air bubbles from lower unit but no water

[NicoPags]

1978 Evinrude 35HP 35853R

Morning all,

I just noticed during a tank test that I had air bubbles coming from the seal at lower unit and exhaust housing. I had the trailer tilted up during the test and found that the clearance under the prop was not enough to let it spin freely during idle, the motor was in neutral. At the same time I noticed the bubbles, I also noticed the lack of exhaust out of the prop. Turned the motor off and took the trailer off my little stand. Made it parallel to the ground as I normally do and turned the motor back on. Exhaust came out of prop as per normal, the bubbles still existed. Exhaust housing was on the warmer side for only a 30 second run. Being proactive without shot gunning it, I drained the lower unit oil and there is not even a hint of water. Am I right guessing that the prop was jammed on the bottom of my barrel and prevented proper exhaust, and in such pressurized the exhaust housing causing air to force out of the seal at the l/u and housing? No other symptoms at all. Fires up instantly even when cold. It still ran wonderful during this small test however not sure internally if some seal actually went. Also, the air leak was directly above the upper drain plug where you service the lower unit oil.


Thank you in advance

 

[Chinewalker]

No seal between the lower unit and exhaust housing. It's normal for some exhaust to seep out of that seam, particularly at idle as there isn't enough exhaust pressure to push it out the prop, under water. The exhaust would need to displace the volume of water in the leg to do that, which is why there is an exhaust relief on the back of the leg.

 

[NicoPags]

Beautiful. Thanks Chinewalker