1992 Yamaha 40 MSHQ shutting itself down at wot

[Douglasdzaster]

Hello everyone, Thought I had fixed this problem due to water getting in the cowling. That’s fixed and no water in there today.
when I run wot , after about 5 minutes the engine starts slowing down and the red warning light comes on. I let it idle about a minute and the light goes off. I forgot to take my temperature gun with me today but I felt the water coming from the tell tale and it felt pretty hot. Engine is peeing at idle and wot. I was wondering if maybe not enough? Can the impeller get weak? If so what do I look for while inspecting it? It’s a fresh water engine and that’s what I’m running it in.
Im going outside now to check the thermostat before pulling the lower unit. All the parts are less than a year old. Complete water pump etc. however I did run the engine in a tank while doing other work on it. This was before I was told to always use muffs. Could I have damaged the impeller with the exhaust water circulating ? Oh and if I had a plug fouling wouldn’t it be missing all the time instead of after wot for 5 minutes? Just trying to cover everything folks. Any help/guidance is greatly appreciated. Maybe my buddy SeaRider will see this.

 

[Douglasdzaster]

Hello everyone, Thought I had fixed this problem due to water getting in the cowling. That’s fixed and no water in there today.
when I run wot , after about 5 minutes the engine starts slowing down and the red warning light comes on. I let it idle about a minute and the light goes off. I forgot to take my temperature gun with me today but I felt the water coming from the tell tale and it felt pretty hot. Engine is peeing at idle and wot. I was wondering if maybe not enough? Can the impeller get weak? If so what do I look for while inspecting it? It’s a fresh water engine and that’s what I’m running it in.
Im going outside now to check the thermostat before pulling the lower unit. All the parts are less than a year old. Complete water pump etc. however I did run the engine in a tank while doing other work on it. This was before I was told to always use muffs. Could I have damaged the impeller with the exhaust water circulating ? Oh and if I had a plug fouling wouldn’t it be missing all the time instead of after wot for 5 minutes? Just trying to cover everything folks. Any help/guidance is greatly appreciated. Maybe my buddy SeaRider will see this.

UPDATE: Thermostat had a little gunk but cleaned right up. Tested it in a pot of water and it’s functioning. About to pull the lu. Can I flush water up the tube with a water hose or through the thermostat housing so that any debris will come out the tube? I don’t want to mess Up by guessing. Any one that wants to share their knowledge is greatly appreciated. Thanks

 

[Douglasdzaster]

UPDATE: Thermostat had a little gunk but cleaned right up. Tested it in a pot of water and it’s functioning. About to pull the lu. Can I flush water up the tube with a water hose or through the thermostat housing so that any debris will come out the tube? I don’t want to mess Up by guessing. Any one that wants to share their knowledge is greatly appreciated. Thanks

UPDATE: No reply’s to my post but will continue to update. Maybe it will help someone else out.
When I pulled the lower unit I found a couple of questions. I noticed the rubber piece that connects the water pump to the pickup tube wasn’t in the pump. I found it was slid about a foot up the tube. How did that happen?
Then I put the lu on the vise and noticed water coming from under the pump around the gaskets. So the pickup tube wasn’t correct and the pump was leaking. I’m hoping this explains the engine not cooling at wot. Waiting on a kit to come in on Tuesday and replace everything. Meanwhile with the lu off I’m going to blow some compressed air back through the pee hole. Remove the thermostat and flush through it with a water hose stuck in a piece of pool noodle to help with pressure and me not getting soaked.
Wish me luck. I’ll report my results.

 

[Faztbullet]

Sound like you found your problems....it should run perfectly fine in a tank as long as water level is above impeller. Muffs can hide problems as its forcing city pressure thru motor along with impeller flow.

 

[Douglasdzaster]

Sound like you found your problems....it should run perfectly fine in a tank as long as water level is above impeller. Muffs can hide problems as its forcing city pressure thru motor along with impeller flow.

Hey thanks for the reply. I found a washer in the break down that’s supposed to be on the tube above the water pump.Water pump kit came in The old gasket on the bottom housing left some remnants so I cleaned it up. Upon farther inspection it looks like the original 1992 part. I thought I’d remove it and clean it up since I have a new gasket for the bottom in the kit (at least that’s what I think the extra one is for).
It doesn’t want to move at all. I’m seeing some corrosion around the shaft area (pleas see pictures). Should I leave well enough alone or work on replacing it too which I believe means replacing the seals under it for the lu as well? Which are not leaking. The rest of the housing looks ok on top as far as the gasket sealing. I appreciate any advice before I open a can of worms. Thanks again for the reply sir.

