1979 Evinrude 115 Idle Trouble

[BoatDr]

Hey guys, it's my first time posting in the engine forum. I posted a bit last year in the Restoration forum while I was restoring my `66 Starcraft. Now that she's been in the water for about a month this summer, the engine has been having some idle problems. I'm actually down at school, but my little brother has been describing the problems for me. He says that at low RPM's the engine is louder and shakes, then eventually stalls out. At higher speed/RPM's (he estimates ~5 mph), it quiets down and stops shaking. When he guns it, there's a slight delay, like the engine is struggling, and then it accelerates and runs normally. I had him to clean the plugs and clean the carbs with spray carb cleaner, but that didn't fix anything I included a video he sent me of it stalling out. Any help is greatly appreciated. Thanks.

-Erik

http://www.youtube.com/watch?v=ivMP9MO_7MU

 

[Solittle]

Re: 1979 Evinrude 115 Idle Trouble

Sounds to me like you need to kick the idle up a bit. What rpms are you at now when in neutral with the boat in the water?

Cleaning the carbs with spray cleaner does nothing other that make what you can see look good. It is the crud in the passages that you cant see that causes problems. I'd adjust the idle rpms before I messed any more with the carbs.

 

[BoatDr]

Re: 1979 Evinrude 115 Idle Trouble

Sounds to me like you need to kick the idle up a bit. What rpms are you at now when in neutral with the boat in the water?

Cleaning the carbs with spray cleaner does nothing other that make what you can see look good. It is the crud in the passages that you cant see that causes problems. I'd adjust the idle rpms before I messed any more with the carbs.

It hasn't had any trouble until now. I do a lot of trolling, so I don't want to kick the idle up too much. Not sure of the RPM's...no tach yet...she's a work in progress haha

 

[BoatDr]

Re: 1979 Evinrude 115 Idle Trouble

Would a lot of trolling gunk up the carbs?

 

[BoatDr]

Re: 1979 Evinrude 115 Idle Trouble

I'll try some things when I get home this weekend. Hopefully it's a quick fix.

 

[BoatDr]

Re: 1979 Evinrude 115 Idle Trouble

My buddy checked it out for me and found a small fuel leak coming from the carburetor area. Hope that's the only problem.

 

[BoatDr]

Re: 1979 Evinrude 115 Idle Trouble

Well, fixed fuel leaks, replaced fuel pump, changed the idle. Got her idling when she's trimmed all the way down, but as soon I trim it up, she stalls out. Any suggestions? Also when I was driving her to the launch, cruising about half throttle, the engine would start vibrating loudly. I would back off the gas and it would go away. I would then bring it back up to speed for about a minute and it would repeat. Thanks guys.

 

[mrcj001]

Re: 1979 Evinrude 115 Idle Trouble

Got her idling when she's trimmed all the way down, but as soon I trim it up, she stalls out.

Carburator floats are misadjusted.

With the carb off the motor and the bowl removed, hold the carb in the up right position. The float should dangle 1" +/- 1/8"


Alot of trolling "could" foul up a carb. Clean them and open the spark plug gap a little.

 

[BoatDr]

Re: 1979 Evinrude 115 Idle Trouble

Well, it's been a while since I've last posted and a lot has happened since August. A good old compression check yielded readings of 0-60-60-90. Not so good. No wonder I was having trouble idling. I'm surprised it even ran! Pulling the head revealed the following on the starboard side:

The mechanic quoted $2500+ for a rebuild, so I decided to take the powerhead down to school and make a project out of it. I tore it down and found that a piston ring had broken in cylinder #1 and the pieces ended up in cylinder #3 and caused the above damage and scoring both of the cylinders. The #1 piston appears charred around the area of the broken ring. I'll post a picture when I get a chance. I found some suspicious areas on the crank:

Is this damage or just imperfections from the casting? The bearing surfaces of the crank look to be in good shape. They are smooth without any discoloration. I still haven't checked the bottom bearing surface because I can't get the bottom seal off. Any suggestions? Are there any other areas that I should inspect for damage? There is some spalling on the surface of the main upper bearings, so I imagine that those need to be replaced. How do I tell if other bearings need to be replaced?

