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

[aphextwin]

Okay, so looking at this video. https://www.youtube.com/watch?v=0AujYWSjIOg

I just take the hose off the PRV, run idle and ensure no water is going out of the Poppitt right?

Check the PRV and then water test to see if it still overheats
after market pumps should work if they are the correct ones for the motor, but how do you know that for sure.

[99yam40]

Check the PRV and then water test to see if it still overheats
after market pumps should work if they are the correct ones for the motor, but how do you know that for sure.

[aphextwin]

Sorry, okay I looked at the invoice. It's part number 18-3395 Water Pump Kit and 18-9659 Syn Gear Oil...I googled and it's SIerra...so definitely not OEM....should I be replacing that with Yammy asap....even the gear oil isn't Yammylube...that's an easy one so I will do that if the boat test works out.

We still don't know if a full genuine water pump kit was used, or just an impeller, or even worse, a cheap after market impeller! but try it in the water first, that's the true test.

[aphextwin]

sorry ugh ear muffs.

99yam40...thank you again for being so response the last day...you and everyone here are amazing guys.

I have no idea how you adjusted the muffler of what you are calling the muffler

[ausnoelm]

We still don't know if a full genuine water pump kit was used, or just an impeller, or even worse, a cheap after market impeller! but try it in the water first, that's the true test.

[99yam40]

Eureka, my god you are right. I adjusted the muffler and now it's pushing water even with the prop in the water. You guys are awesome. We will head to the lake to do the hopefully final test.

I have no idea how you adjusted the muffler of what you are calling the muffler

[aphextwin]

Eureka, my god you are right. I adjusted the muffler and now it's pushing water even with the prop in the water. You guys are awesome. We will head to the lake to do the hopefully final test.

It might be as simple as not enough water pressure from your hose, try it at the ramp fist (with thermostats in) and see how it pumps.

[aphextwin]

When I quoted that was somebody else on a different forum that figured they were overheating because they had debris in their shaft.

Ah okay so that could be something to try the PRV.

there should not be anything inside the water tube heading up to the power head from the water pump.
not sure what you are calling a rubber grommet inside there.

PRV when stuck open dumps too much water at low RPMs to keep the block filled so it overheats

[99yam40]

Well, I tried to simulate the lake before I went out. I put ear muffs on and submerged the propeller exhaust. Exposed the thermostat covers and it went up to 130 F on both sides......no water coming out of the covers at all except smoke and no tell tale either. The back pressure on exhaust is causing it not to push water out? BTW I did re-read the notes and he had run the boat on hose with ear muffs. So at this point I am baffled....
1. Mechanic runs it with hose - water tell tale but no water to t-stat covers
2. I run it with hose - water tell tale but water flow to the t-stat covers no overheat steady at 110F
3. I run it with mufflers and submerged prop - no tell tale and heats to 130F

The next step is try the redlyme and if that doesn't work then take apart cooling jacket?

I am no mechanic by any means but this is telling that there is not enough water pressure going up to the engine and maybe mechanic is right? the bottle neck is the tubing? What do you guys think?

The next step is try the redlyme? Taking apart the cooling jacket won't matter since water isn't even getting there right? Should I check the Poppitt Valve and expose it to see if water is getting there?

Another thing I read is maybe I take the leg aprt again.

"After dropping the lower unit again, I got the motor in a position where i could look thru the water tube to the head of the motor - AHA, there it was, pushed up the water tube a few inches was a rubber grommet." I could check to see if there is any debris blocking it? Should I go try that?

I was also thinking the Poppitt valve but from my understanding, a bad valve is when you are gearing up and it overheats. In this case I am idling and it's overheating.

there should not be anything inside the water tube heading up to the power head from the water pump.
not sure what you are calling a rubber grommet inside there.

PRV when stuck open dumps too much water at low RPMs to keep the block filled so it overheats

[aphextwin]

Sorry you mean try taking it to the RAMP first?

It might be as simple as not enough water pressure from your hose, try it at the ramp fist (with thermostats in) and see how it pumps.

[ausnoelm]

It might be as simple as not enough water pressure from your hose, try it at the ramp fist (with thermostats in) and see how it pumps.

[aphextwin]

Well, I tried to simulate the lake before I went out. I put ear muffs on and submerged the propeller exhaust. Exposed the thermostat covers and it went up to 130 F on both sides......no water coming out of the covers at all except smoke and no tell tale either. The back pressure on exhaust is causing it not to push water out? BTW I did re-read the notes and he had run the boat on hose with ear muffs. So at this point I am baffled....
1. Mechanic runs it with hose - water tell tale but no water to t-stat covers
2. I run it with hose - water tell tale but water flow to the t-stat covers no overheat steady at 110F
3. I run it with mufflers and submerged prop - no tell tale and heats to 130F

The next step is try the redlyme and if that doesn't work then take apart cooling jacket?

I am no mechanic by any means but this is telling that there is not enough water pressure going up to the engine and maybe mechanic is right? the bottle neck is the tubing? What do you guys think?

The next step is try the redlyme? Taking apart the cooling jacket won't matter since water isn't even getting there right? Should I check the Poppitt Valve and expose it to see if water is getting there?

Another thing I read is maybe I take the leg aprt again.

"After dropping the lower unit again, I got the motor in a position where i could look thru the water tube to the head of the motor - AHA, there it was, pushed up the water tube a few inches was a rubber grommet." I could check to see if there is any debris blocking it? Should I go try that?

I was also thinking the Poppitt valve but from my understanding, a bad valve is when you are gearing up and it overheats. In this case I am idling and it's overheating.

[aphextwin]

Thank you I will look into that.

there are some chemical flushes out there to help remove scale from the cooling passages you could try
before ripping the heads and covers off to do a manual scrape
Rydlyme marine descaler is one I have read about in the past
do a web search on it

[99yam40]

there are some chemical flushes out there to help remove scale from the cooling passages you could try
before ripping the heads and covers off to do a manual scrape
Rydlyme marine descaler is one I have read about in the past
do a web search on it

[aphextwin]

I used a garden hose with single side ear muffs. I will call on Monday as he doesn’t work weekends. Thanks

that does not sound like it overheats.
shop may have a test prop to run the motor, but not sure if yours has that.
back the trailer/boat into the water and run it on the trailer.
just make sure it is tied on to the trailer well so it does not jump off.

talk to the mechanic, ask how he was testing .
what kind of water hose connector did he use?
what abut you?
maybe different muffs ,hose, water pressure made a difference

trying to run in gear in a tub will just blow the water out of the tub