one cylinder filled with sand

[jobie]

okay a friend of mine asked for my help, he has a 1984 carver (26 ft) salon cruiser. powered by a merc 260 horse 5.7 ( chev v-8 )fresh water cooled with 355 hours on it. the motor would not turn over , after some troubleshooting we determined that the motor was siezed. we tore it down and after pulling the heads we found that the #4 cylinder was packed with sand. the top of the piston was very corroded and heavily pitted , the rest of the motor looks brand new and there are no signs of head gasket failure. he bought the boat in the condition that it is in and has no histiory of the boat. anyhow a new motor is on order but does anyone have any idea how this could have happened ?

 

[Don S]

Re: one cylinder filled with sand

That's exactly what salt water corrosion looks like after a few months.
Probably from failed exhaust manifold and/or riser.

 

[WizeOne]

Re: one cylinder filled with sand

Wild guess here. I'd look very closely at the exhaust manifolds. Not knowing where you reside, there is a possibility that the exhaust manifold was packed with sand, (hard to believe for a 26 ft cruiser)broke internally from freezing then allowing that sand to flow into an open exhaust valve when the manifold thawed.

Can't see any other way it could have happened. The sand could hardly have gotten in there if someone had tried to do it on purpose.

edit: Seeing don's post, I just assumed your determination of it being sand was correct.

 

[Bondo]

Re: one cylinder filled with sand

Ayuh,......

Or,......
The previous Owner had a rather devious Enemy.......

 

[jobie]

Re: one cylinder filled with sand

it is fresh water cooled ???? i didn't know that raw water flowed through those manifolds. i can only say that the material that was in there appeared to be sand and it was packed solid (probably a complete handfull). there is alot of corrosion in the head ports as well.

 

[HT32BSX115]

Re: one cylinder filled with sand

Howdy,

Well,

If it's a FULL system. (I.E. coolant flows thru the manifolds), you STILL have raw water flowing thru the elbows on it's way out the exhaust.

With a "Half" system, raw water flows thru the exhaust manifolds and riser/elbows.

If the gasket between the elbow and the manifold leaks or fails, or the elbow is cracked, salt water WILL flow into any exhaust valve that happens to be open.

If it sits there for more than a day or so the engine is usually "toast"

it is fresh water cooled ???? i didn't know that raw water flowed through those manifolds. i can only say that the material that was in there appeared to be sand and it was packed solid (probably a complete handfull). there is alot of corrosion in the head ports as well.

 

[jobie]

Re: one cylinder filled with sand

well now its starting to make sense!!! after your reply i went and looked at everything and yes the exhaust port for that cylinder (on the head) is heavily corroded .the port on the exhaust manifold for that cylinder is heavily corroded as well. what a shame a nice motor with only 355 hours toasted because of something as simple as a $5.00 gasket. anyhow thanks for all your help if it wasn't for you guys we would have went ahead , replaced the motor and used the same exhaust manifolds believing that salt water does not pass through them.

 

[jobie]

Re: one cylinder filled with sand

okay , the new motor is here and we are ready to put it in. now we are wondering what the chances are that the manifolds and risers might be okay ??? is the fact that only one cylinder was affected any sort of indication as to whether or not the riser gasket may have failed and therefore the manifolds and risers might be okay ???

 

[Bondo]

Re: one cylinder filled with sand

Ayuh,...

Saltwater Manifolds,+ Risers of unknown history are pretty much Scrap Metal....
And those are already Questionable.....

It's a Brand New Motor,......
Why would you want to Roll the Dice,+ Loose it.....??.....

 

[FreeBeeTony]

Re: one cylinder filled with sand

I would defintely replace both manifolds and risers...........not worth the chance after all the work/money replacing the engine..........just not worth the risk.

 

[jobie]

Re: one cylinder filled with sand

okay , okay i knew it was a stupid thought !!!

 

[jobie]

Re: one cylinder filled with sand

new motor is in . new manifolds and risers are sitting on the garage floor. went to the part store to get new gaskets ( manifolds and risers) . i told the clerk that the boat has a fresh water cooling system. it also has a salt water pump that pumps raw water into the system as well. the clerk tried to sell me block off plates , i told him that the boat had regular riser gaskets on it when we took it apart. so the million dollar question is do i need block off plates or gaskets ???????::

 

[FreeBeeTony]

Re: one cylinder filled with sand

Block off plates are only needed if the manifolds are FWC'd.

 

[jobie]

Re: one cylinder filled with sand

how do i know ? i have only owned raw water cooled boats and have no idea what to look for . there is a raw water pump that pumps raw water through the system. when i pulled the manifolds anti -freeze did drain from them if that is any indication

 

[FreeBeeTony]

Re: one cylinder filled with sand

You really need a manual............

In a fully FWC'd system the return of the coolant out of the engine/thermostat housing will go to the bottom of the manifolds, exist the top of the manifolds and go to the heat exchanger..........the return of the RawWater from the RawWater section of the heat exchanger will exit the boat through the risers........thus a block-off plate is needed to seperate the manifold from the riser......

Don't know if this helps...........

 

[unreel]

Re: one cylinder filled with sand

I have a 1985 Se Ray 250 with a Mercruiser 260. My #6 cylinder is getting water in it fouling the plug. It sounds similar to the situation here. Please someone tell me its a 5 dollar gasket and not a pull the heads and head gasket job. The engine gets 0 water in the oil. It does not run rough except at idol speed. I tryed everything from cap,rotor,carb and then plugs and discovered #6 being oil fouled and wet. To me I believe its water. The cylinder to both sides looks ok. I do have evidence that water has or is leaking from the riser at the base. I did not know it this was normal or may be an idicator that the gasket is shot and is leaking back into an exhast valve.....Is this possible......Where could the water be comming from. I am also getting what I would call steam comming out of my vent tubes from the valve covers onto the flame arrestor. I am friggin lost cause the motor runs good at higher rpm but surges at low rpm. I pulled #6 wire when it was idling and the motor did not change. Could it be this gasket???????????