High oil pressure

[Bhaynes85]

Have a 1998 Prostar 190 350 gm motor. The oil pressure has been running Very high like 60psi at idle and 80 when on the throttle. Oil and filter have been changed recently. Just bought the boat and have only had it out 3 times and every time the oil pressure gets higher. Dropped it off at the mechanic and he said it looks to have 1 to 1.5 extra quarts of oil in the motor. Is this enough to explain the problem or could it be a more ominous problem?? Thanks for all the help mastercraft team talk has yielded no help

[dbutcher]

First, I would wonder about the oil pressure gauge. Next, if there is really that much extra oil in the motor, I would be concerned about fuel dilution (gasoline getting into the oil). Change the oil immediately and see if it happens again. I don't know for sure, but I doubt that extra oil would increase oil pressure?

 

60 psi at idle would not be unusual when the engine is cold. 80 lbs at high RPM may not be disastrous, but you said the pressure is getting higher each time you run it. That is troubling. Still the gauge is the first thing to check (IMHO) and getting the excess oil out needs to be done very soon. I am not a mechanic, just a long time inboard owner. Good luck.

[dbutcher]

The sending unit could be the culprit too.

[vtmecheng]

I agree with @dbutcher. Change the oil and filter again, making sure to really note the dip stick level. If the pressure is still high and level isn't increasing after a couple times out then check the sending unit.

[Bhaynes85]

Will do guys! This forum is really so helpful, I appreciate the help! Are their other things high oil pressure could signal like a bad motor or something disastrous? I just bought the boat and I’m terrified it’s gonna need a new motor, but I’m a glass half full kinda guy!

[Rednucleus]

Get a mechanical gauge (rent at auto parts store) and verify your dash gauge accuracy

[Bhaynes85]

Not gonna lie I have no clue how to do that, hopefully the mechanic will check this!

[MDB1056]

Agree- change it first/ get to the correct volume- see what your readings are - step 1. An additional 1.5 is a significant amount and yes could increase pressure, but again get it out and check it with correct volume first. Operating pressure at speed above 60- I’d be checking further for as noted maybe gauge, sending unit etc

[dbutcher]

I hope your mechanic is a marine mechanic or at least knows not to run your engine without water - hose will work, lake is better. It's way too early to be terrified.

[powbmps]

@Bhaynes85 I've got a 2003 Response with the Monsoon 335 (which is a 350 GM). For what it's worth, my gauge typically shows 80 when on the throttle. No issues with the motor.

[Bhaynes85]

Yes he is a marine mechanic! Hopefully it will just be a gauge issue and nothing more serious!

[UWSkier]

My oil pressure is the same as @powbmps typically around 78 PSI while underway.

[jimski]

I have a rebuilt 350 in a 210 oil pressure is generally the same psi as yourS when cold it’s a little lower when warm.

Do all that every one recommends check the viscosity of the oil your using if it’s still higher you could go to something lighter.

Worst case scenario you have a stuck spring on your oil pump.

 

 

[Bhaynes85]

That makes me feel better, I guess I was just thinking my motor was shot!! The oil is 20/50 weight it’s what the manufacturers booklet recommends.

[Ski_Dad]

i would back that oil down to 15w40 - those are old recommendations - that will drop the PSI a little. Not trying to start an oil debate

[Bhaynes85]

That makes me feel better, I guess I was just thinking my motor was shot!! The oil is 20/50 weight it’s what the manufacturers booklet recommends.

[Bhaynes85]

Why do you say 15/40?

[Ski_Dad]

nothing wrong with either - the 15/40 is a little thinner and will lower the pressure some. Most folks use that in the Chevy 350's.

 

see appedix A: https://indmar.wpengine.com/wp-content/uploads/2016/05/1994-to-2002-Indmar-Operators-Manual-.pdf

[Bhaynes85]

I see where it says 15/40, I guess just makes me nervous after using 20/50 for 20 something years

[jimski]

I’m using 15/40

[Bhaynes85]

Well that makes me feel better will consider changing oil weight

[UWSkier]

Chevron Delo 15/40 at Costco. It goes on sale every few months. Don't worry about it being labeled diesel engine oil. It has all the necessary certifications to run in an internal combustion gas engine.

[Bhaynes85]

Thanks that was gonna be my next question bc all these high weight oils say diesel and motorcycle

[Bhaynes85]

this Forum is a lot more helpful than mastercraft team talk, thank you guys for all the advice! Really puts my mind at ease!

[skihacker]

Walmart, mobil 1 15w50 is usually around 23 bucks for a 5 qt jug

[Bruce_Butterfield]

Virtually any modern oil will work in a ski boat. If you run 5W30 and 20W50 in 2 identical engines for 2000 hours or so, it will take full disassembly and measurements to determine any difference in wear. Both will be running the same to the driver and skier.

 

From the above posts, it seems by far your biggest issue is oil dilution (gas getting into the oil). This is not an uncommon occurrence and can cause significant damage if not corrected quickly. Gas is a solvent and will dramatically reduce the lubrication qualities of any oil. Change the oil and filter immediately with whatever quality oil is available and watch the level daily for the next 5 hours or so.

 

If you notice any increase in the oil level, stop using the boat and get it to a good mechanic to correct where the gas is getting in and get a compression or leak down test done to see if any real damage has been done.

[Bhaynes85]

@Bruce_Butterfield what is the solution to gas getting into oil?

[UWSkier]

@Bhaynes85 a leaky injector is a common cause. Especially if you have good compression.

[LeonL]

This is a kinda stupid question, and in no way an insult to you, but did you check the oil level immediately after the change: or did you just put in what the "book" called for? Sometimes the stick doesn't match what the book says.

