Worn Piston Ring on my Merc 4.3l TKS

fossill

Chief Petty Officer
Joined
Jun 20, 2009
Messages
427
Re: Worn Piston Ring on my Merc 4.3l TKS

I still think it's possible to just need new piston rings installed, along with cylinder honing before re-seating the new ones, without a complete rebuild with all new parts.

Your right it is possible but a waste of time and money as you'll be ripping that engine apart again in short order. Be it mine, I'd rip the head off and if the pistons cabbage, get a long block or crate engine......and make sure you got the root cause of the issue fixed.
 

jdwarns

Seaman Apprentice
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Apr 5, 2009
Messages
34
Re: Worn Piston Ring on my Merc 4.3l TKS

As I mentioned earlier, 200? temps will not damage the engine. Things like improper timing, lean fuel/air mixture at speed, vacuum leaks, etc. can lead to piston damage.
Here are a couple of pages from a service manual to help explain. Note: Many times the edges of the piston melt off and you can actually see a lot of the ring.

http://forums.iboats.com/attachment.php?attachmentid=97654&stc=1&d=1307811924

I'm not saying that I overheated it with 200. I'm saying a previous owner could have. When it hit 200 for me, I shut it down and fixed the problem. The previous owner might have let it get well above 200. Originally, I thought 200 might have overheated it but you helped me understand that it wouldn't, so I'm thinking it might have gotten a lot hotter than that before I came into ownership.
 

jdwarns

Seaman Apprentice
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Apr 5, 2009
Messages
34
Re: Worn Piston Ring on my Merc 4.3l TKS

Your right it is possible but a waste of time and money as you'll be ripping that engine apart again in short order. Be it mine, I'd rip the head off and if the pistons cabbage, get a long block or crate engine......and make sure you got the root cause of the issue fixed.

I absolutely agree. It shall be done :).
Thanks again everybody for your responses.
 

joncrisler

Petty Officer 2nd Class
Joined
Sep 25, 2009
Messages
150
Re: Worn Piston Ring on my Merc 4.3l TKS

I see you are in Annapolis MD. If you decide to replace the engine, contact Seven Seas at Mears Point: they charge 8 hours to remove and replace a stock Merc engine. 4.3's are very common and inexpensive. As for the paint bubbling on the underside, it could also be due to some salt water corrosion or condensation issues, especially if the boat is left in the water. Figure about 10-20% salt water in the Annapolis area depending on rainfall, time of year etc. If the boat runs more or less ok, you might consider just running it this season and schedule the engine swap for the winter time. Maybe do an oil change every 20 hours or so, and use a slightly thicker oil: these are just bandaids to keep you boating, and if you go that route, get tow insurance !!!

I was a bit confused by the "funnel" comment- you should use either a oil can squirter / pump, or fogging oil. Funnels and bottles of oil would just make a silly mess :) Also, one poster apparently checked on your engine and feels it is still under warranty- that deserves a serious follow-up.
 

jdwarns

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Apr 5, 2009
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Re: Worn Piston Ring on my Merc 4.3l TKS

Figured I would provide an update on my progress.
I failed to transfer the warranty in time when I purchased the boat, so that option was unfortunately unavailable to me.
Luckily I enjoy doing this sort of work so I'm not really that disappointed.
I was able to get the engine out for $20 and 15 minutes thanks to a forklift courtesy of Annapolis Navy Yard.
I opened up the top end and it looked pristine. I have plenty of pictures if anyone is interested.
I then drained the oil, flipped it upside down, and took off the oil pan. The #3 cylinder wall is scored almost a quarter of the way around.
It appears as though the piston edge is flared out a little but I'm not sure what caused that unless it majorly overheated? I don't see any metal shavings or any rust. I probably need to take it down further to get the full picture of what happened. At this point, I'll probably just take it to a machine shop for a full rebuild. As long as it's out, I might as well get a fresh start with a fully rebuilt, practically new engine going back in.
I'll try to post a pic here showing the damage...
#3 Cylinder.JPG
 

Pete104

Lieutenant
Joined
Apr 30, 2011
Messages
1,439
Re: Worn Piston Ring on my Merc 4.3l TKS

What the top of the piston look like. I'll bet you have detonation issue.
 

jdwarns

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Apr 5, 2009
Messages
34
Re: Worn Piston Ring on my Merc 4.3l TKS

Thanks for the reply. Bond-o has also mentioned this a few times from the beginning.
I haven't gotten to the top of the piston yet, but I imagine that to be true. I'll keep updating as I find more.
Time to diagnose the cause of detonation to prevent it from happening again once the engine is rebuilt...
 

alame

Cadet
Joined
Sep 9, 2011
Messages
20
Re: Worn Piston Ring on my Merc 4.3l TKS

yep...from the pics thats what it looks like to me too
 

jdwarns

Seaman Apprentice
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Apr 5, 2009
Messages
34
Re: Worn Piston Ring on my Merc 4.3l TKS

Here are a couple pics showing the top of the piston. It appears that a detonation took a chunk out of #3...
#3 Cylinder Top1.jpg#3 Cylinder Top2.jpg
 

jdwarns

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Apr 5, 2009
Messages
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Re: Worn Piston Ring on my Merc 4.3l TKS

I'm not yet very familiar with the inner workings of carbs and how to diagnose the mixture one is providing.
Should I just start taking it apart, look for clogged port(s), and then rebuild and tune it?

