running engine with no oil

H

hadensatbk

Cadet
Joined
Aug 20, 2005
Messages
8
Just purchased a Maxum with the 1995 Mercruiser 5.7, alpha 1, carb motor. After motoring for a few hours without problem, the motor shut down when I throttled off in preparation for docking. There were no problems beforehand, and the oil pressure/temp guages were fine all day. I pulled the dipstick for the engine oil and it was COMPLETELY DRY. Boat will not start now. Did I prob blow the motor?
 
L

lowshovel1

Petty Officer 2nd Class
Joined
Dec 11, 2004
Messages
135
Re: running engine with no oil

was there oil in it when you put it in the water? How long did you wait after shut down to check dipstick? Does the starter turn the engine over? when the oil presure sending unit reads the oil that low it will shut engine down. I would put in the proper amount of oil and try to start it.
 
H

hadensatbk

Cadet
Joined
Aug 20, 2005
Messages
8
Re: running engine with no oil

Well, this is where I start looking really dumb. We bought the boat 2 weeks ago, and I have never checked the oil level. The seller said that everything was ready to go, so I assume that it was full of oil when we purchased it. We've put 4 hours on the motor since we bought it. I checked the oil as soon as it quit and it was dry. I checked again this morning and there was maybe 1/2 inch on the dipstick. The starter will turn the engine over like normal. I've filled it with oil but it still won't start.
 
H

hadensatbk

Cadet
Joined
Aug 20, 2005
Messages
8
Re: running engine with no oil

Something else....just removed the flame arrestor and pumped the throttle. Doesn't appear that any gas is flowing into carb. Is there something that needs to be reset after the oil pressure sending unit shuts down the engine? I noticed a 50amp breaker right next to the carb and tried resetting, but it hasn't helped.
 
Don S

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: running engine with no oil

If you have a 95 engine, it came with a mechanical fuel pump. The oil pressure switch was for the alarm only (same alarm also worked for low gear lube in reservoir and high temp).<br />Now if you have a newer Mercruiser engine with the electric fuel pump then that could do it.<br /><br />Does the engine sound like it's cranking at the same speed as it used to?
 
H

hadensatbk

Cadet
Joined
Aug 20, 2005
Messages
8
Re: running engine with no oil

I'm not sure, but it looks as though it's a mecanical pump (there is no wiring leading to the pump, just fuel lines in&out). The engine cranks the same as it used to, but it won't start.
 
Z

ZmOz

Captain
Joined
Aug 13, 2003
Messages
3,949
Re: running engine with no oil

If it's still cranking over, the oil isn't the reason it's not starting. Although it's a very bad idea, the engine can still run ok even when the oil level is below the dipstick...but not far below. I bought a truck with a 454 a few months ago, after I drove it 30 miles home I checked the oil and it wasn't touching the dipstick. :eek: It still had 4 quarts in the pan though...
 
Don S

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: running engine with no oil

Have you put any oil in the engine to see exactly how low it was?<br />Are you sure there is gas in the tank?
 
H

hadensatbk

Cadet
Joined
Aug 20, 2005
Messages
8
Re: running engine with no oil

I put 4 quarts to fill it, and I believe the capacity is 5.5 quarts. Just in case it was a gas problem, I put 5 gallons in today to make sure. If it did run out of gas, anything special to do to "prime" the fuel system?
 
Don S

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: running engine with no oil

If it was out of gas, it's going to take a bit of cranking to get fuel in the filter and the pump and the carb.<br />Might squirt some gas in the carb (Then put the flame arrestor back on) and try to start it.<br />I would also check your alarm system, if you had low oil pressure, it should have gone off at about 7 PSI.
 
H

hadensatbk

Cadet
Joined
Aug 20, 2005
Messages
8
Re: running engine with no oil

Ok, tried the gas thing and cranked on it for a while....no start! I pulled the plugs- all of them were very black and very dry. Shouldn't they at least have been wet with gas from all of the cranking?
 
bomar76

bomar76

Lieutenant Commander
Joined
Jun 27, 2002
Messages
1,963
Re: running engine with no oil

3 things needed fro spark ignited (gas) engines to function:<br /><br />1. Air (compression)<br />2. Fuel<br />3. Spark <br /><br /><br />when you determine what is missing, let us know.
 
H

hadensatbk

Cadet
Joined
Aug 20, 2005
Messages
8
Re: running engine with no oil

Not sure... I pulled them all out before checking. Should I put the #1 plug back in and try it?
 
L

lowshovel1

Petty Officer 2nd Class
Joined
Dec 11, 2004
Messages
135
Re: running engine with no oil

that would at least verify a no spark problem. Sounds like the carb is running rich(black plugs). check spark at plugs and we'll go from there.
 
You must log in or register to reply here.
Top