 

[Douglasdzaster]

Hey thanks for the reply. I found a washer in the break down that’s supposed to be on the tube above the water pump.Water pump kit came in The old gasket on the bottom housing left some remnants so I cleaned it up. Upon farther inspection it looks like the original 1992 part. I thought I’d remove it and clean it up since I have a new gasket for the bottom in the kit (at least that’s what I think the extra one is for).
It doesn’t want to move at all. I’m seeing some corrosion around the shaft area (pleas see pictures). Should I leave well enough alone or work on replacing it too which I believe means replacing the seals under it for the lu as well? Which are not leaking. The rest of the housing looks ok on top as far as the gasket sealing. I appreciate any advice before I open a can of worms. Thanks again for the reply sir.

UPDATE: the housing cleaned up pretty good. It does have a little pitting so I’m thinking of using a gasket sealant that is none hardening. It’s between Permatex #3 aviation gasket sealant or the #2. I’ve used the #3 and it’s awesome stuff. But I read that it’s not as good on aluminum where it has to fill in any places. This was just a review I read and don’t know how they were applying it. These little pits aren’t that bad and I have never used the #2 but I know its not as thin as the #3.
I just finished cleaning the pump and made the final wipe after the acetone. I’ll let y’all know what I decide and how it works out.

 

[Douglasdzaster]

UPDATE: the housing cleaned up pretty good. It does have a little pitting so I’m thinking of using a gasket sealant that is none hardening. It’s between Permatex #3 aviation gasket sealant or the #2. I’ve used the #3 and it’s awesome stuff. But I read that it’s not as good on aluminum where it has to fill in any places. This was just a review I read and don’t know how they were applying it. These little pits aren’t that bad and I have never used the #2 but I know its not as thin as the #3.
I just finished cleaning the pump and made the final wipe after the acetone. I’ll let y’all know what I decide and how it works out.

Well I went with the #2 and used a tiny trowel. Also figured out the reason for the fail of the pump. The rubber piece that was slid up the pickup tube is actually supposed to be in the pump housing. Didn’t figure this out of course until after I had it together. Always fallow the breakdown in the manual and not off a parts site! I’ll let the sealant I used cure then remove the bolts and lift the housing enough to put it in place. There’s still supposed to be a gasket on the tube I’m waiting on to come in. Then hopefully I’m back on the water. Been some calm days and I hate having the boat down right now. I’m ready for some wot.

 

[Sea Rider]

Some issues,

-It's perfectly OK and safe to test, flush OB motors on muffs as long as you want provided that the water exiting the hose has good pessure and the ear muffs achieves a tight fit onto both water intakes for minimum water loss side of them. A motor should not be tested in a barrel for long time runs as will be cooling the motor with heated water, for that not to happen need to pour fresh water in and remove heated water out via the lower barrel as to maintain a proper colder water temp for longer testing purposes.

-While the lower leg has been disassembled, connect a water hose to the lower water intake tube, remove thermo, put cap back on, flush as long as you like, with removed thermo all the water passages will benefit passing fresh water through them, this procedure will not guaranteed to fully clean those water passages to immaculate clean cond when out of the box, just should remove some filth living in the passages.

-In a highly used/run motor you can't possibly check accurate temp readings with an IR Gun, for spot on accurate temp Comparisson purposes need to take a HP motor out of the box, put it on muffs, start the motor, warm it up for at least 10 + minutes at idle, neutral or geared forward, make 3 separate readings, at middle cylinder head, the area between the cylinder head and the flywheel and middle of the exhaust cover, note down on something all 3 temp readings for future reference to compare them against other same motor, if a motor is having overheating issues will see the huge temp diferrence between a motor with immaculate clean water passages factory delivered with and one at current use for long time periods, much worse if run on salt water.

-An issue nobody has taken into the least consideration is : If your motor counts with internal anodes located on maim internal water passage, expect to be clogged and that passage contributing to increment the overheat on the entire motor way more. How do I know, well I'm the only one here tearing crankases on frequently basis to manually clean internal water passages, on the last 4 restored motors all had internal clogged anodes with overheating issues.

