Good morning
after having overhauled my Volvo penta V6 280 N engine (change of segments using General Motors segments) and after 15 hours of normal operation at 3000 rpm, the alarm sounded (normal pressure and temperature) the mechanic found on a spark plug /6 a few drops of water. (it seems to be the same problem as last year and therefore the cause of this water infiltration has not been identified and repaired.
In your opinion, what is the most probable element for this presence of water?
thank you

 

Not exactly sure what you mean by GM segments. Heads and blocks are new or rebuilt/remanufactured?

Were the exhaust manifolds replaced? Exhaust elbow or riser replaced? If they were not replaced then I would certainly have them inspected and tested. You spent the money on the engine, the manifolds would not have been that much more. Unless they are catalytic converter manifolds.

Why was the engine replaced in the first place.

A head gasket or cracked block could also be causing the problem but unlikely with a rebuilt/remanufactured engine.

Your mechanic who found the drips of water should be able to figure this out.

I assume your gas tank is not half full of water?

 

thanks a lot for your help .
I mean changed the rings of the pistons (in frensh we call them segments ) .I used the rings of the GM v6 L1 rings that are equivalent ( volvo penta don't want to supply new rings)

I didn’t changed the exhaust manifolds, elbow ,and the riser , Because the engine is new less than 20 hours of use .
I hope that the block is not cracked , but for that we will need to dismantel it again (we will do it in a second step)
But today we have noticed, that our manifold exhauster doesn’t let the water flow .please see the attached picture.Normally the water must go out from the extremity isn’t it ????


So may be the fact that the water remain blocked inside the manifold can cause the drops of water on the plugs ????
if the circuit is blocked , so may be we must put in it a liquid , to dilute the salt .
your prompt help will be much apreciated
sami

 

So you reamed the ridge, honed the cylinders and installed new rings? Nothing was done to the heads? Did you verify that the top of the block and bottom of the head were perfectly flat?

I assume your engines is RWC? No heat exchanger or coolant in the engine.

There are different gaskets available to use between the exhaust manifold exhaust elbow. If the engine is FWC (fresh water cooled with coolant) the cooling water does not flow from the exhaust manifold to the exhaust elbow. It's blocked. If the engine is RWC the gasket between the exhaust manifold and exhaust elbow allows cooling water to flow before it mixes with the exhaust in the exhaust elbow. and goes out.

I think you have the wrong gasket there.

As for a few drops of water on the spark plug, I am thinking it's most likely a head gasket issue and/or a surface is not perfectly flat and head gasket not sealing properly.

The head bolts were torqued properly in right sequence?

People sometimes soak the exhaust manifold and exhaust elbow in acid to clean them up. But you need to make sure you have no holes or weak spots between the exhaust and cooling water.

 

hi
yes my volvo penta v6 280N is FWC (fresh water cooled with coolant) and I understand , that the cooling water does not flow from the exhaust manifold to the exhaust elbow, as it is a closed circuit .
But, what about the sea water ? Normally after having cooled the cooling water , it must go out and mixed with the smoke at the extremity of the elbow .
Currently , the only way to the sea water to go out , is through the thermostat .
the thermostat installed on my engine , open only when the sea water is hot .
my question is : is the exist through the thermostat , enough .and is it the only way for the sea water to go out ?or is there an artificial obstruction in the internal circuit of the elbow?(see picture)

for the gasket issue and/or a surface is not perfectly flat and head gasket not sealing properly.Frankly speaking , I didn't assisted to the work done by the mechanical , but I suppose that he done the work properly , as it has enough experience .In the case we will dismantle again the blocks , be sure that I will controle every step by my self .first let us confirm that the sea water flow is correct .
thanks a lot
sami

 

So if you have closed cooling it can be half or full. Full is engine & exhaust manifold. Half is engine only.

The thermostat only controls the water flowing in the closed cooling section. If you have full closed cooling then the sea water after the sea water pump and through the heat exchanger flows to the exhaust elbow, cools the exhaust elbow and gets mixed with the exhaust at the tail end of the exhaust elbow and out the exhaust.

If you have half closed cooling then the sea water after the heat exchanger goes to the exhaust manifold and then to the exhaust elbow and out with the exhaust.

The thermostat is not involved with the sea water.

