Lost # 6 cylinder today

[turbinedoctor]

Well my old faithful finaly let me down today. The family and I put out of Kiptopeake and started heading for the fouth island to do a little fishing, but just as we got to within about a half mile, it started with a slapping sound. I quickly shut it down and checked under the hood but every thing looked good. When started again it did not want to idle and ran rough. Not knowing exactly what was wrong I shut it down and started trying to figure out how to get back to the landing.

Remembering I am a Boat US member I decided to give them a call. They were there with in 45 minutes and started the tow of shame. I just came in from looking into the problem and found that the #6 spark plug had been flattened and the piston is pitted and abused. Looks like a rebuild, used motor or new motor.

Does anyone have experience rebuilding inline 6 cylinders?

:sad:

[spareparts]

i have a freind of mine in Youngsville NC that was one of the best rebuilding those things, I don't know if he would mess with one now. It does take a special set of ring compresors. BTW, if it was running rough, odds are you have more than one cylinder down, I've seen those things with 2 dead holes and two barely above 75 psi idle all day long. You might want to think about repower, they are geiting a bit old.

[cterrebonne]

sorry to hear about the misfortune, but this would be a great time to re power and welcome your self to the world of loop charging.

[kamikaze]

I wouldn't both with a rebuild way to expensive for that engine. BUT i suspect you can find a good powerhead for next to nothing if you keep your eye open. Lots of Merc inline six still available - most have rotten electrical harnesses that do them in. You should look into how far back a powerhead swap is possible with your mid before throwing in the towel.

Kamikaze

[Hammerhead]

I replaced my 165 inline 6 I/O mototr only with a crate motor I paid 2K for a few summers ago. Labor was another 1K,...and overall I'm very happy with the results.

[turbinedoctor]

Yeah I think a rebuild is out of the question but I have a spare parts motor almost identical to this one. I will look into swapping powerheads and going the cheap route for now, but first I want to take this one apart to see what happened inside. If it's something like a weak link that got loose and into the cylinder I may consider buying a used motor and stepping up the HP to around 115 or 150.

[turbinedoctor]

Has anyone had sucess with running 115 hp carbs on a 90 hp inline 6? They are so close to the same engine the only difference I can find is the carbs.

[RidgeRunner]

Sorry to hear obout the tower of power motor. #6 was the one that always went out. I know they don't like running lean. Not positive about the difference in the back drag carbs. Looking it up in my shop manual but it doesn't cover them very well. The main/idle tube jets are different.

Book says 90hp .070main/.092 vent tube
115hp .072 or .074 main/ .092 or .096 vent tube
Depends on serial number.

I rebuilt a 90 inline 6 for a friend back in 1995. The way the pistons go in from the front, all at once, all on the crank as an assembly with very little clearance it really requires the special ring compressing tools and patience. To replace a piston or two is a lot of work because you must remove the crank to take a piston out (no removable cylinder heads)

Whatever you do, do it fast summer is about over. Hope this helps.

[cterrebonne]

Sorry to hear obout the tower of power motor. #6 was the one that always went out. I know they don't like running lean. Not positive about the difference in the back drag carbs. Looking it up in my shop manual but it doesn't cover them very well. The main/idle tube jets are different.

Book says 90hp .070main/.092 vent tube
115hp .072 or .074 main/ .092 or .096 vent tube
Depends on serial number.

I rebuilt a 90 inline 6 for a friend back in 1995. The way the pistons go in from the front, all at once, all on the crank as an assembly with very little clearance it really requires the special ring compressing tools and patience. To replace a piston or two is a lot of work because you must remove the crank to take a piston out (no removable cylinder heads)

Whatever you do, do it fast summer is about over. Hope this helps.

sounds like you need a 4 bolt rebuild.

