Another dreaded Merc 3.7 (470) engine problem. Water in oil

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cclements716

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the boat is a 88 Pontoon with an 3.7L (2 bbl mercarb) I noticed the other day that there was a slight bit of water in the oil. After running the boat in water and under load for the first time since i have had it, it lost between about 1/4" to 1/2" inch worth of water in the reservoir tank and the oil became milkier. So i obviously have a leak some where, or residual water in the oil from when i bought it.

I have taken it down and have the head off of it. It is currently getting machined and all the valves reseated. I have new gaskets for the head, intake, both exhaust gaskets, and the lifter cover and rocker cover. I talked to a very knowledgeable mechanic and he seamed to think that the leak wasn't coming from the head because if so i would have lost more water (this was pretaking the head off). He thought that i may have lost the water through the heat exchanger and the water in the oil was there before i bought the boat.
Its a long story but the people must have flooded the engine before i bought it. The water was high enough to fill the starter (i had no idea until 500 miles and a month later). So that may be it but i would rather go through this than keep changing the oil 10 times and then realize that it is the head.

Once i took the head off the #1 especially and #2 pistons were both "clean" and the 3 and 4 where coked up. With the sight of the i believe that it is the head gasket because if it were the intake or exhaust i would think that it would be in all of the cylinder instead of just two. Can anyone help me out? I am mechanically inclined but this engine has been a fight from day one. Any help will be greatly appreciated. THANKS
 

Fordiesel69

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

cam seal orings?
 

Doernuth

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

Did you compression test before pulling the head? Im guessing no.

It could have just been condensation in the engine if it sat long enough before you started it. This is common when boats sit over the winter that is why it is recomended that the oil be changed in the spring.

How did the head gasket look when you pulled the head? did you see a breach in it?
 

cclements716

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

No it looked perfecty fine. I really don't think that the boat has that many hours on it also. The cylinders where no scared or worn at all
 

stonyloam

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

I will bet that when you get it back together it will be just fine. Make sure the weep hole in the engine waterpump is open. You can check the heat exchanger by pulling the aft (seawater) plug. Let it drain completely then put a small container under the drain overnight to see if any antifreeze comes out.
 

solar7647

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

My money is on the o ring on the cam. The came runs the water pump, there is just a o ring keeping the coolant from getting into the crank case. It's cheap and easy to change.
 

stonyloam

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

My money is on the o ring on the cam. The came runs the water pump, there is just a o ring keeping the coolant from getting into the crank case. It's cheap and easy to change.

Actually there are two seals with a space and a weep hole between them. If the pressurized coolant gets past the first seal it simply leaks out of the weep hole, and the second seal never sees coolant under pressure, so it is unlikely that you would get coolant in the crankcase unless the weep hole was plugged.
 

Doernuth

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

Make sure that the block is perfectly flat before reinstall, make sure that the weep hole is clear and reassemble. Follow the torque specs exactly.

I understand engine headaches, i have twin 165's. Named good girl and bad girl. Good girl on the port side runs wonderfully and other than a tune up no probs.

Bad Girl on the Starboard is another story. Ran problematic for a year then seized. Got a used engine and finally got it installed, block was cracked on both sides. Waiting for the engine builder to finish making one good engine out of two bad ones.

Hope you have better luck with yours than I have.
 

cclements716

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

How do I get the block flat
 

DACEAC

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

you need to check the surface of the block where the heads bolt back on to see if its level. If its not then you need to pull motor and have the block planed back level by a machine shop. planeing the block will probably change the length of push rods you will need to use. Machine shop will be able to tell you.
 

solar7647

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

Actually there are two seals with a space and a weep hole between them. If the pressurized coolant gets past the first seal it simply leaks out of the weep hole, and the second seal never sees coolant under pressure, so it is unlikely that you would get coolant in the crankcase unless the weep hole was plugged.

