First Impeller Job, 1987 OMC Cobra Standard

[Lou C]

Re: First Impeller Job, 1987 OMC Cobra Standard

getting that o-ring to seal around the impeller housing can be a little tricky but using the OMC gasket stealer I've never had a problem with them and I've replaced mine 3-4 times over the 8 years I've had the boat...here's what mine look like one is the one I took out and the other is the new one...

 

[DavidW2009]

Re: First Impeller Job, 1987 OMC Cobra Standard

Lou C,

Thanks for posting the photo.

Did you notice one of the blades in your old housing is pointing backwards?

I'm trying to figure out what causes that and if it's normal.



superbenk,

I hope your assumption is right, and these blades are self-correcting.

 

[DavidW2009]

Re: First Impeller Job, 1987 OMC Cobra Standard

I think I may have answered my own question.

Relooking at the old impeller (the one found to have some backwards blades when housing was removed) under a magnifying glass, I found that there were no wear marks on the trailing edge of the blades.

There were plenty of wear marks on the leading edge of all the blades.

I took some photos to show what I saw.

This means that the blades are self-correcting when it comes to direction. If any of the blades had run facing the wrong way, there would have been wear marks on the wrong edge. There weren't.

The photo on the left shows the leading edges are worn away and flat. (In this view, the impeller rotates CW, so wear should be on the right face of each blade)

The middle photo shows the wear marks on the leading edge.

The photo on the right shows no wear marks on the trailing edge. It's still round.

 

[DavidW2009]

Re: First Impeller Job, 1987 OMC Cobra Standard

......David, I see what you mean about the avaition sealer being a sticky mess to work with, but if you apply it & wait 10 minutes, it gets tacky & is easy to work with at that point.

A few comments:

1. Permatex Aviation Gasket Sealer DOES harden. I used it for (20) years on various air cooled auto & racing engines. And when it hardens to aluminum, it's a pain to get off. It probably will not harden in your application.

2. For clean up, I use a product called "Totally Awesome" from Dollar General Store. $1.00. The stuff actually works on that Permatex (and a lot of other things, too).

3. I'm going to stick with an RTV/silicone sealer because I want the housing to come off without much trouble. I don't believe I'm going to have trouble with leaking with it.

Thanks for the input on this thread, Brad. BTW, "Erie" refers to Lake Erie in your username?

 

[Four Winns Erie]

Re: First Impeller Job, 1987 OMC Cobra Standard

Your welcome David, & yes Lake Erie, where I boat & Erie, Pennsylvania where I live in the suburbs.

 

[Lou C]

Re: First Impeller Job, 1987 OMC Cobra Standard

I had heard that the OMC gasket sealer was the same as Permatex Aviation sealer...but I can say that in as long as a 2-3 year span...it doesn't harden..it will get more firm...but a thermo housing I installed 2-3 years earlier came right off...bolts with the sealer on them came right out...and the same with the impeller housing. SO maybe they are not the same in any case I'll keep using the OMC/Bombardier stuff...you can get it at any place that sells Evinrude outboards and I bet you can order it on line too...a can lasts for a long time...

 

[DavidW2009]

Re: First Impeller Job, 1987 OMC Cobra Standard

Brad,

I've been there many times, Erie, PA.

My father (British) was a sailor on the lake boats (iron ore freighters) in the 1920's up until WW2.

We boated on Lake Erie in the 50's and 60's. We lived one block from the lake and spent our summers on or in it. My dad kept his boats at Fairport Harbour and later at Mentor Lagoons Marina (rented a lot with a dock).

I do miss boating on Lake Erie. Nice beaches along the south shore.

 

[DavidW2009]

Re: First Impeller Job, 1987 OMC Cobra Standard

I finally got a chance this evening to run a raw water pump test on the Cobra.

While on the muffs, and running, I disconnected the water line, coming from the lower end, at the thermostat housing. I had a pail handy. A solid stream of water shot out at least 6-7" into the pail. I had to shut the engine off because it filled the pail very quickly.

I believe the lower end impeller is working just fine. (I forgot to check to see if the engine rotates a few degrees CCW when it's shut off. Have to do that next time.)

I now wish I had tested the old impeller this way, and compared it with the new.