Blown Head Gasket

[bruceb58]

Re: Blown Head Gasket

So I am wondering what the knock would be, wasnt a loud knock, went louder the more I put the boat under load and that also happened at the same time as the head gasket blew. Maybe a bearing?

You were knocking because you had emulsified oil with 0 viscosity!

 

[TFHTECH]

Re: Blown Head Gasket

on allmost every motor that comes from a rebuilder comes with heat tabs on the heads and the expantion plugs thees look like small washers and are filled with lead and solder mixture that are made to melt at a certan temp this is how the builder tell if the motor was ever over heated for there warr. look for thees or have your mech. find them for you allso you can look inside your down hoses to c if they are coming apart as to se they have been burnt from the exhaust. and be shure that the water pump is of the proper rotation for the motor it could some how be a rev. rotation from a sbc as we know there all interchagable good luck

 

[mariner1900]

Re: Blown Head Gasket

each cylinder produces a minimum 100psi! More like 135psi.

This would be your "compression" pressure. Actual "combustion" pressure when a cylinder "fires" would be much higher possibly in the region of 800 too 1,000 psi.

Oil is the primary engine coolant, not water.

I also disagree with this statement. Let's look at an engine. The majority of heat is produced during the combustion stroke. Typically at the beginning of the stroke just after firing. Therefore the hottest part of any engine is the top 1/3 of the cylinder bore and the combustion chamber in the cylinder head. Both of these areas are cooled by water. No oil comes in contact with these areas.

The oils main function is to lubricate. The oil also has a secondary function to remove heat from the bearings not the cylinder block. Both of these functions prevent bearing failure.

wasnt a loud knock, went louder the more I put the boat under load

Sounds like you have done in a bearing or two. I would be dismantling the engine and doing a full inspection. What happens when you get water in oil is that when the engine is not run the water separates from the emulsion and settles to the bottom of the sump. When the engine is subsequently started the water is pumped through the engine as the initial lubricant until an water/oil emulsion is formed again. Water is not a very good lubricant. So every time you started the engine, with water in the oil, you were doing damage.

A total strip down, inspection and overhaul is the only way to ensure that you end up with a reliable engine.

 

[Howard Sterndrive]

Re: Blown Head Gasket

It absorbs exactly 212F before it turns into vapor and wisks away. Problem is cylinder heads get alot hotter than 212F

Nothing turns to vapor because the thermostat keeps the cylinder heads at approx. 180F by bringing in cold lake water.
If they get a lot hotter than 212F on your boat, you have a faulty cooling system.
Water in the crankcase will not contribute to overheating.

A water/oil emulsion will conduct heat just fine, bubbles or not... depends on the detergents in the oil how well it will emulsify.

The engine oil does very little heat removal on a Mercruiser 4.3.. maybe 5% I'd guess.

On a VP 4.3 with an engine oil cooler, it does much more... maybe 15%
That's why VP runs 10W30... oil is cooled.

 

[TFHTECH]

Re: Blown Head Gasket

(oil cooler) oil that is cooled by water not water that is cooled by oil

 

[Aviator5]

Re: Blown Head Gasket

Oil is primary engine coolant, so water is secondary. Interesting, learn something new every day.

 

[TFHTECH]

Re: Blown Head Gasket

my god everyone know water is the coolant oil is the lube

 

[bruceb58]

Re: Blown Head Gasket

my god everyone know water is the coolant oil is the lube

I believe Aviator5 was kidding.

 

[TFHTECH]

Re: Blown Head Gasket

im sorry av. this post is getting stupid and you can fix stupid the only thing that i could think that use oil as a primay coolant was the 911 porsche and that only lasted 2 years

 

[HT32BSX115]

Re: Blown Head Gasket

Oh come on guys.....


Oil IS a coolant. It's just NOT the primary coolant in a marine (or any) engine...

 

[bruceb58]

Re: Blown Head Gasket

Oh come on guys.....


Oil IS a coolant. It's just NOT the primary coolant in a marine (or any) engine... I didn't think this was going to turn into a thermodynamics lesson.....

It wasn't going to be until Jason and achris starts saying that water in the oil ruins the cooling affect that the oil has. In turn they think that would contribute to the engine overheat.

 

[mark_fitzy]

Re: Blown Head Gasket

Well guys got a result, not that one that I was expecting though.

The insurance assessor said that two mechanics are liable, and this is why.

