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Old 02-21-2021, 07:17 AM
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Default 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?
Iím 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, donít 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?


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Old 02-21-2021, 01:54 PM
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Originally Posted by PENN YAN View Post
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?
Iím 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, donít 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.
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Old 02-21-2021, 08:41 PM
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Originally Posted by Ryan00TJ View Post
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 itís at least 5 years old. Just want to do it right to avoid trapping air.
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Old 02-21-2021, 11:50 PM
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Good idea around every 5 yrs.

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.

Last edited by Ryan00TJ; 02-21-2021 at 11:52 PM.
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Old 02-22-2021, 10:21 AM
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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.
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Old 02-24-2021, 06:57 PM
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Originally Posted by 87MirageIntruder View Post
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?
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Old 02-24-2021, 07:02 PM
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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.
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Old 02-24-2021, 09:05 PM
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Originally Posted by PENN YAN View Post
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?
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
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Old 02-25-2021, 07:59 AM
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Originally Posted by Keith Atlanta View Post
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 youíre buying the coil as well??
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Old 02-25-2021, 08:24 AM
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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.
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