7.4 Bravo 1 flush, but no water from exhaust

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stellardog

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Feb 20, 2008
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I have a 28' 1988 Wellcraft Antigua w/ 7.4 Bravo 1 454, which keeps cool when I run it in the water, but when I try to flush it on the trailer, I never get water out of the exhaust. I havn't owned a boat for 15 years and have forgotten, would the thermostat be preventing the flow until it reaches 160 degrees or something? Any other ideas?
 
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dcg9381

Petty Officer 1st Class
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Aug 26, 2007
Messages
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Re: 7.4 Bravo 1 flush, but no water from exhaust

stellardog said:
I have a 28' 1988 Wellcraft Antigua w/ 7.4 Bravo 1 454, which keeps cool when I run it in the water, but when I try to flush it on the trailer, I never get water out of the exhaust. I havn't owned a boat for 15 years and have forgotten, would the thermostat be preventing the flow until it reaches 160 degrees or something? Any other ideas?
Click to expand...

I thought the same thing on my 454 mag MPI - I was watching it pretty carefully, but did manage to smoke the impeller in the process.. The good news was that I was replacing the impeller anyway.

You should see water almost immediately. Impellers don't like to be run dry.

I bought a standard set of muffs and have good water pressure at my house. In order to get water to the raw water pump, I have to put an additional clamp on the muffs. After having my initial problem, I pulled off the feed hose to the raw water pump and made sure I had water to the pump... The additional clamp solved my issue.
 
Bt Doctur

Bt Doctur

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Aug 29, 2004
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19,517
Re: 7.4 Bravo 1 flush, but no water from exhaust

You either trashed the impeller or your cooling comes from a thru hull fitting and not the outdrive.
 
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stellardog

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Re: 7.4 Bravo 1 flush, but no water from exhaust

As a follow-up, I had to squeeze the muffs tight until the impellars began to pump the water. Once it kicked in, I got plenty of water from the exhaust. Thanks!
 
Bondo

Bondo

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Re: 7.4 Bravo 1 flush, but no water from exhaust

stellardog said:
As a follow-up, I had to squeeze the muffs tight until the impellars began to pump the water. Once it kicked in, I got plenty of water from the exhaust. Thanks!
Click to expand...

Ayuh,.....

In That Case,..... Your Impeller is No Doubt Compromised.....

I'd Change it Now,...'Cause it's going to let you down, when you need it the Most....
 
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