Wrong impellar?

[Muddyjeep810]

Hi guys. So a little back story....

I bought this boat a couple weeks ago. This is my first boat in 25 years. I am very mechanically inclined and if it runs, I can usually fix it. Engines anyway. Everything below in an outboard engine I am a complete amateur and learning as I go along. The previous owner swore up and down it ran good. It hasn't. At all.

The first problem was really high idle on muffs. It would rev so high I would just shut it right off so I didn't damage anything. So I put it in the water. Barely started and when it did it stalled going into gear. It was hard to keep it running even. The only way to keep it running was to feather the cold start throttle lever up until it reached max and then the engine would run.

So I brought it home and did a compression test. I think the compression is acceptable.

Cylinder 1 - 120
Cylinder 2 - 105
Cylinder 3 - 110

Not the greatest but the motor is over 40 years old and I don't feel those compression numbers would cause my issues. So next step was the carbs. I rebuilt all three carbs. Added an in-line fuel filter and new plugs. It fired right up and idled ok even though it seemed to be missing just a little bit still. Definitely not smooth running but it mantained an idle and when I shifted into gear (on the muffs) it didn't even hesitate even when I throttled up. I haven't checked the timing or ignition yet.

Anyway, when it started it was shooting a stream of water out of the (what I assume to be) drain hole in the front of the engine right on top of the lower unit. Like not just a dribble, but a stream of water shooting out two feet from the hole.

I started digging and I learned that while this may not be a super huge problem I want to know what is causing it and if I can eliminate it. I pulled the lower unit and took a peek at the water pump. The previous owner said the water pump had just been replaced. It does look brand new, but from everything I am reading and seeing a good water pump impeller should have straight fins. This impeller looks like it is wayyyyy too big for the casing it is in.

Can I borrow some of the infinite wisdom on here for some guidance here? What could be causing the stream of water out of the lower unit? Water pump not aligned on the o-ring correctly?

Thanks in advance!

 

[dwco5051]

That is the way they look in the pump housing. They are positive displacement pumps. Note that the axis of the pump is not in the center of the housing. The rubber vanes fill with water on the intake side and squeeze it out on the discharge side as the vanes are defected in the housing. From what I see in the picture that is a good impeller.

 

[racerone]

Looks good to me.----Take the impeller out.----If new the vanes will go straight.----And that water shooting out is normal.----A 60 / 70 HP model #is ?

 

[F_R]

X2 on the water squirt. That is a drain hole and totally normal. The water at that point has already gone through the powerhead and is heading back to the sea anyway.

Check that motor very carefully for possible water ingestion into the cylinders. That could be the reason for lousy running and engine damage (low compression).

 

[Muddyjeep810]

X2 on the water squirt. That is a drain hole and totally normal. The water at that point has already gone through the powerhead and is heading back to the sea anyway.

Check that motor very carefully for possible water ingestion into the cylinders. That could be the reason for lousy running and engine damage (low compression).

How might be the best way to check for water intrusion? Just inspect all the Gaskets?

 

[racerone]

Model # is required first !

 

[Muddyjeep810]

Model # is required first !

• Model 70EL77S

 

[flyingscott]

Look at the spark plugs if any are shiny clean that is a good sign of water intrusion. Those motors are known for the exhaust gaskets leaking.

 

[Muddyjeep810]

Look at the spark plugs if any are shiny clean that is a good sign of water intrusion. Those motors are known for the exhaust gaskets leaking.

I just bought new plugs so they are obviously shiny and clean. The old plugs definitely were not shiny and clean . They were all black and nasty. The carbs were not in good shape before I rebuilt them.

I will get a better indication using this method of diagnosis once I run it in the water a bit. Hoping to take it out tomorrow. I'm replacing the shift rod and driveshaft seals today in the hopes of taming a lower unit water intrusion.

I have a bad exhaust seal. There was obvious milky lube running down from the driveshaft seals when I laid the lower unit down lon the bench. I'm thinking the bad exhaust seal didn't help with the leaking driveshaft seals.

 

[Muddyjeep810]

Look at the spark plugs if any are shiny clean that is a good sign of water intrusion. Those motors are known for the exhaust gaskets leaking.

When I pulled the new plugs today to rotate the flywheel when bolting the lower unit on I got some very bad news. All three are wet and milky. From everything I've read that means either a bad head gasket, a bad exhaust gasket, or both. Previous owner said the engine did overheat prior to the new water pump. Needless to say my enthusiasm for this motor is draining daily. I like fixing stuff, but damn do I really have to fix EVERYTHING on this motor???