[kamikaze]

What year is the 115 and what year is the 90. May just be the same motor but from different years for how horsepower was rated (powerhead / propshaft) Believe the older (mid 70's) 90/115 in-line six were the same block/porting and carbs where the only difference. I'd go for it, just make sure you can use/mount your 90 electeonic's ( if newer) on the 115 block if it's older. Your not trying to convert a distributor based ignition system to a CDI switch box are you? Maybe more issues with that than mechnicals associated with swapping the powerheads

Kamikaze

[randlemanboater]

If you want to stick w/ a tower of power, just look for a mid 80's 115 and slap it on there.....they are the earlier 150 with 115 stickers, and can be had for 5 or 6 hundred bucks these days.

[turbinedoctor]

Thanks for all the input guys, I haven't decided what to do yet but one thing for sure, it looks like my summer on the water is over.

The carb swap I was thinking about was to put 115 carbs on my 90 if I get it running again. The block seem to be the same just smaller carbs on the 90.

I finaly got the power head off last night but ran out of time. Will start the tear down soon.

The spare motor I have does the same as mine. on mine it wont go past top dead center on # 6 cylinder and my spare wont go past top dead center on # 3 cylinder. What a kick in the NORTONS.

Am searching ebay for used motors but get scared with no warranty, they all say it runs good, well if I listed mine the day before if crapped out, I could have said it ran good also. Who knows when one will die.

Anybody got an extra 10 grand laying around they dont need, send it my way, daddy needs a new motor.

Turbo

[turbinedoctor]

If I stepped up from a 90 hp to a 115 hp how much difference do you think I would see and or notice. None, little or alot?

Turbo

[RidgeRunner]

25 more hp. But same displacement. You might need to reprop for a noticable difference. My guess 5mph and a better holeshot.

[turbinedoctor]

Well I must say I am disappointed, all this way and nobody asked for pictures yet, whats going on with you guys, getting slack in your old age?

Well I finaly got it torn down and found whats making all that racket, and I got pictures to boot. It appears that my lower bearing failed, came apart and some of the balls
from the bearing got into the # 6 cylinder.

Pictures are following but I must warn, these pictures are graphic and those with weak stomachs and little children should leave the room.

































This is what a good piston should look like.

http://www.wellcraftv20.com/gallery/albums/Motor-Torn-Down/100_4634.sized.jpg

This is what a good piston should NOT look like.

http://www.wellcraftv20.com/gallery/albums/Motor-Torn-Down/100_4626.jpg

That shiny piece in the middle lower half is a piece of the ball from the bearing.

Here is a shot of the cylinder head, not the best picture quality but none the less.

http://www.wellcraftv20.com/gallery/albums/Motor-Torn-Down/100_4630.sized.jpg

The dark stuff in the spark plug hole is more ball pieces.

And this is what a good cylinder looks like.

http://www.wellcraftv20.com/gallery/albums/Motor-Torn-Down/100_4631.sized.jpg


Other then a few light scratches on # 6 cylinders wall, which dont show in the pictures, I think it can be honed and reused.

[turbinedoctor]

Well I think I have talked myself into rebuilding the ol' gal myself. I priced all the parts I want to replace while I have it apart and for just under $2000 I can put it back together almost like new. Parts include crank bearings, rod bearings, wrist pin bearings, all new rings, complete set of gaskets and seals, new bolts to replace the old ones and the speciality tools to do the wrist pins and bearings.




Am I doing right or has insanity set in?

Have some pics of the tear down to post later. So far everything looks good.

Turbo

[turbinedoctor]

Anybody got an idea of what kind of break in proccedure I should use when the rebuild is done?

Turbo

[RidgeRunner]

Doc, Insanity is a condition of boat ownership. The fact that you can ask yourself "Am I Insane?" leads me to believe that your mind may still be sound.
Your ability to make a rational decision???:hide:

Break-in oil ratio -- Old School 25:1 (double oil)
I have heard of some going 30:1 on another thread. 25:1 was good enough for all major outboard manufacturers so 25:1 works for me.
No wide open romps for at least 10 hours and then only for a short time say 20 seconds. Do not let it stay at one RPM for long periods of time. The idea is to let the friction surfaces get accoustomed to one another without creating any super hot spots and possible sticking a piston. When you do get some hours on it that motor needs to spin free. Make sure your not lugging the inline 6 they like lots of RPM on the big end. Not positive but 6600 to 7000 is what I remember.

