115 6c TOP piston cylinder issue

[Chris1956]

Yes, the two ring pistons use a keystone-shaped ring. It is not compatible with the older 3 ring pistons.

Most of the 1/4" bolts on the head of my engine could be drilled thru the block casting and a new bolt and nut installed externally. I probably broke 3/4 of them, since my motor was used in salt water. Ironically the one or two bolts that could not be drilled thru, came out without an issue.

 

[ianmoore]

Yes, the two ring pistons use a keystone-shaped ring. It is not compatible with the older 3 ring pistons.

Most of the 1/4" bolts on the head of my engine could be drilled thru the block casting and a new bolt and nut installed externally. I probably broke 3/4 of them, since my motor was used in salt water. Ironically the one or two bolts that could not be drilled thru, came out without an issue.

Mine is a salt water motor too. I was honestly amazed to only have one stuck bolt in whole motor. I went really slow, used heat and lots of pb. I did break off 2-3 bolt heads on that section, but was able to get them off and out.

Honestly, being in the salt is my biggest concern. I’d like to keep this motor for a while. I really like it, but there were some decent salt deposits and I have flushed the motor every time I’ve taken it out.

Anything preventative you did in that regard after rebuild?

 

[Chris1956]

Unfortunately, what I found was that the aluminum alloy of the block was getting softer due to the saltwater exposure. Bolts would strip easier and some of the castings would get some powdered corrosion.

I never flushed my engine because I kept it tied to the dock in saltwater, and there was no good way to flush it.

It was a '77 which was the last Merc 1500 model year. I had it from just about new in 1980, until it thru a rod in 2008, and it was kept in saltwater from 1993 onward. It also sunk at the dock twice, causing me to tear it down and wash it out.

If you can flush it after every use and use corrosion guard on the block, it should last. Fresh fuel and good cooling are essential or they cook pistons.

Also, the motor has no thermostat, so they depend on the engine spinning fast enough to cool the heat it generates. Don't overprop or overload the boat, as the cooling margin is good but there is not a lot of extra cooling.

 

[jimmbo]

What about those rod cap screws? Those are really expensive. I’ve heard that people tend to replace them when they get in crankcase

Those are a Onetime Use Only Screw/Bolt

 

[ianmoore]

Those are a Onetime Use Only Screw/Bolt

Yes. Ive been reading up on them. I read someone working on a rebuild that actually had an issue with new OEM mercury bolts. Does anyone have experience with the WSM road bolts?

 

[ianmoore]

I just got a call from machinist, and he did not have to bore at all. He was surprised, but the 2 cylinders with the missing rings cleaned up at .015. He did suggest replacing all the rings. The issue I'm having is that all of the existing pistons are the 3 ring pistons. I think this is the original powerhead but don't have a way to confirm. I think the 3 ring pistons were replaced with these 2 rings.
-This pic is from the manual and shows both types of pistons for this engine.
-Where can i get the older style 3 ring assemblies for those pistons?

 

[jimmbo]

So you are saying only 2 Pistons need replacing? You can use the 2 Ring Piston as a Replacement
Finding Rings for the 3 Ring Pistons might a Challenge, there are 1 set of 3 Rings here
You might try calling Dealers in your area, as they may have a few NOS collecting Dust

 

[Chris1956]

Gee, doesn't a .015 bore require a new OS piston? Did he bore it or just measure it? The cylinders get out of round. Did he see that?

 

[ianmoore]

Gee, doesn't a .015 bore require a new OS piston? Did he bore it or just measure it? The cylinders get out of round. Did he see that?

I have no experience with machinest, though the shop i intitially took it to that is an awesome mom and pop shop recommended him highly. He didn't rebore. He ended up only re-honing it. if there are questions i should ask him, let me know. i am a bit in over my head, or at least the first time in this deep

 

[jimmbo]

I doubt any Machinist would Hone a Cylinder out to 0.015 Oversize. It would take forever. 0.015 is the first Overbore Size.
2 Stroke Engines tend to have a unique Wear Pattern

 

[racerone]

If rings were broken / missing on these O/S bores it needs a new piston.-----I am not sure 0.015" pistons are available at this time.

