New Mixing Elbow and Groco Flush

[jumpjet231]

When I started my boat after launching her this spring I had smoke pouring out of the engine compartment. the elbow corroded and cracked at the flange mating the mixing elbow and dry riser attached to the turbo exhaust. I called Mack Boring and the tech guy there said this is where 90% of all the 6lp elbows break. Thank God I was still at the pier! After getting a quote from Mack B of over $1000 for the same crappy cast iron 2 piece elbow I managed to get a one piece stainless steel one from John at Oxford Yacht Agency (old Albin dealer) for $1200! It is awesome and fits perfectly into my flush deck. Also, while I was at it, I installed a Groco SSC flushing attachment. Hopefully this will help with the corrosion.

Both were easy jobs. The elbow just has a squeeze clamp, gasket, and a bolt on the support connecting it to the turbo.

[DougSea]

Very nice! And that's one slick looking heat cover.

The flush kit is in my future, costs quite a bit as you get into larger sizes, and I need two.

[RobS]

Nicely done. Do you still have the fracturated elbow. Now that they are removed can you post some clear shots of the failure point?

[jumpjet231]

The flush kit is in my future, costs quite a bit as you get into larger sizes, and I need two.

Mine is a 2" and I think it was $105.

I have pics of the fracture on my home computer. The flange on the mixing elbow is gone. It basically corroded and fell off. It is covered by that squeeze clamp on the diagram labeled 3-1. You can see in the first pic where they came apart. Sorry I can't figure out how to rotate them 90deg clockwise.

[OldDemps]

How many hours on your engine when the mixing elbow failed?

It there any tell tale duty cycle or replacement period other than just changing the elbow preventively?

Thanks

[RobS]

The manual says to replace the wet elbow every 500hrs/2yrs. Seems so premature but there are variables to how long it will last so they have it on what appears to be the conservative side. Usually no warning, just a sudden fracture.

[RobS]

Sorry I can't figure out how to rotate them 90deg clockwise.

I rotated 2 of the pictures in your opening post, I think these would be the ones you were referring to. So it appears this is where the old elbow broke off..

[jumpjet231]

That's where the fracture occurred. The two piece elbow is a weak link. The corrosion around that joint was bad. The rest of the elbow didn't look as bad. I could've probably made it another year or two. The Mack B rep I spoke to was surprised to hear that mine lasted this long. My boat is an '04 and I had the elbow inspected two years ago. My guess is that the marina took the entire assembly off the turbo and didn't undue the clamp joining the two elbows. If I were inspecting them myself, I would just undue the hoses and separate the wet piece from the dry and inspect it for corrosion. There was no corrosion where the dry elbow attached to the turbo. I'm traveling right now. When I get home I'll check my home computer for the pics of the old elbows but I think I deleted them when the shiny new one arrived.

How many hours on your engine when the mixing elbow failed?

About 650 off the top of my head. From what I gathered in all this, after 5 years you are rolling the dice with a breakdown. My timing belt is next. I'm way past that mark as well and I don't think the previous owner had it replaced in the first four years. Anyone know if there is an upgrade kit for a timing chain for the 6lp? Why a manufacturer would put a belt on a interference engine is beyond me.