350 low oil pressure when warm at idle

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Andrew511
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350 low oil pressure when warm at idle

Postby Andrew511 » Sun Jan 06, 2019 8:12 pm

(DD 350) On Monday after fishing 3 days when I got back to the ramp and let it idle it had almost 0 oil pressure. When I hit the gas it goes up to About 35psi at WO. It also developed a small leak at the front and rear of the engine within the last couple weeks. Hard to tell if it’s the oil pan but both leaks are directly under the crank. If I start it cold it has lower than it used to have on cold starts but it will hold 28-35 psi at idle cold. Mechanic says there isn’t excessive play on the crank. Should I try to replace the pump? Or is it most likely worn internals? Any help is appreciated

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Re: 350 low oil pressure when warm at idle

Postby SWAMPHUNTER45 » Sun Jan 06, 2019 8:41 pm

Is it an electric or mechanical gauge?

When was the oil changed last?

If it has run time on oil and filter I would change it and cut open the filter and check for metal.
Many things it can be from a bad gauge, fuel contaminated oil, wear or a host of other things.



I personally had the same type of symptoms with an engine and mine was a cracked oil pump pick up.

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Re: 350 low oil pressure when warm at idle

Postby Andrew511 » Sun Jan 06, 2019 10:00 pm

SWAMPHUNTER45 wrote:Is it an electric or mechanical gauge?

When was the oil changed last?

If it has run time on oil and filter I would change it and cut open the filter and check for metal.
Many things it can be from a bad gauge, fuel contaminated oil, wear or a host of other things.



I personally had the same type of symptoms with an engine and mine was a cracked oil pump pick up.


It’s a mechanical gauge. The mechanic hooked a separate gauge directly to the motor and got same readings. Oil was changed two months ago. Maybe 10 hours on it tops. I’m considering just swapping the oil pump to see.

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Re: 350 low oil pressure when warm at idle

Postby SWAMPHUNTER45 » Mon Jan 07, 2019 8:01 am

You can try that. Is the oil level the same? Does it have a mechanical pump on engine? Remote chance but sometimes they leak into the crankcase or if an electric is to strong it can push gas into the engine and get into the oil. Probably not but that would be a thing to at least consider.


I would check that filter and really look at the oil and element. In the sun any shiny particles are suspect. Tiny little flakes sometimes usually non magnetic indicated bearing wear. Had you recently changed the cam by chance? Worn cam bearings can act this way too. So many what if's....keep us posted.


I would change oil nd filter but that's just me. If your not hearing a tapping or knock try a cheap oil change just to rule oil fuel in the oil.

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Re: 350 low oil pressure when warm at idle

Postby Andrew511 » Mon Jan 07, 2019 8:41 am

[quote="SWAMPHUNTER45"]You can try that. Is the oil level the same? Does it have a mechanical pump on engine? Remote chance but sometimes they leak into the crankcase or if an electric is to strong it can push gas into the engine and get into the oil. Probably not but that would be a thing to at least consider.


I just got the boat two months ago so not really sure about the cam being changed but previous owner did not mention it. As far as mechanical pump I’m not sure either. I’m not a mechanic by any means but I can do a lot of work as far as replacing things. Diagnostic work isn’t really a trait of mine. I’ll change oil and sweep it with a magnet and look for non magnetic particles as well. I do hit a lot of big pot holes while towing and also run some really bumpy near dry mud with it while riding to the fishing holes, so I’m hoping something on the pump could be broken maybe from all the force of the bumps. I’ve never changed an oil pump on a 350 so I may pay someone to do it. My only fear is putting money into it and still end up needing a rebuild. So far it seems like I can get a reman bone stock for around 1200 and the quotes I got for rebuild are higher.

