165 Merc with water in the oil (second post)

[btaylor507]

Hi thanks for looking. I have a question and I'm giving this a second thought.. I have a 87 165 Merc 4 cyl with water in the oil. This seems to be taking on water in the block very quickly. The thing that has me stumped is this is a closed cooling system and doesn't put water into the motor, just a heat exchanger. The antifreeze level stays the same so just wondering if there is a seal somewhere that would allow fresh water into the block.. The motor does run if that makes a difference..Any info would be greatly appreciated.. Thanks so much guys!

 

[btaylor507]

Re: 165 Merc with water in the oil (second post)

also the antifreeze show's no discolor. Stays at the same level and the motor doesn't overheat.. I've asked a couple people and they're stumped too.. thanks again.

 

[johnsland8]

Re: 165 Merc with water in the oil (second post)

I thought the Merc 165 was an inline 6?
Did they have more than one?

 

[btaylor507]

Re: 165 Merc with water in the oil (second post)

yeah there's a 6 cyl and 4cyl.. I have the 4 cyl. 224 CID 3.7L

 

[johnsland8]

Re: 165 Merc with water in the oil (second post)

Regardless of weather its raw water cooled or a closed cooling system, water still has to circulate through the engine block to cool it.
You're not noticing any change in the levels of your cooling system so is your oil level increasing significantly or is the oil just turning milky?

 

[btaylor507]

Re: 165 Merc with water in the oil (second post)

The oil is very milky and went above full when I ran water through it. The antifreeze is perfectly fine hasn't lost a drop.. The heat exchanger is located on the side of the block. I thought fresh water never enters the motor, thought that was the point of a closed cooling system. So the saltwater doesn't get in there.. Thanks for the reply and any more ideas are greatly appreciated.

 

[johnsland8]

Re: 165 Merc with water in the oil (second post)

With a raw/fresh water system, water is sucked up through the outdrive, circulated through the engine, and then spit out.
With a closed system, it works like your car cooling system. You supply the water/coolant and it circulates thru the system. No new water is introduced but the water/coolant in the closed system still has to circulate thru the block to cool it - doesn't it? That's how I understood it to work? How else would it cool?
But I could be wrong, wouldn't be the first time...
Good Luck with your issue... I know trouble shooting these things can be very frustrating!

 

[btaylor507]

Re: 165 Merc with water in the oil (second post)

Thanks bud for the help.. yeah I'm wrong 90% of the time too.. From what I understand fresh water is drawn in and ran through this round tube that's the heat exchanger.. the antifreeze runs into this heat exchanger too.. this unit is separate from the motor.. I just dont see how fresh water could be getting in.. but I dont know much about motors so that why I'm here on Iboats (The best site going I think )

 

[btaylor507]

Re: 165 Merc with water in the oil (second post)

Ok I just made a note of that. The thing that has me confused is that the cooling system(antifreeze) doesn't leak and the engine doesn't over heat. So the leak must be between the ourdrive pump and the heat exchanger right? and if so how is it getting into the motor since the fresh water and engine are separated.. I called a marinia close by and he's never heard of this and said he would look into it. any ideas let me know. Thanks again.