Mercruiser 8.2 w/Cats & Closed Cooling Question

[Searay205]

A lot of bad and incorrect information on this thread. You don't have to replace the catalyst in the manifolds. they will last a lifetime. The manifolds are extremely robust and from my saltwater experience will last a lifetime. the exhaust elbows may need replace if engine begins to overheat OR cleaned and reinstalled.

As far as outboards on a little searay SPX to go from the 150hp to 200hp outboard is a $10K option!!!!! I guess my 5.0 mpi cat with 260hp has that beat since I paid $20k for boat with trailer.

Extremely easy to take cats out of picture with simulator. The 8.2 is a big block it has little individual cats vs 1 big one. Eitherway the same philosophy. New manifolds and riser completely different design then old box style. And OEM have an EPDM coating which I witnessed to be flawless after 11 years.

Thank you politicians for the catalyst its not Mercruiser. That was forced the outboards which will require cats before long.

The problem with the catalytic engines isn't the catalyst or manifolds. A decent shade tree mechanic can retrofit back to old style. the problem is the 38 alarms built into the PCM to protect the cats. They are so fragile. On the flip side I was going to retrofit mine to the old style manifolds, glad I didn't the new cat manifolds are lifetime, twice the wall thickness and have a corrosion coating, and no corners for sediment to build in which causes localized oveheating and cracking.

I found a Mercuriser brochure on google where Mercruiser with the sea core system warranted the cat exhaust system for 500 hours. That pretty good,

 

[Lou C]

Actually the real problem is the EPA and how these bureaucrats who are not elected can write regulations without any regard for cost benefit analysis WHAT SO EVER.
Guess what
World leaders are finally starting to learn the cost of the green “revolution”.
Boris Johnson found out the hard way that his countrymen don’t want to be forced to give up their gas furnaces to install heat pumps.
And in Germany where they were going to close all the nuke plants; have reversed that decision.
I’d like to see research that shows that putting cats on marine engines has any measurable effect on air quality what so ever.

What I’d like to see….investigate safety problems that can result from a 700* heat generator in the engine room of a fiberglass boat that depends on a rubber impeller to supply cooling water. IMHO, it just makes the designed in safety concerns of inboards WORSE. Doesn’t ANYONE care about that?

 

[nola mike]

World leaders are finally starting to learn the cost of the green “revolution”.

Also learning (again) what happens when you depend on unfriendly nations for your energy supplies. Energy independence is a national security issue as well as environmental. And poor mercruiser, you think they're losing money on these parts? Maybe epa or whoever could mandate that emissions components have to be made available through the aftermarket or sold at a reasonable markup. Of course, corporation lawyers are always more clever than the government

 

[Lou C]

True Western Europe depended on us for their security for the cold war and post cold war period and on Russia for nat gas & other resources. This allowed their economies to flourish while avoiding the true costs of security and energy independence. The "green agenda" so trumpeted in Europe, ignored these "inconvenient truths" and now they are in a whole different situation. The real costs of security, energy independence and security, are likely much higher than the public has ever been told, and when you add to that the "green revolution" well all I can say is, can their economies afford it?
We already see developing nations saying they can't and lots a luck getting Russia, China or India to go along with any of these climate policies.

 

[OSeaD37PC]

Not me.

Looks like @OSeaD37PC is in for a rough ride with those 8.2's. Probably best to upgrade to the next generation of exhaust, instead of the 3-CAT style.

@alldodge - I do remeber seeing the 3-CAT exhaust for the 8.2's now that you mentioned it. The 8.2's are definitely a 'fresh water' engine, since they don't seem to have a good option for ocean use.

Will the next Gen exhaust system work and match up to the down tubes ?

 

[alldodge]

Looking at the exhaust for a little while I would say most likely. It needs more review but both the old style and new all use the drain tubes

Look thru the link and select each serial number series. Then select "raw water port" and "raw water starboard". Looking thru the hose connections appear to be similar, so I think it would work

https://www.mercruiserparts.com/8-2l-mag-ec-base-model

 

[OSeaD37PC]

Not me.

Looks like @OSeaD37PC is in for a rough ride with those 8.2's. Probably best to upgrade to the next generation of exhaust, instead of the 3-CAT style.

@alldodge - I do remeber seeing the 3-CAT exhaust for the 8.2's now that you mentioned it. The 8.2's are definitely a 'fresh water' engine, since they don't seem to have a good option for ocean use.

And they were so full of themselves the had the balls to call it a Seacore

 

[tpenfield]

Yes, the in-house built engines (4.5 and the new 6.2) have full closed cooling on their 'SeaCore' versions. For some reason, the old school 8.2L does not have the full system, just the engine block, not the exhaust.

I did a fair amount of research on the 'CAT' engines when I was doing my boat search last year. The fact that the 8.2 is only a half system really limits is use to fresh water.

Was there a critical incident that prompted the need for exhaust replacement? I think the CAT manifolds are more robust than the traditional manifolds, but probably need replacement at some interval when used in salt water. . . . just not sure what that is . . .

 

[aspeck]

We are back from the political brink that almost got this thread closed. Let's keep it on topic and out of politics.