5.0 mercruiser running low temp

[brian4321]

Hi I just bought a 2000 bayliner capri with a 5.0 mercruiser. I've had it out twice now and it runs perfect, but when I turn the key on the temp gauge goes up to just below 100 , then after running it's never gone over 110 . I'm thinking either the temp gauge or sender is bad, or the thermostat is stuck open . What should I check out first? And does it hurt an engine to run cool? I would like to take care of this problem and any help would be much appreciated . Thanks

 

[Fun Times]

Re: 5.0 mercruiser running low temp

Hi there, typically when the temp hardly rises like this, it's the thermostat stuck open usually due to small debris like rocks, etc. So it's best to check the thermostat first.

 

[brian4321]

Re: 5.0 mercruiser running low temp

Thanks... so if the thermostat is stuck open can I just clean it good and put it back together or should I put a new one in?

 

[midcarolina]

Re: 5.0 mercruiser running low temp

If it was me if I had it out I would go ahead and replace it.....

 

[Fun Times]

Re: 5.0 mercruiser running low temp

If it was me if I had it out I would go ahead and replace it.....

+1. Be sure to post your engine serial number if you would like help locating the correct part numbers.

 

[brian4321]

Re: 5.0 mercruiser running low temp

Thanks for the help and my serial number is OL617778

 

[Fun Times]

Re: 5.0 mercruiser running low temp

Thanks for the help and my serial number is OL617778

The complete MerCruiser Thermostat Kit that you can't find in the parts catalog linked below would be Merc part number 807252T5 or 807252Q5.

Also there is an aftermarket kit available here on iboats. Please note that there are two options over the OEM kit. The one linked below is the one you would need to do this job correctly. Just be sure the gasket between the thermostat housing and intake manifold has 2 brass rivets going through it or your gauges may not work correctly. The gasket goes on dry. Mallory Thermostat Kit 9-43157

Mercury, Mercruiser, Force, etc. - STANDARD COOLING SYSTEM - 5.0L / 5.7L ALPHA & BRAVO GEN+

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