MR1 low oil pressure

[cybuch]

I could really use some help from someone who knows more than me. Here is the story:

I have a rebuilt MR1 SBT Engine. I installed it, broke it in, and it runs great. However, when I first start it and warm it up and go WOT, the oil pressure goes up to ~60 psi. Sounds normal, right. Here is where it gets strange, over the next 10 minutes at WOT, the oil pressure gradually drops to 30 psi. It seems to stabilize at 30 psi, but I think that is too low as my other engine hits ~65 and stays there. If I stop for about 10 minutes and start it back up, she is right back at 60 PSI at WOT, but drops. I called tech support at SBT and they said, these engines run at low PSI.

Here is what I have tried so far:
Pulled oil tank, took it apart and check the screen in there, all clear.
Pulled oil pump, installed a brand new one, did find 3 small rubber pieces in that screen (no idea where they came from)
Changed oil filter and used 10W40
Dropped oil pan, all clear in there

After all this, I still have the same issue with the oil pressure dropping.
I did put it on the hose today and warmed it up, when I go hi revs and look in the oil tank, the oil starts churning and spitting up out of the filler hole (not a lot, just spits out droplets). It also gets frothy but not milky, just aerated. Tested my other engine the same way and the oil stays smooth and it doesn't spit back out the filler hole. I am thinking the issue with the oil pressure dropping is due to the oil getting frothy, but I have no idea where to go next.

I do have a Yamaha waverunner I can rob parts from. Was thinking of swapping the oil tank with the waverunner.

Any help is greatly appreciated.

 

[WREKS]

@cybuch Are the chain guides intact. @Jaycav had one delaminate putting shredded pieces in the oil path.

 

[cybuch]

Yes, chain guides are intact

 

[swatski]

@Jgorm , @itsdgm

 

[tdonoughue]

Are both engines' oil at the same level? That could explain one aerating and one not...

 

[cybuch]

Good thought, yes, both are at the same level

 

[WREKS]

You can remove the top of the oil tank and observe the operation of the salvage pump. It splashes a little so cover with a rag. It seems like it is oil starved with the aeration going on.

 

[Seadeals]

If the pump is working (new) you have good flow from the pump. The pressure might be good when cold because clearances at bearings are tighter; but as it heats up, gaps increase and stop restricting the flow (pressure drop). Also the froth is likely due to the increase in flow (more splashing in the crank case before getting pumped again). If a bearing or bearings are worn enough for that, a soap sample of the oil might tell you if you have a lot of metal.

 

[buckbuck]

@cybuch How are you measuring oil pressure? I may want to mod my boat to do the same.

 

[cybuch]

I installed a t at the oil pressure switch and added an electronic sender and ran it to my MFD.

 

[cybuch]

@WREKS have you don this before? If I pull the cover off, the return will definitely spill out and it get to the top of the tank

@Seadeals The motor has 2 hours on it, do you think it would be that worn so quickly?

 

[WREKS]

The top two hoses are for crankcase ventilation and emissions. Oil never gets that high. If it does it pressurizes the crankcase and floods the filter at the bottom of the air box. Then it can blow the semi-circular seals on the valve gasket I will post video tomorrow.

 

[cybuch]

@WREKS that would be awesome! Thank you

 

[Seadeals]

@Seadeals The motor has 2 hours on it, do you think it would be that worn so quickly?

Good point, definitely NOT worn yet...now as for tolerances as delivered by SBT, it could still be a possibility. What PSI does SBT consider “low PSI” and what is acceptable to them as far as warranty?

 

[WREKS]

@cybuch Oil Pump Operation

 

[cybuch]

@Seadeals its a no fault warranty, so I can run it out of oil and its covered. They said the low oul pressure switch some on at 24 psi and since thats not teipping its all good, is what they say

@WREKS I get a 404 error with that link, can you send it again, please.

 

[WREKS]

@cybuch Salvage oil pump operation Does it work now?

 

[WREKS]

@zipper Thanks.

 

[cybuch]

@WREKS yes it does, THANKS!. I will give it a try and see if I can somehow direct the inflow into the tank at high revs and see where the aeration is coming from. I think its coming from the bottom of the tank

 

[WREKS]

@cybuch The feed pump should be drawing the tank down as the salvage pump fills it. The video was made at idle or No-Wake rpm. I reused the o-ring on the oil cooler cover.