You must love that motor. How do you propose to clean up the damage to the block in the head area and around the spark plug? It would need to be smooth to prevent predetonation. Looks like some irregularities to the counterweights on the crank. Probably where the rod was shearing the bearing. If it were my money I would take the block and rotating assembly to a good machine shop. They can check the bore for roundness, magnaflux the rods and give suggestions on which way to proceed. They would be my "second opinion" and they typically do it for cheap $$$. I would consider it insurance for $2K you will spend on the rebuild kit. When my 90 Jrude broke a ring the damage was similar to yours but I replaced the head, you don't have that option. How do the reeds look? They get pricey for that motor. Pistons are not cheap.

If I ain't mistaken where the motor bolts to the boat is BIA standard, you may want to take a breather and spend some time looking for a newer powerplant. Or maybe a inline 6 for a powerhead swap as someone suggested earlier.
Been there with a 84 inline 90. That motor really screamed. Good or Bad depending on your perspective. My .02
Best of luck whatever you decide.

[turbinedoctor]

Thanks for the input Ridge, I was thinking along those same lines for break in. I did not how ever consider the roughness in the head as a starting point for predetonation. I was going to wire brush it clean and a little smoother, I may have to work a little harder in there now.

To late to consider a rebuilt power head since I just ordered $2122.00 worth of parts and tools. I do have a parts 90 inline I am going to get the replacement piston out of, I'll check the head on that one. It should be in better shape, if so I'll use that block.

Thanks, Turbo

[turbinedoctor]

Well I tore down the spare motor and the heads look much better then mine, so I will be using that block, crank and pistons. I am still waiting for the parts to arrive, checked with the supplier and they are waiting for the new wrist pin washers before they ship my order. I am still cleaning parts, so it's no big deal yet. I have to take one piston from my old motor and use with my spare due to damage on # 3 piston. While cleaning the one from my old motor I noticed that the pistons in the spare have a bevel on the intake side, where as my old one does not.

Question: will it hurt to use the piston that does not have the bevel along with the 5 that do?

Turbo

[turbinedoctor]

I dont know if I put it into words as well as it could be, so here are some pictures of the pistions.

http://www.wellcraftv20.com/gallery/albums/Motor-Torn-Down/100_4669.sized.jpg






http://www.wellcraftv20.com/gallery/albums/Motor-Torn-Down/100_4670.sized.jpg

[turbinedoctor]

My other thought is instead of buying a piston at $100.00 is to take the non beveled piston to a machine shop and have it beveled.

Any thought either way?

[RidgeRunner]

Cut it. I don't know the reason for the bevel unless there is a clearance issue in the block at the combustion chamber or different porting from one block to another. If you don't cut it you would have more compression on that hole or worse, interference. You can take it to a machine shop or you can take out the file and do it yourself. You will get it plenty close enough just don't use anything that will cause a build up of heat and make sure it is nice and smooth like the rest of the piston.
I responded to this thread earlier that the tower of power likes to spin free but was wrong on the rpm. Some of the 150 hp inlines like to spin up to 6800 to 7000 but I read somewhere that the 90 and 115 like fewer like 5800 to 6200 max. The fact that it lived as long as it did is proof that you must have been doing it right all along.
How about the tools, were you successful in locating the tools you needed?

[turbinedoctor]

Cut it. I don't know the reason for the bevel unless there is a clearance issue in the block at the combustion chamber or different porting from one block to another. If you don't cut it you would have more compression on that hole or worse, interference. You can take it to a machine shop or you can take out the file and do it yourself. You will get it plenty close enough just don't use anything that will cause a build up of heat and make sure it is nice and smooth like the rest of the piston.
I responded to this thread earlier that the tower of power likes to spin free but was wrong on the rpm. Some of the 150 hp inlines like to spin up to 6800 to 7000 but I read somewhere that the 90 and 115 like fewer like 5800 to 6200 max. The fact that it lived as long as it did is proof that you must have been doing it right all along.
How about the tools, were you successful in locating the tools you needed?

