Big Trouble Brewing?

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digginfool
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Big Trouble Brewing?

Postby digginfool » Tue Feb 16, 2016 5:54 am

A couple rides ago, as I was taking off from the landing I looked down and saw my oil pressure pegged at 100 psi. I immediately let off the gas and oil pressure fell to the normal 65 psi. I accelerated again and oil pressure pegged but slowly came down to normal range once the engine reached operating temp. No other issues that day. This past weekend, I figured I would warm up the engine longer than I normally do and let it get well up in the temp range before putting a load on the engine. Same thing happened; oil pressure gauge pegged at 100 psi until engine reached full operating temperature then came down to the normal 65 psi. The only difference is the last oil change I changed viscosity and these last two rides were in much cooler weather. I've used Mobil1 since the engine was new and initially used 5W-30. I am now using 15W-50. Is this pressure spike due to the higher viscosity and lower temperatures or do I have an issue brewing inside my motor? I'm going to change the oil today and cut the filter open to see if there's any garbage in there. Any of you LS guys have any ideas?
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Tony480
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Re: Big Trouble Brewing?

Postby Tony480 » Tue Feb 16, 2016 6:06 am

What oil do they recommend running? Switching from a 30 weight to a 50 weight is a big change...I would bet money that's the problem. If the motors not setup to run a 50w oil I wouldn't

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Re: Big Trouble Brewing?

Postby chuckitt@earthlink.net » Tue Feb 16, 2016 6:26 am

Your right Tony, if the engine new was a 5w30 engine, then run 5w30. If it is a VVT engine the Valves want adjust properly.

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Re: Big Trouble Brewing?

Postby Rich Andrews » Tue Feb 16, 2016 7:10 am

had an oil pressure release valve go bad on a new truck, same symptoms but the oil wasn't switched as well
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Re: Big Trouble Brewing?

Postby digginfool » Tue Feb 16, 2016 8:30 am

Tony480 wrote:What oil do they recommend running? Switching from a 30 weight to a 50 weight is a big change...I would bet money that's the problem. If the motors not setup to run a 50w oil I wouldn't


That's why I switched. The recommended oil is 15W-50. I can't answer for why I was running the 5W-30. As silly as it sounds, I think that was the heaviest Bennett had on the shelf at the time. I had to go to Autozone to find the 15W-50. The engine arrived full of oil so I have to assume the first run was 15W-50 but the next two oil changes were 5W-30. I was going through the owner's manual looking for information on the wiring harness and noticed I hadn't been using the recommended oil. Before it got cool out, never had this issue. I had heard of oil pressure relief valves going bad in motors before but not specifically the LS. I'm hoping I don't have a plugged passage and that's why pressure is spiking but, then again, I wouldn't think if that was the case the pressure would come down as engine reached full operating temperature. Hoping the oil filter is clear when I open it up.
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Re: Big Trouble Brewing?

Postby Deano » Tue Feb 16, 2016 8:39 am

When you are looking at the weight of a multi-viscosity oil, bear in mind that,
for practical purposes the numbers represent ColdWeight - HotWeight.

The use of different modifiers allow the oil to act like different weights at different temperatures.
The results you are seeing are likely from the difference between 5- and 15- , not the -30 and -50.

I've not witness such a vivid example of this in action, because the radical bulk of my experience is with much more antiquated engines that, by nature and design, run much larger clearances and thicker XX- weight oil than what you are talking about. It would make sense that the smaller clearances are, the less forgiving it would be with the wrong oil, especially when cold. This explains why when it's cold the pressure spikes (clearance to tight), but then returns to normal after it reaches operating temperature (and clearances are larger).

Put in this context it is easy to see where cold, thick oil and small, tight clearances will yield excessive oil pressure until things are warmed up and loosened by attaining normal operating temperature.

