Mercruiser 8.2 w/Cats & Closed Cooling Question

[tpenfield]

Greetings,

I am considering looking (which is another way of saying a long way from buying) at a 2013 Formula 350 CBR with the 430 HP Mercruiser 8.2 MAG HO engines. There is not much info on the engines in the advertisement, but . . .

- The Ad says 'manifolds replaced in 2019' . . .
- Researching a bit about the engine is that in 2013 it would be a closed cooling system (possibly with Cat converters ????). I can't recall when Cats became required.

So, I'm thinking the closed cooling is really a HALF system and the exhaust is raw water (sea water in this case).

I just checked exhaust part pricing for manifold and riser/elbow, and we are talking some serious $,$$$ per engine to replace exhaust.

Just wondering if any late-model 8.2 experts here can shed some light on the engine specifics.

 

[alldodge]

I keep remembering it was 2010 when CAT's where installed by the EPA

 

[Lou C]

My brother just bought a 2020 Chapparal with the Merc 4.5 200 hp. Engine is raw water cooled with cat converters. I tried to convince him to buy the outboard version but he likes to water ski and prefers I/Os for that. The thing I don’t know is if these cat exhaust systems last any longer in salt than the previous style if not closed cooled including exhaust. Might want to ask a local Merc dealer what they see. Having said that if it’s a 2013 and they were done in 2019, then it may be the same lifespan. On a twin engine boat that’s a big financial liability.

 

[Lou C]

PS if you post up an engine pic from the ad it’s easy to tell. These things look totally different than the standard exhaust.

 

[tpenfield]

Thanks for your comments guys -

Yes, 2010 was the transition year, so 2013 would definitely be Cats. There are no engine pictures in the Ad, so I've asked for some, but . . .

I did look up the 8.2 engine parts diagram (with Cats) and it appears that the exhaust manifolds are fed directly from the raw water line before the raw water reaches the heat exchanger.

See below.
.

It does not look like there is the opportunity to have the exhaust 'split' in terms of cooling as the manifold and Cat are 1 giant assembly, then there is a riser/elbow that gets attached.

Pricing for the exhaust manifold and riser are a total of about $1,300 per side ($2,600 per engine). So, I'm wondering if the seller spent upwards of $7K for exhaust after owning the boat for 6 years . . . Seems nuts

Maybe that is why the boat is for sale

Anyway - additional comments/info is welcome. Probably won't go see the boat for a few weeks.

 

[Lou C]

That’s what it is. Plain crazy. Had a friend with a Merc 4.3 and cats and replacement was $4500 parts. They sold the boat!
Ted I think I’d keep the boat you have!
This is why I will never own an I/O with cats. Just another maintenance headache. Only outboards from now on.

 

[tpenfield]

Doing a bit more research into this whole Cat Converter thing . . .

It looks like the V-P engines include the exhaust manifold in the closed cooling portion and only the riser/elbow is exposed to raw water.

The Mercruiser engines seem quite the opposite, where the manifold picks up raw water before the heat exchanger and passes it through to the riser/elbow. It seems like there are some fitting locations on the smaller engine's systems (4.5/6.2) that could be used to convert to a full closed system, but not sure there is such a kit. The exhaust manifolds on the BB GM based engines (8.1/8.2) ECT do not seem to have those fitting locations, from what I can tell, nor do the part diagrams show the cooling system connected in a full closed manner.

So, bottom line would be V-P is OK with salt, as you would be only replacing the riser/elbow at certain intervals. It seems like with Merc, you'd be replacing the entire thing (manifold/riser, etc.)

I guess the introduction of CAT's really pushed sterndrive-I/O configurations to fresh water only, leaving the salt water market wide-open for outboards, if it wasn't already.

 

[paulswagelock]

The Merc is half cooled, so it is sea water heading through the exhaust and cats as you describe. The exhaust in saltwater is a 5 year ish replacement expense, just part of ownership. The cats appear to last a bit longer, but could need replaced as well. Freshwater the stuff lasts 15 plus years, except the cats, they will go bad And need replaced.

 

[alldodge]

Some have bypassed and removed the CAT wink, wink

 

[Lou C]

I agree Ted, the cat converter issue has really pushed the market to outboards and I could see that when we were at the Marina picking up my brothers boat. Yes there are stern drives still being bought but experienced boaters here in the salt know better after having one or 2. To add a $5000 expense every 5-6 years on top of winterizing, spring commissioning and annual drive R&R and service plus here bottom paint for the engine & drive is just too much.
Ted I’d go for the biggest boat you can get with a single 350 hp outboard, as new as possible and put an end to the years of struggling with stern drives.

