Overheat at midrange- verifying

ufm82

Master Chief Petty Officer
Joined
Jul 29, 2003
Messages
827
My 1993 Merc 150XRi idles fine and the gauge sits at 140. At above 4,000 up to WOT, she runs at 175 on the gauge. When pulling a tube at 3,000 rpm it shoots to 250 and the alarm goes off and all heck breaks loose. Shut her down to idle and within 30 seconds the temp drops and all is fine.
I've replaced thermostats previously as routine maintenance and did the poppet valve before due to sand ingestion. The jackets are clean, the t-stats are clean and 1 year old and poppet valve is 2 years old. Water pump 2 years old as well. I read here about making sure the slinger was on the shaft above the water pump or it could cause issues. Any input there?

UFM82
 

ufm82

Master Chief Petty Officer
Joined
Jul 29, 2003
Messages
827
Re: Overheat at midrange- verifying

Anyone?
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,832
Re: Overheat at midrange- verifying

It sounds like you have covered the usual suspects. Is it possible the motor is overpropped for pulling tubes?
 
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