How could water get into a Mercruiser 140?

Trucker-Boater · Mar 19, 2013

Here is the details. I bought a boat (project on the cheap), Merc 140 sterndrive. 1978. Got it home, found the 4 banger is locked up. I removed the plugs, #4 water poured out.

So, I figured it was crapola. I cut the back of the boat off, removed the stern and motor. Tossed the boat and kept the trailer, engine and stern drive. Alpha 1 outdrive.

I pulled the head...

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I found water in #4 and a bit in 3-1. Probably from taking off the head.

OK, I cannot for the life of me figure out how water could get into this engine unless the PO suck this boat. The exhaust manifold looks good. I cannot find any cracks. The head looks ok. The top of the block looks ok. I did toss the head gasket with the boat so I can't determine if the PO blew a head gasket.

OK, so I cranked the motor and it is free. I drained the oil....2 gallons of water then the oil came out. Milky.

I replaced with fresh oil, filter and cranked it with the starter motor. It shot motor oil about 15 feet out from the open port where the oil pressure switch was removed.

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I wiped everything down. The cylinders look fine. The head (as you can see above) #4 has a tad of rust. The valve cover was absolutely clean. The top of the valves were clean. No rust on the valve springs.

I've been told there is a possible crack internal. I was told to pull the pan and inspect the bottom end for cracks. I was told
the head could be cracked. But I cannot see anything. Obviously a pressure tester at a shop....

This 140 is alleged to be a stout motor. The PO said it ran 4-5 years ago then he parked it. Covered patio. We live in a temperate climate. Freeze plugs are intact.

http://tinypic.com/m/fw4upw/1

Ideas?

There was no rust in the water when it poured out of #4. No rust in the jugs. Only a bit has shown up since I removed the head, as seen in the links above.

What ya think?

I would like to re use this motor. Or sell it. But I will NOT sell it to anyone if there is a chance of an internal break.

cecho · Mar 19, 2013

Re: How could water get into a Mercruiser 140?

Bad Head Gasket. Possibly a warped head. That'd be my guess by looking at the images.

Don S · Mar 19, 2013

Re: How could water get into a Mercruiser 140?

This Merc service bulletin should explain it.

View attachment Water Intrusion 01-13.pdf

In a raw water cooled engine, it's seldom, if ever a head gasket.

cecho · Mar 19, 2013

Re: How could water get into a Mercruiser 140?

Don S said:
This Merc service bulletin should explain it.

View attachment 185843

In a raw water cooled engine, it's seldom, if ever a head gasket.

I've owned 4 SBC stern drives. I ended up replacing the head gaskets on 1x 350 and 1x 305. The 305 also had warped heads. Both were purchased that way. Both had damaged / worn impellers. That puts me at 50/50 on bad head gaskets. lol

Then again odd stuff tends to happen to me more than others.

The traces on the heads in the image look like the head gasket was bad. It's hard to tell from the image though. An image of the gasket itself can help.

Trucker-Boater · Mar 20, 2013

Re: How could water get into a Mercruiser 140?

i kick myself for tossing the head gasket. I figured the engine was trashed. So I tossed it in the boat before it went to the dump. (And the seats.....DAUM--)

Now I find boats with good outdrives, needing a 140 AND seats....

I have yet to split the lower end of the out drive. Bet the impeller is a nub....
I'll put a straight edged long ruler on the block and head this week.

More pics for you to view--un touched, not even been wiped off with a rag.

http://tinypic.com/m/fw6hb8/1
http://tinypic.com/m/fw6hb9/1
http://tinypic.com/m/fw6hba/1
http://tinypic.com/m/fw6hbb/1

cecho · Mar 20, 2013

Re: How could water get into a Mercruiser 140?

Take a straight edge and some feeler gauges and see if the head is warped. The 260 HP 350 I bought that that had a bad head gasket had water in cylinder 8. It also had water in the oil. I thought I was buying a 350 with a cracked block. Turned out all it was was the gasket. The head had the rust and carbon traces that I see on yours. Can you take a closer image of the head and block?

Trucker-Boater · Mar 20, 2013

Don S · Mar 20, 2013

Re: How could water get into a Mercruiser 140?

That's not head gasket or warped head. You have water from either the exhaust or intake. Possibly rain in the carb.
Since you have already taken the head off, there is no way to pressure test the block/head,gasket etc. to find what was leaking.
Clean it up, put it back together and see what happens. It's all you can do at this point.

cecho · Mar 20, 2013

Re: How could water get into a Mercruiser 140?

I live near Wichita. I usually fish and boat at Cheney Reservoir... though the water level is too low to put a boat in it right now so I'll be using El Dorado Lake / Reservoir until Cheney gets high enough to use.

You should check the valve seats, if they are pitted they aren't going to seal. If they aren't too bad you can just lap them. I don't think I'd spend the money on new valves unless the engine's OK though.

fishrdan · Mar 20, 2013

Re: How could water get into a Mercruiser 140?

Do the manifold's intake and exhaust passages have any rust in them? I'd fill the manifold's water jacket with acetone to see if there are any internal leaks.

cr2k · Mar 20, 2013

Re: How could water get into a Mercruiser 140?

Did you pull the lifter cover and check for cracks there?

Trucker-Boater · Mar 21, 2013

Re: How could water get into a Mercruiser 140?

Valve cover is absolutely clean. Might have a crack. I'll check it,

Yeah those valves bug me. I might run this head to a shop and have someone pressure test it along with checking the seats.

How could water get into a Mercruiser 140?

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