 

[tpenfield]

@Lou C We are thinking 'twin or triple outboards' big

There are a few Intrepids for sale up in my neck of the woods (ocean), so I may take a look in the coming weeks.

 

[Lou C]

Well my thought is to try to go as new as possible, even if a little smaller because of the high cost of outboards. I think they get a good 10-15 years in salt water after that they are on borrowed time. The sad thing about sterndrives is if you can deal with the maintenance and have closed cooling the engines can last longer than outboards but its the other things, all the little fiddly things that go wrong, that drive you away from them. Add the cat converter nonsense and there's just no way I'd buy one. Like I won't buy a diesel truck today for the same reason. Excess complexity in emission controls can make the owners miserable.

 

[tpenfield]

Just to follow-up on this thread for anyone doing the newer Merc 8.2 in salt water. Definitely half closed cooled and I've seen social media posts about twin engine exhaust system replacements costing $12-15K (marina pricing).

Really a fresh water engine - seems crazy to want to run that particular engine in the ocean. Pretty much leaves the Merc 6.2 and 4.5 SeaCore as the only I/O engines that you'd want to run in the salt.

 

[Scott Danforth]

Remember back in 2010 before the 8.2 was 430hp, it was 525hp where the 8.1 liter was at 425

AD has shown that you can take the 502 to much more naturally aspirated

 

[OSeaD37PC]

Just to follow-up on this thread for anyone doing the newer Merc 8.2 in salt water. Definitely half closed cooled and I've seen social media posts about twin engine exhaust system replacements costing $12-15K (marina pricing).

Really a fresh water engine - seems crazy to want to run that particular engine in the ocean. Pretty much leaves the Merc 6.2 and 4.5 SeaCore as the only I/O engines that you'd want to run in the salt.

I have early version of the 8.2 Mag H.O. E.C. Seacore
Holy Cow! I got the latest MC prices on new manifolds, collectors, 6 cats per motor and 4” risers.
12 cats @ $1800ea = $21600.00
4 exhaust manifolds @ $800 = $3200.00
4 collectors 4 x $800 = = $3200.00
4”risers 2 pair @ $3760.00 = $7520.00
4 ex manifold gaskets @ $60.00 = $240.00
4 collector gaskets @ $120.00 = $480.00
12 catalyst retention rings @ $28.00 = $336.00
4 riser gaskets @ $90.00 = $360.00
half of the required O2 sensors 4 @ $126.00 = $504.00
for a grand total of $37080.00
I got the boat with factory recons and they were supposedly 28k each.
5 years later the exhausts parts for two engines are $ 37k in just parts ?
This is the Last Mercruiser powered vessel I’ll ever own. They are not helping theirselves by screwing people like this.

 

[tpenfield]

I have early version of the 8.2 Mag H.O. E.C. Seacore
Holy Cow! I got the latest MC prices on new manifolds, collectors, 6 cats per motor and 4” risers.
12 cats @ $1800ea = $21600.00
4 exhaust manifolds @ $800 = $3200.00
4 collectors 4 x $800 = = $3200.00
4”risers 2 pair @ $3760.00 = $7520.00
4 ex manifold gaskets @ $60.00 = $240.00
4 collector gaskets @ $120.00 = $480.00
12 catalyst retention rings @ $28.00 = $336.00
4 riser gaskets @ $90.00 = $360.00
half of the required O2 sensors 4 @ $126.00 = $504.00
for a grand total of $37080.00

Why 12 Catalytic Converters? Should be 1 per side, just like all the other parts.

 

[alldodge]

Why 12 Catalytic Converters? Should be 1 per side, just like all the other parts.

The first Gen exhaust used 3 cats on each side.
https://www.mercruiserparts.com/bam/subassembly/31943/14733/160
The next Gen like yours used just one. It also shows the entire man sells for around 800 each.
https://www.mercruiserparts.com/bam/subassembly/31946/16012/160

Osea not to get far off topic, right now I don't see any reason why you couldn't swap out for next Gen, and most CAT motors are closed cool. Also, Volvo is not going to be any better.

 

[OSeaD37PC]

Im just sick about these crazy prices, they have more then doubled over the last 2 years !

 

[nola mike]

Why 12 Catalytic Converters? Should be 1 per side, just like all the other parts.

Read through this thread before noticing the date, thought you were ready to throw in the towel on the Cruisers!

 

[tpenfield]

Read through this thread before noticing the date, thought you were ready to throw in the towel on the Cruisers!

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.