Aplha 1, 3.0 - Exhaust & Manifold Help Please

[cheabb78]

Hello all, long time reader, first time poster, and apologies if this is discussed elsewhere.

We use the boat in a very salty environment in the Middle East. 3 years ago we replaced a rusted exhaust elbow & manifold. We were told at the time, by the Mercruiser Agents here, that the issue arose as a result of us not draining the exhaust and manifold after flushing. The boat goes onto it's trailer after every use, and is flushed religiously.

Now, during a routine check up & service, they tell me that we have to replace it all again, as it is badly rusted.

Go easy on me, I am not mechanically inclined at all, but is this the norm after 3 years? More importantly, was the advice to drain after flushing correct?

We find this all a bit frustrating, as besides the expense, we wait months to get the parts in this part of the world.

Thanks.

 

[Scott Danforth]

first, welcome aboard.

rust is common in salt water boating. normally, lots of the rust can be cleaned prior to replacement. however it is not uncommon to replace the manifold every 5-10 years

do you have pictures of the flanged joint between the manifold and elbow? (you may have to post a bit more to be able to post pictures)

 

[Scott06]

In higher temperatures and salinity levels of the ocean the corrosion will be increased. 3 years does seem very quick as most folks are thinking 5-7 years.

As Scott says post some pictures of the manifold to elbow cooling water passages. It is possible that your mechanic is recommending out of extra caution to replace, as you can ruing the whole engine... or they can be making more money ...

Were they replaced with OEM mercruiser parts or aftermarket? Some of the aftermarket stuff is junk. Barr is a good OEM quality aftermarket company.

You may also want to see if a product like salt away that is injected in the flush will help. You may not be able to rinse away all the salt deposits without it . Not sure about draining after flushing but on a 3.0 it is very easy to do

 

[cheabb78]

Thank you both for your replies, much appreciated. I have attached some pictures of the joint in place, and after they removed it and cleaned. The water leak had got into the plugs, which was causing issues with starting, so definitely needs fixing. These were Mercruiser parts, and replaced in Jan-21.

I'm not doubting the amount of rust, I'm trying to figure out what we can do differently going forward. I have heard of salt away, but haven't been able to find it locally. We have been draining via the 2 drain hoses after flushing, but even our tap water here has a very high salinity, so it could be that this will be the norm.

Thanks again.

 

[Scott Danforth]

Unfortunately that is rusted a significant amount. You could run a file across the surface but it looks like you would have to take off 1-2mm to get it to clean up, however I would suggest a new manifold

 

[cheabb78]

Unfortunately that is rusted a significant amount. You could run a file across the surface but it looks like you would have to take off 1-2mm to get it to clean up, however I would suggest a new manifold

Thanks, I thought as much - have already asked them to go ahead and order the parts. Hopefully ready just as the water starts warming up. Am also looking for Salt Away or equivalent, will try anything to not have to do this again in 3 years

 

[Scott Danforth]

For years I flushed with salt away here on the Florida gulf coast. Also rinsed the trailers with it