Pistons look corroded and damaged

[madramire]

I have a 1984 Johnson 140 Seahorse Outboard, it's not a bad engine, but needs a major overhaul, so I began stripping it down, Compression was always low on both port and starboard cylinders, so on advice from people here I began the painful process of opening this engine up.

I called a marine mech I know and he advised me to strip it down and document as I go along, photographing each stage for easy reassembly, he said it would mean less cost if work needs doing in shop on inner parts such as pistons and so on.

Well... can anyone take a look at these pistons and tell me if they simply need cleaning or should I replace them? Also, does it look like salt water has corroded anything? It does run in both salt and fresh water, and I usually clean it out with the rabbits ears flushing cold fresh water thru.

Hoping this isn't a write off.

Thanks.

 

[R.Johnson]

Re: Pistons look corroded and damaged

Look's like that engine had a lot of water ingestion sometime in it's life. Until you tear it down to find out, I doubt if the crank, and bearings' look any better.

 

[countvlad]

Re: Pistons look corroded and damaged

I have a 1984 Johnson 140 Seahorse Outboard, it's not a bad engine, but needs a major overhaul, so I began stripping it down, Compression was always low on both port and starboard cylinders, so on advice from people here I began the painful process of opening this engine up.

I called a marine mech I know and he advised me to strip it down and document as I go along, photographing each stage for easy reassembly, he said it would mean less cost if work needs doing in shop on inner parts such as pistons and so on.

Well... can anyone take a look at these pistons and tell me if they simply need cleaning or should I replace them? Also, does it look like salt water has corroded anything? It does run in both salt and fresh water, and I usually clean it out with the rabbits ears flushing cold fresh water thru.

Hoping this isn't a write off.

Thanks.

you camed all the way to this point i wouldnt even bother trying to clean/savage parts.. i would replace piston, rings, bearings... how does the rods and crank look?

theres a reason why you had low compression on the pistons and now its time to rebuild.... dont be cheap, ill cost you in the long run...

good luck

 

[madramire]

Re: Pistons look corroded and damaged

thanks guys, first two replies that confirmed my suspicions.

I think I'm gonna finish stripping, taking apart and then I'm gonna get new Pistons, rings and anything else I need.

I'm not sure how the crank and rod looks yet, haven't finished opening it up yet, been working too

But I won't go cheap, I just want reduce the costs by doing most of the work my self, then once the parts are identified that need replacing, I can get them from Crowely Marine.

Gaskets and all that are priced, I got a price of 95 bucks for a piston kit and I think that included the rings.

I thought the engine was due a good overhaul alright, but once complete, hey, should be good for a fair while again right???

 

[wilde1j]

Re: Pistons look corroded and damaged

Do not buy pistons until you're sure what oversize you will need and while you're taking apart, try to find where the water was getting in. Let the machine shop tell you the size and make sure they know what pistons you're buying. Make sure the shop routinely does outboard blocks, BC they are not the same as auto stuff. You may well have to ship the block for the machine work.

Also, inspect the crank journals very carefully. If it needs replacement, you may want to rethink rebuilding, since cranks are VERY expensive.

 

[emdsapmgr]

Re: Pistons look corroded and damaged

It would be unusual for both head gaskets to go at the same time, causing the significant water intrusion in your engine, so I'd be looking at the inner exhaust cover and it's gaskets for the leak. Also, check that inner cover for any porosity in the casting before you reassemble.

 

[madramire]

Re: Pistons look corroded and damaged

Do not buy pistons until you're sure what oversize you will need and while you're taking apart, try to find where the water was getting in. Let the machine shop tell you the size and make sure they know what pistons you're buying. Make sure the shop routinely does outboard blocks, BC they are not the same as auto stuff. You may well have to ship the block for the machine work.

Also, inspect the crank journals very carefully. If it needs replacement, you may want to rethink rebuilding, since cranks are VERY expensive.

------------------

it's been a very expensive lesson for me so far, never buy a used engine without some sort of paperwork history. The engine is in fairness 25 years old, so I'm not sure if it has ever had a major overhaul done on it. Servicing yes, but what does hta tmena more than sparks chaged, oil checked and some basic stuff besides. I'm not even sure it ever had a tune up, as all parts look fairly old.

