Boat Yamaha SBT engine low oil pressure?

[Bondski]

@BondsGarage, I own and work on Seadoo's. I am new to Yamaha engines over the last few years and in trying to help a close friend with his 2007 AR230 have found myself learning a bit. First engine failure on his AR 230 was due to the cooling jacket corrosion described in the forums here. So we installed an SBT engine ....3 replacements ago. All failed for various mechanical reasons and all had low oil pressure after the engines warmed up. Why?

I am now testing engine 4, which was put into a 2006 Yamaha FX cruiser I'm now building and own, so that we could use the doner engine for his AR 230. He has had ZERO issues since we installed the old factory Yamaha doner engine in May. I had good luck with SBT on Seadoo 2 stroke and 4-tech engines.... but not this darn Yamaha MR1.

Now I'm left with getting this jet ski functional, yet it too also now suffers from low oil pressure after the engine warms up (zero oil pressure warmed up on idle). Intentionally high SBT bearing clearance? Dunno, but I plan to find out even if this engine which is now out of warranty gets pulled and disassembled to learn and offer warnings or solutions to others.

Using this forum, I have learned about addition of an oil pressure sensor on the MR1 (Great idea!) I have some video of doing this.

This first video is about adding the oil pressure and temperature sensors. Oil pressure decays at idle RPM. Oil temperature on this particular engine design is VERY hot, which increases the pressure decay. (To combat oil pressure loss SBT even recommended using 20w-50 oil to one of their clients, as you can find in a post online) Unless you add additional sensors to read live pressure and temp, you can only trust temperature and pressure switches (On / Off) provided by the Yamaha OEM to understand operating health. It also appears that Yamaha ECU logic ignores oil pressure below a certain RPM? So why exactly do SBT clone engines of the MR1 have low oil pressure so often reported? We'll Im trying to test and figure this out....Future testing will be done to try to understand all of this, with my new installed sensors. And "maybe" an engine tear down?

Just sharing this, you jet boaters with MR1's might get some info out of these crappy video's I'm trying to make! But really, trying to share info with you and I plan to add more detail soon as we test the SBT against stock Yamaha engines used in my buddies jet-boat.

 

[Babin Farms]

Other than using a different oil what is SBT saying could be the issue. If you have had multiple engines of theirs with the same problem I would suggest getting on the phone with them and not letting this go until you get an answer.

 

[Bondski]

Thanks for the note, but since I'm now out of warranty as this is engine 4, this is now falls on me with either a good or bad outcome. I did have a good proactive chat with them earlier on when I was seeing low oil pressure (initially hour 3, and I'm now at 12 (video was recorded a couple months ago), good chat but not much advice was offered though and this is not going to be warranted anymore.

I'm now very curious to prove or disprove why this occurs on SBT engines specifically. "If it is an issue from SBT", then if so "why?" Or is this due to something else that I missed instead? All I've seen online are complaints on these without a solid reason why the SBT engines failed/ are not good to buy.

Again, I've had very good luck on quality from SBT on other engines (One of my old 2006 Seadoo 4tech RXT engines is now nearing hour 150, and I still maintain this for that owner), just not seeing the same experience so far on the Yamaha MR1 clone engines I have encountered.

 

[Babin Farms]

Out of warranty or no I would still bring this to their attention and see if there may be an issue with their engines. It’s not about placing blame or trying to get something out of them other than hopefully figuring the issue out and I would think that a company that is having issues with their product would want to know to try to make an improvement.

 

[zipper]

@Neutron may have input.

 

[Bondski]

Out of warranty or no I would still bring this to their attention and see if there may be an issue with their engines. It’s not about placing blame or trying to get something out of them other than hopefully figuring the issue out and I would think that a company that is having issues with their product would want to know to try to make an improvement.

Thanks for the comment, I agree and have brought this to attention providing details each time. I certainly support communicating findings. New details I find will also be communicated back and also on this post. I'm separating from any blame here, and for fun working instead to understand why I have the same end result so many times in a row.
I've seen many negative posts on this topic, but haven't come across an explanation with facts or maybe a remedy other than buying a used OEM engine (Which I also did this year, and that 160 hour engine continues to run flawlessly at over hour 200 this season without a hint of low pressure or obvious defect). The #3 SBT warranted engine was removed from an AR230, and a good running 2006 FX Cruiser HO engine I purchased was test run then I removed it the second day and swapped it into the AR230. Then when received I installed the replacement new #4 SBT engine into the Yamaha FX Cruiser I now own, still starts and runs great and again I get the low oil pressure alarm after engine warm up. A new factory Yamaha oil pump was installed into engine 4. (This low pressure alarm and limp mode seems to occur when above 220F oil temp and decelerating below 4-5000 rpm, at idle the gauges shows 0-3 psi when over 180F and 30 psi repeatably on cold start idle). Swapping to 20W-50 full synthetic shifts the low oil pressure alarm up as expected due to thickness at the same or higher temp, but low pressure alarm still occurs at the higher temp and I'll show more details on that. (Adding 50 basically fakes out your alarm at the higher temps, a pressure switch is really intended in a way to assure proper "flow" to the engine components with the head oil supply being the lowest pressure in the hydraulic path.)
I suspect more oil is being supplied to engine componants than by design. Playing with viscosity is a way to make pressure "look better", and if too high of a viscosity can also decrease flow through the engine components.
No blame intended in my post, just want to try to understand this and share what I learn.