The big question is what caused the ring to fail in the first place and can I address the problem so it doesn't happen again? Right now the plan is to bore all 4 cylinders since the compression was crappy on all of them. I imagine the machine shop will determine what OS piston needs to be used depending on the damage. Is it ok to bore all 4 to .030 OS or will this cause problems with overheating? I also plan to rebuild the carbs, and replace the thermostat, fuel lines and water pump. Is there anything else I should replace during the overhaul?

 

[DargelJohn]

Re: 1979 Evinrude 115 Idle Trouble

All the low speed trolling gummed up the piston/rings causing the ring to stick and break at higher speeds. The crankshaft is probably a casting imperfection. You need to totally disassemble and look at all the journal surfaces for damage. I would get a complete rebuild kit from a manufacturer: piston kits, seals, gaskets, rod bearings, main bearings, etc., get cast aluminum piston (no forged). If you are going to the trouble of rebuilding the powerhead, then I would not cut corners. 0.030 over is fine. While apart, be sure to inspect your reed valve cages for imperfections.
Take your time and have fun.

 

[daselbee]

Re: 1979 Evinrude 115 Idle Trouble

I really doubt that a broken ring in #1 could cause damage in #3. They are both on the stbd side, my bet is that side was overheating and coked up, causing both cyls to fail.

 

[BoatDr]

Re: 1979 Evinrude 115 Idle Trouble

I really doubt that a broken ring in #1 could cause damage in #3. They are both on the stbd side, my bet is that side was overheating and coked up, causing both cyls to fail.

The rings in #3 were fine and the piston wasn't coked up like the #1, which surprised me. What else could have gotten smashed between the head and the piston? What would cause just the starboard side to overheat?

 

[emdsapmgr]

Re: 1979 Evinrude 115 Idle Trouble

That engine has a thermostat for each head. If you have a stuck stat, it can affect both pistons on one side. If you troll (idle) all the time, a stuck stat can have a really detrimental affect on both pistons, as all cooling water must go through that stat. Having said that, a stuck stat is not always a primary cause for a ring failure. If the engine spends a lot of time on plane, the pressure relief valves open in the stat housing, flooding the powerhead with a lot of extra cooling water-which should somewhat negate a stuck stat. As a precaution during rebuild, change both stats out and check the operation of hose pressure relief valve. A broken ring on a crossflow is a common malady. Running these powerheads on today's poor (ethanol) fuels tends to accumlate carbon around the rings. If enough carbon builds up over time, it prevents the incoming fuel (and it's oil) from getting to the top ring from the (intake side) backside. Once that happens, the top ring runs hot, rubs the cylinder walls, cracks, then catches a port and distintegrates in the combusion cylinder. The head and piston top get dents. from the debris. Sometimes bits of metal get imbedded in the head, which can later break loose in a new powerhead. Bombardier makes a carbon preventative product just for this situation, called Engine Tuner. It should be used annually in engines that accumlate a high number of hours each year. As long as the seal rings in the crank are ok, I'd be inclined to reuse the crank, even with that imperfection in the picture. The factory permits engines to be overbored up to .030 over without changing the jetting on the carbs. In fact, you can do only one or perhaps two overbores. You don't have to do all 4 unless the cylinders are tapered out of spec and the pistons are oval. Doing a water pump is a must. Also, the carbs need to be completely torn down and gone through. After $2500, you don't want skimp on the overhaul. If you have original fuel hoses and fuel pump on that engine, you may want to change them. The rubber in them from 1979 is not compatible with today's ethanol fuels. When you have the carbs apart, check for bits of black residue/debris in the carb jets...

 

[daselbee]

Re: 1979 Evinrude 115 Idle Trouble

The rings in #3 were fine and the piston wasn't coked up like the #1, which surprised me. What else could have gotten smashed between the head and the piston? What would cause just the starboard side to overheat?

A piece of ring would have to be ejected from #1. The piece would no doubt be moving at a high rate of speed. It would then have to go into the exhaust port of #3. The only time it could go IN is when the piston is down, and the exhaust gasses are being ejected from #3, also at a high rate of speed. That ring piece from number one would have to bounce back toward #3's port, and overcome the gasses rushing out, just at the perfect time, and bounce INTO #3's cylinder.

Does this sound likely to you? It does not to me. That head damage was likely from an event earlier in the engine's life.
Do you know the history of the ehgine? Has it had cylinder damage in the past?

