No Pressure After Oil Change

[andrewterri]

I drove the boat (2014 Merc 4.3 MPI EC) on Thursday to warm the oil up for an hour or so with the family. I came home and changed the oil, pumped it out with a electric pump using a dip stick hose, changed the fuel filter, oil filter, and did other maintenance. I did the same maintenance that i have done the last two years. This time when we took the boat to the lake and went to start it there was no oil pressure and after about 4 seconds the alarm went off. In the past after an oil change it takes about 4 seconds for the oil pressure to come up and it happens after a half second after the alarm goes off. This time it did not so i shut the engine down. I rechecked the filter, oil level, checked for any oil in bilge and than tried again. As soon as there was no pressure and alarm was about to sound i turned the boat off. I brought it home and went to the dealer to get another new oil filter. Filled it with oil and put it on. Same problem no oil pressure. I must have done something like pulled a wire or blew a fuse but for the life of me I can not figure it out. With shortened hours at work now I really do not have the money for a dealer so any help really would help us.

Smart craft app threw the expected codes. Low oil pressure and power reduced.

 

[tank1949]

do you have oil pressure switch and ALSO an oil pressure sending unit? As a rule, an oil pressure switch drives an audio/visual alarm. The sending unit usually to a gauge at your helm... I am restoring an older MC V8 with duals. The former owner disconnected all the audio alarms/switches and only had sending units. I have since reconnected them. If your switchs' wiring goes to ground, it could be triggering alarms. If you oil sending unit helm gauge reads correct pressure, then I'd trace for loose wire that may be grounding. Look anyway!!!!! Use a mirror to examine under motor, if you cannot see wiring. Many MC V8s (I am not 100% sure on other engines) have oil pressure switches on the block near oil filters and are a real pain in the butt to access. They are also difficult to see if they leak and real easy to bump loose or break wires connecting to them. I relocated mine to next to my oil pressure sending unit by adding a "T" 1/8" NPT female manifold. There is a possibility that your distributor drive that powers oil pump or oil pump is defective. I highly think not. My wife owns a Duramax diesel Z71. EVERYTHING goes through her truck's computer. I suggest that you buy a manual about your boat/motor and read to be sure on all the wiring and if there is a computer on your boat/motor that you must consider. Good luck!

 

[alldodge]

Being an EC motor do you have smartcraft display and/or analog oil pressure gauge?

went to the dealer to get another new oil filter. Filled it with oil and put it on.

Do you have a remote oil filter? If so I'm finding the filter goes on upside down, and if the filter was filled prior to install it would pour out when trying to screw in place

Finding your motor has 2 sensors located port side down low where the remote oil filter would be attached, or where the filter would be installed. One is for the gauge and other is for the PCM

 

[Lou C]

https://www.mercruiserparts.com/bam/subassembly/31509/15417/125

look for a disconnected wire on part #17 (oil pressure sending unit)….

 

[andrewterri]

Thank you guys. I am going to check for the disconnected wire at #17. I know I must have done something. I do have the remote oil filter. We take very good care of our boat, always complete maintenance per mercruiser's manual and store the boat on covered lift or in heated garage. I know that doesn't really mean anything but for the pump to just randomly fail a day after running fine and changing the oil and filter seems crazy. Lou, on looking up a parts diagram, there shows to be a small filter or check value on where the remote filter oil lines attach to the block. Can I remove the oil lines and get to the filter? I can not tell by the diagram if it can be accessed. Thank you guys again

 

[alldodge]

I think your talking about item 12 in the link and list as a bypass valve

https://www.mercruiserparts.com/bam/subassembly/31509/15417/150

I'm hoping that its a part mislabel, but don't know right now. Maybe muc would happen to know if it has any bearing.

If you go to the local autoparts place you should be able to get a loaner mechanical pressure gauge. Remove either of the senders and attach the mechanical gauge. Once fired up you can verify if the oil pump is working

 

[Lou C]

Agreed AllDodge beat me to it was going to advise the same thing. Use a mechanical pressure gauge to test. You should be seeing approx. 40 psi on that gauge after a cold start.

 

[andrewterri]

that what I was going to do (get the mechanical gauge) but wont that just cause further damage to the engine if the pump has failed? Is there anyway to lubricate the engine so if the pump is bad i don't damage the cylinder walls? I thought about putting a little oil in each cylinder but not with the cats on that engine. I think that would damage or plug them.