Interestingly enough, this same scenario is why you should always warm up an AC engine to check the oil pressure before you buy it. I know of a couple folks along the way that didn't do that and bought a wore out engine that held
great oil pressure cold, but did not come close after it was warmed up. :shock: Same scenario, and with straight weight oil to boot.
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Re: Big Trouble Brewing?

Postby Deano » Tue Feb 16, 2016 8:48 am

Guess I still type to slow, didn't see your last post. In your first post,
you neglected to mention that the 5w-30 was not the recommended oil.

Still will be hoping for you that going back to the 5w-30 'till spring has sprung will
resolve that issue as it seems like you get more than your proportional share of grief.
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Re: Big Trouble Brewing?

Postby Oilfield Trash » Tue Feb 16, 2016 8:51 am

digginfool wrote:A couple rides ago, as I was taking off from the landing I looked down and saw my oil pressure pegged at 100 psi. I immediately let off the gas and oil pressure fell to the normal 65 psi.


At idle your at 65psi?

I've been running 15w50 since the first change of the 30 weight break in oil (at 8 hours) in my LSA. At warm idle I'm around 45psi and I've never even seen over 65psi even at WOT.

Are you running Canbus guages?

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Re: Big Trouble Brewing?

Postby digginfool » Tue Feb 16, 2016 8:59 am

Oilfield Trash wrote:
digginfool wrote:A couple rides ago, as I was taking off from the landing I looked down and saw my oil pressure pegged at 100 psi. I immediately let off the gas and oil pressure fell to the normal 65 psi.


At idle your at 65psi?

I've been running 15w50 since the first change of the 30 weight break in oil (at 8 hours) in my LSA. At warm idle I'm around 45psi and I've never even seen over 65psi even at WOT.

Are you running Canbus guages?


I know I said let off the gas but not completely off. What you have is exactly what I normally have; around 45 at idle, 65 when RPMs are up, all the way to WOT. I'm getting the spike at high throttle settings before the engine has reached full operating temp. I still have 65 psi at cruise RPM even when engine is spiking at high RPM.
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Re: Big Trouble Brewing?

Postby Olf Art » Tue Feb 16, 2016 9:23 am

Diggin, I had a similar problem once and changing the oil pressure sending unit fixed it. I agree with Tony480 that 30W to 50W is a big change, but I'd look at replacing the sending unit. JMO
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Re: Big Trouble Brewing?

Postby Oilfield Trash » Tue Feb 16, 2016 10:42 am

15w50 is the recommended oil for this engine.

So are you running canbus gauges?

I doubt on your new engine that you have already had a sending unit fail. If you're running analog gauges I'd suspect a connection.

Also, something to think about - There's a pressure relief valve in the oil pump. A spring controls the valve. I think that spring will allow for "wide open" flow by 65 psi. Maybe it's possible that somehow you got some junk blocking this valve from opening.... I'm no expert but I also believe that once the engine reaches operating oil temp that this spring valve is no longer in control. This would make total sense as to why this isn't an issue once your engine reaches full temp.

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Re: Big Trouble Brewing?

Postby digginfool » Tue Feb 16, 2016 12:07 pm

Just finished changing oil and tearing filter apart. Filter was clean; no debris. Figured out why I was using 5W-30. It's printed on the oil filler cap. Since I had already purchased it, I stayed with the 15W-50 and plan to continue using it since that's what Marine Power recommends. Plus, the 15W-50 has zinc additives in it that the 5W-30 does not. No time to run the boat right now but perhaps later this afternoon. OT, as I stated above, I've heard of the pressure relief valve sticking on engines before. Hopefully, some fresh oil will help flush it out if that's the problem. I suppose it's possible the spring also works like a thermostat in that once the engine reaches full operating temperature, it stays open all the time. I could see that being used so that the oil in the engine warms up fully before running through a cooler and/or filter where cold ambient conditions could keep the oil too cool.
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Re: Big Trouble Brewing?

