Photo's of Scored Cylinder. What now?

[paperdesk]

Yes! I finally got my boat back, and did a good decarb. It smoked a lot, but when it was done there was no appreciable difference in the compression test as compared with before the decarb. The motor still starts hard and doesn't want to idle.<br /><br />So, I now have the intake, carbs, and leaf valves completely off, and have found that one of the leaves is "sprung" or in other words, it doesn't sit tight against the opening. I am hoping this could be at least part of my problem, so I guess I'm in the market for a new leaf plate. <br /><br />What causes a leaf valve to become "sprung"? Is there something in the cylinder that causes it? I want to fix the source of the problem.<br /><br />Thanks.<br /><br />Ted

 

[paperdesk]

Re: Photo's of Scored Cylinder. What now?

So, I now have the head off on one side, and found that the cylinder that had lowest compression also scoring on it. The other one seems fine, and I suppose the others will be ok too since the compression on them was all about the same.<br /><br />So, here's the question. Is it possible and advised to bore out one cylinder only? It seems like that might cause balance problems? Of course I don't really know anything about it, but hope some of you who've been thorugh it might shed some light for me. I'm assuming that the major cost is buying new pistons, is that right? I guess there are shops here that can bore out the cylinders. Any advice on what to do? What if I leave the cylinder as is. Will it cause more damage? I'm also wandering if the leaf valve will improve performance, or may even be the majority of my problems? Please post your wise counsel!<br /><br />Thanks,<br /><br />Ted

 

[paperdesk]

Re: Photo's of Scored Cylinder. What now?

P.S. For those that don't know, I have a 135hp 1973 Evinrude. Local mechanic wanted 2K to fix it. I don't have a lot of $$ to put into it, so I'm hoping for the cheapest fix. I can do the mechanical work myself.

 

[ledgefinder]

Re: Photo's of Scored Cylinder. What now?

You said the cylinder was scored. How did the top of the piston look? Was it melted or pitted? Was the top ring land broken (area around the rings), or were there other signs of a broken ring? <br /><br />If the piston and head look fine, what were the compression readings?

 

[paperdesk]

Re: Photo's of Scored Cylinder. What now?

I only pulled off the head, so I can't see the rings or sids of pistons. The top of the piston looks fine, no pitting melting that I can see. <br /><br />The scoring is all in one area about 1 1/2 inches wide, and within that there are maybe four grooves (not very deep, but I felt them right away when I ran my finger around the cylinder. It is almost lik a ring scratched it, or some junk got into the cylinder. The rest of it is fine.<br /><br />The compression is as follows:<br /><br />#1 110<br />#2 115<br />#3 111<br />#4 100<br /><br />My problems as you can guess, are with #4. Incidently the bad leaf valve also serves that cylinder. I don't know if it could be related though, since the leaf valve isn't broken, just "sprung".

 

[Bass Runner]

Re: Photo's of Scored Cylinder. What now?

If the cyl isn't scored to deep you can hone and rering, then replace the reeds and you should be good to go unless you find something when you tear it down. Hope you get it going

 

[Bass Runner]

Re: Photo's of Scored Cylinder. What now?

If the cyl isn't scored to deep you can hone and rering, then replace the reeds and you should be good to go unless you find something when you tear it down. Hope you get it going

 

[paperdesk]

Re: Photo's of Scored Cylinder. What now?

That sounds good! I'm still having a hard time finding a source for these kinds of parts, like rings, seals and gasgets. Is it available here at iboats? If not where else?<br /><br />Thanks

 

[Solittle]

Re: Photo's of Scored Cylinder. What now?

Boring only one cylinder is an approved practice by OMC. The weight of the oversized piston is matched to factory specs. so out of balence should not be a problem. <br /><br />Your mechanic's 2K estimate is for a complete rebuild. Most of the heavy duty wrenches here will estimate the cost of a rebuild at $2-300.00 per cyl if you do it yourself with a marine machine shop doing the boring & sypplying the piston.<br /><br />Were it mine I would follow Bass Runner's advice. You could always tear it down again & punch the hole if his suggestion dosen't do it.

 

[paperdesk]

Re: Photo's of Scored Cylinder. What now?

Sounds like good advice! It really didn't take me too long to get to where I am in tearing it down, in fact it was much easier than I expected!<br /><br />I can't believe how helpful the OAM service manuel is! I think it should be required reading for any boat owner, whether they do any of the work on their own motors or not!<br /><br />Thank you, and if anyone has more words of wisdom for me please pass them on!<br /><br />Ted

 

[paperdesk]

Re: Photo's of Scored Cylinder. What now?

