496HO Advice Needed
 

Hello Everyone, I use this site to answer questions about my boat all the time. I know the search button is my friend and I've used it many a time but now, I need help.

I have a 2001 Sonic Prowler with a 496HO. It has just over 300 hours and has unfortunately sat idle for the past year. Long story short, while I was cleaning it up the other day, I noticed one of the hoses was broke off the water rail under the manifold. So, I took off the water rail and one of the bolts sheered on me.

I ended up taking both manifolds along with the water rails off to clean them up. I decided to order 2 new water rails because of all the corrosion inside them. Since, I have the manifolds off, I'm going to change the plugs/wires, oil, and fuel/oil filters.

Is there anything else that I should do since I have this much of the motor taken apart ? Any input would be appreciated. Thanks in advance !!

You have the very early Mercury 496 aluminum exhaust manifolds with the aluminum water rails that rot out pretty quickly in salt water. I t may be difficult to get the bolts out to replace the rails. You can buy new rails from Mercury and sometimes find a set on Ebay. be careful to carefully check and pressure test the manifolds as if the rails have rotted thru the manifolds may be close to failure and a leak there will quickly destoru the engine. You can find a lot of almost like new later model manifolds that are iron and last much longer in salt water use also on ebay. You only need the lower manifold as the risers are stainless on all and interchangeable and will probably outlast the boat.

As for plugs, use AC DELCO 41-983 available at any parts house and Wix makes a nice replacement filter part #51060R we use and you get them from any Napa parts house.
Raylar carries the replacement plug wire sets if needed so call us toll free for those if needed.

Dont forget to change the spin on fuel water seperator whether you think its needed or not.

If the engine has not been started for a year as you said, disconnect the fuel injector harness at the intake and crank the engine quite a few times to get the oil up in the vlave train, lifters and bearings before firing this engine up for the first time. While the exhaust manifolds are off you can also spary some light lubricant in the exhaust ports as the engine is being cranked over to get some lubrication in the cylinders and on the rings.

Best Regards,
Ray @ Raylar

This is the exact information I was looking for. Thanks so much !!! I will be calling you later today for the plug wires.