 

[BoatDr]

Re: 1979 Evinrude 115 Idle Trouble

Well, I took another look at the pistons (it had been a while since I had them packed away) and took some pictures:

The #1

The #3

Looks like you were correct daselbee. Forgive my ignorance...never done this befrore. It appears a piece of the #3 piston cracked off. So, the starboard side was probably running hot, most likely due to a stuck stat as emdsapmgr had mentioned. Here's some shots of the cylider damage:

#1

#3

Could I get away with just boring two cylinders/replacing pistons on the starboard side if the port side is within standard specs? Or do I have to do all four?

 

[daselbee]

Re: 1979 Evinrude 115 Idle Trouble

Ummm....

First thing that stands out....look at the ends of the piston pins...wow...those are really coked up. (Carboned up). I never saw any that bad. Really. And what is with that cylinder rust? Has this set up for a while? If rusty, you will have to bore it, I think.

But anyway, that engine ran coked up, broke all kinds of things...

I just repaired one that did the same thing. STBD side and all. Truly. I did it on a shoestring budget, and cut all kinds of corners, and the darn thing runs great.

First off, I measured the bore damage. It was within specs to simply hone out the really bad looking stuff. Guess what? I left two serious scores (one in each cyl) per the owners request. Your scores are much worse that the ones that I left. You could barely feel them with your fingernail, but you could absolutely see them. I also hand chamfered the gouges in the ports left by the broken rings. I just kinda smoothed it with the air die grinder. The owner didn't want to bore the engine...no money.... I split the crankcase, never disturbed the port side at all. Port head stayed on, as it had good compression. Crank stayed in. I honed the stbd side with the crank in place, used a simple three stone drill powered hone and plenty of oil, and replaced the two pistons with Sierra STD pistons and rings, (even tho there were two scores in #1 and #3). I re-used all the bearings, put it back together, fired it up and it is good right now with 120 psi all around and strong running, steady idle. The only new parts were the pistons, rings (2) sets, and the associated gaskets.

Only one thing...don't use Sierra gaskets, I learned, and I am not real pleased with the Sierra thermo kit. I truly believe the Sierra springs are weaker than the Evinrude springs, but I am not sure yet.

Yes you can only do one side. I cut major corners. I am NOT recommending you do the same thing. I am simply describing what I did to get the motor running for my friend. I had to look out for dirt and debris, honing slag, etc. But yes, you can only do the stbd side if you want. Most shops will not guarantee anything like I just described.

Examine what you have and proceed with your best feel, based on other's recommendations.
I BET I GOT LUCKY.

 

[BoatDr]

Re: 1979 Evinrude 115 Idle Trouble

I picked this boat up a few years ago as a project boat for about $800. I had never purchased a boat before, so I never bothered checking the compression. The engine ran, which was good enough for a kid who just wanted to go fishing haha. I think I only changed the lower unit fluid and plugs. Looks like it had a few other issues! At least it was a good learning experience.

Rust was also an issue with the lower bearing. The top plate was completely rusted, the lower bearing was rusted on the outside which made taking the lower bearing cap off a pain in the ***. Is there anything else that rust could affect?

I don't know how much money to put into this thing. Being a student, I'm on a shoestring budget, so just getting the thing running decent again sounds like the best plan. Especially since I'll be in residency for the next 5 years and I won't have any free time to use it. But at the same time, I hate half-assing things. I also think that since I've put so much time into this boat, I'll probably hang onto it for the rest of my life for nostalgic purposes alone. It's a tough call.

 

[daselbee]

Re: 1979 Evinrude 115 Idle Trouble

I looked again at your pics of the cylinders, and it seems as if one of those gouges is at least half way through the side of the cylinder sleeve.
If so, that is some major damage, and I doubt you will get this engine repaired as cheaply and easily as you would want.
If you have to bore it, you will absolutely have to strip the block. The rebuild kits are available, and they have bearings, pistons, gaskets, etc. V4 rebuild kits for newer engines run about 750 bucks. Machine work on your V4 would probably run 200-250 for boring and honing 4 cyls.

Look here for an example of a rebuild kit.
http://cgi.ebay.com/ebaymotors/John...6755019QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear

You are up to 1000- 1200 (with miscellaneous costs) and that is with you doing the work yourself.
I hat it when one of these things self-destructs. The parts are so high, and the value of the motor is generally low...
The economics of repairing is very iffy. At any rate, good luck with whatever you decide.