This is new..low oil pressure

ric · **Posted:** Sun Feb 05, 2012 2:29 pm

Went to go take the boat out for a spin today before the superbowl parties... engine has around 5psi at idle, at cruise (3200) maybe 25? and fluctuates pretty bad. Just a few days ago it was solid 20-25 idle, 40-50 cruise. How do I know it's really low? When the pressure dips to 5 or less at low idle, you can hear a slight knock! I shut it down right away.

I'm going to first change the oil/filter with a heavier grade oil and see what happens. Engine doesn't burn an ounce of oil, and as of 30 minutes ago it's still golden in color and I never take it above 4000rpms.

Awesome.

LouC · **Posted:** Sun Feb 05, 2012 6:17 pm

What grade did you have in there? Volvo used to recommend a straight 30 synthetic, I have used Chevron Delo 400 in either straight 30 or 40 weight, with both my hot idle pressure is about 20 psi, running pressure ranges from 40 to 55 or so. The HD oils that are rated for both gas and diesel use work great in marine inboards.
Despite what some will say, I think that straight weights hold their viscosity better than multi vis oils when hot. Of course, you might just have a bad sending unit, try disconnecting the connector from the sending unit, look for corrosion, clean it up and reconnect. Then run it again, but the knock you heard, suggests that the pressure was low.

ric · **Posted:** Sun Feb 05, 2012 11:23 pm

I was using 5w40 rotella. I'll go to a straight 40 or 50 weight tomorrow. It's not bad timing for new motor and I knew this day would come one day with the 4cly (they all blow), but I hate spending the money!

Borchik · **Posted:** Mon Feb 06, 2012 7:09 am

Straight 30 Synthetic is what is recommended. I would not go with a straight 50Wt, thats too thick for a 3.0L. I would go with a HD straight 30 or 40 at the most.

pet575 · **Posted:** Mon Feb 06, 2012 11:52 am

Have you alternated back and forth between synthetic/synth blends and regular oil? I was told by my dealer that doing so can cause your oil pressure sensor to act erratically. Doesn't explain the noise you're having along with it, though.

ric · **Posted:** Mon Feb 06, 2012 11:59 am

pet575 wrote:

Have you alternated back and forth between synthetic/synth blends and regular oil? I was told by my dealer that doing so can cause your oil pressure sensor to act erratically. Doesn't explain the noise you're having along with it, though.

I really don't think it's the sender. It gives all the signs of actually having low oil pressure. It's a rainy day here in Florida (finally!) so I'll swap out the oil and filter tomorrow. I know it's a longshot, but It's all I got.

Borchik · **Posted:** Mon Feb 06, 2012 12:55 pm

if you are bored grab a hack saw and cut the filter canister away near the base where it threads on, you can get a good look at the filter element and see if there is metal on it.

LouC · **Posted:** Mon Feb 06, 2012 1:06 pm

The other thing you can do is to send an oil sample to Blackstone labs, they will tell you everything you need to know about what's going on inside you engine. That will tell you if there is wear from cylinders, pistons, bearings, water in the oil, fuel in the oil and also if the oil's viscosity broke down under your usual use. I'd do this and a compression/leak down test, on any engine I was concerned about, before doing anything. So save a sample of that oil when you change it.....

ric · **Posted:** Mon Feb 06, 2012 1:52 pm

LouC wrote:

The other thing you can do is to send an oil sample to Blackstone labs, they will tell you everything you need to know about what's going on inside you engine. That will tell you if there is wear from cylinders, pistons, bearings, water in the oil, fuel in the oil and also if the oil's viscosity broke down under your usual use. I'd do this and a compression/leak down test, on any engine I was concerned about, before doing anything. So save a sample of that oil when you change it.....

Thanks, I will. I ordered a test kit.

From what I can read, my engine has all the signs of the pressure release valve gone bad in the oil pump. Lower then normal oil pressure at low RPMs and low at high RPMs (normal at normal rpms) and wildly fluctuating oil pressure.

ric · **Posted:** Mon Feb 06, 2012 7:01 pm

I'm going to raise some hell!

The few month old KN oil filter failed internally... 3-5psi idle, 25psi cruise. I put a new filter on, oil pressure jumped up to 20-25 idle, 45 at 3200rpm cruise! When I shut off the boat, it stayed at 20 for a lonnng time. With the KN it would drop right to 0. I'm having the oil in the filter sent off for testing, and calling KN tomorrow. I didn't change the oil yet, but I will now and a new oil pressure sender. I swear to god, if there's any internal engine damage they're going to pay for it.

LouC · **Posted:** Mon Feb 06, 2012 7:12 pm

Wow that is surprising, I have never used a K&N but I thought they had a good rep. Personally I have used Sierra Marine filters for about 10 years worth and never had a problem with oil pressure. If I could not use Sierra, I'd use Quicksilver. I know you can use automotive filters but in salt water I like to use a marine filter because they don't rust as fast.

TX H210SS · **Joined:** Thu May 27, 2010 9:10 am **Posts:** 1488

When u swap the oil u may as well put another filter on too. Contaminents from other filter may have been filtered thru to new one.

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This is new..low oil pressure

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