I would not take the engine apart at this point to check for perfect flatness of the two mating surfaces at the head gasket but would ask whoever put the engine back together if it was checked. The surfaces can be machined to be perfectly flat.

 

So if you have closed cooling it can be half or full. Full is engine & exhaust manifold. Half is engine only.

The thermostat only controls the water flowing in the closed cooling section. If you have full closed cooling then the sea water after the sea water pump and through the heat exchanger flows to the exhaust elbow, cools the exhaust elbow and gets mixed with the exhaust at the tail end of the exhaust elbow and out the exhaust.

If you have half closed cooling then the sea water after the heat exchanger goes to the exhaust manifold and then to the exhaust elbow and out with the exhaust.

The thermostat is not involved with the sea water.

I would not take the engine apart at this point to check for perfect flatness of the two mating surfaces at the head gasket but would ask whoever put the engine back together if it was checked. The surfaces can be machined to be perfectly flat.

 

hi
from your explanations ,I confirm that my engine is half closed .(the exhaust manifold and the exhaust elbow are cooled with sea water) .
let’s be clear , my engine has 01 thermostat behind the exchanger for the engine close circuit , and one in each elbows : total 03 .
probably my engine was destinated for very cold countries like Canada or Sweden , where the sea water is very cold (so the thermostat will open only when the engine is hot)

but what I can’t understand is that the elbow is not perforated in its tail as on usual exhausts seen on you tube .
the sea water remain inside the elbow and is evacuated , only when the water is hot but through the thermostat circuit not like all the other usual exhausts and as you perfectly explained : then the sea water after the heat exchanger goes to the exhaust manifold and then to the exhaust elbow and out with the exhaust. IN MY ELBOWS IT DOES NOT GO OUT DIRECTLY WITH THE EXHAUST .
My question is : have you ever heard about elbows that are not perforated to keep the water flow (see attached the green flow ).

If my elbows due to excess of heat (my country is hot ) has fissurated because they are not well cooled with sea water in permanence , this will PROBABLY explain the presence of water in my plugs

thanks
sami

 

Almost guaranteed some sea water is flowing into and mixing with the exhaust all the time. Otherwise the rubber exhaust would melt. It may recycle some to keep the manifold around the catalytic converter at operating temp. But some goes out all the time.

 

You are absolutely right .
I think I have a catalytic elbow that needs to go to high temperature before being cooled .
But if it becomes hotter than required , will this damage the exhaust and make cracks that will cause sea water to leak????

 

One thing to keep in mind is all the water pumped by the sea water pump leaves your engine. If you sea water pumps 5 gom then 5 gpm is leaving your engine (5 gom is an example only). What may change is the ration of water being recirculated vs going straight out.

 

Hi
Yesterday we controlled the exhauster and verified that it is in a good state.
After a discussion on a forum in Facebook, I finally understood, that the problem of water in the plugs , is due to a known phenomenon : EXHAUST REVERSION .
It is a conception default on the volvo penta V6 280 N, that sometimes and RANDOMLY makes the water SUCKED backward, instead of being expulsed with the exhaust .
It is exactly the same problem than last year sudden stop.
The local agent of Volvo refused to apply for the warranty, because they considered that the water that entered the pistons, was due to my bad sailing behavior :wrong backward movement.
Now that I know that the problem is not due to my fault , I will ask for a compensation.
BUUUUUUUUUTTTTT
I don't think that Volvo penta is the kind of companies, that cares about its customers .

 

I am not sure I believe it.

If you stop the boat suddenly with the engine still running the exhaust is still pushing exhaust gases out. No water gets in any cylinder.

If you stop the boat and turn off the engine while very unlikely some water could get into a random cylinder with it's exhaust valve open. But the water has to rise up to the height of the exhaust elbow or riser. It could be a few drops or fill the cylinder. And would be a random cylinder.

Unless there is a fire I cannot think of any reason why one would suddenly stop the boat and shutoff the engine

 

please find the steps of this year breakdown
after a cruise of 30 km at 3000 rpm
I stoped gradually keeping the engine working , then one minute later I started again and reached for about 500 meters a spped at 3200 rpm.
Then the alarm sounded .
So I immediatly stopped the engine and turned off immediatly the engine .
what kind of explanation do you suggest ?

 

If you get an alarm you need to read the code and not guess what the issue is. I bought a Diacom for that very reason.

 

thanks