small crack in the lower unit

[peteinmaine]

I have a 1987 Chapparel 20' bowrider with a V-8 350/260hp Alpha One...I just noticed a small crack in the lower unit strating at the prop-shaft area and spreading upward...pretty sure this is new, but maybe happened last season....so the question: do I need to replace the entire lower unit shell, or is there a weld/patch kit that would do it...can;t imaging I can just leave it as is, but I hate to spend many $$ on this great, but old boat. <br /><br />Thanks

 

[flashback]

Re: small crack in the lower unit

well most likely what has happened is a seal has worn and you are getting water in your drive unit. so, drain the unit, patch the drive with some JBWELD, and give it a try. if it works, great!, if it doesn't , then buy a new bottom end and then be sure it doesn't leak. PREssure TEst.

 

[peteinmaine]

Re: small crack in the lower unit

I'm not sure I understand....this does not seem to be a pressure area, it's just a crack in the shell/housing...will JBWELD work on this?

 

[sea wolf]

Re: small crack in the lower unit

u can try the jbweld but i don't think it will stop the crack from travelling. the problem with welding the lower unit is the heat may damage the seals. just my .02.

 

[wheels4]

Re: small crack in the lower unit

Drill a small hole at the end of the crack.This will keep it from spreading.Then try the JB weld.

 

[2770]

Re: small crack in the lower unit

I have a good friend that had the exact problem.He drilled a small hole at the end of the crack and sanded all the paint off the area and patched with marinetex.He had the boat for several years after the repair without a problem.Prepare the surface carefully and the marinetex will do the job. CC

 

[MrBill]

Re: small crack in the lower unit

I concur with the others...JB Weld does a phenomenal job. I purchased a lower unit shell last summer thinking I would need it, but instead was able to adequately repair with JB Weld. I now have shell, willing to sell to anyone who needs it.

 

[MrBill]

Re: small crack in the lower unit

peteinmaine: One thing that nobody mentioned that could be a problem if the crack begins at or near the rear (nearest prop) on the rounded portion of the lower unit...Hoop Stress. This type of stress is normally associated with stress in a pipe wall resulting from fluid pressure, or in the case of a lower unit, radial pressure exerted outward as a result of screwing in something like a carrier assembly. With this type of pressure, applied circumferentially any bond to repair must be stronger than the material it self. A very difficult repair, but very much worth trying inexpensively with JB Weld.

 

[peteinmaine]

Re: small crack in the lower unit

thanks all.....MrBill I still may need to buy that lower unit shell off ya!

 

[Trent]

Re: small crack in the lower unit

If you use this in saltwater, My bet is you have corrosion built up between the bearing carrier and the housing. You can stop drill if you like but its not going to stop the problem. Just keep using it. I know it looks bad but its common on older saltwater Mercrusiers.