1980s Yamaha/Mariner 2hp 2B Cooling Water Circulation

[chrisparr]

Hello all,

I ran my outboard for the first time the other week and noticed there wasn't any water coming out of the exhaust port on the leg just by the mounting bracket. I've seen many videos and comments on this forum that you should see water there.

So I've taken it apart and boy were the channels in the exhaust plate (if that what it's called?) between the leg and power head clogged up. Cleaned all of this out, and reassembled with new impeller and gaskets. Started it up today and still no water exiting the port.

Hmmm. So I broke this down Pulled the power head off, stuck the leg is a wheelie bin full of water with a drill connected to the drive shaft and it does pump water up the pipe. A steady flow.

I then wondered if it was the port clogged up. I can feel exhaust gas exit, but you never know, so I stuck the hose pipe down the leg intending to fill it up to see if water flowed..... the only problems is it didn't fill up enough to reach the port. There is ample room for water to flow out of the leg above the gearbox at the bottom of the leg. I'm pretty sure the engine can't pump water at a greater rate than the hose, so I wouldn't expect to see water exit at the port.... but why do I see videos of this and people commenting that we should see water at the port.

Confused. What I'm going to do next is take the power head and put water manually down where it would be pumped in and see if it flows out where it should without issue. if that is the case I think I can put it back together and I'm good.

I'm just very confused as to why everyone else's Yamaha/Mariner 2B that I've seen in video's behaves differently.

Any thoughts?

 

[VicS]

You would only normally see a few droplets or a mist blown out of the relief port. Most of the cooling water and exhaust gas leaves via the outlet above the prop

You say you cleaned the water passages between the exhaust housing and the power head but did you take the cylinder head off and clean the passages in the power head itself. If not maybe that is also choked up resulting in a relatively low water flow through it

 

[steve66]

Water galleries are a pain in the backside. As Vic correctly states you may need to completely strip and clean. Make sure the water pipe grommet is ok where it enters the water pump housing.
Once you get it somewhere near i advise replacing the two powerhead to leg gaskets and head gasket if you remove it

 

[chrisparr]

The water pipe grommet at the top of the water pump housing is new and I've tested the pump is ok (comes up to the power head fine).

My theories aside about how much water can build up in the leg, I've cried to manually put water into the intake on the power head to see if it would exit at the outlet, and it does not. At least not under gravity (I have no setup to force water in there under pressure).

I'll take the cylinder head off and clean in there to make sure.

Thanks for the input guys, and thanks for confirming my thoughts about seeing water at the relief port.

 

[chrisparr]

So took the head off and sure enough there's lots of salt build up.


Where the water exits the head is quite hard to get at and was blocked solid. Best thing I found was to pour boiling water in there and eventually it unclogged and the salt cleared away.

Oh and yes, those are two bolts that snapped off when unbolting the head (bottom two)

Oh well, at least when it's back together I know water will be circulating correctly.

 

[mulla]

Very interesting thread, have you gotten it all back together?
I also have a mariner 2m 6a1 from -89.

When I ran it in a bucket after a fresh impeller change it did squirt water from the exhaust relief port, not a steady stream but since it doesn't have a telltale you should not expect more.

When running it on the water under 3/4 gas for a minute or so I did notice that the engine got quite hot to the touch so I'm also thinking of cleaning the water galleries.
I'm guessing that you replaced the head gasket but did you replace the three gaskets/guides between the leg and the powerhead or where they reusable?
I'm somewhat conflicted since I only spent 40£ on the motor and a complete gasket set is about 30£

 

[chrisparr]

Yes, it all went back together and runs fine.

I can see the difference in the amount of water that squirts out. Like you say, not a steady stream but clearly enough to show no blockages.

I did have to replace all the gaskets. The workshop manual states the upper gasket between the exhaust plate and the power unit should have gasket sealant. The last person had used it and it meant I couldn't get the gasket off in one piece. I also used sealant when replacing it.

I also replaced everything else (impeller, oil seals etc). You are right that the cost can mount up. I think I spent over 100 which may seem like a lot given these seem to go for between £175 and £300, but unless you have proof that these jobs have been done, you are probably going to have to do them soon with a second hand motor.

