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Old 12-08-2016, 04:45   #16
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Re: Water in Perkins 4-108 Oil Sump

No pistons are perfectly sealed against the barrels. Scratches, polished or worn bores make it worse. If the exhaust manifold fills with water, and an exhaust valve is open(on a 4-cylinder engine, one is always open), water will slowly seep past that piston.
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Old 12-08-2016, 07:16   #17
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Re: Water in Perkins 4-108 Oil Sump

[QUOTE=skenn_ water will slowly seep past that piston

That must be some clapped out engine. The Perkins has 5 ring pistons. If water could leak past them I doubt the engine would have enough compression to even run.
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Old 12-08-2016, 07:26   #18
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Re: Water in Perkins 4-108 Oil Sump

[QUOTE=Guy;2187873][QUOTE=skenn_ water will slowly seep past that piston



That must be some clapped out engine. The Perkins has 5 ring pistons. If water could leak past them I doubt the engine would have enough compression to even run.[/QUOTE]


Water will go past any engine piston given time.


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Old 12-08-2016, 07:44   #19
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Re: Water in Perkins 4-108 Oil Sump

[QUOTE=Sailmonkey;
Water will go past any engine piston given time.


How much time are we talking about?
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Old 12-08-2016, 08:21   #20
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Re: Water in Perkins 4-108 Oil Sump

[QUOTE=Guy;2187896][QUOTE=Sailmonkey;

Water will go past any engine piston given time.





How much time are we talking about?[/QUOTE]


Anywhere from hours to days. Piston rings by design are dynamic seals and provide a labyrinth path to reduce leakage, as well as relying on pressure to form the final seal. When static the rings relax and bypass occurs. At what rate depends on the age of the engine as well as the original tolerance of the engine.


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Old 12-08-2016, 08:36   #21
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Re: Water in Perkins 4-108 Oil Sump

[QUOTE=Sailmonkey;
Anywhere from hours to days. Piston rings by design are dynamic seals and provide a labyrinth path to reduce leakage, as well as relying on pressure to form the final seal. When static the rings relax and bypass occurs. At what rate depends on the age of the engine as well as the original tolerance of the engine.


That is only true for the top couple of rings The rest have springs & expanders. With 5 rings, multiple segments, end gaps of just a few thou, carbon, oil, I don't think water is going anywhere anytime soon.
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Old 12-08-2016, 08:53   #22
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Re: Water in Perkins 4-108 Oil Sump

[QUOTE=Guy;2187951][QUOTE=Sailmonkey;

Anywhere from hours to days. Piston rings by design are dynamic seals and provide a labyrinth path to reduce leakage, as well as relying on pressure to form the final seal. When static the rings relax and bypass occurs. At what rate depends on the age of the engine as well as the original tolerance of the engine.





That is only true for the top couple of rings The rest have springs & expanders. With 5 rings, multiple segments, end gaps of just a few thou, carbon, oil, I don't think water is going anywhere anytime soon.[/QUOTE]


The rings with springs and expanders are wiper rings, not sealing rings.


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Old 12-08-2016, 09:11   #23
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Re: Water in Perkins 4-108 Oil Sump

[QUOTE=Guy;2187539]
Quote:
Originally Posted by roverhi View Post
Usually water in the oil is backflow from the exhaust. Water syphons into the exhaust and back flows into the head and then into the pan.

How on earth does water get from the cylinder into the oil pan?
Past the rings.
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Old 12-08-2016, 12:12   #24
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Re: Water in Perkins 4-108 Oil Sump

Changing the track a little, do these engines have wet or dry liners ? I am wondering about possible water paths to the sump. Timing cover seems to be the main one ( I presume that some of the water jacket opens to the front of the engine), oil cooler unlikely, as there is no oil in the water. I am fairly sure that the sump is perforated too, so am (not) looking forward to lifting the engine. I will have a look underneath first, with an endoscopic camera. Any idea how much a 1004T engine weighs ?
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Old 12-08-2016, 15:36   #25
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Re: Water in Perkins 4-108 Oil Sump

The 107 has wet liners with 2 Orings that leak out a small hole in the side of the block, It would need a double O ring failure to let water into the oil pan. The 108 is has dry liners with no O rings necessary. There is no path for water into the oil sump from under the timing cover. The only soft plugs are on the back behind the flywheel and on the outside of the engine. They used stainless soft plugs so they don't usually fail anyway. The really old Perkins had common oil system for both the engine and the transmission. In that case a leaking soft plug behind the flywheel could put water in the oil.
The heat exchanger would leak oil into the water not vise versa.
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