Merc 3 liter Gurus / rings question

**David Borg** · 05-17-2018, 09:55 AM

The later 3 liter models have the bottom piston ring with a small step . Merc says it helps to push the oil upwards.
Can you use normal rings without the step on the bottom ring? Honestly I can't see why not since the previous models did not have it ,but maybe there is a reason which I do not know?

Thanks in advance
David

**David Borg** · 12-12-2019, 02:36 PM

To the top
Maybe someone has used both rings and compared
Thanks

**Chaz** · 12-13-2019, 11:53 AM

If we are talking Opti's .. I have never looked at the rings. My interest is to get the piston off the rod .. and in my scrap alum bin.

If you look at the 179 ring you will see it fits all (but opti) for $26.99 ea.
The 179-1 is for Opti at $45.99 ea.
But then, all their oversizes (.015 - .030) say they fit Opti's, but are back to $26.99

http://parts.promarineusa.com/produc.../30/210/1030/1

As I remember it, the oil hole in the sleeve is well below the rings @ BDC. If the cut, is facing up, I can see the ring "plowing over" the oil wedge and bringing a bit of oil up in the cut.
If it is facing down, then it acts as more of a scraper to shear the oil off of the wall.
In any event, you could always grind the hole a little oblong if you feel you need more oil.
Now ya got me curious .. LOL I'll have to do a little dumpster divin ...

**David Borg** · 12-13-2019, 12:35 PM

Not opti's , Downdraft EFI s .Merc oem bottom ring has a small step, pro marine rings don't have it. I have seen this on 2004 250 hp and also on 2003 225 hp. EFI . The 4 butterfly intake EFI s dont have it. I was just wondering if it is that important since the aftermarket pistons do not have it.
Thanks a lot

**billybob** · 12-14-2019, 10:45 AM

I have rebuilt about 30, 3.0 optis & I have never noticed a step on the rings. There are 2 things I think are important, when rebuilding. Overbore all cylinders .002 to .003 thousandths. A heavy hone works good. Also when installing p,head, torque all nuts in correct sequence & ft. pound rating. Why U ask. When I first started rebuilding these. The first ones I rebuilt would come back between 4 mo,s & 1 year, hurt again. We didn,t care, cause when U are a platinum dealer. If U rebuild a motor & it does not last a year. Merc. will send a new p,head. They all lasted. One time when I was in service school I asked why that was happening. They let me talk to reman. employee. He said they overbore every reman. block. Since I started doing that, I have never had 1 come back. Of course clean fuel inj,s. & direct inj,s. before installing in rebuild. GOOD LUCK.

**Chaz** · 12-14-2019, 09:52 PM

Originally Posted by David Borg

Not opti's , Downdraft EFI s .Merc oem bottom ring has a small step, pro marine rings don't have it. I have seen this on 2004 250 hp and also on 2003 225 hp. EFI . The 4 butterfly intake EFI s dont have it. I was just wondering if it is that important since the aftermarket pistons do not have it.
Thanks a lot

Wiseco and WSM use a thinner ring (both) than Merc uses. A thinner ring will rev higher before it flutters. With std bore Merc pistons, all I have ever done is to coat the pistons, plateau hone the block, and use Pro Marine rings.

Also when installing p,head, torque all nuts in correct sequence & ft. pound rating. Why U ask. When I first started rebuilding these. The first ones I rebuilt would come back between 4 mo,s & 1 year, hurt again.

They came out with an updated service bulletin. If you look down at the bottom #10 you will see where you are to leave #9 +#10 @ 25 ft/lbs , while you take #1 thru #8 to 40 ft/lbs ..
When I showed a young company man what I did to fix their weak **** block, he said : We won't be making the 3.0 - 3.2L platform much longer anyway.
I said .. coming from you ..I'll take that as a compliment ... and feel free to use my repair to give your blocks the structural integrity to torque all bolt the same without fear of pulling #6 out of round and sticking the piston ...

**powerabout** · 12-15-2019, 07:11 AM

Who bolts the adapter on when honing?

**Chaz** · 12-15-2019, 11:26 AM

Originally Posted by powerabout

Who bolts the adapter on when honing?

Power ... you're wise beyond your years

The bad news is .... they aren't very flat from the factory ..

Just like the blocks ..Oops, there's one of my little "ribs" sticking out of the rag..

**powerabout** · 12-16-2019, 11:43 AM

cant take all the credit, someone wiser than me passed that one on. ( OMC guy)

**Chaz** · 12-16-2019, 01:33 PM

What .. ? Did you miss the memo about the front half and torque plate ..

**Chaz** · 12-18-2019, 12:59 AM

Well David, you 100% correct ..

I dug out some junk today, while my mill was walkin up and back, up and back ..

The ring does have a tiny little groove ...

At BDC the top of the oil hole in an Opti is .725" down from the piston crown ...

Which is right here on the piston ..
So I can't speak for the cut and it's purpose pertaining to oil control . The piston somewhat cuts off the oil flow ... except for a brief time when the piston is towards TDC and it uncovers the hole and squirts oil in the crankcase .

I marked the sleeve .. top line is 3.0L bottom is 3.2

**David Borg** · 12-18-2019, 02:50 AM

Originally Posted by Chaz

Well David, you 100% correct ..

I dug out some junk today, while my mill was walkin up and back, up and back ..

The ring does have a tiny little groove ...

At BDC the top of the oil hole in an Opti is .725" down from the piston crown ...

Which is right here on the piston ..
So I can't speak for the cut and it's purpose pertaining to oil control . The piston somewhat cuts off the oil flow ... except for a brief time when the piston is towards TDC and it uncovers the hole and squirts oil in the crankcase .

I marked the sleeve .. top line is 3.0L bottom is 3.2

Thanks for taking your time to check.
It makes sense in an Opti . But these rings were in a 2003 225hp EFI downdraft and I have also seen them in other Late model Efi s . The sleeve of these EFI s have the same hole similar to your pics. I will take a pic of the sleeve later.

Did merc just use opti rings on these or do I really need to use these rings .I normally use Pro marine rings which do not have the step but in this case Im not sure
Thanks

**Capt.Insane-o** · 12-18-2019, 02:15 PM

No point in manufacturing 2 different rings for essentially the same purpose

**Chaz** · 12-18-2019, 02:16 PM

David, lets take care of the important stuff first .. How are the canoli's in Malta ..??

Heavenly .. I'll bet ...

If the sleeve's have the oil hole, then by all right's it's either an Opti block .. or Mother Merc used Opti sleeves. Do your bleed lines go into the oil hole ... or into the boost port ??? Not that it matters too much .. other than to narrow down exactly what you have.
I have ran them both ways. As well as put left sleeves in right holes and right sleeves in the left side and drilled an intersecting hole over to the boot port. With any of the above configurations .. there was no difference, the little check valve guy kept pressure from going back into the entry side or the reed cage area.

I don't use, used rings .. and I certainly don't buy pistons and rings from Mercury.
If the skirts haven't collapsed, like I said .. I coat the pistons ( these have both the dry film on the body and the heat barrier on the crown ) and use new Pro rings ..

This motor is going on a Mirage. It's .030 with coated skirts ...

**David Borg** · 12-18-2019, 02:45 PM

Cannoli`s are great here I`m sure you will love them.
Thanks a lot for your feedback . Yes it has the oil hole exactly were the bleedlines go and possibly as you stated its got opti sleeves .
That powerhead looks sweet with that custom rail and billet heads