Lack of cooling water flow at idle and low rpm.

[Lubak572]

5.7 GSIPEFS raw water cooled overheating at idle/low rpm. Brand new impeller, new long block, exhaust, etc.. changed all seals in drive and water pickup tube. Have fuel cell cooling return line off- don't get any flow until 2000 rpm. On muffs in driveway. Other motor runs fine cools at idle. Assuming something in drive isn't right. Any thoughts?

 

[Lubak572]

Old impeller was fine , no missing pieces. I replaced anyways. Brand new thermostat. Water flows good at 1500 + rpm and cools down via temp from laptop hooked up. I guess I will be pulling drive again...

 

[QBhoy]

I’d look at the oil cooler to see if it’s drawing air and losing the prime to the pump

 

[Scott Danforth]

Look at the fitting at the drive

May be corroded and you may be sucking air

You may also want to back flush from the raw water pump back

 

[Lubak572]

This is from it on the muffs from standard garden hose. I also have fuel cell return water line off watching flow and watching ECT temp om my Axiom MFD. I did the same with watching starboard motor which is fine both temp and water flow.

 

[Lubak572]

Would it be better with boat in water? As compared to muffs on trailer?

 

[Wave34]

If you're on the trailer, try to lower the front, and test.

Also, test your raw water pump in case the bearing seal is leaking air. Pump sucking air instead of water. It happened to me. I vacuum tested and pressure tested all sections from the outdrive to the pump to finally find that.

 

[BRICH1260]

Do you have a "blue cap" flush port? If so, you might try running on that to see if symptoms persist. If not, you probably have an issue in the drive pick up tubing somewhere.

 

[Lubak572]

Do you have a "blue cap" flush port? If so, you might try running on that to see if symptoms persist. If not, you probably have an issue in the drive pick up tubing somewhere.

No

 

[Scott Danforth]

did you look at the fitting where the hose is between the gimbal housing and the transom shield?

 

[Lou C]

If these are SX drives there is a plastic fitting in the pivot housing that can crack and leak water. There is also a clean out under the plastic cover that covers the shift linkage so you can back flush the raw water intake hose. What you can do to test that fitting is to cover the water intakes on the drive with duct tape & then tilt the drive up enough so you can see the hose that goes from the pivot housing to the gimble housing. Then disconnect the raw water intake hose at the impeller and fill it with water to see if water is leaking from where that hose goes into the pivot housing. If so that plastic fitting could be it.

 

[Lubak572]

Took in to shop. Mechanic thinks housing may be worn. Yes plastic nipple and water pipe on drive were changed when I had it apart. Will update when I hear what problem was.