junkyardwarrior
Seaman Apprentice
- Joined
- Sep 28, 2008
- Messages
- 40
25HP twin carb 395cc (IIRC) premix motor
I work for a local dealer, and we spend a lot of our fall and winter months working with 25esh outboards mounted to duck boats. Many of our duck hunters are fairly rough on their motors as expected (comes with the duck hunting territory). Long story short, we had a rash of powerhead replacements in the last season. From Nov through Jan we replaced I think 9 or 10 powerheads and all but two were low compression (75-80 psi on each one), disassembed and found leaking or broken labyrnth seal in between the upper & lower cylinder. On the Yamahas, they're an aluminum seal shell with a rubber inner seal that rides on the surface of the crankshaft.
I would like input from those who have been in the outboard repair business as to what could be causing these type failures?
It seems like some were really beat up (broken/bent props, broken skegs, broken av-plates, etc) and some were really CLEAN. One was almost new but Yamaha bought the powerhead for that one--but the factory tech could not explain why the seal failed and said that he'd never even heard of it. Some of the seals were shattered. One had a missing locating pin which let the seal rattle around and dinged up the crankcase. One or two were just really loose on the crankshaft-so much that they would not seal and one I actually could not tell visually that the seal was problematic but a leakdown test sure showed that it was. I'd like to know what could cause these things to fail so that we can better educate our customers. That is important.
Also, I'd like to know if anyone may have any insight as to how to press the crankshaft halves apart to replace the labrynth seals-as I've personally never done one but I now have a few spares to play with.
I work for a local dealer, and we spend a lot of our fall and winter months working with 25esh outboards mounted to duck boats. Many of our duck hunters are fairly rough on their motors as expected (comes with the duck hunting territory). Long story short, we had a rash of powerhead replacements in the last season. From Nov through Jan we replaced I think 9 or 10 powerheads and all but two were low compression (75-80 psi on each one), disassembed and found leaking or broken labyrnth seal in between the upper & lower cylinder. On the Yamahas, they're an aluminum seal shell with a rubber inner seal that rides on the surface of the crankshaft.
I would like input from those who have been in the outboard repair business as to what could be causing these type failures?
It seems like some were really beat up (broken/bent props, broken skegs, broken av-plates, etc) and some were really CLEAN. One was almost new but Yamaha bought the powerhead for that one--but the factory tech could not explain why the seal failed and said that he'd never even heard of it. Some of the seals were shattered. One had a missing locating pin which let the seal rattle around and dinged up the crankcase. One or two were just really loose on the crankshaft-so much that they would not seal and one I actually could not tell visually that the seal was problematic but a leakdown test sure showed that it was. I'd like to know what could cause these things to fail so that we can better educate our customers. That is important.
Also, I'd like to know if anyone may have any insight as to how to press the crankshaft halves apart to replace the labrynth seals-as I've personally never done one but I now have a few spares to play with.