496 Broke ?
 

i believe my 496 took a s**t. i was cruising on the bay about 40mph and the smart craft alarm starting beeping. i checked the gauges everything was normal except the fuel gauge was low. i came off plane figured the fuel quit sloshing around and everything was ok. after trying to take off the engine starting breaking up and missing. i stopped the boat again and notice this time the temp gauge was warm and rising. i started the boat again leaned over the back and it was pumping water, wtf... after sitting for about 20-30 minutes i went to re start the engine and the starter could barley turn the engine over. not like a low battery but like the internals had a tight spot and something was seizing up. after a 3 hour tow and drinking every beer in the boat here i am posting my story on a sunny sunday with a broke down p.o.s. so what do you guys think i should do.pull drive and engine ? any simple tests? cost effective repairs or replacemnts ? sorry abut the long post. all and any info appreciated.....

Did You Pull The Plugs And Check For Water.?

no, do you think it might be water reversion? is it possible with my application?

Pull the plugs

its possible in any application. How old is the engine?

bought boat new 2003 496 ho
150 hrs w/electric choice exhaust

pull the plugs. you may need to change the gasket for the riser also. Im sure some other people will chime in. good luck.

I had a battery issue that acted very similar to your problem. The batttery voltage dropped and then the alarms started going off. Then the engine would miss and backfire like crazy. I replaced the battery for that engine and all my problems went away. Check all the basics first before pulling a motor or outdrive.

the last couple of times out i thought the volt meter seemed higher than normal, but i thought it was just me..

Form one 496 owner to another with BS on the 496's.

While I did not have your problem on the 496, I had similar issues on 454 mags. Make sure that you do not have water in your oil. That will "freeze" the motors and hard to start.
Also check your starter conncetions make sure they are not corroded. I had injection problems with my 496's and they ran like chit.. (3out of the 8 was firing) Make sure there is no water in your tank or try to run it from fuel from a gas tank. (be carefull tho)
The 496's computers will try to compensate for anything if not right and then they won't run well or not at all. If you have a slightest exhaust leak the 496's will act up like no other. Have it put on the scope.
( I am still looking for a good serv. tech. in North of Tampa.) Anyone knows any??

. :angry-smiley-055: :angry-smiley-055:

Your alternator/voltage regulator may have took a dive. Pull your dipstick first and check for level/water. If it's normal "chances" are you won't have to pull plugs, look elsewhere.

Get a scantool on it. Can't get to one? Check all the simple stuff like connecters including the main engine harness connector. Take it apart, and snap it back in. Check others as well. May be a grounhd in the transom harness. Do a search here for all 496 issues and there's a post concerning the harness as well as other very informative angles.

The other simple issue could be fuel related. Pull fule filters and pour into a glass pickle jar or something and let set for a bit to see if water or other junk shows up. Change them anyway. Change the inline filter too. The one between the boost pump and fuel tank. Might even want to go thru the little bit trouble of popping a couple injectors out to see if they have junk in them.

All stabs in the dark without being able to get a scantool on it, but also likely suspects.

Rob,
Before you do anything else, take everyone elses suggestion and pull the plugs, then turn the engine over to see if there is any water in the cylinders. A cylinder full of water will very easily bend a connecting rod if you try to start it :( Do that check before you do anything else. It could be a blown head gasket, which is not that terrible a repair, but if it hydrolocks and bends a rod ....... :angry-smiley-055:

Pulled the plugs last night, and the very last one I pulled I believe # 7 had water. I turned the engine over and more water shot out. I sprayed wd 40 in the cyl. I put plugs back in hooked up water muffs and the engine started. It did however have a miss, only running on 7 cyl. after testing I found that # 7 cyl was dead but I do have spark on #7...also when the engine was running I didnt hear any noise....

Ok guess its time to pull the heads. I would run a leak down test first but these engines are easy to take apart.

Ouch! Wish it would've been something more simple. Good luck.

Cracked head/blown head gasket on closed cooling would mean anti freeze not water in the cylinder
Are you loosing coolant out of the resevoir or has the level dropped?
Or more than likely it would have oil in the coolant resevoir.
Did you happen to look at what came out of #7? If it was anti-freeze then its a head gasket?
If its water I would say more along the lines of a cracked manifold or riser.
You'll take the riser, manifold off before you get to the head so sheck that manifold out for a crack before you go for the head.

If you loose the intake valve train only such that the intake valve does not open but the exhaust valve still does obviously that cylinder will not fire plus that cylinder will suck in sea water from the wet exhaust. Personal experience. A simple compression test will tell that story.

It was water not dex-cool... no water in oil, no oil in coolant reservior.
I did restart the engine on the muffs after I drained the water from the cylinder. If were cracked manifold or riser wouldnt it refill that cylinder again ????

yes if its cracked it will refill again. If the manifolds were cold when you started up the crack may not have opend up though. Did you check again for water in the cylinder after you were on the hose? I would compression check first. If it is a valve problem you won't have much at all. A bad valve or cracked manifold would be unlikely out of stock 496. Since it was 7 all the way at the back of the manifold at the lowest spot I would think would be more like water renentering? Do you have silent choice? Also check and see what code was set when your alarm went off. If its port manifold temp or water pressure you might be onto something.

496
 

Rob...What did you find out. It is important for people asking for help to follow up with the cause and solution so we all can learn.

Chris

Yes, don't leave us like this.

ditto

Are you boating on salt water? 4-5 years is not unusual to have a manifold corrode through.

ROB,
I have a similar situation on my newest purchase. 1990 Checkmate.
My situation is the sameexcept that my boat ran perectly right up until I put it away.
Wouldnt start the next day.. Water in 2 cylinders
I also think you will not find if it is a manifold leak too easily until it is back in the water. In my case I surmised that on the trailer the water would still empty out via drive. When it was in the water it had no place to go so it cam in through a crack whil the engine cooled creating vacuum. Not sure if this is possible just guessing. Let us know what happened I cannot get to my boat till the weekend and would be appreciative of any info

vig,
rob has not been logged in since August 2007. It's not very likely he's going to respond. You would be much better off starting your own thread.

The aluminum exhaust manifolds do leak. You can take the risers off and look inside the exhuast manifold and you will see bubbles that look like tree sap. When we checked for leaks we found literally 100's of the spots. It was on a 2001 with 900 hours.

You sucked a valve ,do a compression test on no 7 I have used heads 1000.00 a set Bob at 4127810881