 

[Neutron]

Usually when you get loss of oil pressure when warm at low rpms, the mains are wiped.
Have you checked with a mechanical gauge? Thats what i would do. If its accurate then i would disassemble and inspect everything.
Everything that oil flows needs to be looked at. Its there, you just cant see it. It can also starve from oil if restricted before the pump causing low oil pressure. But usually that happens even cold
Send me a PM and i can give you my number and i can talk further about it if you like

 

[Neutron]

On a side note about SBT. You only hear about the bombs, not about the thousands of good engines they produce. They have been around for a long time, you dont do that if your products suck.
Back when it was all 2strokes most did blow up because the consumer didn't fix the problem that caused the original to blow up. With 2 strokes there was a fine line to work with.
I have seen plenty of skis with their engines in th that are just fine with hundreds of hours on them

 

[Brad_Ct]

I’m going through this with one of their engines now myself. I am getting low oil pressure alarms on initial cold start up and when I back down on the throttle quickly. I have talked to them and installed a mechanical oil pressure gauge to verify what the oil pressure actually is like they asked.

After installing the gauge I was showing 16 psi at idle and 26 psi at around 3k rpm with a cold engine, unfortunately I have not had the boat on the water to check any further due to the weather here in SWFL the last couple of weeks.

 

[Bondski]

I have not tested using a mechanical gauge, thanks for sharing... I'm going to try this. Warmed up RPM above 8500 and my pressure gauge is max scale at just about 100 psi. (Sounds high, but its been this way since testing started)

 

[itsdgm]

Great video and research @Bondski. I’ll be following to see what you uncover.

Just to clarify, are the engines that you’re receiving from sbt doing this right out of the box? Or does this develop over a period of time?

 

[Brad_Ct]

Great video and research @Bondski. I’ll be following to see what you uncover.

Just to clarify, are the engines that you’re receiving from sbt doing this right out of the box? Or does this develop over a period of time?

My engine had no issues for the first 3 hours, and it does not make any abnormal noise that I can tell.

 

[Bondski]

Great video and research @Bondski. I’ll be following to see what you uncover.

Just to clarify, are the engines that you’re receiving from sbt doing this right out of the box? Or does this develop over a period of time?

Thanks. Each engine eventually exhibited the same low pressure alarm issue during a break in process. But I can't say these issues occurred right out of the box because none of mine were taken to a higher RPM right away after installation during my own break in process. (whether that's needed or not, a slow break in process is what I do). Through break in, I slowly ramped these up to a sustained higher RPM more and more over initial hours run time.

I can say the problem only occurs as the engine is fully warmed up and taken to higher RPM. By about hour 5-7 hours initial run time the engines I have been working with eventually started to trigger a low oil pressure alarm as RPM was raised to above 8000 and then was decelerated. I've never had the alarm come on during sustained higher RPM runs until deceleration occurs, it alarms only after deceleration as the oil pump slows down.

Warmed up and above this 8000 RPM level, on deceleration they all eventually went to limp mode.

In general, it seems that this occurs when oil temperature was initially above 220F using 10W-40 oil.

 

[Bondski]

I have not tested using a mechanical gauge, thanks for sharing... I'm going to try this. Warmed up RPM above 8500 and my pressure gauge is max scale at just about 100 psi. (Sounds high, but its been this way since testing started)

I have not tested using a mechanical gauge, thanks for sharing... I'm going to try this. Warmed up RPM above 8500 and my pressure gauge is max scale at just about 100 psi. (Sounds high, but its been this way since testing started)

I've been thinking a-lot about the comments on mechanical gauge testing (Thank you). So I have a liquid filled 60 psi pressure gauge coming this week for more accuracy. My plan is to remove the intake/ exhaust and swap this gauge in place of the pressure sending unit I installed, then reassemble and test on the hose to get this warmed up. I think it will a worthwhile test to "Gauge" my accuracy. Hoping I can get oil temps near 140-170 range on the hose, will throttle cooling water at some point and monitor exhaust temps to try and balance this so I have some repeatable warm oil data against the Amazon special gauge I'm currently using. More to come...

 

[Brad_Ct]

I've been thinking a-lot about the comments on mechanical gauge testing (Thank you). So I have a liquid filled 60 psi pressure gauge coming this week for more accuracy. My plan is to remove the intake/ exhaust and swap this gauge in place of the pressure sending unit I installed, then reassemble and test on the hose to get this warmed up. I think it will a worthwhile test to "Gauge" my accuracy. Hoping I can get oil temps near 140-170 range on the hose, will throttle cooling water at some point and monitor exhaust temps to try and balance this so I have some repeatable warm oil data against the Amazon special gauge I'm currently using. More to come...

Any updates on this?
I talked to SBT technical support again and explained what I was getting for oil pressures and he thinks it’s an oil pump issue. I have ordered an oil pump rebuild kit from them and have another oil pump assembly from another engine. My plan is to rebuild this pump and swap them out.

 

[Bondski]

I've been thinking a-lot about the comments on mechanical gauge testing (Thank you). So I have a liquid filled 60 psi pressure gauge coming this week for more accuracy. My plan is to remove the intake/ exhaust and swap this gauge in place of the pressure sending unit I installed, then reassemble and test on the hose to get this warmed up. I think it will a worthwhile test to "Gauge" my accuracy. Hoping I can get oil temps near 140-170 range on the hose, will throttle cooling water at some point and monitor exhaust temps to try and balance this so I have some repeatable warm oil data against the Amazon special gauge I'm currently using. More to come...

Any updates on this?
I talked to SBT technical support again and explained what I was getting for oil pressures and he thinks it’s an oil pump issue. I have ordered an oil pump rebuild kit from them and have another oil pump assembly from another engine. My plan is to rebuild this pump and swap them out.

Sorry, no updates yet. I ran this a couple more times since my last comment and plan to start my next dive into it over the winter. One update I suppose is that after more runs, a cutaway of the oil filter shows a clean system with no metal shavings.