Warning horn diagnostics 200 EFI

[blackboat]

Doubtful, unless the others were loose also. Any gaskets appear to be distorted into the center passage?

The old gaskets actually looked pretty good and there didn't appear to be evidence of water moving between passages or gasket material moving to obstruct poppet movement.The other bolts weren't tight enough but weren't just hanging there either.Apparently there is a lot of pressure under the poppet cover or Merc wouldn't have used 4 5/16 bolts to secure it so I guess it's possible that water could have been leaking between passages or out under the cowling.If problem persists,my next move will be to check the new pump installation and look for obstructions in the block after I get the pressure gauge installed.

[blackboat]

Update... Still sounds over heat alarm if running 2000 to 3500 rpm.Water pump was removed,everything was pristine and installed correctly.What would be the correct method for checking and flushing water passages? Not sure the thing is actually over heating.Could it be a faulty temp sensor? If so,how do you test it? At what temp would you expect it to trigger warning? Am presently also dealing with a no start condition but think I have that figured out.Pressure gauge port is threaded but not drilled all the way through,have to remove the head to avoid getting metal in the passage.A new 4 stroke is looking better every day but I'm not going to let this old sob beat me!

[EuropeanAM]

You said "everything was pristine and installed correctly" in regards to the Water Pump. Did you happen to snap a picture of the gaskets:

1. Below the impeller plate

2. Below the Water Pump Base?

Odds are pretty high that you have a portion of one of these gaskets torn or missing.

[blackboat]

The gaskets were all good.I do remember during installation the impeller housing felt strange when tightening up,like the new base wasn't seating properly.It took an extreme effort to get the base out again and I'm thinking that was the case.There were no witness marks on the base gasket you would expect to see.It seems like the studs were slightly miss drilled originally as I always have trouble sliding the gaskets and impeller plate over the studs and the locator pins on the base.These were OEM Merc parts.

[EuropeanAM]

Gaskets are a pretty snug fit- have to be pretty careful with them.

There is one particular trouble area in that one gasket... almost looks normal, but in reality many of the engines exhibiting these symptoms actually have an area of the gasket torn away.

[blackboat]

Got a new pump kit,will give it another shot.This is a case of "it was working fine,now it doesn't". What changed? The only thing was a new water pump assy for general maintenance and upkeep.Don,I'm convinced that it was me that screwed this up as the temp alarm switch works properly and the block was flushed from the bottom and top with no apparent restrictions.

[blackboat]

Got the new complete water pump assy and the water pressure gauge installed. Gauge was connected to the bypass hose with a "T" per instructions. It now has ZERO pressure at idle and maybe comes off zero slightly at 2000 rpm on the hose muffs.Very little water appears to be moving through the bypass or at least no pressure is built up.Head temps 160 starboard,150 port 4 minutes after startup and continue to rise.Thermostats are opening at the correct temp.It has to be sucking air or leaking water somewhere.Nothing has been changed except a new pump last fall.It ran great before that and was put in storage for the winter.I have owned this motor since new and have installed several new pumps in the past with no problems.
I'm really stumped here. Don,Joe,Savage,Leon,others....you guys have bailed me out many times in the past. I'm only asking for 1 more time.....

[JOE54]

suspect poppet problem , or leaking base gaskets

[blackboat]

Water pressure is now 2 psi at idle.8-10 from 2000 to 3000 rpm where the overheat happened,17-18 wot. No warning now but on water testing not quite the same as actual fishing conditions so we will see. Poppet was checked and rechecked and good. Base gasket was good but...the base never seemed like it pulled up tight to the LU,the studs are off center in the base holes and it binds up when installing.Ended up tapping it to get it seated.Merc dealer slipped me an after market impeller as a genuine factory piece which was obviously not as resilient as OEM. Anyway,not sure what the problem actually was but back to running. Thanks,everyone!!