 

[andrewterri]

Alldodge, That is the part I am talking about. I though if some trash got into the oil it might have plugged it up. From the best I can tell when i removed the filter, oil was not making it up the line to the remote filter. When i changed filters I only let the engine run for about 7 seconds to fill the filter. Since I put oil in the filter to help prime it so i wont run dry as long, I can not tell if oil made it to the new filter I put on. That is about the time it takes after past oil changes to get the pressure up.

 

[andrewterri]

I just saw your earlier question all dodge. Our boat has analog gauges and we have installed smartcraft which gave us the obvious codes.

 

[QBhoy]

Normally I’d be certain that you’ve knocked or disturbed the oil pressure sensor which is usually always next to the oil filter up the back port side of the usual 4.3...but most 4.3 mpi I’ve seen have the remote filter on the front upper port side of the engine and away from the sensor.

 

[alldodge]

Is there anyway to lubricate the engine so if the pump is bad i don't damage the cylinder walls? I thought about putting a little oil in each cylinder but not with the cats on that engine. I think that would damage or plug them.

Yes, the distributor is removed and a drill is attached to the rod (item 4) and then it will build pressure. Drill turns normal direction clockwise

https://www.mercruiserparts.com/bam/...1509/15417/140

When i changed filters I only let the engine run for about 7 seconds to fill the filter

Previous post was 4 seconds

The motor may need to run more then 7 seconds to build oil pressure. As you said it normally only takes 4 sec

Putting oil in cylinders will not help the motor, the issue is if the bearings are getting oil

 

[andrewterri]

Thank you guys. I was able to squeeze next to the motor with a mirror (having to remove a dividing wall on port side) and see there is a blue wire on the sending unit. I could not see any other wire and was thinking there should be two wires. The sending unit went right into the block. I thought there was another sensor in there so I am going to be doing some research. Thought the sending unit and pcm sensor was there. The bottom of the sending unit has alot of corrosion (white). When i bought the boat it was not winterized correctly and popped a core plug somewhere above that sending unit. Cant remember what plug it was but dealer fixed it before we bought the boat. Are those sending units prone to failure?

Can i remove the brackets that holds the computer easily to get access to the dizzy? I have a new cap and rotor but was to nervous to move the computer out of the way last season. Now, I really don't have a choice as I can not afford a dealer. Do I need to disconnect the battery? If I spin the shaft in the dizzy to prime the pump will it through it out of time?

One last question, If i run it again to see if it builds up pressure how long should i let it run?

 

[QBhoy]

I’ve maybe missed some of this but where are we with it now ? You shouldn’t need to remove the ecu to get at the Diz, what ever you are doing there. Just the air filter big plastic cover that says 4.3 mpi on it. Just be careful with those tiny torx screws that hold the diz on. One is almost alway blind and done by feel.

if you are reading absolute zero oil pressure you’d know and hear all about it very quickly. Is there plenty of oil getting to the rocker covers if you turn it over with the kill cord out and maybe even plugs out ? I’m thinking it’s still maybe the sensor.
maybe I’ve missed some of the post. I’ll have a read.

 

[alldodge]

Thank you guys. I was able to squeeze next to the motor with a mirror (having to remove a dividing wall on port side) and see there is a blue wire on the sending unit. I could not see any other wire and was thinking there should be two wires. The sending unit went right into the block. I thought there was another sensor in there so I am going to be doing some research. Thought the sending unit and pcm sensor was there. The bottom of the sending unit has alot of corrosion (white). When i bought the boat it was not winterized correctly and popped a core plug somewhere above that sending unit. Cant remember what plug it was but dealer fixed it before we bought the boat. Are those sending units prone to failure?

Can i remove the brackets that holds the computer easily to get access to the dizzy? I have a new cap and rotor but was to nervous to move the computer out of the way last season. Now, I really don't have a choice as I can not afford a dealer. Do I need to disconnect the battery? If I spin the shaft in the dizzy to prime the pump will it through it out of time?

One last question, If i run it again to see if it builds up pressure how long should i let it run?

With the connections being hard it wasn't knocked off, but white stuff may have caused some corrosion to the connection. There is another sensor, but the sensor could be below and to the rear of the distributor.