Apart from the issue with salt build up, they seem to be a bullet proof little motor. I'm just making a point to flush it through with fresh water when I can.

 

[mulla]

Yes, it all went back together and runs fine.

I can see the difference in the amount of water that squirts out. Like you say, not a steady stream but clearly enough to show no blockages.

I did have to replace all the gaskets. The workshop manual states the upper gasket between the exhaust plate and the power unit should have gasket sealant. The last person had used it and it meant I couldn't get the gasket off in one piece. I also used sealant when replacing it.

I also replaced everything else (impeller, oil seals etc). You are right that the cost can mount up. I think I spent over 100 which may seem like a lot given these seem to go for between £175 and £300, but unless you have proof that these jobs have been done, you are probably going to have to do them soon with a second hand motor.

Apart from the issue with salt build up, they seem to be a bullet proof little motor. I'm just making a point to flush it through with fresh water when I can.

You have a workshop manual? ?
Where did you find it and do you mind sharing? I've been scouring the internet but haven't found more than the exploded drawings and the generic owners manual.

I'm thinking of removing the cylinder head to see how bad it is and take it from there since the head gasket isn't to expensive

 

[chrisparr]

You have a workshop manual? ?
Where did you find it and do you mind sharing? I've been scouring the internet but haven't found more than the exploded drawings and the generic owners manual.

I'm thinking of removing the cylinder head to see how bad it is and take it from there since the head gasket isn't to expensive

It came with the engine which came with the boat

It's not for my exact version, it's for a newer model (I think 1986 onwards) which has oil seals in different places, a different (taller) impeller housing, and a different gasket arrangement on the gearbox, but it's still a good reference.

If you are getting a good squirt of water out of the exhaust part every 1 to 2 seconds then your head may not be so blocked up, but unless it's only every been run in fresh water I can't imagine there isn't any build up in there.

If you are going to do the head just make sure you give the bolts on the head 1) a good soaking in penetrating fluid, and 2) when you think they've had enough, repeat that again.

I didn't do step 2 and snapped the head off two of them. I managed to extract one using heat, but the other wouldn't budge and I snapped it again level with the block surface. Ended up drilling it out and re-tapping. Couldn't get a centre very well on the bolt and there was a 50/50 chance I'd wreck it, but thankfully I managed and it's back together and running.

 

[mulla]

Went ahead and separated the leg and the motor today, there was some salt build-up but it wasn't completely blocked.
With the drive leg of I think I can access and clean all channels except the one going around the cylinder, I'm probably going to try and pour some vinegar into it to see if it cleans out.

Is the channel that goes around the cylinder connected to the outlet that is circled in red, and are these the only inlet/outlet ports in the block? If it is then I should be good filling it with vinegar right?

Also, does anyone know what the hose that is circled in green does? It says that it's a drain but I can't understand what it's draining, cooling water?

 

[VicS]

Went ahead and separated the leg and the motor today, there was some salt build-up but it wasn't completely blocked.
With the drive leg of I think I can access and clean all channels except the one going around the cylinder, I'm probably going to try and pour some vinegar into it to see if it cleans out.

Is the channel that goes around the cylinder connected to the outlet that is circled in red, and are these the only inlet/outlet ports in the block? If it is then I should be good filling it with vinegar right?

Also, does anyone know what the hose that is circled in green does? It says that it's a drain but I can't understand what it's draining, cooling water?

ITYWF that the hose is an oil drain

I think you may have the water circulation the wrong way round ???

It should be easy enough to remove the cylinder head to clean our the waterways round the block and the head
If you are going to just acid clean it use something stronger and more concentrated than vinegar. Acetic acid is a very weak acid vinegar only contains about 5%.
A sulfamic acid based descaler would be my first choice
followed by a lactic acid or citric acid based one
.
.
.
vinegar would be at the bottom of my list.

 

[chrisparr]

Correct, water goes in through the slot circled in blue, circulates around the cylinder, and comes out the hole circled in red. As VicS said, the pipes circled in green are nothing to do with water circulation.

The outlet from the cylinder is quite small, goes through 90 degrees and down to that hole.