Hone or deglaze?

[canoemang]

I am in the process of rebuilding my 86 Merc 115 L6. I had Cylinders #3 n #4 and #5 run lean and chew up the rings. I can not feel or notice and marring on the cylinder walls (i got lucky), i caught it before it got bad and stopped running it so i didnt do more damage. The Middle and lower carb ran lean due to wrong jets, i talk to a old time mechanic and he rejetted them for me so this wont happen again.

So my questions is should i use a 3 blade deglaze tool or use a 3" flex hone?

I have done a bit of research and have read pros and cons on both.

I will be using 3 new pistons and new rings on all 6, all 6 pistons are standard size.

As a side note: i am amazed i used to be intimidated to crack this motor open, fairly simple and straight forward.

After this i will be using what i have learned to rebuild my 84 L6 115 :0

Thanks in advance!

 

[wired247]

Re: Hone or deglaze?

Use the ball hone. You need a chamfer on the ports and the ball hone will give you that.

Theyre a lot easier to take apart than to get back together. You should have the late rods on that though so you can get the pistons and rods in first instead of the old goofy way where everything had to go together as an assembly .

 

[Chris1956]

Re: Hone or deglaze?

Lucky for you. You should also rebuild the fuel pump, clean all fuel screens and rebuild the water pump with new impeller, gaskets and wearplate. Perform a link and synch.

f you have back drag carbs, clean the screens under the brass elbow and tee fittings that allow fuel to enter the carb covers.

I like the hone.

 

[Chris1956]

Re: Hone or deglaze?

One more real important thing. If you have screws holding the connecting rods together, replace the screws with new ones. If they are bolts and lock nuts, they may be reused.

 

[canoemang]

Re: Hone or deglaze?

Ball hone it is and yes it is the new style rod's. Fuel pump and inline fuel filter and impeller are all new/rebuilt.

I do have the back drag carb's and i have eliminated the jet/vent on the top and have put a bb in the line between. As for the screen at the elbow? i do not know what you mean..

so a 3" ball hone is what i have been reading.. correct?

Thanx again for the info guys, sure do appreciate it.

 

[wired247]

Re: Hone or deglaze?

Yes. 3 inch ball hone.

 

[Chris1956]

Re: Hone or deglaze?

Hey Canoe, Those back drag carbs has a small stainless steel screen under each brass fitting on the carb tops. The fittings are where the fuel lines connect. I have had them clog up....

 

[Faztbullet]

Re: Hone or deglaze?

he Middle and lower carb ran lean due to wrong jets

You had something else happen as each carb feeds 2 cylinders so it is impossible for #5 to run lean and not have #6 lean also. You want to run a rigid hone like a Sunnen thru the cylinders lightly to see if it they have any taper as it will so up as dark untouched area usually around the intake ports. I rarely see a inline that does not need boring......

 

[canoemang]

Re: Hone or deglaze?

You had something else happen as each carb feeds 2 cylinders so it is impossible for #5 to run lean and not have #6 lean also. You want to run a rigid hone like a Sunnen thru the cylinders lightly to see if it they have any taper as it will so up as dark untouched area usually around the intake ports. I rarely see a inline that does not need boring......

what do you think happen?

I am new to this but let me throw out my 2 cents..

Inline 6's are notorious for burning out the 3rd cylinder, due to the middle carb running lean and with gravity involved the 3rd cyl even gets less gas, so the 3rd n 4th are shot. Would it make sense that a similar thing happened with the bottom carb and the 5th cyl and it was caught (due to comp test) before the 6th went?

again i am new to this..

 

[canoemang]

Re: Hone or deglaze?

I rarely see a inline that does not need boring......

If the cylinders are not scored or marked why would it need to be bored over?

Can't i just hone it and add new rings?

Also.. STD bore is 2.875" correct?

I picked up a micrometer yesterday and im going to do some measuring this morning.

Again.. thanks for any and all info, it is appreciated.

 

[Faztbullet]

Re: Hone or deglaze?

Inline 6's are notorious for burning out the 3rd cylinder, due to the middle carb running lean and with gravity involved the 3rd cyl even gets less gas, so the 3rd n 4th are shot.

Ole wifes tale as gravity will not effect a atomized vapor, the reason # 1 and #3 fail on a inline is ignition problems and sometimes cooling.

If the cylinders are not scored or marked why would it need to be bored over?

Because they wear at a taper due to short stoke and side thrust of piston.....

Can't i just hone it and add new rings?

Yes if the cylinder are in spec... you need to mike the cylinders as shown below, if its over .003 of spec (2.875) it will need to be bored. Also mike the shirts of piston as this is wear they wear out at...

 

[canoemang]

Re: Hone or deglaze?

Fazt.. i am assuming you meant piston skirt not shirt.. correct?

Ive miked what i can just to verify pistons are std, and they are all the same.

I am seeing .015 and .030 oversized pistons, i am assuming it is the physical piston size that is larger, not JUST the rings.

I'll check out the rest of the measurments and make sure it is within tolerance, now to find a cylinder bore gauge..

tools add up fast..

