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Mercruiser 5.0L with Alpha One legs - Engine oil pressure issue

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Mastervall

New member
I have a boat with two Mercruiser 5.0L with Alpha One legs.
The one leg lost all the oil from the reservoir. Exactly at the same time the engine oil pressure gauge went down to zero and temperature from the normal 150 went up to 200 (250 is the maximum on the gauge). The engine alarme went off, and I shut down the engine.
When tied to restart the engine to times, the oil pressure on the gauge shows normal pressure and in 2-3 seconds later the gauge going to zero.
Is anyone have a clue, how the two issues came up exactly at the same time?
Has the engine oil pressure gauge any connection with the leg oil?
I was thinking that the engine oil pump is completely separate from the leg and the engine oil pressure gauge is indicating only the engine oil pressure!
Any help is appreciated!
 
Mastervall said:
I have a boat with two Mercruiser 5.0L with Alpha One legs.
The one leg lost all the oil from the reservoir. Exactly at the same time the engine oil pressure gauge went down to zero and temperature from the normal 150 went up to 200 (250 is the maximum on the gauge). The engine alarme went off, and I shut down the engine.
When tied to restart the engine to times, the oil pressure on the gauge shows normal pressure and in 2-3 seconds later the gauge going to zero.
Is anyone have a clue, how the two issues came up exactly at the same time?
Has the engine oil pressure gauge any connection with the leg oil?
I was thinking that the engine oil pump is completely separate from the leg and the engine oil pressure gauge is indicating only the engine oil pressure!
Any help is appreciated!
Click to expand...
the only way I would think they are related is that you got something over the water intake ports that caused an over heat. The water going through the drive cools it so I am wondering if the drive got hot and smoked a seal causing the loss in drive leg oil.

While oil gets thinner at higher temps I would not think the gauge would drop to zero. is there still oil in the engine, do you get a normal ish gauge reading now? you can always put a mechanical gauge on it to see what engine oil pressure is.

250 is hot on the rubber components in the exhaust system and where the exhaust goes through the drive. Willing to bet the lower seal in upper or seal under the water pump is leaking. Would take drive off an pressure test, look for melted exhaust components, water pocket in upper and water tube up from impeller pump might be melted
 
Mastervall said:
I have a boat with two Mercruiser 5.0L with Alpha One legs.
The one leg lost all the oil from the reservoir. Exactly at the same time the engine oil pressure gauge went down to zero and temperature from the normal 150 went up to 200 (250 is the maximum on the gauge). The engine alarme went off, and I shut down the engine.
When tied to restart the engine to times, the oil pressure on the gauge shows normal pressure and in 2-3 seconds later the gauge going to zero.
Is anyone have a clue, how the two issues came up exactly at the same time?
Has the engine oil pressure gauge any connection with the leg oil?
I was thinking that the engine oil pump is completely separate from the leg and the engine oil pressure gauge is indicating only the engine oil pressure!
Any help is appreciated!
Click to expand...

It needs to be hauled out of the water and checked out unless you find that the line from the outdrive's reservoir has a leak or came off.

The dash gauges take their own time to react, so it may not have happened simultaneously- the engine may have overheated after the oil pressure was lost.

Did you check the dipstick? How low is it?

Engine and outdrive oil sytems are separate- how old is the boat, are the engines and outdrives original and when was the service performed WRT outdrive seals and gaskets? How long have you owned it and how strict are you WRT service intervals?
 
Dieter said:
the only way I would think they are related is that you got something over the water intake ports that caused an over heat. The water going through the drive cools it so I am wondering if the drive got hot and smoked a seal causing the loss in drive leg oil.

While oil gets thinner at higher temps I would not think the gauge would drop to zero. is there still oil in the engine, do you get a normal ish gauge reading now? you can always put a mechanical gauge on it to see what engine oil pressure is.

250 is hot on the rubber components in the exhaust system and where the exhaust goes through the drive. Willing to bet the lower seal in upper or seal under the water pump is leaking. Would take drive off an pressure test, look for melted exhaust components, water pocket in upper and water tube up from impeller pump might be melted
Click to expand...
Thank you for taking the time writing back for my issue.

The engine oil.level didn't change at all. It has new oil to the right full level.
 
jimn said:
It needs to be hauled out of the water and checked out unless you find that the line from the outdrive's reservoir has a leak or came off.

The dash gauges take their own time to react, so it may not have happened simultaneously- the engine may have overheated after the oil pressure was lost.

Did you check the dipstick? How low is it?

Engine and outdrive oil sytems are separate- how old is the boat, are the engines and outdrives original and when was the service performed WRT outdrive seals and gaskets? How long have you owned it and how strict are you WRT service intervals?
Click to expand...
Thank you for taking the time writing back for my issue.
 
jimn said:
It needs to be hauled out of the water and checked out unless you find that the line from the outdrive's reservoir has a leak or came off.

The dash gauges take their own time to react, so it may not have happened simultaneously- the engine may have overheated after the oil pressure was lost.

Did you check the dipstick? How low is it?

Engine and outdrive oil sytems are separate- how old is the boat, are the engines and outdrives original and when was the service performed WRT outdrive seals and gaskets? How long have you owned it and how strict are you WRT service intervals?
Click to expand...
Thank you for taking the time writing back for my issue.
 
Update.
We hauled the boat out of the water and checked out the leg!
The gear is completely shear off! It's unbelievable! You can't see any gear teeth left!
The previous owner had a mechanic to change the bolt joint and of course is connected with the gear right after.
Probably, the mechanic didn't placed the whole thing back properly and the most likely the gears were not sitting properly engaged the teeth of the gear tightly enough!
Now we're ordering the upper section of the leg, to install the new one, and after that we'll see how the engine runs.

The engine oil is normal. Before we pull the boat out of the water, we started the engine and the oil pressure gauge showed oil pressure but the engine alarm was going off.
We'll do one step.at the time to see what else is going on!
It might be gauge failure! Some times devil plays games, all happened at the same time! We'll see!
 
If the upper unit is failed then the vertical drive shaft isn't turning so the water pump isn't turning either.
 
Droid said:
If the upper unit is failed then the vertical drive shaft isn't turning so the water pump isn't turning either.
Click to expand...
Thank you for your time to write back.
We hauled the boat out.
The leg is at the mechanic and we'll see if we'll change only the gear or we'll change the upper section of the leg.
 
If the upper gear set was ground up, don't ignore the lower unit as it is very likely to have collected the majority of the shavings ....
 
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