oil out of dipstick???

[blasep]

ok the motor is a 1978 470 mercruiser.. has been running good but now it will idle fine but under a load it will shoot oil out of the dipstick.. I had a good amount of oil on the deck. I put oil back in and idled back in but when I would try to give it gas it would do the same.. about a month ago I disconnected the hose from the valve cover to the carb.. (blow by?? not sure what it is called) that was spitting some oil in the carb and causing her to stall, but that was a month ago and it has ran good until now???
also the oil to me looks thin but I dont think its water , the coolant level is full..
any help is appreciated
thanks
Nick

 

[Daddy5295]

Re: oil out of dipstick???

Time to do a compression check. That's what happens when you have excessive blow by. Sounds like it's leaking past the rings.

 

[1730V]

Re: oil out of dipstick???

Checking the compression is a must. Also, make sure there are no restrictions in the crankcase breather system.

 

[wire2]

Re: oil out of dipstick???

Any detectable knocking? May have a hole in a piston.
As above, compression test.

 

[JustJason]

Re: oil out of dipstick???

if you can check the compression. However, I would make sure the crankcase breather is super clean

about a month ago I disconnected the hose from the valve cover to the carb.

why did you do this?

I wouldn't be surprised if this is just a case of an overfilled crankcase. (ie~ ya put to much oil in it)
On sterndrives (especially older) it is pretty much imperative that
when you change the oil you fill the crankcase to the fill mark when the boat is on the water, and the hull is loaded with the weight it normally would be when the boat is in use.
Depending on how the boat sits in the water, wether or not there is a lot of weight in it, and if that weight is in the front or the back, it can change how the oil level reads on the dipstick dramatically. A couple of degree's in the angle of the boat in how it sits relative to "level" can make a dipstick reading go up or down by an inch or more.

 

[Don S]

Re: oil out of dipstick???

For oil to squirt out of the dipstick tube, the crankcase has to be pressurized. Too much oil will cause aireated oil which causes lifter collapse and noisy lifters long before it's forced out the dipstick tube.
Serious ring problems or a holed piston is about the only reason you will get that much crankcase pressure.

 

[wire2]

Re: oil out of dipstick???

>>Depending on how the boat sits in the water, wether or not there is a lot of weight in it, and if that weight is in the front or the back, it can change how the oil level reads on the dipstick dramatically. A couple of degree's in the angle of the boat in how it sits relative to "level" can make a dipstick reading go up or down by an inch or more.<<

Um, I don't think so.

Most engines have the dipstick tube in the middle of the engine specifically for that reason. Tilting the engine will have a minimal effect on the dipstick, only the front & rear of the oilpan see a difference.

Late OMC stringers hydraulically tilt the engine for trim adjustment, far more than 2?. I've had one since '84, oil level reading isn't affected.

 

[blasep]

Re: oil out of dipstick???

thanks for the very quick replies.. ill start with a compression test. I removed the hose because it was spitting oil into the carb, not a lot of oil like now...
I didnt notice too much knocking or noise, maybe a little but nothing major I didnt realize until I saw oil.. before I go rings. how would I check the crancase breathing system??

 

[Don S]

Re: oil out of dipstick???

Check the compression first, then report back with the results.

 

[wire2]

Re: oil out of dipstick???

Unlike cars, a boat crankcase breather is just a vent tube from each rocker cover and open ended at the flame arrester.
Just remove one from the arrester, wipe it clean & blow into it. You should hear air coming out the other tube.

 

[Benny1963]

Re: oil out of dipstick???

also check oilfilter may be restricted run comp first oil thru dip stick
is usually blow by from crank case pressure being high due to res in vents
or ring failure at comp rings
b1963

 

[blasep]

Re: oil out of dipstick???

ok, I did a compression test.. hopefully I did the test right but I found in all four cylinders were right around 150psi..
but also I found when I drained the oil there was a good amount of fuel in oil.. I removed the fuel pump and the diaphragm was pretty worn and seems to me if you get some pressure in the pump fuel could make its way into the engine.. not really sure about all this as im still learning.. but is it possible that I was overfilled with oil/fuel mixture and not sealing the rings causing blow by.???

 

[farmboy]

Re: oil out of dipstick???

Check for a stuck carb float or faulty needle/seat. Do you have a fuel line petcock? If so, do you close it while your boat is on the trailer? For that much fuel to overflow the carb and end up in the crankcase, pressure has to be building in the fuel tank. Is the tank vent clear? It is possible for fuel to enter the crankcase from a bad fuel pump diaphram, but it always fills the sight glass first. If this is the condition, the engine would have a difficult time running properly, if at all.

 

[Don S]

Re: oil out of dipstick???

Do you have a fuel line petcock? If so, do you close it while your boat is on the trailer? For that much fuel to overflow the carb and end up in the crankcase, pressure has to be building in the fuel tank.

You BETTER not have to have a valve on the tank for that problem. There is a vent in the tank, if it's plugged, then the engine wouldn't run very long after the pump created a vacuum in the tank.
A bad fuel pump will cause that much fuel. The diaphram will allow gas into the crankcase. Or, the pump will force extra gas up the clear tube into the carb (a safety overflow) or the carb needs attention. But the shutoff valve better not be needed, if it is, it's a bandaid fix at best.

Nick
How often do you check your oil level??? Did the oil level fill that much in one trip?

 

[blasep]

Re: oil out of dipstick???

don... Probably been two trips out since I changed the oil and I checked the level a few times.. it looked ok but a few times I couldnt really see the level since the oil was so thin.. it was very thin the last trip when I had all the problems..not really sure how much fuel was actually in there but it seemed like a lot.....
Ive only changed the oil once since ive only had the boat for a few months...It did look a little thin but I just blew if off as the boat was sitting for a while..

 

[Don S]

Re: oil out of dipstick???

If the engine seems to run ok, replace the fuel pump, Before you have an oil pan explosion.

 

[blasep]

Re: oil out of dipstick???

new fuel pump is already on the way..

 

[farmboy]

Re: oil out of dipstick???

Hope the new fuel pump does the trick

 

[JustJason]

Re: oil out of dipstick???

pan explosions are fun
... and hella messy!!!!

 

[blasep]

Re: oil out of dipstick???

thanks for all the help.. I hope solves the problem.
could I really have a pan explosion??