 

[ianmoore]

If rings were broken / missing on these O/S bores it needs a new piston.-----I am not sure 0.015" pistons are available at this time.

Yes. I am getting new pistons, but I’m trying to get more into from the shop. I asked him to measure and bore if needed to next size. He ended up only honing them and when I reached out about them being possibly out of round they basically said they weren’t great and that I could either put it back together or toss it. I’m currently still in the polite state but getting pretty pissed. I was really clear.

If he had called me and given me w choice on what I would want to do…or if they get the numbers back and they are still in spec.. I would be fine.
I get why people don’t do this. There just aren’t enough people doing it and you have to deal with a lot of bs

 

[racerone]

People simply buy new motors.-----Rebuilders are retiring.-----Shops are reluctant to do major repairs.

 

[ianmoore]

People simply buy new motors.-----Rebuilders are retiring.-----Shops are reluctant to do major repairs.

I get it. Hopefully I can find a good path through this. I don’t mind it not being perfect but taking it down to the pistons and cylinders, would be nice to have the motor running right.
It is also crazy the price of motors these days. I live in the Seattle area and am convinced there is an inside track to get the motors from the uber rich who re power “just cause” but for some reason I want to keep this one going.

My boat is a really cool ‘59 glassware that I restored and I feel like any more modern of a motor will just be weird

 

[ianmoore]

I get it. Hopefully I can find a good path through this. I don’t mind it not being perfect but taking it down to the pistons and cylinders, would be nice to have the motor running right.
It is also crazy the price of motors these days. I live in the Seattle area and am convinced there is an inside track to get the motors from the uber rich who re power “just cause” but for some reason I want to keep this one going.

My boat is a really cool ‘59 glassware that I restored and I feel like any more modern of a motor will just be weird

Glasspar seafair sedan

 

[ianmoore]

I am in the process of getting parts to rebuild. Ok stock on eBay, but the rings for the 3 ring pistons are expensive enough, and hard to find that it almost seems better to get new pistons.

Is there any quality drop with the WSM parts? I am mostly finding old stock mercury, but there are a couple of pistons and also rod cap bolts

 

[ianmoore]

I wanted to give an update. I got block back from machinist. Though i would have liked to get actual measurements, he told me the current pistons would work well in the cylinders. The one nick i had(in cylinder 6) was beyond the compression chamber and he said was a non issue.

I sourced all new(old stock) pistons of the same dimensions, but all 2 ring. They are arriving this week.

Ive been going through the block, cleaning all surfaces for gaskets, and chasing all the holes. I have the one headbolt that broke on head. I tried reverse driliing but couldn't get it out. I am putting a time cert in that section

I went through the carbs. They all looked pretty good to me, couldn't see any detris, but cleaned them thoroughly and have rebuild kits coming.

I am going to rebuild water pump, replace all fuel lines, and rebuild fuel pump.

I have to replace trim pump motor, which was severely corroded. Was trying to do it without taking motor off boat, but broke a couple of bolts(with pb and heat) and realized at this point its easier to just remove the small parts of motor left. That will give me a chance to inspect the transom and see if Ive gotten any water intrusion

 

[racerone]

Bleed inserts checked if equipped with 5 of them?

 

[Chris1956]

While you have it apart, check the swivel pin for binding. If those two bushings get corroded the motor will be hard to steer, and if it is all together, you will hate yourself. Ditto on the top and bottom rubber motor mounts.

See if you can thru drill the broken water cylinder head water jacket cover. The old IL motors (early 70s) had thru holes and nuts. My '77 water jacket cover bolts were tapped, but you could drill thru the casting on the upper ones and put a nut on it, as the casting had a "pocket" for it.

 

[ianmoore]

Bleed inserts checked if equipped with 5 of them?

If im correct, those would be beneath the balance and the bleed hose? I have the 3 screw in to left of carb and then the one that goes from c6 up to c1. I have no bleed restrictors in any of those cavities. I'm assuming they sit beneath the threaded inserts?