Re: [OMC-Boats] Some Thoughts on Justin's Cooling Issue

From: Lee Shuster <lks@...>
Date: Wed, 2 Sep 2009 07:57:26 -0600

Glad to hear you found the blockage with everyone and Ethan's help.
I scanned a factory flow diagram, yesterday but it was too large for

Maybe Phil can grab it and put it on the web?

I also included the factory text description of the details of the

On Sep 1, 2009, at 8:57 PM, Justin DeSantis wrote:

> Thanks for the advice Lee. I'm fresh from coming in from the boat.
> Still have 42 year old grease under my nails. I'm happy to say that I
> found the problem. I want to thank everyone for their input.
> Especially Ethan who's been shooting me nuggets of advice off list. So
> a big public thanks to him. He was a big help. Ok, so in case anyone
> else goes through this, I'll explain what I did and what found as
> best I can in the hopes it may help others. Warning. This is going to
> get long, and it might get confusing. It's hard to explain and I was
> too focused to take pictures to illustrate.
> Ok, to review, my issue was no water flow through the port side hose
> from the intermediate to the manifold. Removing the hose allowed the
> water to flow, so my problem was obviously past the intermediate. And
> since the problem was the same on the garden hose or when running in a
> tub, I was able to eliminate the impeller as the culprit and rule out
> poor water pressure from my garden hose.
> So my first thought, and Ethan's suggested place to look was the
> manifold. Seemed obvious. Problem was, with both caps off the manifold
> on the port side, I passed a straightened coat hanger through the
> manifold water jackets easily. At this point the problem should have
> been obvious, but my lack of knowing how the system worked prevented
> me from seeing it. But that comes later.
> So I buttoned it all up and tried again. Same problem. Ok, now I took
> off the covers on each side of the tilt pivot to look for clogs or
> extra grease. Nothing. At this point, Ethan sent me a suggestion.
> Start pulling off lines and blowing through them to see where air
> wasn't moving. On the port side, one hose was blocked. On the
> starboard, both side allowed me to blow air freely. Ok, now we're
> getting somewhere. I knew the problem wasn't in the manifolds or the
> intermediate. I also know it wasn't in the thermostat housing. That
> only leave one place, the elbow between the manifold and exhaust.
> So I removed both so I could compare them to each other. Once I had
> them off, I finally got a real good idea of how the cooling system
> works, and started making progress. If you look at the elbows, they
> have 3 water jackets. But the manifolds have two. The cavity in the
> elbow that the water enters, meets a dead end at the manifold. So
> there is a passage in there to route the water into the other water
> jacket. I hope this is making sense. So, after looking at the other
> elbow, I figured out where the passage was. Some tapping to loosen the
> carbon and some poking with a straightened coat hanger and a little
> bit of air from the compressor and it was opened up. Flowing freely.
> I bolted everything back together and lo and behold, water flowing in
> both clear tubes! I can't tell you the relief I felt. One minor
> problem left. I have a leak where the elbow on the starboard side
> meets the manifold. So tomorrow I have to make a new gasket, no
> biggie. But it does raise one new question. I was able to find the
> leak because it was on the outside. But what if it was leaking into
> the manifold? Once I bolt it all together for good, is there a way
> that I can be sure it's not leaking into the manifolds? Cause I could
> see that causing big issues. Is checking the oil for water the only
> way? Thoughts?
> Thank you all for your help so far. You've all been a great help.
> On Tue, Sep 1, 2009 at 8:20 PM, Lee Shuster<lks@...> wrote:
>> After thinking about your cooling issue some more today I'd offer the
>> following troubleshooting tips:
>> Water flow has an analogy with electrical current flow. In USAF
>> electronics
>> troubleshooting, we were taught to always break the circuit or path
>> in
>> roughly half. Make a check, verify and move "up" or down the path.
>> Seems like that same approach can logically be applied to
>> troubleshoot
>> cooling flow?
>> It seems you have described a situation where your tell-tale
>> (pisser) is
>> barely dribbling, right? One pivot end-cap (Port) apparently shows
>> signs of
>> water, while the Starboard side end-cap is relatively dry.
>> I wonder if you could partially restrict or block flow on the
>> "good" side
>> and see if the flow increases or blows through any obstruction on
>> the weak
>> side?
>> You could pull of the top cover of the intermediate housing, where
>> the hoses
>> connect to the exhaust elbow and look to see if there are passage
>> obstructions between there and back to the pivot point?
>> As mentioned before there is the distinct possible of too much grease
>> clogging up the trunion/pivot water passages, where the
>> intermediate and
>> vertical drives mate up.
>> There could also be an obstruction within one side of the vertical
>> drive
>> (upper gearcase), but that seems unlikely. Another real possibility
>> is the
>> impeller pick up tube and pickup screen mesh, which may be partially
>> clogged?
>> Further down stream you can check both elbows for obstructs. Just
>> remember
>> both the elbow and the manifold(s) have three separate passages: 1)
>> Water
>> supply, 2) Water return, and 3) exhaust gas.
>> Your problem seems to be on the supply side, before even getting to
>> the
>> starboard exhaust elbow. The motor seems to be happy with a reduced
>> supply,
>> but then it's not doing much but idling so far.
>> Lee
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Received on Wednesday, 2 September 2009

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