Sydwayz

iTrader: (1)

Follow the white and green air lines downward. One is Port Forward. One is Starboard Aft. You can see them in the water drain system Mercury parts diagrams. http://www.mercruiserparts.com/Show_...R+DRAIN+SYSTEM

QUICKEST way to find them: put some air in the system, and let the water drain out of the block. You will see two streams of water pouring out of the motor for about 20-30 seconds.
*The actuators do NOT replace the water in the system. They open two valves which allow the water to drain out via gravity. BECAUSE of this, you cannot use this water drain system for full blown winterization.

When the springs are going south (soft) in the actuators, you will have (sea) water showing up in the bilge, running over 3000 rpms give or take. This will likely by the only indicator as these are far after any water pressure sensors. Mercury sells rebuild kits for the actuators. The forward one has been replaced on both of my engines once over the years.

In a pinch, you can de-install the actuator and replace it with about a 4-5" long piece of 1 1/4" OD pipe/PVC.

chiefy

An update on progress-

1. I removed the flush check valve setup (I only run in fresh water) so all the check valve BS is out of there)
2. Found a small kink in the hose to the fuel cooler...not sure if it was enough to restrict flow, but I'm guessing any small restriction = bad

Didn't find any seaweed or fish in any of the plumbing. I'll get a good run in tomorrow and hopefully this overheat business is done with.

28Eliminator

I helped friend out for about a month to get his fixed. The alarm isn't very informative, but with the Rinda scanner we finally found that the exhaust on one side was getting hotter than the other by about 30 degrees. We flushed and back flushed all kinds of stuff, and had water flowing through both exhaust. Once started looking closer at the exhaust, we could tell by touch after 5 minutes of idling that the port side exhaust was to hot to touch. Although he doesn't have CMI's and just the standard Gil manifolds, the problem could still be the same. To finally get the blockage cleared, I had him rev to motor up to 2,000-2,500rpm and I pulled the raw water hose going to the manifold from the heat exchanger(I think). It blew a bunch of sand out of there. I had him shutoff the motor and we hooked the hose back up and the problem was solved. Just another possible location to check out keep an eye on.

BUP

iTrader: (9)

# 9 is an open vent hose for when you pull the water release drains. It usually is routed to the top of the motor and just sits there or tied wrapped to other hoses. Again just a air vent hose. Do not hook it to anything and keep it out of the way of anything that's rotating and do not tie wrap completely tight because you will close pinch it off..

chiefy

Just concluding on this one - the shop I brought it to mis-diagnosed the problem. I have no idea what code reader they were using (they are a Merc dealer) but the engine never had an overheat issue. Three things were putting it into guardian mode 1. faulty shift position sensor, the ECM intermittently thought it was in neutral while I was running at speed. 2. Faulty oil pressure switch and 3. Faulty ground connection at alternator causing the ECM to not get steady voltage/current (from what I understand - the ECM does weird things when it doesn't have a steady supply of power)..

Was lucky to find a shop who got me back up and running in a couple of days after the other shop took 6 weeks giving me back nothing but a giant invoice.

Thanks to everyone for their advice. This community is an amazing resource.

BUP

iTrader: (9)

Thanks for the update and the shop that fixed it did good because sometimes that shift switch does not show up in a scan. For ecm / pcm engines it can be a problem child. It is called shift switch or shift in gear switch as it is a switch not a sensor. These motors with voltage problems can be hard to trace as you have 12v sensors and 5 v reference sensors / circuits.