Some points of note are:
1. The engine always ran well when running, never above 30 knots, but it wasn't weak in any way.

2. The Telltail was always strong, never hot and always there...

3. It didn't idle very well, but I thought that was compression related.

4. I replaced the sparks recently but they became black and fouled very quickly, and I thought I seen what looked like water in the SB Cylinder - so I began suspecting leakage somewhere.

5. There was a black smoke coming from the exhaust while running fresh water thruto flush at home, but never any white smoke that I remember, but I might have missed it... could have been there, and I missed it.

6. It is a thirsty engine, but the boat is not that heavy, so I would have thought better fuel consumption with the more powerful engine, wrong - it ate the fuel - but again, this could be compression related. It's pushing an SSV-167 Galstron Shallow-V, electric start engine.

I can't really think of any other things I noticed with it... but I knew it needed the overhaul.

To be honest, I'm glad I'm doing this as it means at least "I" know what has been done and what condition it will be in.

The cost can be spread over time, I'm not in a mad hurry to fix her and get out again just for the sake of it.

I want it done right, and part of me knows that a big part of the repair on this engine will be done in shop - but again, since most of the work will already be done, I don't mind that.

So long as when it's done, and rebuilt, the engine is like new. (fat chance, but sure, once can dream)

I'll post a couple more pix for more advice once I have gotten down to the crank and everything else checked.

The Porosity is something I will check for sure, to id where leaks are coming from, also, in fairness, the Gaskets were actually intact, not damage to them no cracks, tears or wear, but they look very old.

We'll see what's needed and if it costs the grand for the crank to be replaced, well so be it, better than spending 10k that I don't have on a new engine.

cheers for the advice so far.

 

[HybridMX6]

Re: Pistons look corroded and damaged

You may not have noticed white smoke and only noticed black smoke as 1 or more cylinders may not have been firing, especially if water was getting in. The black would be unburnt fuel, which means the oil would not be burned either. Once mixed with normal exhaust, it may become difficult to separate the white from the black. Would also explain your poor fuel economy. I'd do a thorough rebuild on it, not just engine internals. Carbs should be rebuilt with new kits, all new fuel hoses installed as well to protect against ethanol in the fuel these days, etc. I did a complete overhaul on a 3cyl 60hp, and my total bill so far is up to $1500, with new waterpump included in that price. Did not need a crank or rods, but did replace all bearings also.

 

[madramire]

Re: Pistons look corroded and damaged

You may not have noticed white smoke and only noticed black smoke as 1 or more cylinders may not have been firing, especially if water was getting in. The black would be unburnt fuel, which means the oil would not be burned either. Once mixed with normal exhaust, it may become difficult to separate the white from the black. Would also explain your poor fuel economy. I'd do a thorough rebuild on it, not just engine internals. Carbs should be rebuilt with new kits, all new fuel hoses installed as well to protect against ethanol in the fuel these days, etc. I did a complete overhaul on a 3cyl 60hp, and my total bill so far is up to $1500, with new waterpump included in that price. Did not need a crank or rods, but did replace all bearings also.

I think that's the plan alright, a complete thorough rebuild and hopefully it will last a while then.

I'm planning on selling this boat once the engine is fixed, I want to be a weekend cruiser instead. Do some longer journies.

But at least then I'll know the engine is worth selling.

 

[captgm]

Re: Pistons look corroded and damaged

Since you're looking for opinions I'll give you mine!---1st off- I don't want to offend you but that motor is pretty old to be putting a lot of money into.......The pistons look real bad and who knows what other problems you'll encounter with a 1984 motor that looks like it has had water intrusion. not sure if its worth putting a lot of money into, you will need a lot of new parts and honestly you should upgrade and rebuild other parts and components while in there if you want it to run good and last. ... when your done you will still have a rebuilt 84 motor. check the buy and sell forums you can find good used late model motors for what it will probably cost you to get the old girl back in tip top shape..


Good Luck
GM ><>

 

[madramire]

Re: Pistons look corroded and damaged

Time for a little update here:

The Crank is clean, there is a positive mark here I think, meaning that I won't have to replace this one.

