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Perkins 4.108 Overheating

electric mike

electric mike

New member
Hey all,
My marine Perkins 4.108 has been overheating. Gets up to 230/240 after 15 minutes of running.

Here's what I've done already:
  • Replaced diesel fuel, added additive
  • Fuel filter change
  • Oil & filter change
  • Replaced water/exhaust mixer, was rusted and inhibited raw water flow. Raw water flow is great now
  • Removed, disassembled, and flushed out heat exchanger
  • Checked all coolant hoses for clogs and damage, replaced a few bad ones
  • Opened what I thought was the thermostat housing, but there was no thermostat inside
    • Engine coolant is a milky yellow color
  • Replaced coolant pump impeller
    • Previous impeller had broken inside the pump
    • 8 of the fins had broken off
    • Recovered 2 fins from inside the pump
    • 6 fins still missing somewhere inside the system
Things I haven't done:
  • Completely drain and replace coolant
  • Replace gearbox oil filter
  • Check gearbox oil filter for missing impeller fins
  • Find the 6 missing impeller fins
Anyone know what the problem might be?

Here's a diagram I drew up of my cooling system:
OMWGWOZ.png
 
Engine coolant is a milky yellow color
Click to expand...
When motor overheats, does the Overflow fill up?

Is coolant staying clean now?

Might put a short piece of clear hose between raw water pump and heat exchanger. The clear hose will allow you to see if there are any bubbles

Is it actually overheating, as in using a IR Temp gun and measure thermostat housing and compare reading with boat gauge
 
Yes, the overflow fills up.

The coolant is still a milky yellow, even though I've put new coolant in. So I'm not sure the new coolant is being circulated into the engine.

I'm only looking at the temp gauge. I haven't checked it with my IR temp camera yet, but that's a great idea. The coolant lines get pretty damn hot though.
 
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