running hot....

[special k]

took my 28te w/6lpa-stp for the season shakedown and found her running hot,over 180-190* at about 3400 rpm and a steamy exhaust. kept her below or at 3000 for the rest of the trip and she was running around 175* (slightly below the 180 mark on my albin gauge) . raw water impeller less than one season old and less than 100 hours and plenty of water through the exhaust at idle at dock. coolant level seems ok but i have not changed it since i got boat 3 yrs ago.

have seen this addressed on this forum but not paid attention to possible solutions. is there a product to run through the cooling system that may clean it out some. fresh water side or raw? and should said product be left in or full flush afterward. all seemed well when she was put to bed last november.

any input greatly appreciated.

mick

[efishnsea]

The name of the product is Rydlime. You run it through the raw water side of the heat exchanger. Care should be taken to make sure it does not come in contact with aluminum which should not be a problem as the heat exchanger is all copper. Other members have attested that this product works wonders and they lose 5 to 10 degrees. Good Luck and tell us how you make out. Bob

[RobS]

Aluminum in marine engines is not harmed by Rydlyme, only the zincs. You have to pull the zincs off the brass caps and reinstall the caps without the zincs when conducting the flush and then Install new zincs when done. Here is a post I did after my flush. viewtopic.php?f=7&t=2054&p=12420&hilit=Rydlyme#p12420

But, looking at the circumstances here: fine last year but running hot on shakedown...

Leads to believe there is something going on here...
Did someone fill the slots of the intake with bottom paint? Is it clear inside?
Is the strainer not closed or seated properly and she is sucking air?
Is the seacock not fully open? Problem with the handle/ball connection?

Plenty of exhaust water flow at idle does not prove enough flow at other rpms.

Yanmar coolant should be changed at least every other season. Seems crazy but this is a small displacement high rpm very costly aluminum engine, hence she needs her TLC! Coolant change is cheap and easy, be sure to use the proper coolant

[Cape Codder]

Can you check (with diver's mask) if the raw water intake is clean "inside".
For several years, until I found a way to treat metals with an anti-fouling routine, the inside of the strainer was filled with marine growth, restricting water flow at the end of the season. Mostly barnicles.