No oil pressure

[connersh]

I apologize if this is a second post. This my first time using this forum and not quite sure if I know what im doing. I have 1989 mercruiser 270hp alpha 1. Was out cruising yesterday and when I was docking the engine cut off. had to try several times to start and it cut off again and when I did get to dock I noticed no oil pressure. if engine had not cut off and hard to restart I would say it is sensor but when I tried to restart awhile later the oil pressure was at 3 lbs. I have never had problem starting engine. I had been out cruising for about 30 minutes and engine was running good,. only when coming in to dock did it cut off. I put boat in water on Friday first in over year. had run boat in yard with good oil pressure before launching on Friday. How difficult is it to repair or replace oil pump? or would it be worth it since boat and engine is 1989 model. Where is oil pump located in engine. Had plenty oil and it was good and clear. have not run boat very much in last 6 or 7 years. what could be problem? Thanks

 

[gm280]

:welcome: connersh to iboats...

Before you go off and buy replacement parts, verify that you have oil so start with. Then check the oil sensor next. Because it seems odd that the oil pump would totally stop pumping out of the blue like that. It may be just a bad sensor that triggers the computer to not allow the engine to start. Worth the check first anyways... JMHO!

 

[Bondo]

Ayuh,..... Welcome Aboard,...... The oil pressure sender should be just aft, next to the distributor, or down low, port-side, just aft of center of the block, near the oil filter boss,....

Take the wire off it, 'n ground out the wire,.... The gauge should Peg to High,....
Clean the connection, 'n try it again,.....

Also, you can "T" the fittin', 'n add a mechanical oil pressure gauge, to cross-check yer electric gauge,....

Another thing, pull 'n clean to shiny metal clean, the battery's connections, 'n the battery's (-) connection to the motor's block,.....

 

[henleyhale]

A motor running without oil Will be loud! The heads will start clacking somthing horrible, And It'll Only Run For about 30 seconds, so unless you heard the heads start chattering I wouldn't think you had a heart attack.

 

[flipbro]

What was your oil pressure before you had this problem?

 

[connersh]

The oil pressure had been reading about 40psi. Well, I have friend who repairs boats. Talked to him yesterday and he told me to crank engine for about 15 seconds and look in the oil filler hole of valve cover and if there was oil pressure I should see oil splashing around. So when I cranked engine the oil pressure gauge read about 35-40 lbs. I had already looked in hole before cranking and there was a small amount of oil at the bottom of the slanted cover. But when I cranked engine and the oil pressure showed 35 lbs I looked in hole but there was no additional oil. Still showing oil pressure and no change in the amount of oil in valve cover. Then the oil pressure on gauge started fluctuating from 3 to 40 lbs. I increased throttle and the pres

 

[Bt Doctur]

your looking at the rocker arm thru the filler hole. oil will never "splash" around in there. its pumped up thru the pushrod tube and kinds trickles down the rocker arm
Verify the wiring by grounding the blue wire at the sender. gauge should peg to the right.
To confirm actual oil pressure, remove the sender and install a mechanical gauge

 

[connersh]

Sorry that my reply got cut short. When I increased the throttle the oil pressure guage showed about 60 lbs. I took the boat out for about quarter mile and guage was reading 30-40 lbs. I came to idle and looked in the valve cover and still no additional oil than what I originally saw b0efore starting engine. Took the boat back to dock and then towed to landing to bring it home. I wasn't going to take a chance of totally ruining the engine.i did not mention earlier that when I checked oil on dipstick it reads about two or three inches above the full mark. I don't remember overfilling the engine with oil. it is very clear on the dipstick but what I see in the valve cover the oil is very dark-the very small amount that is in the bottom portion of cover is maybe 2 ounces. thanks for the above replies.

 

[gm280]

connersh, usually when you see more oil then you poured in, you could have gas in the oil too. Smell the oil on the dipstick and see if you can smell the presents of gas. If so, you have more issues then low oil pressure. If the oil level was raised because of water, it would look milky... Of course if you do have more oil then needed, it could be foaming and that could cause the fluxuation of oil pressure as well because the oil level would be getting foamed up by the crank shaft spinning in the oil level. Best of luck and do come back on here and post what your results were. I am interested and I know others are too...

 

[alldodge]

I had been out cruising for about 30 minutes and engine was running good,. only when coming in to dock did it cut off.

checked oil on dipstick it reads about two or three inches above the full mark.

I think GM found your issue, your pumping gas into your engine and loosing pressure because the oil is now so thin. Check the overflow tube (clear) going from the pump to top of carb or arrestor. Then pull the fuel pump and check

Got an engine serial number?

and :welcome: to iboats

 

[connersh]

Well, I have removed all oil and filter from engine. Oil was so thin and a lot more than five quarts. It does appear there is gas in the oil. GM said that if I have gas in the oil I have more issues. Have also talked to my friend and told him that appears gas is in oil. He says that the only way gas would probably be getting in the oil is that the fuel pump is bad and it must be pumping raw gas into the crankcase.he seems to think that the diaphragm must be bad and allowing gas to enter crankcase. That would account for the very very thin oil and would most likely be the reason oil pressure goes way down when idling and back up when throttling. Do any of you agree that the fuel pump is most likely the problem? Thanks very much

 

[alldodge]

Well, I have removed all oil and filter from engine. Oil was so thin and a lot more than five quarts. It does appear there is gas in the oil. GM said that if I have gas in the oil I have more issues. Have also talked to my friend and told him that appears gas is in oil. He says that the only way gas would probably be getting in the oil is that the fuel pump is bad and it must be pumping raw gas into the crankcase.he seems to think that the diaphragm must be bad and allowing gas to enter crankcase. That would account for the very very thin oil and would most likely be the reason oil pressure goes way down when idling and back up when throttling. Do any of you agree that the fuel pump is most likely the problem? Thanks very much

Yep that be the problem, replace it and go boating

 

[gm280]

I concur with AllDodge. Replace the fuel pump, put in fresh oil and filter and happy boating. Glad you found your problem... :thumb:

 

[connersh]

Thanks for the replies. I have ordered fuel pump but I am curious as to how the fuel pump can actually dump gas into the crank case. There is a fuel line coming in from gas tank and one going out to the carb. So how does it put more gas in the crank case unless it pumps too much into the carb and then the engine gets flooded and extra gas leaks past the rings into oil pan. Not being a mechanic I am just puzzled. But I am happy if the fuel pump is the problem. Thanks

 

[Bt Doctur]

A fuel pump has a rubber diaphram than can crack or rupture. Usually you see it in the clear tube going to the carb, Sometines it leaks gas out the back end into the crankcase.