1988 Yamaha ELG 40 , trying to change water pump/impeller

[tmorriss]

I'm having a problem trying to remove the lower unit so I can change out the pump. Got all 5 bolts out and separated the lower unit. Problem is it only comes about an inch apart, and then it doesn't want to go any further. I've done some review in the service manual, and watched some videos of others doing this and it looked pretty straight forward. I did not see where it indicated I had to disconnect anything else. Just remove the 5 bolts and wiggle the lower unit out.
It's not coming and I don't want to force it and break something.

Has anyone done this on this model? I must be missing something.

Thanks in advance for any advice.

 

[99yam40]

I believe that old of a motor would be a push pull shift shaft not a splined shaft that twists.
so you would need to loosen a lock nut and unscrew the barrel nut on the shift shaft to separate it

 

[boscoe99]

I am seeing 6 bolts.

 

[99yam40]

If a bolt was still holding it ,I do not think the lower unit would move 1 " apart like he mentioned


I still think he has to disconnect the shift shaft

 

[tmorriss]

I'm almost 100% there are only 5 bolts here(but having never done this, I cannot be sure). I DO see what Boscoe99 is referring to in the parts schematic, but I think that '6th' bolt is the trim tab bolt, and I had removed that also. So 99yam40, I think maybe you got it. I do see this 'tube', with a lock and barrel nut connection on the front side that looks like the 'shift shaft' you mention. I'll take another stab at it and disconnect that. Thanks for the info folks. I'll let you know how I make out

 

[tmorriss]

Well, I got it apart and it was the shift shaft. Unfortunately the old impeller(was the original, based on the bolts had no type of wrench marks etc), had two fins with chunks out So they are in the engine 'somewhere'

Aside from that, I have another weird thing now. THe impeller looks really out of line with the gasket and housing. I know that you are supposed to 'fold' the fins into the housing, but they are no where symmetrical ?
Checks these pics out
First one is the old impeller with the two busted fins at about 10 and 2 oclock

THe second two are the new impeller installed, See how it overhangs the gasket significantly on the front,(but not on the back side.
This can't be normal? Can it? I double checked the parts and it's the OEM Yamaha package and it's the right part number. Bought it off Crowley marine and even confirmed part number with local dealer before I ordered it.
I know the fins will fold in, but wth? This means they will ALWAYS be more bent and in contact with housing on the front side. Is it possible this is by design to allow for improved water flow?

 

[99yam40]

it is by design

 

[tmorriss]

Thank you very much.

 

[racerone]

They have to be offset.-----That is how the space between vanes changes for the pump to work.

 

[tmorriss]

Ok...so on to the next task. Finding and removing those pieces of impeller. So far I've tried
-back flushing from from the tell tale hose fitting on the exhaust cover
-back flushing from the thermostat housing(after removed thermostat and 'hoped' to find pieces there, but no luck
Then, I tried air and vaccum
Hooked up a shop vac to the water tube where it leaves the intermediate housing while at the same time blowing compressed air through from first the tell tale host fitting and then the thermostat housing.

I have not found any pieces of the old impeller.
When I back flushed with water, there were a couple small black flecks in the water, but just a few and very tiny, so I don't even think there were from the impeller.

I really don't want to take the engine any further apart.

Is it possible these pieces just got chewed up over the years and are gone?

This was ALL original parts. This have never been taken apart that I can see

Any other suggestions on finding these and getting them out? I'm out of ideas

 

[99yam40]

does the motor have an overheating problem?
if it still does then you will need to open it up farther to see what is blocked

 

[tmorriss]

I've owned the boat for about 12 years. in that time, I've had the buzzer go off maybe 4 or 5 times. I shut the engine off immediately, and in a couple minutes, I start up and go and no buzzer. On the other hand, I'll trolled literally all day long many times, and it's never gone off. So given that, I would not necessarily consider that overheating. The plugs have always looked good. But anyway.... the buzzer is what got me looking and I read the impeller should be changed every few years, so I thought maybe the buzzer was caused by the impeller. So this was really just a preventative measure I was taking(until I found the impeller missing pieces)

 

[99yam40]

well then run it and see how it goes.
if no overheating then no reason to open it up more

 

[tmorriss]

Thx for the input. That is what I'm thinking also.

 

[tmorriss]

Ok, one more question on this. As I said, this is 1988 ELG40. I have 'a' Yamaha outboard service manual that supposedly covers 1984-1996 2hp - 250hp. I downloaded this years ago, and I can't remember where from, but I 'thought' it was THE Yamaha published service manual. Anyway, The manual calls for torquing the bolts to fasten the Lower unit to the Intermediate at 29 ft lbs. My motor has 5 bolts total. The shorter, bigger ones(the 14mm) are two on each side, and the long smaller one(the 12mm) is the one under the trim tab. I have a torque wrench and I torqued the 14mm ones to 29 f lbs. But as I was doing the smaller one (the 12 mm) under the trim tab down, I got nervous because it just did not seem to be feeling right. SO I took it out and checked it and didn't see any threads coming out, so I put it back in again and started torquing it again, starting at 15 and going in 1lb increments. I chickened out and stopped at 19 because it just 'seemed' that it was tight and didn't seem to be getting harder to tighten really.
I thought 29 was too much for that skinny bolt initially, but now I'm wondering if this manual I have is not completely accurate because it's not SPECIFIC to my motor.

Can someone confirm what the torque is supposed to be on that 5th bolt under the trim tab on this motor perhaps?
Thx in advanceh

 

[tmorriss]

I found a 'generic' torque chart for the size/len bolt that calls for 8-12nm. So I took it out, cleaned, re loctite and torqued it to 8nm

 

[racerone]

The 29 FT-LBS sounds high.

 

[tmorriss]

Yes. Fortunately I don't think I damaged anything.

 

[99yam40]

I never torque those, just tighten up where it feels good to me.
but I was an automotive tech in an earlier life.

I have never seen a Yanaha manual that covered all those HP motors before, so I think it is an aftermarket manual you have

 

[maineiac5586]

Did you pull the flat impeller plate? I just did a pump on a yamaha 8 hp 4 stroke and all the blades were off the impeller. I lifted the impeller plate and found all 6 fins.