 

[wired247]

Re: Hone or deglaze?

"tools add up fast.."

They do but if its something you want to last a few seasons just hone it and throw it back together. It might not be 100% but it will still be tighter in the bore than a V4 OMC. If its something you don't mind running a few seasons until you get the pistons together etc for full rebuild then buy the pistons and schedule it in for a 30 year rebuild down the road. You really don't need the bore gauge.

 

[Jlawsen]

Re: Hone or deglaze?

You had something else happen as each carb feeds 2 cylinders so it is impossible for #5 to run lean and not have #6 lean also. You want to run a rigid hone like a Sunnen thru the cylinders lightly to see if it they have any taper as it will so up as dark untouched area usually around the intake ports. I rarely see a inline that does not need boring......

Yup, the cylinder walls might feel smooth because the scoring is filled in with aluminum. You can hit them with a rigid hone or wash them with muriatic acid run a bore gauge down them and then make a decision about boring or honing. If you all want to fill up your stones with aluminum go ahead and skip the muriatic acid. I can't afford it.

The Sunnen rigid hone is the only hone you should use although there are some decent knock off's out there that aren't too bad for low use applications like yours. The three blade (stone) expanding hones are nothing but a recipie for disaster. The brush and ball hones are finish hones. I've seen what happens when people try to use them to cleanup cylinders. If you owned a bore gauge you'd now immediately why I'm going to tell you that it's not the right tool. FYI, you use a die grinder to chamfer ports and you better know what you're doing or you can really make a mess out of a cylinder wall.

 

[redjmp]

Re: Hone or deglaze?

I have the same year of motor and I have a feeling something is amiss.
If it ran too lean, then I'm sure the piston crowns would also take the hit and not just the rings...
Do you see bits of metal deposited on your plugs?
Or are your plugs rusty?
I slowly lost 10lbs compression in #4 over the last few years and it turns out to be the inner water jacket gasket was leaking and letting water into the hole whereby it steam-cleaned the oil off the cylinder walls causing quicker wear.
I too run a one size bigger jet in my top carb just to maintain an extra safety margin on #1 but maybe your merc guy was fooled by someone else doing the same thing.
As Faztbullet said, its impossible for #5 to run lean and not #6.

 

[canoemang]

Re: Hone or deglaze?

Do you see bits of metal deposited on your plugs?

No sirs..

Or are your plugs rusty?

No rust anywhere and all 6 plugs were identically covered slightly with oil.

Ive done the quick shutdown method to test for water leaks in the inner water jacket and no apparent issues.

The only thing affected were the rings. i'll put up pictures of the 3 pistons.

The crown did get beat up from chunks of rings bouncing around, which i assume is "normal" considering..

 

[Jlawsen]

Re: Hone or deglaze?

No sirs..



No rust anywhere and all 6 plugs were identically covered slightly with oil.

Ive done the quick shutdown method to test for water leaks in the inner water jacket and no apparent issues.

The only thing affected were the rings. i'll put up pictures of the 3 pistons.

The crown did get beat up from chunks of rings bouncing around, which i assume is "normal" considering..

O.K. so it's obvious to me that you aren't all that familiar with what happens when a lean out occurs. When it happens the fuel that normally becomes trapped in the squish area is depleted. This raw fuel provides cooling to the top edges of the pistion and prevents flash over. If you lean out a cylinder, the fuel in the squish is inadequate and this results in the flame spreading out and over the edges of the piston.

When this happens the ring lands carbonize and the rings begin to move outward. Eventually, a ring will move so far out that it hangs in the port and either breaks the piston or breaks the ring. If you look at the top of the piston and edges you'll see a definite pattern and the top edges will be rounded and erroded. There may be some damage on the piston top from the broken ring but normall broken ring pieces go right out the exhaust port non stop.

If I wasn't 300 miles from my shop waiting out a minor wind storm before I go fishing, I'd post a few pictures of some pistons that I keep around as momento's.

 

[canoemang]

Re: Hone or deglaze?

JLawson - Your correct, as i said in post #10 i am new to this and learning. I have done all of my own motor work for the last 22 years. I am new to outboards and trying to learn. Thanks for the "Lean Lesson". It is all appreciated.

All skirts are 2.865

All 3 pistons, most have small chunks missing and some have rings missing. From the looks of the tops of the pistons i thought it got chewed up from the rings, i had no rust anywhere and had no metal shavings anywhere during disassembly.

Cylinder and Piston #3

Cylinder and piston #4

 

[canoemang]

Re: Hone or deglaze?

Cylinder and piston #5

So 3" ball hone,3 new pistons,new rings for all is my plan. Also a complete gasket kit.

 

[jimmbo]

Re: Hone or deglaze?

Something went wrong with 3 and 4. Number 5 I think inhaled a piece of number 3s piston ring. I say that cause 1, 3, and 5 share the same exhaust manifold and exhaust tuning does create pressure pulses that flow back into the cylinder. Number 5 is clean compared to 3 and 4.