496 alam every minute
 

2004 w/ twin 496's I start the boat and after it warms up two beeps every minute.
drive fluid full
antifreeze good /water temp good
oil preasure good
water preasure good
What could it be!!!!!!!!!!!!!!!!!Then if I take a ride for ten minutes over 4000rpm the hard alarm goes off untill I slow down.then the two beeps go again.

take it to get scanned??

And when you get it scanned if there are no codes let it run and watch the idle counts. If it doesn't drop down to 40-50 after a minute or two you have a bad Idle Air control.

On my HO, I've had three things cause alarms so far, first time I just needed to flush the heat exchanger out, just sucked up a little sand and I wasn't getting good water flow

Second, my IAC valve went bad, it was about 90 bucks for a new on, also the engine wouldn't idle and was stalling alot. Thats on the top rear of the intake manifold.

And last was my water pressure sensor, when it went it was intermittent at first then I couldn't even get the boat to plane, it reduced the engine to 20% power by 1800rpm. That was 85 bucks, not to bad, that sensor is on the first cooler the sea water hits on the back of the engine near the transom assembly...

I had the same problem. Very frustrating. Turned out to be sand/debris scoring in sea water pump housings. Expensive, but did the trick.

Sonic,

Do you have a smartcraft monitor? If not, I highly recommend one. You'll get real time engine info including alarm codes. Plus all the other benefits like fuel burn, etc. Get a Northstar unit and you can have GPS too.

With the Smartcraft you'll be able to immediate feedback on all of those 496 alarms you seem to be plagued with. Plus, you will get more accurate engine data as compared to the the analog gauges.

Just a thought.
Techman

thanks guys i will have a friend scan it tuesday.Just to let you know The heat exchangers were both taken off this past winter to preasure check I did have a leak and replaced one.

Had e same issue. Mine was the water pressure sensor as well. 110 bucks and done..........hours of pulling my hair out though

Where is the best place to buy one?

I am having all kinds of alarm issues as well with my 496. Had it scanned and the codes were for low block pressure. Also showed an overheat of 190 degress about the same time. Pulled impeller out (I freaking hate that job) only to find impeller is good. I back flushed the hoses and found no debris. So I am at a loss right now.

I too am looking to install a smartcraft gauge in my boat. I found the SC1000 in white and black on ebay for around $188 new. It only comes with a 3' cable so I am still looking for the extension cable to run it back to the harness on the motor..... SInce my the Drivers dash is full, I am going to mount the Smartcraft Gauge on the passanger side. The Velocity has a Gauge Blank on the Pass. Dash. Thats the only place I have.....

my boat is fixed your the winner.bad idle control valve.98 bucks plus labor.
thanks eveyone

The impeller can be good and still have low pressure. Look at the ends of the housing if there is any wear or scoring it need to be replaced or fixed. It has to be perfectly smooth. I bought a repair kit that had two plates and some gaskets and a new impeller. It took about 30 mins to install and fixed my pressure problems.

Sounds exactly like the water pressure sensor...or the impellers.
Happened to a buddy's 05 that had 496HO's. He replaced the one sensor and did both impellers since they had 80hrs on the clocks.
Problem solved.

Where's the best place to get a Smartcraft system?

Avoid Wagmar!
 

After reading this post I thought it might be helpful to let all Merc 496 owners know the importance of the SCAN TOOL!
There are only two types of beeps on the Guardian alarm system on these engine. One is the constant beep for initial start up and low drive lube.

There are 26 other conditions on the engine that can trigger a two beeps per minute alarm, so it is imperative to have access to or own and use a scan tool to identify what is causing the alarm.

The Merc PCM555 diagnostics manual and the #30 - 496 engine manual are also nice,necessary and relativly inexpensive and simple answers to a lot of questions about these engines, alarms, codes, service, etc.

Moral of this Story, get the tools and information you need to maintain and check your engines for problems.
Don't try to practice the WAGMAR procedure to much!
WILD ASS GUESS MADE AT RANDOM!

Best Regards,
Ray @ Raylar

HI Ray
where can i purchase one?

I back flushed my whole system and put a new impeller is and still same GD alarm at anything over 3700 RPM. I did notice scoring on the end of the housing when I put the impeller in. So I guess that is next... In addition to repairing the housing I will be adding a Smartcraft Monitor as well. I had my CPU scanned at the marina and it showed low block pressure (Ironically my screen name here is low_psi, go figure...)

For the scan tool call Rinda in Chicago @ 773-736-6633

Best Regards,
Ray @ Raylar

I added a water pressure gauge in for these reasons. the Livorsi gauge is only $60, it was worth every penny

Impeller Housing = $309. Ouch! Oh well, it's only money......

You can buy the kit and dont need to replace the pump. It will do it again. The kit has two stainless steel plates and you won't have the scoring problem. I replaced mine with the kit and the water flow has increased out the exhaust. Got the kit from my local dealer. You can call him, ask for Max 847-458-6488. Sold with or with out the impeller.

Rob

I think the kit you are refering to is for the plastic impeller housing. I have the all brass housing...

This kit is made for the brass housing not the plastic. I have a 2005 with twin 496 and put the kits in. Worked great.

Well since I already ordered and paid for the Brass housing I will install it and next time I will look for the repair kit.

I replaced the Impeller & Housing on Friday. Still getting low plock pressure alarms when running over 3800RPM......... Anyone have any ideas? Could I possibly just have a faulty pressure sender? Any way to test them?

not your hair

you might be sucking air before the sensour, loose hose clamp,are you getting water in the bilge? those blow off valves to drain the exhausts get clogged or weak springs and they open if your sensour is on the waterpump check everything back,look at the pins in your sender we have seen them bend over

If you buy the Diacom Software with the sensor test lead kit you can test all the criticals.

The 496 digital oil pressure sender and the digital water pressure sensor are the same.

http://www.mercruiserparts.com/Show_...Gimbal+Housing #20,,#16,, might be plugged some what,,,i sucked up seaweed into the out drive,that totally blocked off water flow to the sea pump,,,this week,,,if you could run some compressed air thru it might help

That is my next step. The mechanic at my local marina suggested that #15 & #16 can sometimes work them selves loos just enogh to bring in air when in the higher RPMs.

Looks like my issue was poor contacts between the plug and water pressure sensor. Little electric contact cleaner and so far so good. Damn that was frustrating!

Thanks for the info Ray.

It's BACK!!! I got 1.5 runs on it before the alarm started going off again. I have changed the sensor plug (my mechanic had one laying around) and am now waiting for the sensor to come in (ordered yesterday). I am praying that it is the sensor that is bad. With the corrosion I found on the plug, I am guessing the same corrision can be found on the pins of the sensor...... Other than that, the next thing I remove from this boat will be the drain plug :hothead:

I had my mechanic scan the computer again, just to be sure I am still chasing the same problem. According to the last alarm The motor was at 3520 RPM and the block psi was @ .66 lbs. I find it very hard to believe that I was running less than 1 lb at that RPM, if I was there would have been overheat alarms. Instead, according to the ECM, when the alarm went off the boat was running @ 165 degrees.

So all signs are pointing to a bad sensor. So I have installed a new one this afternoon and will test again this weekend. I did notice some corrosion on the pins of the sensor and also noticed some sand in the sensor itself. It is very possible the sensor got packed with sand and was having a hard time reading higher psi.

Replaced the sensor and ran it hard for a good long while. Alarm NO MORE!!