Water psi...Yesterday i started...

[SRSD320]

Water psi...

Yesterday i started our 2004 320SD gas 496's with BravoIII outdrives, cooled by sealed system, to check starts and gauges as today I am taking the boat 8 miles for spring haul out and servicing.

All is great, except Port water psi reads 4.8 while Stbd reads 14.0.

In August we had Stbd issues, thought then to be caused by lack of cooling, so mechanics installed new throughhull raw water intakes...but only connected the Stbd one. The Port one is to be connected at this spring servicing. Adding the new intakes was to augment, help the factory intakes through the outdrives, which have narrow pipes in this Mercruiser year. 

So two questions, as its Sunday. Mercruiser CS phone line and no mechanics are around: what is factory water psi usually, as read on your gauges? And, besides watching temperature and water psi gauges on this short trip, do you know, recollect any issues that might arise?

Thanks!

tim 

[Korkie]

BRAVOITIS

[Korkie]

Low Pressure at the gauge is an indication of poor pre load. Pump not getting enough water. On Bravo IIIs, the water intake coming thru the outdrive gets corroded and blocks off the flow. This causes a low reading at the gauge. It will cool the engine at slow rpms, but as soon as you start running, gets hot fast.
To diagnose for sure, pull the hose plate off the top of the outdrive housing inside the boat. If it is all corroded, you have just diagnosed Bravoitis. 2 ways to fix - remove drives and install kit from Merc. It is a fix to the problem or you can just install thru Hulls with strainers - that is what I did. Both motors run at a cool 170 no matter what the rpms are. For the high pressure - if that is at idle (14psi) then I suggest removing the heat ex changers and cleaning them with muratic acid. On the 496 Bravo IIIs the sea water comes through the system and it is un strained, therefore and little pieces of "stuff" clogs up the heat exchanger. This will cause you to run hot at higher rpms even though your psi is high. For it is hoigh because it is pumping against the restrictions in the exchanger.
Pull both motor exchangers and clean them anbd have through hulls with strainers installed and you will not have this issue any more.

[SRSD320]

Thanks, Korkie. Do you think i'll have Port water temp issue for this 8 miles trip to the mechanics dock today?

[Korkie]

may have to go slow. You can try it on plane, if your engine temp gets to like 192, Smartcraft will go into survival mode and you will lose throttle in that motor. Will still idle and get up to about 1200 rpms. No getting around Bravoitis. It has to be repaired as explained earlier. If you are not a do it your selfer, your mechanic will know exactly what Bravoitis is. Again, through hulls are the way to go. I did a ton of research bore I went that way. The opinion was 10-1 to go with thru hulls over the Bravo III kit. Also, you do get some outdrive cooling from the raw water going thru the OD (very little). So I put drive showers on as well.

[Korkie]

SRSD320 - Did you make the trip?

[SRSD320]

All good. Call if you want to talk. I’m in pst. 604 240 8572

[SMT]

Check your sending unit could be a bad gauge.