Oil Pressure

[drh1965]

I finally got around to fixing the oil pressure alarm on my Universal M18. Unfortunately, I now have an alarm ringing continously. The oil pressure switch is buried under the exhaust manifold/cooling reservior and I can't get it out without quite a bit of disassembly. I have a few questions:

1) Would it be likely that the oil pressure switch is dead after 20 years?

2) If the oil pump is not pumping properly, would the engine behave weirdly? I have't notice anything out of the norm.

3) Assuming the oil pressure is low, and that this problem has been going on for a long time, is it safe to assume the engine might be in serious trouble?

I guess I'm trying to gauge whether or not I've got to get this problem fixed immediately or it it just the oil pressure switch? Any educated guesses?

[johneri1]

Hi fellow Newport guy--my educated guess is that the engine has oil pressure or you would have had bearing problems by now. HOWEVER the need to fix the gauge/alarm is top priority to keep from having problems. . . . I hope you like your Newport as much as I like mine!

[Alan Wheeler]

The answer is Yes and No.
You may or may not have a problem. You may or may not have the engine sound or perform strangely.
This is just the oil pressure alarm switch? is there a pressure sender going to a gauge??? What does the pressure read if there is??
There is no mucking around with faults like this. You need to varify the pressure. If the pressure is OK, then the situation is not urgent. But if you have no way to varify the pressure, then yes it is urgent and should be dealt with before you run the engine again.

[drh1965]

Originally Posted by johneri1

Hi fellow Newport guy--my educated guess is that the engine has oil pressure or you would have had bearing problems by now. HOWEVER the need to fix the gauge/alarm is top priority to keep from having problems. . . . I hope you like your Newport as much as I like mine!

Hi. It seems like a solid boat. I'm just working through all the years of neglect now so I haven't really been able to enjoy her.

[drh1965]

Originally Posted by Alan Wheeler

The answer is Yes and No.
You may or may not have a problem. You may or may not have the engine sound or perform strangely.
This is just the oil pressure alarm switch? is there a pressure sender going to a gauge??? What does the pressure read if there is??
There is no mucking around with faults like this. You need to varify the pressure. If the pressure is OK, then the situation is not urgent. But if you have no way to varify the pressure, then yes it is urgent and should be dealt with before you run the engine again.

Alan, my boat doesn't have a gauge. It just has a pressure switch that shorts out when the oil pressure hits a preset low. I had bought the parts to retrofit a gauge but the sender unit was too big to fit. I think this may be the time where I try to find a pro to check out this engine...

[Zach]

Find out what threads are used on the sender, and install a brass pipe with a T. Put the pressure switch on one side and install a pressure sender for a gauge on the other end. (I like electronic senders, they are less likely to break thin nylon lines and fill up the bilge!) Track down the manufacturer of the switch, or purchase one with a known rating... There should be a pipe plug somewhere on the engine that hooks up to the main gallery so a tech can hook up a gauge. If it has one, you can install your gauge sender there... and the T to obsolete the original pressure switch of unknown rating.

Is the oil old (oil experiences a viscosity cut as it is heated) or diluted with fuel? In the meantime you can drain it and replace with a slightly thicker viscosity. What weight are you running?

Oil pressure problems can be anything from a clogged pickup tube or screen, worn out oil pump/pump drive... or worn out bearing clearances.

[Alan Wheeler]

my boat doesn't have a gauge.

OK, it is best to get hold of one and do a test. Just emporary is fine, but I would be looking seriouse at buying and fitting gauge set. You really need to confirm the operating pressure, both at idle and at speed.
Ensure you have fresh oil, clean filter and the correct viscosity rating. Old oil or Oil with a wide ranging vicosity can be problematic in older engines. Mono30W is the most common oil grade.

[drh1965]

The oil is only a month old. Straight30 Rotella. I don't think it is diuted by I'm not exactly sure what to look for. You guys are worrying me. Sure hope this doesn't turn out to be another big ticket problem.

[David M]

Another possibility is that on older diesels with thousands of hours, at idle sometimes the oil pressure alarm will sound simply because the gap between the engine bearings has increased letting the oil flow out faster partially bypassing the oil galleries thus producing a lower pressure at idle. The alarm should always go away above an idle though.

Also, oil pumps do wear over time dropping the oil pressure somewhat. They though very rarely completely fail.

Look inside the pour spout of your valve cover with a flashlight when the engine is running...do you see fresh oil getting to the cam and the valve lifters? If it is dry then shut it down immediately...you have a problem.

[never monday]

go buy an $8.00 oil pressure sending switch at NAPA. I can't remember if you have the one pole or two. I'ts mounted on the starter side down low. The switches fail all the time.

[Alan Wheeler]

Also to add, what RPM does the engine idle at. It is common for many of the Perkins to drop oil pressure too low if it idles to slow.

[drh1965]

Originally Posted by David M

Another possibility is that on older diesels with thousands of hours, at idle sometimes the oil pressure alarm will sound simply because the gap between the engine bearings has increased letting the oil flow out faster partially bypassing the oil galleries thus producing a lower pressure at idle. The alarm should always go away above an idle though.

Also, oil pumps do wear over time dropping the oil pressure somewhat. They though very rarely completely fail.

Look inside the pour spout of your valve cover with a flashlight when the engine is running...do you see fresh oil getting to the cam and the valve lifters? If it is dry then shut it down immediately...you have a problem.

The engine has around 2000 hours. I say around because I can see that the hour meter is not factory installed. I'd also say that the last 1200 were put on with very, very low maintenance.

Interesting idea looking down the head cover. I'll definitely try that.

Thanks!

[drh1965]

Originally Posted by never monday

go buy an $8.00 oil pressure sending switch at NAPA. I can't remember if you have the one pole or two. I'ts mounted on the starter side down low. The switches fail all the time.

Thanks. I have the new part. I just haven't decided whether or not I have the confidence to tackle taking the exhaust manifold and the exhaust off myself. That could cause a ton of down time if half the bolts and studs break off. I assume a pro has all the tools and access to the parts to knock this out alot quicker than I can. Besides, the exhaust riser and elbow need to be replaced anyway. Would you guess that the oil pressure relief valve will need to be replaced as well? That thing is impossible to get out without lifting the engine off its mounts...

PS. The switch is single pole.

[drh1965]

Originally Posted by Alan Wheeler

Also to add, what RPM does the engine idle at. It is common for many of the Perkins to drop oil pressure too low if it idles to slow.

It idles at around 950RPM.

[never monday]

Originally Posted by drh1965

Thanks. I have the new part. I just haven't decided whether or not I have the confidence to tackle taking the exhaust manifold and the exhaust off myself. That could cause a ton of down time if half the bolts and studs break off. I assume a pro has all the tools and access to the parts to knock this out alot quicker than I can. Besides, the exhaust riser and elbow need to be replaced anyway. Would you guess that the oil pressure relief valve will need to be replaced as well? That thing is impossible to get out without lifting the engine off its mounts...

PS. The switch is single pole.

Why go through all that hassle? pull the alternator and oil filter and go from the front. I remember the N28 having a small access door under the stairs.