Mercruiser 170 water in oil issue.

[8AteEight]

Im sure this has been posted before, but I cant find anything that really describes the problem, at least with any detail.<br /><br />I have an '85 Tara with the Mercruiser 170, which gets A LOT of water in the oil. I bought it in January with a "perty chocolate-milk" type oil. I changed it, and I finally got to test it. <br />I ran it in the lake last night, for a total of 30 minutes. Just sat there on the trailer, warmed it up, and shifted the gears. <br />It seems to Run okay, and It was cooling great (after I got the Heat exchanger sealed) But after I pulled it out of the water, I checked the Dipstick. The oil level was up a full quart, and it had more water than it did B4.<br /><br />So, One big question I have is: could this really be just the cam seal, or (with a leak that big) could it be a cracked block?? I mean, I expected a little leak if there was to be one, . . . . .but wow!!!

 

[rodbolt]

Re: Mercruiser 170 water in oil issue.

hello<br /> its easy to find. use an automotive pressure tester. are you getting any water on a spark plug?<br /> the cam seals do leak occasionally and the system holds 7 psi or so.<br /> at 7 psi a small leak speeds up rapidly.<br /> those engines were also noted for popping head gaskets. the 3.7 looks similar to an auto engine. its not. dont even think auto with it. there are more quirks to that motor then even merc knew about.

 

[8AteEight]

Re: Mercruiser 170 water in oil issue.

Kule. Thanx for the reply. I did have it pressure tested just after I bought it, and the mechanic said everything was good that way. Thats whats throwing me for a loop. He says its now a cracked block, and Im not so sure. I mean, with it being a closed cooling system, and Im not losing any coolant (I dont think) <br /><br />No water on the plugs, so I dont think its a HG. It turns over and fires excellent. It just pours water into the crankcase. AARG!!!!<br /><br />Thx again for the help though.

 

[Don S]

Re: Mercruiser 170 water in oil issue.

and Im not losing any coolant (I dont think) <br />

There is the big question right there. Because if you are not loosing coolant, then you aren't getting water in your oil because it's a closed cooling system. There is just no way possible.............. Unless<br /><br />Unless you have 2 seperate problems. If you have a bad heat exchanger, it could be allowing raw water into the closed side of the cooling system. Then if the seal is bad on the cam at the same time, you have water in the oil, and a full reservoir when you pull the cap off. And if you happen to be in salt or brackish water the seal and the head gasket could go away very quickly.

 

[8AteEight]

Re: Mercruiser 170 water in oil issue.

Hmmm. Didnt think of that. Luckily, Im very inland, so I dont have any saltwater to worry about. I am on my way to check it out now, so Ill let you know.<br /><br />Does anyone have the slightest incline that its a cracked block?? So far everyone on the forum says its the seal. (which is good, it saves me $1500 over a remanned one. )

 

[8AteEight]

Re: Mercruiser 170 water in oil issue.

Ok, its back in the shop. and eventually (like by Xmas) they will get around to fixing it. This isnt my usual mechanic (kuz he refuses to try to fix it) and these guyz are slower than cold tar.<br /><br />Its a good thing its rainy and cold right now, otherwise Id be really pissed that I cant go boating.