97 Vmax 150 - mechanic replaced the thermostats and water pump, still overheating!!

[99yam40]

Thanks Jason, so I was able to pull it out and checked. Stock is no continuity and hot it opens up. After cooling down it goes back to no continuity.

Now looking at the service manual for possible overheating issues.

Passed
1. Thermostat - checked and does open up at high temps
2. Thermoswitch - checked for continuity no issues
3. Water Pump - mechanic replaced them
4. Water passages - Was able to get water out of the thermostat covers and was able to monitor temp of cylinder heads (they were at 120F tops on the lake)

Haven't checked
1. Charge Coil - haven't checked
2. Spark Plugs - mechanic put new ones in (could he have put in wrong ones?)

Also, when I brought boat home. I moved key to ignition, buzzer went off. I topped the oil and and no more buzzer.

99Yam40 - You mentioned to check for low voltage. My bro in law hasn't come over yet but when he said the reason potentially why all the warning lights went off was because it's on the lake it's a sustained voltage. That makes sense to you?

And how do you fix a low voltage problem? Is that checking the
1. Lighting coil
2. Rectifier/regulator
3. Fuses
4. Battery Leads
5. Battery

Thanks

nope that makes no sense to me.
yes check all of those and connections to the ECU or CDI to make sure there is not a bad/corroded connection.

If filling the oil tank stopped the buzzer, I would find out why the motor tank was low to start out with and if that stopped all of the other lights/alarms ,I have no idea how that would cause the other lights/alarms

[aphextwin]

Thanks! Before I took it to the lake, I did double check the oil level on the remote tank and engine tank. Remote tank was full and engine was right between the max and low levels. That is what's odd...no buzzer testing at home.

Soon as got in water, the buzzers all went off and the oil level kept on going down and took it out of the lake when it hit below min level. That's another part that is wrong as well..ugh one step at a time. I turned on ignition this morning with the min level..buzz, filled it above min level and now no buzz.

I'll check those things for low voltage issue...thanks again!

nope that makes no sense to me.
yes check all of those and connections to the ECU or CDI to make sure there is not a bad/corroded connection.

If filling the oil tank stopped the buzzer, I would find out why the motor tank was low to start out with and if that stopped all of the other lights/alarms ,I have no idea how that would cause the other lights/alarms

[Jason2tpa]

Oil is delivered to the main tank near the top of tank via the reserve tank/pump. Oil exits the main tank at the bottom and heads down to oil injection pump, then to carbs via hoses. Oil seems to be disappearing from the main tank as you noted...but it shouldn't. Where is it going? It's not siphoning back to reserve tank given the oil enters into the main tank well above the bottom level line. Could only be 1 of 2 things in my mind...main tank oil leaks into the lower cowling which I would believe you'd notice....or the oil tube check valve(s) have failed and the oil is draining into the carbs. But again, I would believe you'd notice that much oil leaking from carbs and eventually into silencer and out into lower cowling.

Anyone else puzzled on where this oil is going if user reports no oil leak??



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[aphextwin]

Hi Jason, I might be wrong.

Okay, took pics of the engine...does this look like it's leaking? I should have looked at the bottom of the cowl when I left. I'll check the tubes to see if there is any leaks later today but took some pics. Visually it looks like #9 - oil hose has oil leaking down. Hopefully that is it....and not the check valve since I don't have a Mity vac??

I've attached some pics.

1 (Large)_LI.jpg

2 (Large).jpg

3fixed (Large).jpg

Oil is delivered to the main tank near the top of tank via the reserve tank/pump. Oil exits the main tank at the bottom and heads down to oil injection pump, then to carbs via hoses. Oil seems to be disappearing from the main tank as you noted...but it shouldn't. Where is it going? It's not siphoning back to reserve tank given the oil enters into the main tank well above the bottom level line. Could only be 1 of 2 things in my mind...main tank oil leaks into the lower cowling which I would believe you'd notice....or the oil tube check valve(s) have failed and the oil is draining into the carbs. But again, I would believe you'd notice that much oil leaking from carbs and eventually into silencer and out into lower cowling.

Anyone else puzzled on where this oil is going if user reports no oil leak??



212.jpg

[aphextwin]

Okay after some more digging. I noticed two things. The oil pump lever is not touching the stopper.
not touching.jpg

I'll adjust it to make it touch. Would that cause an oil leak though?
instructions.jpg

Then I also noticed the joint link is partly broken off. It does move the oil pump lever but there is alot of play? Would it affect it?

link.jpg

2021-06-03_16-05-49.jpg

That's it for now. Would that cause the oil leak since on resting position the oil pump lever is not touching the stopper? Could I try that first and see? Or as you said it is either the check valves or main tank leaking?

I also saw that the sensor for remote tank wasn't connected!
Tank.jpg

[aphextwin]

Here is the video on the play I get when moving the oil pump lever up and down.

[Jason2tpa]

Looks like you found the issue why the reserve tank isn’t filling the main tank with the harness unplugged. In regard to the mechanical oil pump, I would adjust the pump to specs. And that plastic piece holds the articulating arm into the carb by snapping down. So long as you can confirm the arm doesn’t pull out of the carb it shud be good. If it does I wud replace.

[aphextwin]

Thanks everyone for the help!

[aphextwin]

Update we took out to the lake again this weekend. No problems, started fine and didn't get any buzzer sounds. Kept checking the thermostat covers and steady 115F. Was even able to go WOT with no problem. Cleaned the cowl before I left and no leaking oil and it's refilling correctly (as Jason2tpa mentioned it was the unplugged harness).

Wanted to thank you guys Jason2tpa , 99yam40 and ausnoelm for the advice. You guys are amazing and patient. I also bought myself the Yamaha service manual. You saved me from spending $3K or losing $3k selling a boat that mechanic said was going to be an expensive fix. Our kids are happy that they can now go boating and fishing this summer.

Thanks again you guys rock.

[byron.akhavi@gmail.com]

Great work!!

[Jason2tpa]

Great news, thanks for sharing. Kudos for perseverance!!