If redoing the complete water pump will be proper time to redo a complete gear case's seals for peace of mind and avoid water intrusion and oil emulsification which is nada bueno. So, the water flooding the pan was not due to a faulty pan gasket ?

Happy Boating​

 

[Douglasdzaster]

Some issues,

-It's perfectly OK and safe to test, flush OB motors on muffs as long as you want provided that the water exiting the hose has good pessure and the ear muffs achieves a tight fit onto both water intakes for minimum water loss side of them. A motor should not be tested in a barrel for long time runs as will be cooling the motor with heated water, for that not to happen need to pour fresh water in and remove heated water out via the lower barrel as to maintain a proper colder water temp for longer testing purposes.

-While the lower leg has been disassembled, connect a water hose to the lower water intake tube, remove thermo, put cap back on, flush as long as you like, with removed thermo all the water passages will benefit passing fresh water through them, this procedure will not guaranteed to fully clean those water passages to immaculate clean cond when out of the box, just should remove some filth living in the passages.

-In a highly used/run motor you can't possibly check accurate temp readings with an IR Gun, for spot on accurate temp Comparisson purposes need to take a HP motor out of the box, put it on muffs, start the motor, warm it up for at least 10 + minutes at idle, neutral or geared forward, make 3 separate readings, at middle cylinder head, the area between the cylinder head and the flywheel and middle of the exhaust cover, note down on something all 3 temp readings for future reference to compare them against other same motor, if a motor is having overheating issues will see the huge temp diferrence between a motor with immaculate clean water passages factory delivered with and one at current use for long time periods, much worse if run on salt water.

-An issue nobody has taken into the least consideration is : If your motor counts with internal anodes located on maim internal water passage, expect to be clogged and that passage contributing to increment the overheat on the entire motor way more. How do I know, well I'm the only one here tearing crankases on frequently basis to manually clean internal water passages, on the last 4 restored motors all had internal clogged anodes with overheating issues.

If redoing the complete water pump will be proper time to redo a complete gear case's seals for peace of mind and avoid water intrusion and oil emulsification which is nada bueno. So, the water flooding the pan was not due to a faulty pan gasket ?

Happy Boating​

No the pan gasket holds water good. Lol I turned myself farther around so I could see the entire motor better while running wot. My transducer for my depth finder had broken and was kicking up a bunch of water and soaking the motor with a shower. It was epoxied on and didn’t break all the way so when I’d slow down it fell back into place and the depth finder worked fine. Lol I was also running without the bottom skirt on the motor so the water had bolt holes to get into as well. I found me a picnic area on shore and got out and removed the transducer and no more water. Haven’t shared me getting a new transducer with the admiral yet. I’d hoped to be able to cool it on the boat for a little while. I just got a new set of truck payments. Lol
By the way can you tell me how often the head gasket should need a new torquing? I know I need to replace since none of the other maintenance was kept up with before I got the motor. Probably the original gaskets judging by the engine paint on them.

 

[Douglasdzaster]

No the pan gasket holds water good. Lol I turned myself farther around so I could see the entire motor better while running wot. My transducer for my depth finder had broken and was kicking up a bunch of water and soaking the motor with a shower. It was epoxied on and didn’t break all the way so when I’d slow down it fell back into place and the depth finder worked fine. Lol I was also running without the bottom skirt on the motor so the water had bolt holes to get into as well. I found me a picnic area on shore and got out and removed the transducer and no more water. Haven’t shared me getting a new transducer with the admiral yet. I’d hoped to be able to cool it on the boat for a little while. I just got a new set of truck payments. Lol
By the way can you tell me how often the head gasket should need a new torquing? I know I need to replace since none of the other maintenance was kept up with before I got the motor. Probably the original gaskets judging by the engine paint on them.

Forgot to ask. When I hook the water hose up to the tube with the lu off where all should the water come out? Anywhere besides the tale tail?

 

[Faztbullet]

It will come out "pee" tube and exit out exhaust and idle reliefs. There is a water wall that comes down exhaust tube to cool it and dampen noise. Also cools top of impeller housing. and prop hub.

 

[Sea Rider]

When pan gaskets have not been re torqued to specs shortly after break end period ended, could end having any of these issues. Overheating and blowing the gasket's area that rests under the exhaust port, exhaust fumes exiting the lower powerhead and motor missing when running at high rpm, water flooding the pan, motor running louder than used to...​

This is a prime example of a pan gasket that was never re torqued tight back to specs from out of the box, exhaust heat has eaten up the entire exhaust side compared to a new one. Usually re torque the pan's gasket after first 5 run hours from a new install and a second re torque at next 5 run hours. At ten run hours will have seated perfectly on both mating surfaces.