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keebo
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Re: 350 low oil pressure when warm at idle

Postby keebo » Mon Jan 07, 2019 2:36 pm

I would say worn cam bearings being the most likely suspect if there is no other noises.
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Re: 350 low oil pressure when warm at idle

Postby SWAMPHUNTER45 » Mon Jan 07, 2019 7:27 pm

If you suspect wear do the oil change and use a 20w-50 oil and Lucas oil stabilizer.

40% - 50% Lucas is what I would try, blend it with the 20w-50 and see if that ups the pressure.

If your pan holds 5 quarts use 3qts oil then add 2 quarts Lucas.

If its a flat tappet cam don't forget to ad in the ZZPD additive.

pm me if your confused

It is not uncommon for people to do a cam swap and shortly (20-50 hours) after the install have a bearing wear issue as not every shaft is perfectly in spec and if the original was tight and the replacement a loose fit as it wears the pressure can drop. Try the oil dope and see what you get your only talking $40 in oil and filter try it.


Lucas says you can use it up to 60% in worn engines fyi.

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Re: 350 low oil pressure when warm at idle

Postby SWAMPHUNTER45 » Mon Jan 07, 2019 7:39 pm

What is your mechanic that inspected the engine saying?

Did you have a power loss?

You sure no odd noises ?

Is it hydraulic lifter motor?

I'm super suspicious of the oil change it before doing any more running.

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NorthWestFloridaBoy
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Re: 350 low oil pressure when warm at idle

Postby NorthWestFloridaBoy » Wed Jan 09, 2019 12:16 am

It's DD then it's more than likely high clearance on the mains. Especially that last one that takes all the gyroscopic forces. On my old DD 350 I used to have that was always the case. Decent pressure when engine cold then drops down to low to nothing after warmed up at idle, yep time for bearings.

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Re: 350 low oil pressure when warm at idle

Postby SWAMPHUNTER45 » Wed Jan 09, 2019 4:56 pm

I suspect a great amount of wear is avoidable if effort is made to enhance the lubricants utilized and in rebuilds the correct bearing type is installed.

Many don't know that the only thing that keeps the journal from contact with the bearing surface is a thin film of oil. As such if a insufficient oil is utilized wear is fast to claim the engine.

Strong advice would suggest a good quality oil such as Rotella T 15w-40 or Castrol GTX 20w-50 blended with 20% Lucas oil stabilizer and about 6 ounces of CompCam159 Breakin additive will afford you your best defense based on Mr Branches years of research.

The oil serves as a good quality lubricant and carrier. Adding Lucas helps to cushion and the CompCam additive boosts the ZZPD helping all critical wear points.

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Slidin Gator
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Re: 350 low oil pressure when warm at idle

Postby Slidin Gator » Wed Jan 09, 2019 9:47 pm

Andrew511 wrote:Mechanic says there isn’t excessive play on the crank. Should I try to replace the pump? Or is it most likely worn internals? Any help is appreciated

Symptoms are classic bearing wear. Mechanic could be right about limited crank play, but that doesn't tell you about the condition of the cam and rod bearings. I have never had an oil pump wear out without going through a few sets of bearings, but it's worth putting in a new one to match new bearings (pretty cheap insurance). Regardless, you have to drop the pan to change any of this (except cam).

Bearings and gear pumps themselves are cheap parts if you are competent at turning a wrench and reading instructions. Otherwise it's the mechanic labor that cost's the money and reman short blocks are cheap.

In the mean time, you should follow Swamp's advice on juicing the oil. If it were me, I would just drain half the oil out and refill with STP Oil Treatment, Lucas or 140 weight gear oil (whatever it takes to make oil pressure) and give it hell, it's already worn out. Some day it will blow a rod out the side of the block but should be good for a while, at least then you will feel like you got your money's worth. That plan worked great for 2 years on my end, then one day I found myself floating with no power down in the Keys, luckily we still had 1-1/2 days worth of beer on the fishing boat!
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Re: 350 low oil pressure when warm at idle

Postby swamper2 » Fri Jan 11, 2019 8:15 am

cut your filter open and see what is in the element
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