The Piston rods are slightly discoloured but in very good shape.

The Pistons them selves look to have carbon or oil deposits on them, which I believe is the greyish/brown matter we see on the top, otherwise they look kind of okay, I do think they either need repairing, as in... cleaning, and one definitely needs replacing as it is scored.

The Water intrusion that may have occured was from the exhaust. Once I got the powerhead out of the cowling and on to abench, upon opening the exhaust manifold up, the gasket was blown, it was smothered in oil and gunge... and it was as black as coal in there.

The other side to is, there is a part on the Starboard side of the exhaust that is broken... it's not intact, this had to have been put together this way, during a repair or what ever... I will take another picture and upload this very shortly. This worries me as I am wondering does this affect the compression in the cylinders in any way since there may be a build up of gases and/or oil/fuel that can't escape or is leaking... I'm replacing that part regardless.

The rest of the engine looks good.

I have to dismantle the crank/rods/pistons yet, but I will do that today, it's indoors now and easier to work with.

I am then planning on getting all new gaskets, replacing that broken part (which is metal, and odd that it's broken, it was also missing screws, wasn't fastened in place at all - just hanging there inside the Exhaust ), once I have spoken to OB Marine in Dublin and determined what Pistons I need, I will order those, new sparks and change the oil.

I will clean, make sure all surfaces are smooth and even and I will make sure the exhaust is gleaming clean.

Then, hopefully I won't encounter any more problems once back together.

But I am really glad the Crank is in good shape - piston kits are only 90 bucks a pop ... a crank was gonna be near impossible to get aparrantly.

Any other advice anyone has to offer, I'll be very grateful for it.

(Oh, everything I have done so far is documented step to step, and photgraphed, so I know what I have to do in reverse.)

Also, the bearings on the bottom of the crank are in very good nick and the bearings at the top are perfect too... so I think the main culprit here has been the Exhaust and its gasket. (Feel free to correct me if wrong )

 

[madramire]

Re: Pistons look corroded and damaged

Pistons are certainly in bad shape.

The Port pistons are in incredibly bad shape - the lower piston was missing the outer ring and the upper was scored so bad I can't believe it never made a scraping noise or anything in there in the cylinde.

There is a huge groove in the piston due to a lip of metal in the cylinder itself.


So at least now, finally, I know that there is ? wee bit of work to be done on the cylinder, just a tad eh!

The pistons are being replaced.

The Rods are ok, and I am very relieved... very very relieved that I don't need a new Crank... very clean and shiny

I think it's increadible that someone put this engine back together in the shape it's in.

1. The rear " " in the exhaust is completely broken and the gasket was blown.

2. The Upper Port Piston was missing a ring

3. The Inner Cylinder on the lower port side had a huge "lip" jutting up, and is obviously the culprit for the groove in the piston. Why was this not bored/ground even from the start?

4. There doesn't seem to have been a tune up done on the poor girl, ever!!

At least now I think I am ready to leave the cylinder in to the shop, get new parts, gaskets and sparks, change the oil and get her back up and running.

What does the jury think???

 

[emdsapmgr]

Re: Pistons look corroded and damaged

I think you may need 4 new rods. The rod caps are matched to the rods when machined at the factory. I see they are removed in the picture. Do you have some way to identify which caps go on which rods? If the caps are not exactly matched to the rods, you will fail the crank rod bearings.

 

[madramire]

Re: Pistons look corroded and damaged

I think you may need 4 new rods. The rod caps are matched to the rods when machined at the factory. I see they are removed in the picture. Do you have some way to identify which caps go on which rods? If the caps are not exactly matched to the rods, you will fail the crank rod bearings.

The caps are all documented and photographed, I have a good record of what I did so when putting back together, I don't screw up.

To be honest, I won't be putting together again alone, I have a marine mechanic friend that will be helping me when he is back from Singapore.

My main concern is making sure that the cylinder with the uneven interior is smoothened/ground even and buy new pistons so that the shop can fit them for me.

My other concern is the exhaust, need to replace that broken part, and all gaskets, after it has had a nice cleaning.

Feels great to know exactly what is being done to it now, and feels very positive for getting back up and running.