V6 135hp 1988 Getting hot at low RPM.

aussieflash

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Feb 5, 2011
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Common problem,my V6 getting warm at low rpm and fine when I throttle up.
Changed the impeller and going to check/replace Tstats and Poppet.
While leg is off is there something else i can do.Should i flush water or air backwards through cooling system?Anyone know how to do this?Im thinking of blasting water through tstat hole.
 

Chris1956

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Mar 25, 2004
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27,036
Re: V6 135hp 1988 Getting hot at low RPM.

You can test the poppit with hose pressure on the copper water tube. Give it low pressure and poppit will stay closed. Higher pressure and it will "poppit" open, and dump much more water.

It is probably just your 'stats that are bad.
 
Joined
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Re: V6 135hp 1988 Getting hot at low RPM.

Sounds like it is just your impeller, when you take it out the veins on the impeller will probably be warped.
 

aussieflash

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Re: V6 135hp 1988 Getting hot at low RPM.

Thanks,I was going to just check stats and poppet,now i think ill just replace them.
Yes the impeller had a permanent bend(dont they all).Other than that it looked in excellent condition.One of the gaskets was a little messed up with little pieces missing.New kit installed.
Thanks Chris,ill try that.I also want to flush in reverse and have screen/cloth on intake water tube end to see if any debri comes out.Ill put hose at telltale end then try hose direct in Tstat hole and blast away.
 

aussieflash

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Re: V6 135hp 1988 Getting hot at low RPM.

Just an update.Took out Tstats and couldnt believe my eyes.These look like they havnt worked in years.(had boat for 1 year).
How can my engine still be in working order,or are these things stuck half open??Inside head cover looks OK,from what I can see.
See pics..selling old Stats cheap...lmao
 

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sschefer

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Nov 13, 2008
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Re: V6 135hp 1988 Getting hot at low RPM.

Ah heck, those look fine... LOL.. just kidding. That could be your problem. Do you have a water pressure gauge? Having one helps trouble shoot these types of problems.
 

Faztbullet

Supreme Mariner
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Mar 2, 2008
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15,589
Re: V6 135hp 1988 Getting hot at low RPM.

Replace them with the Sierra 18-3543 S/S thermostat and 18-0182 thermostat gasket (2 count)
 

aussieflash

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Feb 5, 2011
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1,004
Re: V6 135hp 1988 Getting hot at low RPM.

Got new Stats.Want to clean up stat hole on engine (see pic).Should i just chisel away or is there a magic salt dissolver out there....what about vinegar??
 

aussieflash

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Feb 5, 2011
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1,004
Re: V6 135hp 1988 Getting hot at low RPM.

Gday all,
just an update.Replaced both Tstats and Water Impeller.Also flushed tstat holes with hose and placed bucket under mid section(leg removed).Found sand and bits of shell etc in bucket.Took boat out for 2 hours and heating problem fixed.
 
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