1980 Evinrude 7.5hp with no overboard indicator stream.

[Pappy]

Just an FYi or to help someone out..........
A customer brought me a 1980 Evinrude 7.5hp in gorgeous visual condition. Very low hour engine.
He had just purchased it a couple months ago and I was the 3rd (and last) to look at it.
Complaint was no overboard indicator stream.
First "mechanic" put a pump in it and pronounced it repaired.
Second one put a pump in it and told the customer he removed a restriction...and pronounced it repaired.
My labor rate is 96/hr. so I am usually the last to get these engines that have been previously worked on.
Started the engine in the tank and verified no water stream. Blew out the indicator hose even though it had exhaust gases coming out freely.
Pulled the thermostat cover and started the engine to verify water was not filling the block. It was not. Exhaust gases only.
Pulled the powerhead.
Was prepared to pull the exhaust cover and/or the cylinder head if necessary.
Pulled the exhaust tube off the bottom of the powerhead and found that the upper water tube grommet was melted and shut off. Very similar to the issues I see with the 9.9-15hp engines. A simple replacement grommet and a powerhead base gasket is all that is necessary.

Photo showing the upper tube grommet, melted and restricting water flow.



And a photo for the heck of it showing whats left of the flow from a solvent hose attached to the other end of the water tube.



Hope this is of some help to someone along the way.

 

[CedarRiverScooter]

Not good for the reputation of the guys who didn't bother to water test!

What do you think caused the grommet to disintegrate? Old age?

 

[Johnny]

Pap - that right there would drive me stupid nuts trying to find the problem !!!
could it occur in larger pre-1980 OMC motors such as a 25-35hp ?
I already had the emotional meltdown on the stupid 25hp diverters.

Thank You for sharing !

 

[CMOS]

Nice post Pappy.


CMOS

 

[dkonrai]

Not good for the reputation of the guys who didn't bother to water test!

What do you think caused the grommet to disintegrate? Old age?

Yup old age. Seen this with older mercury motors too.
I will use a 3/8 clear hose to check water flow before installing a lower unit. I just put the hose on the water tube. Takes a second to make sure water passages are clear.

Sent from my LG-M210 using Tapatalk

 

[nccatfisher]

Not good for the reputation of the guys who didn't bother to water test!

What do you think caused the grommet to disintegrate? Old age?

I am going to go with heat from original water pump going out.

 

[timsmcm]

I'm with pappy. Any old motor (omc) small series I will look at the motor parts breakdown and see if it has water tube gromets. If so I try to talk customers into changing them out. But I have to tell you, most won't do it. I don't get it. There is no way I want to be stuck on a big lake (in the middle) with only a paddle. And there is also the chance of the dreaded toasted motor. Yech.

 

[Pappy]

Sometimes I wish these engines could talk........
There were no normal tell-tale signs of an overheat on the engine.
I know from experience that the 9.9-15hp grommets fail from heat distortion. I made a similar post a few months ago with photos of that.
This is the first I have seen on this series of engine though so I thought it was noteworthy.
If the replacement grommet sticks well above the top of the water tube like the 9.9-15hp does I will trim the excess so it cannot repeat the failure.

Here is a pic of one of the 9.9-15hp grommet failures



And the 7.5hp

 

[Pappy]

After the parts came in today I installed the new grommet.
There is a visible lip above the exhaust casting flange surface.



The grommet cannot move on the water tube. It is held in place by the flange on the water tube/groove in the grommet.
So, I cut it flush with the surface.