Since I have 5 non beveled pistons I will probably play with one to do it myself. As to the rpm's the manual calls for 5000 to 5200. I have the largest jets in the carbs to make sure it is rich, use only Quick silver oil and as per two different mechanics which dont know each other, I run premium gas for the octane, helps prevent knock. I have most of the tools coming with the order of parts and found the two tools that are NLA at Powerhouse marine, these two are in my pocession now. If you need to do a rebuild on one of these let me know and I can sent up a rental plan for the tools. LOL

[turbinedoctor]

Well its been a long time in the making but I finally got her running on the muffs. Now I just need to put her in the water to set the idle in forward gear. She sounds better than ever.

I will try to post photos from where I left off along with quick captions for those who are interested.

Durwood

[turbinedoctor]

Well I put my Dremal to work and I think it turned out pretty good.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4680.jpg

[turbinedoctor]

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4683.jpg

[turbinedoctor]

Most of my parts arrived along with my tools.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4684.jpg

[turbinedoctor]

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4685.jpg

[turbinedoctor]

Time to start putting all this back together.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4697.jpg

[turbinedoctor]

Upper bearing insertion tool.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4698.jpg

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4700.jpg

[turbinedoctor]

Using the drive shaft for a engine building stand.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4702.jpg

[turbinedoctor]

Replacing the reeds while I am here.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4716.jpg

[turbinedoctor]

Installing reed valve bearing blocks.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4725.jpg

[turbinedoctor]

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4726.jpg

[turbinedoctor]

New rod bearings.


http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4727.jpg

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4728.jpg

[turbinedoctor]

Rods onto the crank.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4731.jpg

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4732.jpg

[turbinedoctor]

Center main bearings.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4733.jpg

[turbinedoctor]

Piston pin tool.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4736.jpg

[turbinedoctor]

Now the pistons go on.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4737.jpg

[turbinedoctor]

With new piston pin bearings and washers.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4740.jpg

[turbinedoctor]

Putting all 6 pistons in at the same time was pretty easy with the ring compressor kits.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4741.jpg

[turbinedoctor]

Installing the upper and lower bearing end caps.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4757.jpg

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4758.jpg

[turbinedoctor]

Inspecting the rings. All OK, none broke on the way in.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4762.jpg

[turbinedoctor]

Some where along the way I forgot to take pictures but here it is back on the mid section and wired up.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4998.jpg

[turbinedoctor]

Thats all the pictures I got for now.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_5005.jpg

[RidgeRunner]

Can you imagine trying to do the rings without the tool? :clap: Those motors scream...Do you have it running?

[Blue_Runner]

Great job Turbo! I wish I had that kind of skill.

[bigshrimpin]

Turbine - I am worried about the journal in this picture. Were those water marks or just oil? . . . Did they come out with crocus cloth? In this pic . . . They look like a bit like chatter marks.

http://i87.photobucket.com/albums/k127/lmsgps1990/Boat/Motor%20Rebuild/100_4725.jpg

[RidgeRunner]

Big Shrimpin I believe that is the reflection of the metal building/Quonset hut.

[turbinedoctor]

Yes those marks are a reflection. You had me worried for a minute but if you look close you will see a redish line down the middle, that is the reflection from my engine hoist.

I have more invested in the tools than I would like to confess to but I wanted to make sure it went together right.

Yes she is running, I have a short video of her first time. I did not have an hour meter before so I installed one before I fired it up for the first time. I now have 1.3 hours on it but they are all on the muffs or in a tub. I need to put it in the water to set the idle while in forward gear.

I have rebuilt auto engines before but never a outboard let alone a 2 stroke.

All and all I am happy with the way it has turned out so far. I'll try to keep you posted as the break in process.

Durwood

[Skools Out]

don't forget to run double oil during first 25 hours for break in to prevent ring damage.

[turbinedoctor]

30 gallons of 25:1, gottcha covered, even installed an above deck tank to keep from having to double the 60 gallons in my inboard tank.