One more question though. Does anyone know whether I can remover the piston without taking the powerhead off? I have the heads and carbs off, but I'm hoping to avoid taking the powerhead completely off. The manuel explains complete disassembly, and I'm hoping to avoid that if possible.

 

[G DANE]

Re: Photo's of Scored Cylinder. What now?

Can you post a Picture of the scored area ? <br /><br />It is sometimes possible to run it with minor scoring, and compression readings are still within 10-15% diff, which is what the factory specifications are.<br /><br />I would replace reed blades with new ones, I dont think they are that expensive. As far as I remember lots of motors use the same reed leaves, though. NEVER turn old reeds when reusing, they are prone to breaking, then, thats what I learned.

 

[G DANE]

Re: Photo's of Scored Cylinder. What now?

Honestly, if the scorings are minor, I would lean to replacing reed leaves and run it. You can take compression readings now and then, in exa every 25 - 50 Hrs. The scorings can be from an old overheat or something. But I would prefer if you got someone with more experience than me to second here, and a photo of the scoring would be Great. Where are they located ? Above intake ports ? If there, you can remove by-pass cover and take a look at side of piston and rings too, small job.

 

[paperdesk]

Re: Photo's of Scored Cylinder. What now?

Ok, I'll look up the bypass cover in the manuel and see how to get it off. I'll try to take a photo of the cylinder tomorrow and post it too. Yes, they are above the intake ports. Thank you. I'm too tired to type anymore, so I'll hit it tomorrow. <br />Thanks.<br /><br />p.s. is it ok to use aftermarket gaskets like this: http://www.go2marine.com/frameset.j...tion/GoBPage/id/92926F/hiLiteSku/92926/&df=70

 

[ledgefinder]

Re: Photo's of Scored Cylinder. What now?

If the pistons look OK, you could run it the way it is. However, even without any piston pitting I think it's possible you're overheating cylinder #4, so you probably want to do some checking. I'd clean the carbs, new pump & thermostat (or at least check the thermostat), and check the WTO timing. Also, particularly since you've got the head off, make sure the water passages in the head are clear & put new deflectors in. Two-strokes heat up when run lean, so it's particularly important to check those carbs. <br /><br />I'd be tempted to back the WTO timing off two degrees, and maybe go one size richer on the mainjet on the scored cylinder. Other than that, chances are #4 will run that way for a long time and I wouldn't be hesitant to run it. The scores will get worse, though, something to consider if you are eventually planning a rebuild. I wouldn't rebuild a motor that old, unless for sentimental reasons. <br /><br />I've got a 1973 135 parts motor sitting in the barn. If I remember right, the lower end of the lower reeds (2&4) have some corrosion. If the upper are the same, you're welcome to them for the shipping ($5), jslobvan@exit3.com.

 

[paperdesk]

Re: Photo's of Scored Cylinder. What now?

That's really nice ledge. Thank you. I just bid on an e-bay auction, but if it doesn't work out I'll be very happy to take you up on that.<br /><br />By the way, what are the deflectors? I can't find them in the manual.<br /><br />I'm also a little confused about the continuing advice not to rebuild. Are you saying it is better to buy a rebuilt powerhead? If so, wouldn't it be cheaper to get the old one rebuilt? Especially if I did the work myself? The used and new motors I've priced are really expensive.

 

[paperdesk]

Re: Photo's of Scored Cylinder. What now?

Here are the photo's of the bad cylinder.<br /><br /> http://www.youngdisciple.com/Ebay/Ted's/PICT0246.JPG <br /><br /> http://www.youngdisciple.com/Ebay/Ted's/PICT0251.JPG <br /><br /> http://www.youngdisciple.com/Ebay/Ted's/PICT0252.JPG

 

[moderator1]

Re: Photo's of Scored Cylinder. What now?

^

 

[G DANE]

Re: Photo's of Scored Cylinder. What now?

Hi Ted - Good pictures. I'v seen worse run for a long long time. Fix the reed problem, and do what ledgefinder says. Retard the ignition a tad, overoil a bit, check for overheat causes, and enjoy it.

 

[paperdesk]

Re: Photo's of Scored Cylinder. What now?

Ok! Sounds like a winner to me! I can't thank you guys enough! I'm learning fast, but really appreciate the advice from the "wise ones".<br /><br />Ted