RUSTY SPARK PLUG should I be concerned?

Trashman

I have a 2004 350 mag mpi horizon. the boat is still on the trailer so I thought I'd replace the plugs. All the plugs looked good except one.  It's the 2nd cylinder from the transome on the port side. Not sure if that's important.  The others looked a little wet with gas/oil when pulled.  It hasn't ran since November.    What if anything does this indicate? Should I be concerned?   

frenchship

Looks like water got into that cylinder, if it was only the threaded portion that had rust it
it would not be bad, but even the tip has rust. 

Trashman

@alswagg, not sure how to pressure test cyl but I'll google it. Lol.  Is there a way to check the manifold easily?  In your opinion, is this something a handy person can do or do I need a marine mechanic? I apologize  For all the questions, this now has me a little panicked. 

rasbury

This is not good- not a mechanic but the only reason you would have a rusted plug is water in the cylinder. You have to find out why before you ruin the motor. I would get to a mechanic and get tho looked at before you run the motor.

Handymans342

A clean fuel burn with high octane looks rusty

BellevilleMXZ

Best way if you havnt turned Engine over is to stick a boroscope in that hole and have a look see.

craigswardmtb

It's pretty easy to pull the manifolds to have a look. You will likely see rust in the manifold if you have a leak. Pb blast the bolts the day before and use oem new gaskets upon reassembly. Als suggested tests are the best bet though. 

Trashman

Ok. Thanks for the info.  As far as the bolts, would you use a small impact to remove? I will soak them first with pb.  

J3ff

ah man, sorry to see this, lucky you found it though, otherwise you'd end up like me, missing out on three weeks during the peak of summer !!

Trashman

J3ff said:

ah man, sorry to see this, lucky you found it though, otherwise you'd end up like me, missing out on three weeks during the peak of summer !!

Your situation is what is freaking me out, lol.   I don't have the checkbook to go through what you had to.   

So... Talked to previous owner via email and he never replaced manifold and risers in the eight years of ownership.  I'm assuming they were never replaced by his po.  I'm just going to replace risers and manifolds and be done with the guesswork.  @Alswagg, any recommendations on aftermarket or pen or where to buy? I'm looking at Michigan motors package.  Also.  Am I ignoring anything by replacing the parts?   Thanks for all the help so far. 

J3ff

Trashman said:

J3ff said:

ah man, sorry to see this, lucky you found it though, otherwise you'd end up like me, missing out on three weeks during the peak of summer !!

Your situation is what is freaking me out, lol.   I don't have the checkbook to go through what you had to.   

So... Talked to previous owner via email and he never replaced manifold and risers in the eight years of ownership.  I'm assuming they were never replaced by his po.  I'm just going to replace risers and manifolds and be done with the guesswork.  @Alswagg, any recommendations on aftermarket or pen or where to buy? I'm looking at Michigan motors package.  Also.  Am I ignoring anything by replacing the parts?   Thanks for all the help so far. 

Just heading out on the boat for the first time after sitting with the tax man all day. All I'm going to say is it's good I left the tank full... after last year's experience with this boat and today's tax bill....I'm kind of down for the count for a while!! 

randy56

@J3ff thanks for keeping our government employees working

Trashman

ok thanks al, I have been going through the extensive archive in the forum. my eng serial # is OM682901 that doesnt seem to come up in parts searches   oem is kind of pricy for me.  I was hoping to save a few bucks, what would be your second choice?   

Cableguy Greg

Trashman said:

ok thanks al, I have been going through the extensive archive in the forum. my eng serial # is OM682901 that doesnt seem to come up in parts searches   oem is kind of pricy for me.  I was hoping to save a few bucks, what would be your second choice?   

Your serial number starts with a zero. It is 0M682901. It came up using a zero in the Mercury Parts catalog. https://www.mercurymarine.com/en/us/parts-and-accessories/parts-catalog

I just ordered a dry joint exhaust manifold from MichiganMotorz for $335. That was the OEM manifold. Now I just need to find the time to install it.

Trashman

Cableguy Greg said:

Trashman said:

ok thanks al, I have been going through the extensive archive in the forum. my eng serial # is OM682901 that doesnt seem to come up in parts searches   oem is kind of pricy for me.  I was hoping to save a few bucks, what would be your second choice?   

Your serial number starts with a zero. It is 0M682901. It came up using a zero in the Mercury Parts catalog. https://www.mercurymarine.com/en/us/parts-and-accessories/parts-catalog

I just ordered a dry joint exhaust manifold from MichiganMotorz for $335. That was the OEM manifold. Now I just need to find the time to install it.

Hmm, that went right over my head.  Thanks.  

jme097

If its one thing I have learned while owning a boat, its not to go for cheap over quality. Spend the money and put OEM on there especially if you're talking manifolds/risers

Trashman

Ok, so I removed the manifold assembly. Hosestly I don't think they are bad looking at all.  
What I noticed:
The second bolt from the transom on the manifold was not tight

There was moisture in the two center ports in the manifold.

Very Small droplets of water were on the shaft of the valves looking into the engine. 

The exhaust flappers look fine and looking into the y pipe looks clean with just a small amount of pitting. 

The elbow had loose flakes of rust packed into the small round hole. Wasn't packed solid but a good amount.  

The 3" spacer looked like it had corrosion where it mates to the stainless steel gasket. 

Thats all I got.  Gonna post a few pics later.  Gonna order parts tomorrow. 

Trashman

Ordered my oem parts and they should be in soon.  I did a search and can't find some info
do I use sealer on any of the gaskets in between the manifold and the spacer/elbow? 
Torque specs? 
Heres a few pics of the old manifold/spacer/elbow. 

Trashman

picked up parts today. was told no sealant on anything.   could not find torque specs on the manifold or riser. anyone have that info?

reneechris14

reneechris14