MR1 engine overheating on the hose; steam coming from pisser.

[MOA_Chaser]

Changing the oil on my boat today, the port side went fine without incident. I switched over to starboard, fired up the engine and turned on the hose. After a while the water came from the exhaust like it should. But after a while I noticed the RPMs going up, and I noticed that the temperature warning light was on. Steam was coming out of the pissers, but no water. I threaded weedeater line down through the pee holes and it went several feet in as usual. Started the engine back up, and still have the same trouble.

What else should I be looking for??

 

[Babin Farms]

Do you normally get water coming out the pissers while on the hose?? A lot of us don't.

@WREKS is more in tune with the cooling system of these engines than myself and should be able to help diagnose your issue.

 

[WREKS]

@Babin Farms @MOA_Chaser I would start by checking the thermostat. It is upstream from the water pilot.

 

[Cambo]

Does the oil look Milky ? The reason I ask is that the exhaust manifold can breach/deteriorate sending hot exhaust gas and steam into the cooling water the water also makes it past the rings into the oil creating milky oil.

 

[MOA_Chaser]

Does the oil look Milky ? The reason I ask is that the exhaust manifold can breach/deteriorate sending hot exhaust gas and steam into the cooling water the water also makes it past the rings into the oil creating milky oil.

No, as a matter of fact I just went out and checked the oil I removed. I had put it in an old windshield washer fluid bottle so I'd be able to see any water after it separated. Nothing but dark oil in it.

 

[MOA_Chaser]

Do you normally get water coming out the pissers while on the hose?? A lot of us don't.

I thought that we did, but when I checked with my son (who was outside the boat while I was changing the oil on the non-overheating engine, he said it was just steam. So I guess that's a non-issue...

 

[WREKS]

@MOA_Chaser Sometimes it takes a minute or two, running at idle, before the thermostat opens. The pilot usually does not stream but a dribble until the thermostat opens and RPMS are above idle, as in No-Wake mode.

 

[MOA_Chaser]

OK thanks everyone for the advice... but it ended up being something pretty dumb that I didn't think of.

I got up this morning and double/triple checked all the water lines, no kinks anywhere in them. I started it up on the hose again, and the overheat light came on again a few minutes later. I sat there while it cooled down, then thought MAYBE I should try shutting off the tow valve for that engine.

Well, that fixed it. I ran it on the hose at idle for 30 minutes with no overheat warning light. Apparently my water pressure isn't quite enough for the starboard engine. I'm not sure why it doesn't trigger the overheat line on the port engine, but I'm putting a note in my maintenance specs to make sure I shut off the tow valves before running it on the hose in the future.