Postby odcjohn » Tue Feb 16, 2016 12:45 pm

I SECOND THE PRESSURE RELIEF VALVE HAVE SEEN IT MANY TIMES

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Re: Big Trouble Brewing?

Postby jopete » Tue Feb 16, 2016 1:04 pm

put some black tape over the guage and run that motor like u stole it.

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Re: Big Trouble Brewing?

Postby Tony480 » Tue Feb 16, 2016 3:28 pm

I have had first hand experience with the oil pressure relief vakve sticking. It cost me a motor...it does happen although no the moat common thing.

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Re: Big Trouble Brewing?

Postby digginfool » Tue Feb 16, 2016 4:57 pm

Ran the engine and still same thing. Called Marine Power and they said fairly common issue. As long as the oil pressure is settling down into a normal range, no codes being thrown or engine going into limp mode, just run the engine the way it is. Said if I'm really concerned about it, just keep off the throttle until full temp but do not go back to 5W-30, I need to run the 15W-50. Thanks for the input!
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Re: Big Trouble Brewing?

Postby Dirtman » Tue Feb 16, 2016 5:09 pm

Diggin. I see they said it is a common problem, but what did they say was likely the cause? sticking relief valve as some had assumed? I know the situation that I had years ago was caused by a different problem( lack of good maintenance) but I had an old pick up that would get pressure high enough to blow the filter gaskets out so be very careful if you continue to run it this way.
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Re: Big Trouble Brewing?

Postby Lwells » Tue Feb 16, 2016 5:20 pm

Oil pump pressure relief valve, oil sending unit or gauge. Running different viscosities of oil will make very little difference in oil pressure. We ran 15-50 in our racing engines in all temps and conditions and oil pressure was in same area as our tow vehicles running 5-50. Hope this helps

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Re: Big Trouble Brewing?

Postby Tony480 » Tue Feb 16, 2016 6:49 pm

Lwells wrote:Oil pump pressure relief valve, oil sending unit or gauge. Running different viscosities of oil will make very little difference in oil pressure. We ran 15-50 in our racing engines in all temps and conditions and oil pressure was in same area as our tow vehicles running 5-50. Hope this helps

That's because both of those oils are 50 weight

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Re: Big Trouble Brewing?

Postby digginfool » Tue Feb 16, 2016 6:53 pm

That's one of my concerns. I won't be very happy if I start blowing rear main seals.
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Re: Big Trouble Brewing?

Postby digginfool » Fri Feb 26, 2016 10:59 am

There may be more to this than I thought. While working on a header bolt issue, I removed the header and noticed one cylinder had not been firing. Now I'm wondering if the high oil pressure is due to a cooked piston. :banghead:
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Re: Big Trouble Brewing?

Postby Tony480 » Fri Feb 26, 2016 11:09 am

Please tell me your joking... how is a cooked piston gonna cause high oil pressure? And you couldn't tell it was on 7 cylinders? You might want to get a new hobby

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Re: Big Trouble Brewing?

Postby digginfool » Fri Feb 26, 2016 11:28 am

Tony480 wrote:Please tell me your joking... how is a cooked piston gonna cause high oil pressure? And you couldn't tell it was on 7 cylinders? You might want to get a new hobby


Compression entering crankcase is how. Don't forget, this is a supercharged motor. It could push more air in than can get out through the PCV. Plus, it may not be a hole in the piston; could be getting past the rings. As far as running on 7 cylinders, the motor was still running smooth but I had noticed it had dropped 200 rpm at WOT this past weekend while on KCOL.
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Re: Big Trouble Brewing?

Postby Tony480 » Fri Feb 26, 2016 11:37 am

Your a special kind of stupid! Lmfao.
Dropped a cylinder but didn't miss and now has more oil pressure. Wtf kind of **** are you smoking?

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Re: Big Trouble Brewing?

Postby digginfool » Fri Feb 26, 2016 11:58 am

Just finished compression test. All 8 cylinders are between 145 and 150 psi.
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