454 Crusader Overheats at higher RPM

[wake5150]

1995 33' Tiara pushed by two (2) 454 Mercruiser Crusader (XL) EFI Inboards. Fresh water cooled.<br /><br />At idle and speeds through Trolling, both engines will run about 150 degrees. When you bring the boat up to cruising speed (3k+rpms), the port engine runs hot and overheat system shuts it down.<br /><br />Done so far..<br />1) Cleaned out the heat exchanger, which looked fine anyways<br />2) Tightened belts<br />3) Inspected impeller on sea water pump, looks good<br />4) Given wrong thermostat by West Marine, so couldn't change that yet.<br /><br />Sounds like thermostat not opening enough? Considering swapping thermostats between engines and running in the morning?<br /><br />Any other suggestions, comments, 2cents? Diagnostic advice?<br /><br />Thanks<br />-Wake5150

 

[Don S]

Re: 454 Crusader Overheats at higher RPM

Did you take the impeller out and look at it? While the vanes may all be there, they may not straighten out like they should and will then pump less water. Impellers should be changed every 2 to 3 years.

 

[wake5150]

Re: 454 Crusader Overheats at higher RPM

Don,<br /> My Father-In-Law removed and inspected it (on the water). He seemed to think it showed no signs of wear. I believe he replaced it last year.<br /><br />Don, do you buy into the thermostat theory? What else is common?<br /><br />Thanks<br />Chris

 

[wake5150]

Re: 454 Crusader Overheats at higher RPM

Bump.

 

[tommays]

Re: 454 Crusader Overheats at higher RPM

you have the two common things after those you have to start looking for other reasons why water cant get in the motor,sea strainer,bad hoses,ect<br /><br /> or why it cant leave the motor like a cloged exaust riser ect<br /><br /><br />tommays