Stump the chump! Or, F300 Water Pump housing & the mystery of the missing groove.

[oldmako69]

You may recall that I had an engine overheat at high power settings due to low water flow when operating above a certain RPM. Let's call it 3500 for argument's sake. You may also recall that I found about two inches of O ring seal missing. I surmised that this missing O ring allowed just enough high-pressure water to bypass the water tube leading to the powerhead.

So I ordered a new O ring. Yam part.

Here's the daily dilemma. The water pump housing has a small groove machined into its base which holds that O ring in place. Except that it doesn't go all around the circumference of the housing. There is a section where that groove pushes tight toward the center of the housing and the groove "loses" its ability to hold the ring. It's no longer a groove. I called the local YAM dealership and asked the parts guy to take a peek at a water pump housing. I was hoping to hear him say that my housing was bad. Nope. His caps have the same (incomplete) groove.

The O ring is too tight for the "groove" and pulls out, particularly where there is no groove. Oddly enough, this is not where my ring was missing.

So what the hell? I am unable to get the ring to sit still long enough to get the cover back on. Has that O ring shrunk? Can I yank on it and try and stretch it a tiny bit? Grease will not hold it in place. Melted Sugar Babies will not hold it in place. An act of God won't hold it in place. A groove would hold in in place, a 360-degree groove but the wise engineers at YAM decided to eliminate about 25 percent of it.

Learn me WTFO.

[TownsendsFJR1300]

Perhaps some Yamabond sealer in the "trouble area" first and let it set up fully.
Then, see if it'll go around the rest of the housing..

[oldmako69]

Excellent suggestion. Thanks.

[DennisG01]

Do you happen to have a picture of the area? I'd just like to see it!

Here's a thought - but no idea if it will work. For the VST o-ring, it's sometimes necessary to put the o-ring in the freezer for an hour because it can be "just a bit" too big. It sounds like you have the opposite problem. What if you gently heated it up with a heat gun?

[Keithbaja]

Any good auto parts store should carry "Gaskacinch" been using for over 40 yes. Works great. Specially on that rubber w/p seal your dealing with..

[oldmako69]

1. This site won't accept a picture from my iPhone 8. The wrong format or something and I have no idea how to change it.

2. I am using gasket glue.

3. Will try stretching it gently and using Townsends suggestion in post number 2. Adding a bit of heat might also do the trick.

4. Why in the hell did Yam make the groove like this? There has got to be a reason.

5. I suppose that it's possible that the O ring I bought from Boats.net is old as hell and shrunk a bit. I say this because I remanned these pumps last fall and I don't recall having this problem then.

[panasonic]

Put the oring in a coffee cup of boiling water. I use hylomar gasket maker to glue the oring on the housing.

[TownsendsFJR1300]

Any updates?

[oldmako69]

I was waiting on some other parts to get it all done at once. So, parts showed up but I have yet to perform the work. I'll let you know.

[oldmako69]

Stumbled across this today.....

Here's the fix. I had DEFECTIVE water pump housing. This was a YAM part purchased online and came in a YAM box. I took it to my local YAM dealer and he just smiled. He had already run across this issue. According to him, my housing was a knock-off and not a legit YAM part. He said the YAM parts are so expensive that fake (bogus) parts were showing up even at the dealership. He showed me that a proper housing is a TINY bit shorter than my part and that the steel impeller housing actually sits proud of the bottom of the plastic and that housing holds that O ring in place.

Added this to help the next guy. Maybe.

[DennisG01]

Stumbled across this today.....

Here's the fix. I had DEFECTIVE water pump housing. This was a YAM part purchased online and came in a YAM box. I took it to my local YAM dealer and he just smiled. He had already run across this issue. According to him, my housing was a knock-off and not a legit YAM part. He said the YAM parts are so expensive that fake (bogus) parts were showing up even at the dealership. He showed me that a proper housing is a TINY bit shorter than my part and that the steel impeller housing actually sits proud of the bottom of the plastic and that housing holds that O ring in place.

Added this to help the next guy. Maybe.

Definitely!!! Thanks for the update!

[99yam40]

Stumbled across this today.....

Here's the fix. I had DEFECTIVE water pump housing. This was a YAM part purchased online and came in a YAM box. I took it to my local YAM dealer and he just smiled. He had already run across this issue. According to him, my housing was a knock-off and not a legit YAM part. He said the YAM parts are so expensive that fake (bogus) parts were showing up even at the dealership. He showed me that a proper housing is a TINY bit shorter than my part and that the steel impeller housing actually sits proud of the bottom of the plastic and that housing holds that O ring in place.

Added this to help the next guy. Maybe.

what online place did you buy this fake part from?
we all need to know to keep from buying from them.
did you contact them and complain?
doing nothing is not the correct thing.

[oldmako69]

I'm afraid that I don't recall, but I BELIEVE that it was Boats.net.

What really got my attention was when the parts guy at Norfolk Marine knew INSTANTLY what was wrong as he had seen it already. And he complained that they received bogus parts as well. That last part had me scratching my head.