Engine Room Discussions

[Roos]

I have a fairline with double 3208 ta 425 hp, after winter storage one of the engines alarmed for high water teperature. At first i thought it was the water temperature regulators, i have change thouse, i have changed the impeller and cleaned the heat exchanger. The flow in the heat exchanger was 30% stopped in the return. After these measures the alarm didn't go off idling for 1,2 hours, but when i took a testdrive it started to alarm after 20 minutes. Temperature rased at similar speed in the two enginnes but this one didn't stop at 80 deg cels. What shall i do next ? I'm thinking of cleaning the aftercooler, any other suggestions ?

[RM_FNTS]

You seemed to hit the obvious items to check.

What do you mean by "The flow in the heat exchanger was 30% stopped in the return"

You would expect to see restriction in the inlet to the exchanger.

If there was foreign material in the outlet of a component than I would expect to see the same material in the inlet of the next component in the circuit.

Check the transmission cooler as well, any restriction in the sea water circuit will contribute to the issue.

Can you tell if one engine is pumping more water than the other? I know its hard to tell but it is a good indicator to tell if the system has the capability to reject sufficient heat.

[Roos]

Hi! When i remover the heat exchanger i found that where the water is suppose to turn arround and go back through the exchanger some of the pipes were stuffed with crap. It seemed to be salt or corroded part of an zink anod. Is the transmission heat exchanger hard to check ?

[njc1979]

Did you clean the aftercoolers after you removed them and found them clogged???

[RM_FNTS]

Shouldn"t be too hard to check

its at the rear of the engine above the bell housing.

Remove the hoses and visually inspect

I know it is easier said than done on some vessels

The sea water circuit is a series circuit, a restriction anywhere will cause reduced flow everywhere.

[Roos]

Ok, i will try to clean he aftercooler tomorrow and inspect the transmission cooler. How big restrictions to flow should i be looking for ?

[Roos]

It was the heatexchanger which ws glogged, the aftercooler is still to be inspected.

[RM_FNTS]

There shouldn't be any visual restriction

Ideally clean as a whistle

Come minor deposits are OK

Are all the Anodes deteriorated?

Definitely replace all that are required

Is the aftercooler jacket water or sea water cooled?

a serial number would help

[Roos]

It's seawatercoold i belive, the seawater goes from the pump, to the aftercooler, to the heat exchanger, to the tranmisson cooler and then out through the combustions i belive.

[umairanwar]

check sensor or switch

and installed temp gauge