It doesn't appear that anyone has been down this exact road you are on. I completely understand wanting to install all new stuff. Did it myself. Buy the one shown in your original post and "make it fit" then post YOUR results. It may help someone else. FYI, I bought the 3"x 23" coolers for my boat and they are huge. My boat originally came with the really small coolers (7.4 liter) mounted to the side of the block not on the "bell housing" Because of their size, I ended up mounting the new coolers to the center stringers below the engines. That turned out to be a major PIA to plumb but I didn't have a choice. You will probably have to build new hoses anyway so you can move it around almost anywhere you want. Like you said, do it now while it's out. Did you look at the bell housing mounted "Plate coolers"?

No, not really. Haven't done much research into that style other than reading they are more proficient than tube style. Wasn't really looking into changing the whole set up. Guess I was thinking it could be a simpler swap with just a larger diameter cooler.

I may just be the guinea pig for this. I know being too efficient can be bad as the oil never gets hot enough to evaporate any moisture built up during condensation. This is where I'm relying on the thermostat to help.

Thanks for your input.

lol. I figured he didn`t want it because of the issues mentioned , not because one self absorbed mentally ill person said I ripped people off yet he couldn`t come up with a single example.
No worries, I don`t sell junk but completely understand.

Looking through the classifieds I see this Merc Racing 600 SC for sale. Look at the pics and it has a 2" oil cooler like the one on my engine.

https://www.offshoreonly.com/classif...le-o82863.html

Also the Merc Racing 525 (which we kinda know is underrated) has one as well.

Are the parts sites just trying to make sales? Because Merc has no problem using the 2" oil cooler on the blue engines.

I wonder if the closed cooling affects the oil temps differently than a fresh water cooled engine? I would think it shouldn't make a difference.

It seems to me that you might be trying to solve a problem that doesn't exist? I mean I totally get you in wanting to do a 'one and done' installation due to the location of that *****...but doesn't objective evidence suggest that the cooler you have is fine? One thing for sure I wouldn't do is 'upgrade' to that Hardin unit as I too feel, as you suspect, that it would create all sorts of fitment problems.
So...IF you decide to use your existing cooler...how confidant are you in its integrity? Or are you replacing it regardless with something new?

What makes you "think" you need a better oil cooler? Just curious. You know I've been following this engine upgrade as it is something I intend to do before too long (switch to a HP500EFI), provided all the stars align, lol!

My 496 have a TINY oil cooler. Boost i every seem it run was 250.

I would try what you have now. It looks to be at least twice the length of the cooler I had.

Personally oil cooler and headers I wouldn't buy used. But that's just me.

New cooler for sure. The engine that it was installed on had nothing but corrosion problems.

Figured I needed a larger cooler from reading the performance parts sites. They rate a 2" cooler up to 425HP and 450-700 for 3".

As I posted above, I see Merc is using the same size cooler for the SC 600, so if it works for that, it should be fine for my application too.

Looking more like I will stay with the 2"

Thanks for the replies

This is how big the stock cooler is on a 496


https://cimg2.ibsrv.net/gimg/www.off...627a71a5a2.jpg

Probably a good call. I think my new oil thermostats are going to be constantly cycling because the coolers are waaaaay to big. 3" x 23"
https://cimg4.ibsrv.net/gimg/www.off...f50b2a49cc.jpg

Holy cow, that's small.