View Full Version : Engine Sediment

05-09-2010, 07:42 PM
I installed a shower this winter and when i went to use it this spring the hot water pressure was extremely weak. Naturally I took off the hot hose and the screen was filled with sediment from the engine. I take the hot from the drain on the passenger side of the of the block.
I initially ran the engine with the hot disconnected from the mixing valve and inserted into a bucket. When I would start the boat i would get quite a bit of black sediment (looks like painted metal) coming out of the hot hose. I did this several times (starting engine, let it run, rev it a bit, run, turn off and let it drain, repeat). Each time I got plenty of sediment to come out so I removed the hot fand the drain plug entirely.
When running the engine the sediment was coming out and when I stick my finger in the drain hole you can feel the sediement there and actually prod it to come spewing out of the drain hole. When I would stick a stick up there to shake things up, even more sediment comes out. It seems to be neverending.
Anyone have this problem? The real issue is where is all this coming from and why. I am assuming that the risers and manifolds are probably worth taking a look at, but thought I would throw this info out there and see what others know.

05-09-2010, 07:57 PM
When I replaced the gaskets in my 85 S&S (gaskets between the headers and risers and between the block and headers) -- I was SHOCKED at the amount of sediment I discovered...... It looked EXACTLY as you have described here (painted metal).... I would bet that's where your sediment is originating from.....

05-09-2010, 08:03 PM
Did you do anything besides replace the gaskets in order to get rid of it?

05-09-2010, 08:10 PM
Yes -- I had the headers and risers magifluxed and dipped.....

05-10-2010, 11:15 AM
hmmmm... Let me throw this out there (I know different conditions = different results, etc...) but for those who have replaced the manifolds and or risers, about how long were the old ones on there?
Can the way I winterize have an effect on the life of them? For full disclosure, the boat is a '97 with only 550 hours. Clean body of water, but living in NH, it only sees action from May to October.

Miss Rita
05-10-2010, 02:53 PM
My I/O engine (5.7 L) always has flakes of dark rusty metal that come out when I drain the engine in the fall. Shouldn't be much of a surprise, considering that the engines are made of cast iron and full of water.

I don't expect that the MC 351 will be any different.

05-10-2010, 03:54 PM
The surprise is the amount that is still coming out. Not even close to being able to run the hot feed on the shower with out serious and instant clogs. I have been attempting to remove the debris for several days.

captain planet
05-10-2010, 05:12 PM
Do you beach your boat?

The reason I ask is, my buddy had an X-5 that was a Cypress Gardens boat that was beached a lot. Each time the boat was beached it would pull a little sediment/silt into the engine. One year my buddies boat lost compression in one or two of the cylinders. Upon tearing the engine apart, there was a bunch of sediment that was found in the rear of the engine (engine sits on an angle) and was preventing the heads from cooling properly and the valve seats warped on that/those cylinders.

This happened several years ago so some of the finite details I can't remember, however overall most of this info is correct.

05-10-2010, 06:58 PM
Never been beached.

05-10-2010, 07:17 PM
Do you beach your boat?
Upon tearing the engine apart, there was a bunch of sediment that was found in the rear of the engine

i hope you find the cause of the Black flakes, and Thanks to Planet for the Valuble Beach info...

05-10-2010, 07:35 PM
Maybe run your hot water source off of the intake manifold where the heater would get it's water. It's up top, might not suck up the sediment/rust.
I ran the hot source to my shower in my X2 from here...mainly beacuse it was easy, but there might be a side benefit??

05-11-2010, 12:09 AM
Mine is here. I have only used the shower a couple of times. no rust as of yet. hope it helps...


i did ifx the loose spark plug wire by the way...


05-11-2010, 12:26 PM
I had to change mine to where the heater was hooked up, cause it kept clogging up.

Have not had any problems since.

05-13-2010, 01:30 PM
Don't have a pic of that setup by any chance? I am going to have to move the hot feed from the drain since I can't seem to eliminate the rust problem.