Over time they create a grove in the camshaft, it can and does get bad enough that the weep hole can't release the coolant fast enough to keep it from getting in the crankcase. Those seals are not as press fit as one would think witch is why they are installed with lock tight to hold them in place.
 

cclements716

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

Can any tell me exactly or preferably show me the weep hole. I looked for it today for about 45 mins and could never find it. Does anyone know the torque specs? Taking the head off a 23 year old motor, they were torque to a degree of breaker bar and 12 lb maul. Haha. I reinstalled the head and exhaust today just waiting on the intake seals now. Does anyone know of a way to find out what push rod I need? There are 3 or 4 different ones for the same engine on mercruiserparts. I bought some today that were for the same era 470 ford head but they are about 1/16 or 1/8 shorter. Should I keep looking or is this within tolerance?
 

solar7647

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

Can any tell me exactly or preferably show me the weep hole. I looked for it today for about 45 mins and could never find it. Does anyone know the torque specs? Taking the head off a 23 year old motor, they were torque to a degree of breaker bar and 12 lb maul. Haha. I reinstalled the head and exhaust today just waiting on the intake seals now. Does anyone know of a way to find out what push rod I need? There are 3 or 4 different ones for the same engine on mercruiserparts. I bought some today that were for the same era 470 ford head but they are about 1/16 or 1/8 shorter. Should I keep looking or is this within tolerance?

The weep hole out let is located to the lower left side of the front of the engine if you are looking at the Balancer. As you can see in the image, there are two seals. If the first one goes bad, the coolant should get traped between the two and beable to drain through the weep hole. But if the seals cover the weep hole from inproper instalation or failure the coolant can not drain. Also if both seals are bad the coolant will take the path of least resistance and go into the cranck case.

weephole.png


The torque specs for the head are listed in the image below

headtoruqesequance.png


And the general list of torque specs

torquespec.png
 

mik2.0

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

I am currently working on a 79 470 that has pretty much the same symptoms. my trouble shooting brought me to the exhaust riser gasket. what happens is while sitting the gasket leaks coolant into the exhaust manifold and over time fills up and leaks into #4 cylinder through the exhaust valve and when the level gets high enough leaks into #3. the motor sits at an angle that was why these two cylinders were affected. I found this by capping off all antifreeze inlets and outlets.( I did this by cutting apart an old inner tube and using original hose clamps.) then with the manifold sitting upright I filled it with water put on the radiator cap. I then hose clamped the over flow tube to my air compressor hose. I put enough pressure to expand the inner tube caps on the inlets. I then waited then after awhile I noticed water working its way up to the #4 exhaust opening. this may sound crude but it worked
 

cclements716

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

We got everything back together but ran into another problem. I checked the weep hole but found it to be clear so i think it had to be one of the other gaskets. I have not changed the head gasket, both exhaust, intake, and the thick carb gasket and rocker cover. While i had the head out i went ahead and had all the valves taken out, cleaned and reseated. We put everything back together the other day and torqued everything to specs. but found that now my outdrive is leaking at the transom around the bottom. I checked the bottom bolt but due to the exhaust outlet i could only tighten one side. It was slightly loose and the drips did slow when i tightened it but did not stop completely. I think to fix it throughly i need to just take it off and change the gasket but considering i have been working on the boat since january and have yet to take it on the water this year i really want to just use something like 3M 4200 and caulk it to get by for the rest of the summer. The transom is aluminum so i know there will be some flex but not nearly as much as fiberglass. What are yalls thoughts on this? Also does anyone have the best method on getting the milk out of the engine. My idea was to drain the oil, replace with oil 3 times, then fill with diesel run for maybe 3 seconds, drain, fill again with oil, run for maybe 30 seconds, then put the good oil in it. What about sea foam?
 

stonyloam

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

I would think draining it than filling cheap oil and new filter, run till it is up to operating temp, let it drain while you retorque the heads, then a good filter and oil (I like quicksilver 25-w40) should do it. That will get out all but a tiny bit of water, and any left will come out as you run it.
 

