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1974 Tri-Hull 18’ with Mercury 188 hp - overheating
Posted: Wed Aug 11, 2021 8:21 pm
by LOZ James
Yes, this near-50-yr-old “Grandma Cobalt” still runs and she has been running really well, except lately. After launching and running for 5 minutes or so, engine overheats. No digital temperature indicator - just a primitive display with green, yellow, red and an arrow. Need some guidance on most probable causes and suggested actions, while refraining from any jokes. Thanks!
James
Re: 1974 Tri-Hull 18’ with Mercury 188 hp - overheating
Posted: Wed Aug 11, 2021 8:29 pm
by Big Block Power
Impeller and tstat. Plugged intake?
Re: 1974 Tri-Hull 18’ with Mercury 188 hp - overheating
Posted: Thu Aug 12, 2021 12:04 am
by bruceb58
When was the last time the impeller was changed? If you don't know, change it. Needs to be changed every other year.
Also, add a real temp gauge. Besides oil pressure, a very important gauge.
Re: 1974 Tri-Hull 18’ with Mercury 188 hp - overheating
Posted: Thu Aug 12, 2021 6:52 am
by AsLan7
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Hey James. So glad you found us!
As mentioned above... the impeller, thermostat, or something covering the outdrive intake are your most likely culprits. Check those before exploring further.
Any pics? We love them here.
And welcome aboard mate!
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Re: 1974 Tri-Hull 18’ with Mercury 188 hp - overheating
Posted: Thu Aug 12, 2021 1:52 pm
by Lockey14s
yup. Start with the impeller and go from there
Re: 1974 Tri-Hull 18’ with Mercury 188 hp - overheating
Posted: Fri Aug 20, 2021 4:38 pm
by LOZ James
Thanks all ... it was indeed the tstat!
Re: 1974 Tri-Hull 18’ with Mercury 188 hp - overheating
Posted: Fri Aug 20, 2021 7:58 pm
by AsLan7
LOZ James wrote: Fri Aug 20, 2021 4:38 pm
Thanks all ... it was indeed the tstat!
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Sure thing buddy...and all we ask for is a pic or two in return.
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