[Bhaynes85]

@UWSkier if you mean fuel injector my engine is carbureted

[Bhaynes85]

This could make sense though bc the bilge does seem to collect gas as well as water.

[LeonL]

Does it run rich, black smoke, exhaust fumes smell of gas?

[Bhaynes85]

The exhaust does smell like gas to me not sure if it’s just exhaust though, no black smoke though. Yes checked the oil level!

[Bruce_Butterfield]

There are several places gas can get into oil. One of the more common ones is a rubber diaphragm in the fuel pump that leaks gas into the crankcase. It all depends on the fuel pump if you are susceptible to that problem or not. Could also be a bad valve, bad rings, carburetor dumping in more gas than it can burn or a host of other fairly major issues. Again, change the oil and keep an eagle eye on it for the next few hours.

 

You mentioned that you just bought the boat. Was the oil changed by the previous owner? If you are really lucky, he just overfilled it, but it would be unusual to get 1-1.5 qts extra. Most engines take 4.5-5 qts and oil commonly comes in 5 qt jugs.

 

How many hours on the boat and what is the general condition of the engine? Smooth running, lots of power or cough and sputter, hesitating? Any blue or black smoke out the exhaust or smell of burning oil? Gas in the bilge is not a good sign either.

 

[dbutcher]

Gas in the bilge sounds dangerous. There are many places that could leak gas starting at the tank all the way to and including the carb. I am not an expert, but it may be possible that the carb can leak gas into the crankcase even when the boat is not running.

 

On oil, you should read the owner's manual for your engine. My 2015 PCM manual specifies 15w/40 with classification GF-4SM. SN is the updated SM. You are right that 15w/40 is typically diesel oil, and not all diesel oils have either the SM or SN classification. I have been told that the SM or SN makes the oil acceptable for use in gasoline engines.

[Bhaynes85]

@Bruce_Butterfield Yes the previous owner changed the oil. 760 hours. No blue or black exhaust that I have noticed. Runs smooth but a lot less top end than I would expect from such a large motor, I know this could just be my perception!

[vtmecheng]

Bilge should never have gas. Sounds like you may have some issues that need to be addressed right away. I wouldn't be comfortable taking a boat on the water that's collecting gas in the bilge. Take it to a marine mechanic, make sure to tell the person about the extra oil, seemingly higher pressure, and fuel in the bilge.

[Bhaynes85]

@vtmecheng I agree, hopefully this isn’t going to cost an arm and leg since I just bought the boat! We shall see

[UWSkier]

@vtmecheng is right. Cease operation of that boat immediately and get it to a reputable shop. Fuel in the bilge is no joke.

[Bhaynes85]

Well I dropped it off at the shop hopefully it can get sorted out! We left the lake immediately and took it to the shop!

[vtmecheng]

Good move. Let us know what the results are. This is especially not fun with a new-to-you boat. Good luck.

[BraceMaker]

@Bhaynes85 - alot of the MC teamtalk action has moved to the facebook page - good or bad... who knows just has happened.

 

Still good stuff available on TMC - but you may need to wait a bit.

[Bhaynes85]

@vtmecheng thanks will do hopefully he can know something this week.

 

@BraceMaker yes I do not use Facebook so it’s frustrsting, their forum is a little dated compared to this!

[Fast351]

FWIW, 80 PSI is nothing to worry about. 60 PSI cold at idle is very normal.

 

In general, the rule of thumb for MINIMUM oil pressure is 10 PSI/1000 RPM.

 

The way the upper end of oil pressure is set is there is a plunger in the oil pump with a spring behind it that relieves oil pressure once the spring pressure is overcome. There are 4 different kind of oil pumps: Normal, High Volume, High Pressure, and HV/HP. In order to get high volume they increase the size (height) of the oil pump rotor. Not sure if any marine builders are putting HV pumps in their engines, that's usually used to overcome looser tolerances in the crank bearings in race engines. Then there are high pressure pumps. They increase the spring pressure in the plunger. These are used for very high RPM engines that need more pressure at higher RPMs.

 

Normal oil pumps have their pressure cut off set around 70 PSI. When the engine is cold sometimes the blowoff plunger can't flow enough oil with thicker oil and you'll see 80 PSI at speed. This isn't a problem normally. If you start getting over 80, that might indicate a problem.

 

For more info on this, look here:

 

https://help.summitracing.com/app/answers/detail/a_id/4825/~/do-i-need-a-high-volume-or-high-pressure-oil-pump%3F

 

BTW, I would

 

1) Figure out if your oil pressure gauge is accurate. Most are not.

2) Be much more concerned if the amount of "oil" in the crank case is growing. That is usually fuel getting in there, or water if the oil is milky. Or maybe the oil was overfilled when the oil was changed.

 

 

 

[Bhaynes85]

@Fast351 I’m thinking gas is getting into the oil somehow bc the pressure has gone up each time we have taken the boat out and the gas smell!

[Bhaynes85]

Update: the mechanic I took it to decided he couldn’t fix it and sent me to another shop.

[Rednucleus]

@Bhaynes85 Keep that mechanic's number handy - he's honest and knows his limits and will likely help you with other needs in the future!

[vtmecheng]

Did he at least identify what the problem is?

[Bhaynes85]

@vtmecheng pretty much said everything everyone here has said. He irritated me bc he advertises that he works on inboards but told me he hated doing it when I picked up my boat sooooo why advertise it!

[Bhaynes85]

And even if the boat gets fixed I tore my ACL last time out skiing so my season is shot either way, first year having my own boat and it’s FU***D lol