salty3rd

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

I had water in the oil and I was told to run kerosese in place of the oil till the engine was hot. You want to make sure all the water droplets are out of your main bearings. I drained it and did a couple of oil changes on it before i put the final oil in. I didnt have any problems after that. Good luck
 

cclements716

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Re: Another dreaded Merc 3.7 (470) engine problem. Water in oil

You will never guess what i found once i reinstalled the rocker cover and heated up the boat in preparation to drain the oil, no milk. Not one bit of milky oil. So here is my best guess, when the head stuck the valve fuel was being dumped into the cylinder most was being burned but some was being left behind because of the inability to escape the chamber. This inturn mixed with the oil creating what looked like water in the oil. But now since it has been about 3 weeks the gas that was in the oil pan has now evaporated. I did run the engine for about 45 mins got it good and warm and then sucked out as much as possible. I bought a rotary pump that goes on a drill but it couldnt seam to suck the oil through the hose. I then bought a manual pump that did work better but it took about 2 hours to get most of the oil out and im still not sure that it is all gone. Any thoughts? I had an idea for anyone who does have water in their oil and has to change is numerous times to get it clean. Go to your local tire repair/ oil change shop, and ask them for their used oil. Just bring a 5 gallon gas can (clean of course) and fill it up. They will most probably do it considering they have to pay a recycling fee (normally) and you can get all the oil you can stand to get the water out. I know it isnt the right weight and its "dirty" but it really dosent matter its going to be in there idling on muffs and under no load. And your going to drain it all right out. That was my solution for effectiveness and cheapest way to get it done. So now i have 5 gallons of spent oil that i have to bring back but im happy to do so knowing that i dont have a leaking cam seal. Salty i have heard that also, diesel also works really well but i dont think that you are suppose to run it for very one with it in there maybe only 10-15 seconds.
 

cclements716

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Reopening of an old thread. Oddly enough i sold the boat that october but i have now bought it back. I know i know, what an idiot for buying back 3.7l. But i really like the boat and the things that i have done to it (new rails and seats) make it ooh like a nearly brand new boat.

past 2 years: Previous owner had the boat completely rewired, the bellows and gimble replaced, oil changed, new spark plugs etc done at a local shop.

I bought the boat, ran daily on muffs in my driveway for a few days just to make sure it was going to run before i towed it all the way to the camp. Everything seemed fine idled great no problems.

Put it in the water, had to adjust the dale slightly but not much. Headed out, got about 1 mile down river (cruising around 3k) and the boat acted as if it had slipped out of gear. Turned it off, checked to make sure we still had the prop and that the shifter was in fact engaged the lower unit, It was.

ONce completed we restarted the boat and allowed it to idle while we looked over it. At this time i noticed that the temp gauge rose quckyly and shut down the engine. I then realized that the output shaft from the coupling to the outdrive was not spinning, therefore not running the raw water pump.

I feel confident that the coupler is the culprit. Any other suggestions?

If it is the engine and drive will have to be pulled from the boat. While doing so should i just purchase a rebuilt short block or just fix what i have? I feel like if i am going to pull it out of the boat i might as well do some PM. IE - oil pump, oil pan gasket, water pump gaskets, clean or replaced the heat exchanger, etc. Any suggestions? Or would a repower with a newer 2000-and up 3.0l mercruiser be a better idea? I have found a 2002 Mercruiser 3.0l with alpha 1 gen 2 drive package for $2000 (boat transom is rotting) Engine has 260 hours on it.

Or should i just replaced what is broken and worry about the other items as they arise? Thanks!
 
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Did you smell any burnt rubber when it happened?

Myself , if it runs well and has good compression on all cylinders I'd put the new coupler on it.

You can still run the engine on the trailer with the entire outdrive removed. Stick the garden hose in the water inlet in the bellhousing, where the large O'ring is, turn the water on full and it will cool off the engine just fine.
 
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