496 Questions
 

Hello I am new to the forum. I boat out of Delaware, Indian River Bay with our Penn Yan 30 Rampage which has a 496 MAG base model #0M025585.

The boat was originally purchased spring 2003, came with 5 year extended service plan.

The boat was used exclusively out of Baltimore inner harbor. From 2015-2019 it sat due to owner health problems.

We bought the boat fall 2019 with total ~260hrs on the key switch. Now have ~400hrs.

Have had the following done by professionals: new impeller kit, starter, booster pump, oil change, transom assembly service, lower unit service/paint/anodes.

This year the boat was used in saltwater without flushes (except winterizing). We now have it on a lift so can flush it after each use.

After reading through this forum I have some questions.
Manifolds and risers: What can you tell me about these, are the risers carbon steel or stainless?
I’m going to pull the risers and manifolds off and inspect, I have the full OEM set of gaskets/turbulator/bolts. I read about the trick to use two longer bolts with the heads cut off to keep manifold gasket aligned when installing the manifolds. What inspection criteria am I looking for to replace these? Does anyone have a diagram of raw water flow path through the manifolds and risers? I assume raw water cools the manifolds? Any other helpful tricks?

How do I know which generation cool fuel setup I have? Is the fuel cooler a double wall protection from the seawater or single wall?
Read the warnings about the filters and paint, unsure if it applies to me. Have zero problems, don’t like to open things up if there is no issue. I read that some folks had those fuel cooler snap off bolts, besides spraying them with kroil any other recommendations to keep them from snapping?

tune up:
I read BUPs old posts about spark plugs will do what he said. What I am worried about is removal, the block has some corrosion around the existing plugs. How do you clean that up before removing the plugs, just a small softer wire brush or pipe cleaner and vacuum out? Any helpful tricks?
Do you recommend I replace the spark plug wires as well?

Heat Exchanger:
I read about end caps and gaskets. Do they make test kits for the exchanger (on a bench after removal)? The manuals do not have a good process for draining the dexcool and refilling to avoid trapped air, can someone walk me through it?

Welcome. Manifolds are raw water cooled. Early manifolds were aluminum. Later models were cast iron. Risers were always stainless. Pull your risers to inspect the manifolds. You'll be able to look into exhaust portion as well as water jacket. Pressure test if you suspect a leak.

Going off your year and sn you likely have the Gen 2 cool fuel. No worries on the paint issues. Enter your engine serial number and this website will break down your parts.....
mercruiserparts.com

Replacing the heat exchanger end cap gaskets does not require draining the engine coolant. That is the raw water side. I replace end cap gaskets about every 3 years.

Thank you, I want to drain and put new dexcool into it because I think it’s at least 5 years old. Just want to do it right to avoid trapping air.

Good idea around every 5 yrs.
https://cimg4.ibsrv.net/gimg/www.off...276f88e03f.jpg
Drain coolant from block drains circled in pic. Refill thru coolant reservoir to correct full level. Install cap and run engine at IDLE to operating temp. Allow to completely cool and top off resevoir if needed. Very simple procedure.

Ryan gives good advice here. You should have a cool fuel 2 so no worries about paint.

And, with the coolant reservoir it will purge itself just fine on its own, just watch the level in the tank. And yes, replace those end cap gaskets on the exchanger. Those can be changed without draining the coolant like Ryan said.

You should have aluminum exhaust manifolds, my 2004 are aluminum. Risers are stainless.

Are you guys replacing those as a preventative measure because they wear out/deform and let seawater migrate into the coolant side or do you mean just replace them if I open up the heat exchanger to drain out any dexcool in there?

Another question I have is what spare parts do you guys carry with? This boat is run inshore often and offshore occasionally so I like to be prepared. I have a serpentine belt, impeller, solenoids, a few raw water cooling hoses/clamps, and fluids and filters of course.

The end caps are just pre-cut rubber circles, they deform after a while and suck in. The plug wires arent really worth it. I never noticed a difference even in high-performance applications on the 496. The stock wires are good over 500 hours I believe (somebody fact check me on that)

On the plugs, find the 5/8 thin wall socket that has the 4 inch extension already attached. I always liked them for the 496 plug replacement event. I never lost a belt but I carried the old ones with me.

You didnt being up oil :) I preferred Mobil 1 20/50 and really liked Amsoil 15/50 or straight 60 Dominator. Use a good filter - I usually used Napa Gold

Thank you! On all of my past 350/260s and this engine I run mercury or quicksilver oil and filters. Got a pile of them when Gander Mountain went out of business and can usually pick up oil when on sale. I looked up plug wires cost and holly cow! Are they connected right into each ignition coil so you’re buying the coil as well??

You dont need wires, I have hundreds of hours on my coils, you dont need them either. Use the big oil filter, it helps with idle oil pressure.

No, they are not connected. Neither is Mercruiser with reality.

Many threads on high quality replacement wires for more normal prices. One thread is very recent.

It’s the .060” plug gaps that wear out ignition components faster than they should. I feel like a broken record. :)

When the exchanger gaskets warp, they won't let the seawater into the coolant side, that's not what they are sealing, it's just the end caps they seal. When the warping happens, they can restrict seawater flow through the cooler and it runs hot then.

If you are dying to replace your plug wires, here is a set some of us have used. I have them on mine now, made in USA Moroso wires for $70. 18-8838-1 84-881698,496-8.1 lr, distributor less ign, Ignition Parts mag star Wire Sets.Ignition Wire Set 120/140 discount high voltage ignition wire sets, s.s. coil core magstar v-6 wire sets, v-8 magstar ignition wires discounted, mercruiser h.e.i.

For spare parts, an IAC valve is common to carry. There's been lots of forum conversations about these as you can get genuine or aftermarket ones. Many caution using the aftermarket ones so I went with OEM for a spare myself.

Thanks

Thanks for the xchanger explanation, that helps a lot. I am most certainly not looking to replace the wires, and really have no reason to replace the plugs either so we’ll see.

Will read up on the IAC (Had to google that). Thanks again

Can anyone recommend a good experienced mechanic who will travel to my boat location and has worked on 496s in the southern Delaware/Ocean City MD area? I had all of my service done near Annapolis last year prior to moving the boat. I have a reputable mechanic that I trust, but he does not work on these engines much at all so it is always nice to have someone on retainer that is very knowledgeable with the engine. The boat is stored on a lift with no ability to trailer, so local marinas are not an option for that reason as well as a few other reasons.

Just searching forums. I need new wires for my 496 MAG's, I clicked the link, called and got a disconnected number? Is there another avenue for the Moroso wires? Thanks.

Their FB page has no posts since 2017

yeah I saw that and the website was last updated in 2017. I had to double check this thread date and the site/wires are still recommended but I can’t find the wires on a search. So anyone that had a link to the wires or alternative I’d appreciate it. Thanks.

edited. I did some more searching, the Volvo Penta 3861295 is the same wire as the Merc wire for ~$75 a set from all the posts comparing the two. Everyone said they were identical when changing them. FYI for anyone looking, I think I’ll give them a shot.

Still keeping my eyes out for a good mechanic in southern Delaware/OCMD area. # knockonwood