Now that the pan's water intrusion and the water pump's lower rubber grommet has been sorted out and assume the motor is cooling right, go for the CRC decarbonizing process...

Happy Boating​

 

[Douglasdzaster]

When pan gaskets have not been re torqued to specs shortly after break end period ended, could end having any of these issues. Overheating and blowing the gasket's area that rests under the exhaust port, exhaust fumes exiting the lower powerhead and motor missing when running at high rpm, water flooding the pan, motor running louder than used to...​

View attachment 349155

This is a prime example of a pan gasket that was never re torqued tight back to specs from out of the box, exhaust heat has eaten up the entire exhaust side compared to a new one. Usually re torque the pan's gasket after first 5 run hours from a new install and a second re torque at next 5 run hours. At ten run hours will have seated perfectly on both mating surfaces.

Now that the pan's water intrusion and the water pump's lower rubber grommet has been sorted out and assume the motor is cooling right, go for the CRC decarbonizing process...

Happy Boating​

I had my can of CRC with me last time until this happened. I’m concerned now about how long it’s taking the last parts to come in for the water pickup tube. I’ve assembled the water pump waiting. I used a little marine grease in the cup for the impeller to install. Now it’s sitting without the grease being rinsed out. Wondering if I screwed up?

 

[Sea Rider]

Not an issue sitting dry, applying grease, love lube, olive oil is just to rotate CW the new impeller inside the liner (cup) once the water pump is working those lubricats will disappear with use.

Happy Boating​

 

[Douglasdzaster]

Not an issue sitting dry, applying grease, love lube, olive oil is just to rotate CW the new impeller inside the liner (cup) once the water pump is working those lubricats will disappear with use.

Happy Boating​

Well I finally got the parts and put everything back together the other day. Hoping I got the damper seal correct. Diagram shows it on the tube with a washer above and not coming out of the pump, it wouldn’t fit in the pump anyway . There’s another one in the pump that was missing as well as the damper and washer.
Put it on the muffs and it peed strong at first then seem to let up just a little I think when the thermostat opened maybe. Gave it a little rev one time and it definitely was stronger as the rpms increased.
Going to try and take it out tomorrow. Was hooking it up this evening to the truck and remembered everything expired in August. Oops! I got the tags for the boat just have to go get the trailer tags and my fishing license first thing in the morning. If she runs well I’ll do the decarbing. I’ll report back.

 

[Douglasdzaster]

Well I finally got the parts and put everything back together the other day. Hoping I got the damper seal correct. Diagram shows it on the tube with a washer above and not coming out of the pump, it wouldn’t fit in the pump anyway . There’s another one in the pump that was missing as well as the damper and washer.
Put it on the muffs and it peed strong at first then seem to let up just a little I think when the thermostat opened maybe. Gave it a little rev one time and it definitely was stronger as the rpms increased.
Going to try and take it out tomorrow. Was hooking it up this evening to the truck and remembered everything expired in August. Oops! I got the tags for the boat just have to go get the trailer tags and my fishing license first thing in the morning. If she runs well I’ll do the decarbing. I’ll report back.

Boat ran it’s best today! Absolutely no issues! I couldn’t be happier. I feel like all the work is finally paying off.I ran it more today than on any of the other outings. I tried to run it out of fuel but still have about a gallon left. It doesn’t use that much. I even circled the entire lake three times at wot without stopping. Found some new fishing territory I’ve been wanting to find.
I kicked myself in the pants though. I took everything I could possibly need. Tools , spare prop , extra filters ( normal stuff). Everything , but I forgot the dang can of CRC. Perfect day for it too. Hardly any other boats on the water and it was smooth as glass at times. Never did get more than a ripple on the water. Next week I won’t forget. I want to go back this weekend but I got two grandkids birthdays tomorrow and a brand new grandson we haven’t seen yet to go see Sunday.
I really appreciate all of the help and advise and wisdom that has helped me on this journey of bringing the boat and motor back to life. Especially those CARBURETORS that I almost declared dead when I first opened them up.
I know I’m not done yet with maintenance and learning. But it sure was a nice day today thanks to everyone’s help.