Get a mechanical gauge and install where oil pressure sensor is. If pressure does not build quickly then I would stat thinking something broke (oil pump shaft or oil pump).

You can remove the PCM and if so do disconnect the battery. Before removing the DIZ remove the cap and mark where the rotor is pointing on the DIZ body. Then mark the base of the DIZ and the block. This will allow the DIZ to be reinstalled

With gauge on the block it should take no more then 15 seconds.

 

[Lou C]

Thank you guys. I was able to squeeze next to the motor with a mirror (having to remove a dividing wall on port side) and see there is a blue wire on the sending unit. I could not see any other wire and was thinking there should be two wires. The sending unit went right into the block. I thought there was another sensor in there so I am going to be doing some research. Thought the sending unit and pcm sensor was there. The bottom of the sending unit has alot of corrosion (white). When i bought the boat it was not winterized correctly and popped a core plug somewhere above that sending unit. Cant remember what plug it was but dealer fixed it before we bought the boat. Are those sending units prone to failure?


Can i remove the brackets that holds the computer easily to get access to the dizzy? I have a new cap and rotor but was to nervous to move the computer out of the way last season. Now, I really don't have a choice as I can not afford a dealer. Do I need to disconnect the battery? If I spin the shaft in the dizzy to prime the pump will it through it out of time?

One last question, If i run it again to see if it builds up pressure how long should i let it run?

there appear to be 2 things the large one is an actual oil pressure sending unit that sends an ohm reading to the dash gauge, these usually have one connector (blue wire) and they ground where it screws into the block. That ground should be clean & free of corrosion. The other one may be a pressure switch for the warning system, these will alarm if pressure drops below a certain point, it may have a 2 wire hook up but I’m not familiar with the newer engines and how they are set up..

 

[andrewterri]

As soon as I can find a gauge i am going to test it. Hoping I can get the sender unit off with the amount of corrosion and rust around it. I am going to try to get it off tonight. Does the alarm go off the gauge reading or the pressure itself? I.e... if the gauge somehow went bad and is not showing pressure when there is will it still trip an alarm?

 

[andrewterri]

I was able to find a gauge at harbor fright but they are closing early because of the virus so i have to get it tomorrow. Autozone and everyone else around here does not have them. Can I take the sender unit off without oil coming out? Is there any other way to check it, like turn the engine over and see if it sprays out? Lol

The forum website was down yesterday for me and now i have to wait another day. I can not stand having something broken and not fixed ready to run, even if i don't plan on using it. Think it was a military thing drilled into me all those years ago to always take care of your gear and have it ready to go at a moments noticed.

 

[muc]

You should have 2 oil pressure sending units. one will have one wire on it and is for the gauge only, the 2nd sender will have 3 wires and it feeds info to the ECM. The ECM controls the horn.

What exactly did you see on the smartcraft? There are 3 possible codes/descriptions.

The part that you asked about in post 5 is the oil bypass valve. It's job is to bypass the oil filter if the filter gets plugged. I don't think it could cause a no oil pressure situation, but I'm not sure. It could be serviceable with the engine in the boat, but would be hard to do because it is staked in place.
The oil pressure regulator is part of the oil pump. You have to pull the engine and drop the oil pan to get to it.

I wouldn't be to worried running the engine for up to 20-30 seconds. One of the marina's I worked at. We had a slip customer that would change his own oil. He would suck out the hot oil and then start the motor back up and rev it up. Then he would suck the oil again and change the filter. Then add the new oil and run the engine to check for leaks. When I asked him what the heck he was doing, he told me he had done it this way for years and the reason he did it this way was the oil filter would be empty and he didn't have to worry about making a mess! I don't think I would recommend this way to change oil. But I know he did it for at least 3 years and his boat was still running when we asked him to leave for other reasons. He had a chev 350, so a lot like your engine.
So when you start yours to check pressure, I recommend you increase the RPM to 1500 for about 10 seconds.

With a computer controlled engine, you should always disconnect the battery before doing ANY service.

 

[andrewterri]

Maybe I am not giving it enough time to pressure up. I thought about giving it some light revs says for about 15 seconds. If it does not pressure up than I would think there is clearly a problem. Guess i can try that tonight since im kind of at a stand still. I do not have the smartcraft gauges, it is the vesselview i was using. I think i might have said smartcraft earlier. So think that starting and reving a little will be okay since i cant get the gauge?