Intermittent Raw Water Flow Issue with Perkins 4-108 (CD36)

[Evergreen]

Hello:

Intermittent raw water flow issue with Perkins 4-108:

Normally my engine has no water flow issues.

However, this year, I have gone to start the engine twice and had no raw water flow from the exhaust. Both times it happened after sailing (but only once was the boat healed over significantly). The first time I stopped and restarted the engine several times before it finally had good flow the last time. During the episode I even dove under the boat (in Maine - brrr) to make sure that nothing was blocking the intake. Yesterday - after a relatively flat sail it did it again. However, this time I had good flow following the first restart. The strainer is clear and I change my impellor every year even if I don't need to. When the engine has flow it runs perfectly and has normal temperature.

Does anyone know what might be causing these intermittent flow issues????

Thanks in advance for any input you may have.

[tjr818]

I think the first thing to do would be to check that impeller. It's easy to do and inexpensive. Even a new one can be faulty out of the box (bag?).

[psjanker]

Heat exchanger equipped....if not perhaps scale shifting within the engine?

V/r

Pete

[Joe Mac Phee]

Pump seems to be losing its prime. Consider the possibility of an air leak on the suction side of the raw water pump.

Joe

[bottomscraper]

I'm with Joe on this one.

Do you have one of those Perko raw water strainers? If yes it might be leaking from the top cover cork gasket or one of the two cork gaskets on the top and bottom of the sight glass. Gasket kits are about $20. Also check the sight glass for cracks.

[Matt Cawthorne]

Check to see if your pump cover plate is worn. My Perkins failed to draw water for the first time this year. After messing around a bit I polished up the outside of the pump cover plate and flipped it over so the inside was now out. That fixed the problem immediately.

Matt