Mercruiser 3.0LX exhaust elbow rust

[mike1266]

Hi guys,

So last time I posted about a leaking gasket on my 3.0 Mercruiser exhaust elbow. I got some time to take it apart today and wanted some opinions on it.

I notice a fair bit of rust inside the water passages, none are flaking off but they seem more attached in small clumps. I noticed very small drops of rust in the exhaust pipe, but I don't think any water's been leaking into there while the boat is running.

The pipe that connects to it has a lot of dust from the exhaust but it is a rust color. I wiped off some from the top side to show the original colour. Is this normal? I thought it's supposed to be a black color. When I opened my thermostat housing, the thermostat was also covered in some rust colored slime-ish thing. Is this just the rust being run thru the system and its normal?

I've included a pic of the elbow and the pipe right below it for reference. The gasket is still on there but I will be flat filing it all off if the elbow can be used. Ultimately, I want to know if it would last me another season or two because I really haven't got the time to order another one right now. As for the thermostat, I ended up getting a new one since it was easily accessible to me.

Thanks for any input.

 

[Scott06]

i assume this is a fresh water boat by looks of things ? Exhaust pipe looks fine the elbow you want to scrape the gasket off and look at 1/4” wide piece of metal between exhaust and water passages, if it corroded replace it. That’s where water can leak into exhaust and cylinders . If it’s not too bad file or belt sand flat otherwise replace

 

[mike1266]

Hi Scott thanks for the reply. This was a freshwater boat for many years, but I've used it in salt for half the season last season. This season I intend to mainly use it in salt. I flush my engine with fresh water for about 10 minutes minimum to get all the salt out afterwards.

One problem is that the metal is 1/4' wide at the top, but when I felt inside it felt like the metal was warped a bit outwards towards the water jackets, is this normal? I included a picture that I drew that may help with the understanding of it. It is a "dissected" view of the elbow.

 

[Bondo]

One problem is that the metal is 1/4' wide at the top, but when I felt inside it felt like the metal was warped a bit outwards towards the water jackets, is this normal?

Ayuh,..... Welcome Aboard,...... They fail at the gasket surfaces,..... rarely to never elsewhere,.....

 

[Scott06]

Ayuh,..... Welcome Aboard,...... They fail at the gasket surfaces,..... rarely to never elsewhere,.....

Yep. If gasket surfaces are ok reuse them. In fresh generally they outlast the boat if properly winterized, now that you are in salt you should be checking the, periodically and replacing manifold and elbows every 5 or so years

 

[mike1266]

Awesome, then that means my elbow and manifold have some life left in them. I flat-filed the surface and they are shiny metal now :joyous: