2000 380 DA

[techmitch]

For what its worth.

Exhaust Manifolds

Exhaust manifolds are important, and ignoring them can potentially lead to expensive problems, perhaps an engine rebuild.

www.boatus.com

Unfortunately our boats are approaching the 1/4 century mark, and I'm alway finding things that need attention.

I was taking it slow.

 

[Chris-380]

What do the plugs look like?

Here is the ones he change out middle of last seasom

First 2 are 1,3

 

[techmitch]

Here is the ones he change out middle of last seasom

First 2 are 1,3

1 looks good again, 7 looks fair and 8 is turned again?

 

[bfernald0]

If you've got one cylinder at 75, in all likelihood you've got a valve that's partially stuck open or something else rather dramatic going on with the valves on that cylinder.

I'd remove the valve cover and the manifolds/risers. By removing the valve cover, you can inspect the rockers, valve stems and cams on that cylinder to see if there's anything amiss up top.
By removing the manifold/riser on at least that side, you can also look at the exhaust valve to see if there's an issue there. If you've got corrosion in the exhaust ports and/or in the exhaust passages in the manifold/riser, in all likelihood that's the cause of your issue.

Excessive moisture, corroded valves/seats, stuck valve, bent valve stem, severely low compression.

The fact that you've got severely low compression in only one cylinder leads me to the conclusion that something catastrophic happend in the valvetrain for that particular cylinder. Between removing the valve cover and the manifold on at least that side and inspecting the valve components for that cylinder, I'm betting the problem will present itself.

I see a valve job in your friend's future. On the bright side, it doesn't sound like he had a hydrolock situtation, a bent rod, etc.

How old are the manifolds/risers?

 

[Chris-380]

If you've got one cylinder at 75, in all likelihood you've got a valve that's partially stuck open or something else rather dramatic going on with the valves on that cylinder.

I'd remove the valve cover and the manifolds/risers. By removing the valve cover, you can inspect the rockers, valve stems and cams on that cylinder to see if there's anything amiss up top.
By removing the manifold/riser on at least that side, you can also look at the exhaust valve to see if there's an issue there. If you've got corrosion in the exhaust ports and/or in the exhaust passages in the manifold/riser, in all likelihood that's the cause of your issue.

Excessive moisture, corroded valves/seats, stuck valve, bent valve stem, severely low compression.

The fact that you've got severely low compression in only one cylinder leads me to the conclusion that something catastrophic happend in the valvetrain for that particular cylinder. Between removing the valve cover and the manifold on at least that side and inspecting the valve components for that cylinder, I'm betting the problem will present itself.

I see a valve job in your friend's future. On the bright side, it doesn't sound like he had a hydrolock situtation, a bent rod, etc.

How old are the manifolds/risers?

Ty for this
Fresh water boat, original manifolds/risers

 

[bfernald0]

Ty for this
Fresh water boat, original manifolds/risers

Omg. 20+ year old manifolds/risers?!

That's your answer.

Lol

 

[bfernald0]

You boys live in a different universe up there. I'm painting, flushing with saltaway, spraying everything with yamalube in a desperate effort to keep these repowers looking like new, and I still find rust everytime I'm down there.

 

[Strecker25]

I'd guess 80% or more of all boats near us have the original manifolds and risers. Most recreational owners don't even know it's a replaceable component

 

[bfernald0]

Going to buty my next boat up there and ship it out.

 

[Strecker25]

it happens a lot, but they also fetch a serious premium when billed as 'freshwater only'

Fortunately our boat was sold new on lake Ontario and has lived here its entire life. Almost no surface rust anywhere, original paint on the engines, etc. I only replace zincs every few years

 

[bfernald0]

it happens a lot, but they also fetch a serious premium when billed as 'freshwater only'

Fortunately our boat was sold new on lake Ontario and has lived here its entire life. Almost no surface rust anywhere, original paint on the engines, etc. I only replace zincs every few years

Let me know when you come to sell ;-) Zincs every few months, more so during the summer months. Fully flush with saltaway after every run. Manifolds/risers every 3-5 yrs. Paint/yamalube constantly. A losing battle all the way around.

 

[Chris-380]

I'd guess 80% or more of all boats near us have the original manifolds and risers. Most recreational owners don't even know it's a replaceable component

No one on our lake has changed manifolds, unless it came from salt. It’s just not a common thing around here

 

[techmitch]

No one on our lake has changed manifolds, unless it came from salt. It’s just not a common thing around here

The plug read and the oil sample are the what's. Let's find out the why.
Did your friend have any drivability, running or stalling issues this year or last?

 

[dtfeld]

No one on our lake has changed manifolds, unless it came from salt. It’s just not a common thing around here

Its not just the salt, The exhaust gas/cooling water are acidic, and will cause corrosion from the exhaust cavity out, and if you boat in hard water you can get build up in the cooling passages. The walls are notoriously thin and made of shitty cast iron.

I'd at least be opening up and inspecting once in a while. Unfortunately, when the manifolds/risers fail, they take out all kinds of expensive things. I know when I was looking to buy a big block powered boat, I budgeted new manifolds and risers. They aren't that expensive.