Marinette Boat Forum

Hi all. My exhaust is "surging" from my Stbd engine. Water flows normal, then slows to a trickle, then blasts out like a volcano. That whole cycle takes about 10 seconds. The engine isn't running hot. I checked the exhaust to see if there was a low spot in the pipe or hose and saw nothing. All appears in good shape. I checked various spots for temps with laser recently and didn't see anything jump out at me, although I wasn't particularly looking for the cause of this issue. Just checking in general. I read online it could be the lake water cooling system pulling air in somewhere. My engines are closed cooling. Would a worn impeller do this? Going to check strainer seal next time I go up.. Anyone else had this issue?
Thanks!
Sean

Sean

Sucking air or bad impeller.
Easy to check for sucking air hard to check bad impeller. but you already knew that.
bill

Thanks, Bill. When it comes to boats, "easy" is always a relative term. There isn't much between the strainer and block intake so yes it should be "easy".. My water pump is a Sherwood and fairly "accessible".. Also a relative term!
Thanks!
Sean

Isn't that the way it suppose to work? Mine pukes out every 10 sec or so just like yours.

You are on the right track with the strainer and impeller, but you might want to check to make sure the hose from the oil cooler to the water pump is reinforced hose and in good shape. One season my starboard engine was driving the mechanics and me crazy. Three impellers and a rebuilt pump later, I systematically began pulling and inspecting each hose starting from the seacock. I discovered a crack in the hose right underneath the clamp on the intake side of the water pump. I replaced it with hose I had on hand, but it was not reinforced. So I discovered the hard way that the suction from the pump will make unreinforced intake hose collapse occasionally. It's a wild guess, but that might be causing your engine to burp. And if you're pulling air you may wear out the impeller sooner.

At the dock they think I'm paranoid, but I always check to make sure both engines are throwing a steady stream of water before I untie.

Good luck.

You might have a collapsed exhaust hose. I've seen them where the outside looks just fine, but a layer of hose inside is blocking the flow. If that's it, you can visualize water and exhaust backing up, then blurping by in a burst of flow.

Jeff