Back in september I had the leg serviced and inlet yoke etc put on, turns out that when they put the leg back together they didnt use some sort of gasket sealer on the gasket near the water pump and as the plate(sorry not sure what he talking about)has a bit of corrosion, and the surface isnt completey flat and with out sealer of some sort to take up what gaps that where there because of corrosion, that it must have let air through and thus creating it to overheat. So he is blaming that mechanic for not repairing the leg the way it should have been done.

He is also blaming the other mechanic that has the boat now because back in April of last year I had the boat rewired completely and well some alarm should have went of telling me that is was overheating and it didnt! the assessor checked to see if it worked and it dosent. So apparently he is at fault for that.

The insurance company are going to pay for a new gimble bearing, starter motor etc but thats about it. Although the insurance assessor is going to try and put pressure on both mechanics to help out.

I have to wait for a full report next week from the insurance company and go from there. He said that is did overheat as there are signs of it there, so the motor will have to be pulled completly down. Why is that???:

You know the sad thing,I purchased this boat back in Feb of last year, it cost me $14000 and since then I have paid $11,500 in repairs not to mention how much this is going to cost me!!

 

[Howard Sterndrive]

Re: Blown Head Gasket

Why is that???:

Pistons are only round within a certain temperature range. When an engine overheats, the pin boss areas swell and the pistons start to get tight in the cylinders.
This scores the cylinder walls and damages the pistons.

Your bearings are also likely damaged due to the water in the oil.

 

[mariner1900]

Re: Blown Head Gasket

It is conceivable that a head gasket can fail without overheating but still appear as overheating.

Ok Well I didnt get any foam from the breather caps, but I did get alot of sludge in the rocker cover, remembering I did run it for four days with water in the oil before I had the head gasket problems.

Mark, from your explanation of events.
1. The bung was left out and boat filled with water.
2. Water entered engine.
3. You operated the the engine for four days, with water contaminated oil, before the problems occurred.

Here is possibly what happened.
1. Engine had water in the oil.
2. The water/oil emulsion would have caused poor lubrication eventually leading to the bearing failures, hence the knocks, and possible partial seizure of the pistons. Which would be the apparent signs of overheating that are probably visible in the cylinder bores
3. As the engine was failing higher throttle settings would have been required eventually reaching the point where WOT was required but engine was not accelerating I.E labouring.
4. The result of 3 would have caused higher than normal cylinder pressure and temperature.
5. The result of the above is burning and weakening of the head gasket until it "blew".

Unfortunately for you most insurance companies do not cover "consequential damage" that is why they will only replace the starter motor. If you had got the insurance company involved when you first filled the boat with water then you probably would have been covered.

You said that the engine that failed only had 40 hours on it an that engine had been fitted by the insurance company. What happened to the original engine?

Where in Oz are you?

 

[JustJason]

Re: Blown Head Gasket

Man o man... I was going to reply to this last night but the storm knocked the power out.

Let me reitterate... Oil is the primary coolant, you guys aren't seeing the big picture. Your only seeing what the little temprature gauge on the dash is telling you.
Half the time it's wrong anyways...


Oil has 4 properties, or 4 things it needs to do in order for an engine to function.

Cool, Clean, Lubricate, and Seal In that order.

Therefore the hottest part of any engine is the top 1/3 of the cylinder bore and the combustion chamber in the cylinder head. Both of these areas are cooled by water. No oil comes in contact with these areas.

There is 1 truth in there and everything else is false. The hottest part of an engine is the combustion chamber, and i'll give you that, but the second hottest part is the crown of the piston, the head tends to run a bit hotter than the piston crown, but not by much, and here is why. Oil cools the piston. Oil does cool that top 1/3rd of the cylinder as you put it, ever hear of an oil control ring or scraper rings? Oil coats everything just under the 2nd compression ring, and I think that covers the top 1/3rd of a cylinder wall.

If oil was not the primary coolant, pistons would contiunually expand until they siezed. Water obvisouly does not cool the pistons (unless of course you have water in your oil ) Ever take apart a diesel... What are all those oil injectors in the sump for... To Cool, Without them the pistons would overheat. Water does not come into direct contact to the hottest parts of a running engine, but oil does.
Who cares what the water temperature of the block is.... If the pistons are 1000F degrees instead of the 5-600F that they should be... It's going to blow up if oil doesn't cool the pistons.
Same thing goes for the bottom end of an engine, If oil didn't cool the crankshaft, the main bearings, the rod ends, their temperature would rise infinitely until everything swells and the engine stops dead. Water does not cool the bottom end of a block, oil does.
Oil also does cool the head. Sure water goes in 1 side and exits the other. But it does not swirl around the valves, or what would be the backside of the combustion chamber. Hey what cools the valves and keeps them from expanding to the point that they stick???????? Oil.

