Thermostat Question on a 4.3l Mercruiser

H

hit4thefence

Cadet
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Feb 26, 2012
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I have a 1988 Searay with a 4.3l mercruiser engine. The left side big hose coming from the thermostat is getting a back flow of boiling water flow. It seems like the water is flowing through the thermo ok but water from the block is back flowing. Any ideas?
 
H

hit4thefence

Cadet
Joined
Feb 26, 2012
Messages
10
Re: Thermostat Question on a 4.3l Mercruiser

I have a 1988 Searay with a 4.3l mercruiser engine. The left side big hose coming from the thermostat is getting a back flow of boiling water from return hose off water pump. It seems like the water is flowing through the thermo ok but water from the block is back flowing. Any ideas?

To rephrase that....
 
achris

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: Thermostat Question on a 4.3l Mercruiser

Sounds like you may have blocked exhaust elbows or manifolds... Pull the elbows and check them....
 
H

hit4thefence

Cadet
Joined
Feb 26, 2012
Messages
10
Re: Thermostat Question on a 4.3l Mercruiser

The elbows(whole exhaust system), engine, impeller, thermostat, original poppet valve I sprayed with wd40, etc.. Basically a new install. Ive been testing and tuning everything seemed fine for the first week and water test. As of week 2 it started this issue.
 
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