5.7 v8 No I mag

[Simonhall1282]

5.7 v8 mpi mag. Can anyone help with a part number for a new oil pressure sensor.

Simon

[mmwjr]

Do you have the engine serial number or at least the year? To be clear you are asking about the sender for the helm gauge, correct?

[Simonhall1282]

I'm not able to get over to the boat unti next week to get the serial number but I can tell you it's a 2006

[jrsick]

You have same sender as I do, p/n 18-5899 (Sierra), or 8M0068784 (Mercury).

[Simonhall1282]

I was down on the boat yesterday and i wasn't able to locate the oil pressure sensor. Any ideas?

[mmwjr]

Originally Posted by Simonhall1282

I was down on the boat yesterday and i wasn't able to locate the oil pressure sensor. Any ideas?

Still not sure which one you are looking for. The helm gauge sender should be mounted near the distributor on the top rear of the engine. The alarm and fuel pump senders are located on the port side of the block just above the oil filter or where the remote oil filter adapter connects to the block, standard GM location.

[Simonhall1282]

I will go have another look today. The helm gauge sensor is what I'm looking for. Thanks for your help Mike

[mmwjr]

It’s a bell shaped sensor like in this link.

https://www.amazon.com/Pressure-Send...a-574196842012

[Simonhall1282]

Ok I've replaced the sensor and the gauge is still reading high pressure. About 50psi on idle and almost 80psi with max revs.

[Simonhall1282]

Could this be caused by a faulty gauge?

[mmwjr]

Originally Posted by Simonhall1282

Could this be caused by a faulty gauge?

Only way to be sure is get a mechanical oil pressure gauge from an auto store and temporarily hook it up to compare. You could have a faulty oil pressure relief valve.

[donald]

As Mike said ck with a mechanical gauge.
The oil pressure on my 5.7 reads 75lbs when leaving the dock but drops to 30 to 50lbs when warmed up.
Is this reading when cold or warmed up?
If it is that high after running for a while I would have it cked out.
If it drops to 30 to 50 lbs I would just go ahead and use it.
Don

[Simonhall1282]

I've ordered a mechanical gauge, will be here tomorrow. When it's first fired up the idle pressure is over 50psi and does come down a little once warmed up.
What's the worst case scenario this could be?
I'm crossing all my fingers as I'm supposed to be heading to Poole on Saturday for the boat show

[jrsick]

Are you certain that you are running the correct oil viscosity and have a good oil filter?
If pressure is confirmed high with the gauge, the next step is to replace the pressure relief valve. You can change this valve yourself if you have reasonable access to your oil filter.

[Simonhall1282]

I'm 100% certain that the oil and filter are both correct. I just did an oil and filter change and this problem started at the end of last season.
I do appreciate the help on this site. Thanks guys.
I will keep you posted, should have an update tomorrow evening.

[Simonhall1282]

With regards to the pressure relief valve, where is that located? I do have very easy access to the oil filter.

[jrsick]

Part is called a "valve assembly, filter," it is what you screw your oil filter into. I have not changed one, but have heard it is not difficult. It is held on by two bolts.
Go to an online parts store with parts breakdown pages, i.e. marine engine, mercruiser parts, enter your serial number and go to "cylinder block and camshaft" section. You'll recognize the part and know exactly where it is.

[mmwjr]

If you have a remote oil filter it where the adapter connects to the engine block on the rear port side down low. i.e. where the filter would be in a car application.

[Simonhall1282]

Ok I'm on the boat now with the manual gauge.
Idle is 45psi
2000 is 60psi
3000 is 65psi
This is with the engine warm

Is that too high?

[mmwjr]

While these are high they are still ok. If you were seeing 80 then I would say it needs to be addressed.

What weight oil are you using?