You can run an engine for a little bit without water, (or forever if it's air cooled) but you can't run it without oil. If oil had NO cooling properties then engines wouldn't work.

So I stand by my statement... Oil is the primary coolant, in any engine.

Water would be a secondary coolant, as some engines by design do not require water.

Then air, the outside ambiant temperature, would be the 3rd coolant. If it is very cold then air cools very well, if it is very hot out then the temperature differental is less and air doesn't cool as effectively. If you put a motor in a box and the box didn't vent it's concievable for an engine to "easy bake oven" itself to death.

Heat has to radiate somewhere... and it starts with the oil


And i'm not saying that water in the oil caused the head gasket to pop, I only said that having water in the oil, even for a little bit, causes all sorts of gremlins.

Don't bother repairing the head until you tear apart the lower. 10 bucks says the overlay on the main bearing are wiped out.

 

[bruceb58]

Re: Blown Head Gasket

Its still not the primary coolant. Think about it. You have 5 qts of oil which has 50% of the heat capacity of water and one fourth of the heat transfer characteristics. Yes it spot cools small parts of the overall mass of the engine but water is how all the heat leaves the engine.

 

[JustJason]

Re: Blown Head Gasket

You might as well start teaching then Bruce. Because when I was in school it was clearly taught that oil is the primary coolant in every engine. (i'm sure I still have some notes in my box of school stuff that I can scan) It doesn't matter if water cools better, or that you have more water than oil.
Water does not cool the hottest spots on an engine, oil does.
It doesn't matter how you think about it, if oil did not cool first, any engine, or anything that takes oil, would grenade.
What cools the gears and bearings in the drive? It's oil first, then water second. Primary/secondary.
What cools a manual transmission or rear differential in an automobile? It's oil first, then air second.
In an automatic transmission, ATF is a hydraulic fluid, and not an oil, cooling is not a function of hydraulic fluid, so they must use and external cooler/radiator.
On anything that takes oil, it's oils primary job to cool whatever it's going into. Then it Cleans, Lubricates, and Seals.

I'm not quite sure why your not seeing this. Hopefully Don or Bondo or Rodbolt will see it and put it into different words. Oil cools an engine, it is the first thing to cool an engine, and because it's the first it is the primary.
On big diesels or even gas engines that are under constant heavy duty load. We use seperate oil coolers to bring down the oil temps, so colder oil can re-enter the engine and help cool it.(and to aslo keep the oil from going into meltdown.)

 

[Howard Sterndrive]

Re: Blown Head Gasket

Man o man... I was going to reply to this last night but the storm knocked the power out.

Let me reitterate... Oil is the primary coolant, you guys aren't seeing the big picture. Your only seeing what the little temprature gauge on the dash is telling you.

you sure that was a storm?
maybe someone was trying to spare you the humility....

Here is how heat is removed from a Mercruiser RWC engine, in order of magnitude:

1. Coolant - more than 1/2 of a rwc marine engine's heat is removed this way
2. Intake/Exhaust - about 1/3 of the combustion heat leaves via the exhaust replaced with cool incoming air
3. Other - the remaining 1/6 leaves via ambient heat radiation from the block. If you want to include the engine oil in this a heat transfer medium, then fine.

 

[wire2]

Re: Blown Head Gasket

..... It is the job of the oil to get sprayed all over the top of the cylinder head, absorb heat, and drain back into the pan.....

On a classic GM 350 (low pressure oil pump version) as used in hundreds of thousands of cars and pickups in the last 30-40 odd years, there's only a fraction of a liter of oil per minute pumped up through the lifters, through the tiny holes in the push rods, and dribbled onto the rocker arm. Then it drips off the rocker onto the head and drains back to the pan.

It definitely does not "get sprayed all over the top of the cylinder head, absorb heat..."

There's a water jacket below the rocker area, with water flowing at a thermostatically controlled temperature of ~180? F to cool it.

 

[shouldsellit]

Re: Blown Head Gasket

This is good stuff.