It sounds like the Rear main bearing on your engine is loose. Way too loose in fact.
There is also an oil seal on that Bearing. It may have died too.

The Mechanic will have to check on that. I'm sure he will though. Keep the parts, show us the photos.
 
Thud, engine/tranny been together for past 15 months. Bought it 6/2012. You do have a point. Will have rear main engine seal checked also.
 
Bruce, is this a counter rotating engine / tranny ?
If so, there are special seals that have the wiper vanes reversed.
This my have been overlooked.
 
Gary, one of them is counter-rotating, but not sure which one. Wiper vents, huh? Learning never stops here. :-)
 
Standard rotation for a GM motor is LH (counter clockwise looking from the rear), so your counter-rotating transmission should be STB.
 
Oil seals have ridges designed to wipe oil back into the engine. In a counter rotating engine the mechanic has to make sure to order the right seal or it can start to wipe oil out of the engine after only a very little wear,,,, like 20 hours...

135359226_Front_Crankshaft_Oil_Seal_for_VOLKSWAGEN_AUDI_s.jpg
 
quote:
Originally posted by BillK

Standard rotation for a GM motor is LH (counter clockwise looking from the rear), so your counter-rotating transmission should be STB.

Click to expand...


Unless the BW transmission has a reduction gear ratio that reverses output like mine. That puts the CW counter-rotation RH engine on the port side with a LH prop.
 
The guy who rebuilt the gear inspected the damper plate and said definitely needed replacing. Let you know if that works. Thanks again for the help.
 
Make SURE tranny is NOT overfilled with oil when you put it back together. Damper plate failure usually results in noise at idle. Has no effect on seal.
 
Gear and new damper plate installed, seems to run ok. However, with forward gear engaged while tied at dock, shaft now has irregular spin cycle. Port shaft spins at a constant speed. Why would they be different?
 
Tranny guy says the spool valve is causing the irregular spin cycle. Will know tomorrow...
 
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