Also, could a spark plug with too small of a gap cause that plug to overheat and detonate? I don't know why I didn't notice it earlier, but upon further inspection of my spark plugs, #3 had a noticeably smaller gap.
 

joewithaboat

Lieutenant Junior Grade
Joined
Jul 3, 2011
Messages
1,172
Re: Worn Piston Ring on my Merc 4.3l TKS

Other than being burned the pistons look like the engine was running rich...full of deposits??? Goes against a lean condition which defiantly could cause the burned piston. Were the plugs used the correct ones?

Was the engine ever over heated badly? That could have caused rings to loose tension and just have a poor/ dirty running condition and then went on to pre ignition from hot spots.

Anytime I have burned a piston from running lean everything was very clean.

How many hours on this rig? Has it always be yours?
 

bnicov

Petty Officer 1st Class
Joined
May 25, 2009
Messages
348
Re: Worn Piston Ring on my Merc 4.3l TKS

That's why no shop would quote you on just replacing rings. That's pretty nasty looking. Is your short block rebuildable or not?? If not, you need a new or rebuilt shortblock and your heads should be looked at as well since they are off. Spend the money now and have peace of mind. Next, your carb should be professionally rebuilt and the fuel system looked at since a lean condition was the likely culprit of the detonation that pooched your engine. Fix it right now and pay once, otherwise you'll have to tear it apart again and pay twice.
 

Bondo

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Apr 17, 2002
Messages
71,320
Re: Worn Piston Ring on my Merc 4.3l TKS

Also, could a spark plug with too small of a gap cause that plug to overheat and detonate? I don't know why I didn't notice it earlier, but upon further inspection of my spark plugs, #3 had a noticeably smaller gap.

Ayuh,... That's the results, not the cause,....

A piston strike closed the gap on the plug....
I'm not yet very familiar with the inner workings of carbs and how to diagnose the mixture one is providing.
Should I just start taking it apart, look for clogged port(s), and then rebuild and tune it?

It sounds like you got Alota learnin' to do...

Yer motor has Serious problems, 'n really needs a trip to a Machine Shop for inspection, in anticipation of a rebuild....
Or,...
Buy a Long Block, 'n learn how to rebuild the Fuel System, 'n tune it....
 

jdwarns

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Apr 5, 2009
Messages
34
Re: Worn Piston Ring on my Merc 4.3l TKS

Other than being burned the pistons look like the engine was running rich...full of deposits??? Goes against a lean condition which defiantly could cause the burned piston. Were the plugs used the correct ones?
There are a lot of deposits on the other cylinders, which I believe could point to rich condition, cold (incorrect) plugs, and/or worn piston rings allowing oil to pass to the top of the piston.

Was the engine ever over heated badly? That could have caused rings to loose tension and just have a poor/ dirty running condition and then went on to pre ignition from hot spots. How many hours on this rig? Has it always be yours?
I have reason to believe the engine over heated with the previous owner. When I came into ownership of the boat, it started to overheat on me due to poor water flow on the port side (same side as #3 cyl). Although I shut it down right away and fixed it, who knows how long the previous owner ran it like that. I'm the third owner. The previous owner did this boat no favors... Kept it in the brackish water and only used it once or twice per season. That's a recipe for marine growth clogging the cooling ports.

Is your short block rebuildable or not??
The cylinder heads are immaculate, but I have the type of personality that pushes me to have the whole thing rebuilt or purchase a long block rather than a short block. As long as I have it out, I'm gonna do everything I can to get a "fresh start".

Ayuh,... That's the results, not the cause,....
A piston strike closed the gap on the plug....
Damn, that was my first theory and I had it all typed up before talking myself out of it.
Thanks for bringing me back.

It sounds like you got Alota learnin' to do...
Exactly why I'm here and I can't say enough how much I appreciate everyone's contributions. I just hope I can contribute enough back to provide others with the same level of help I've received

Yer motor has Serious problems, 'n really needs a trip to a Machine Shop for inspection, in anticipation of a rebuild....
Or,...
Buy a Long Block, 'n learn how to rebuild the Fuel System, 'n tune it....
I'm calling around to find a good machine shop to do a full rebuild. I also plan on purchasing a carb rebuild kit and learning how to tune it properly. I also plan on getting my intake manifold cleaned up. If I can't find a good shop to rebuild it, I found this long block for sale...
http://www.boat-superstore.com/Boat-Reman-Longblock-43L-2000-Up-43L-V-6-Remanufactured-Pro-Series-Long-Block-Assembly-By-Mercury-Quicksilver_p_44687.html
Seems pretty reasonable unless anyone has a source for a better deal? Thanks again to everyone for helping.
 

Bondo

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71,320
Re: Worn Piston Ring on my Merc 4.3l TKS

Ayuh,.... I clicked on yer link, then the "about Us" button....
The area code is my area, so I googled,...

Best I can figure, a Logger just downstate from me has a few websites, that drop-ship everything known to man....


For $2,600.00, I think you can buy a crate motor from yer local GM Dealer....

Donno...
 

jdwarns

Seaman Apprentice
Joined
Apr 5, 2009
Messages
34
Re: Worn Piston Ring on my Merc 4.3l TKS

Ayuh,.... I clicked on yer link, then the "about Us" button....
The area code is my area, so I googled,...

Best I can figure, a Logger just downstate from me has a few websites, that drop-ship everything known to man....


For $2,600.00, I think you can buy a crate motor from yer local GM Dealer....

Donno...

There were a few benefits I saw to purchasing from the link I posted:
- $10 shipping
- No sales tax

Their site doesn't provide much information on what is included. The picture shows valve covers and an oil pan, which typically aren't included in a long block purchase, and I know better than to trust pictures. Doesn't really matter either way since my valve covers and oil pan are perfectly fine, but I just like to know exactly what I'm getting. They also don't provide any information on core charge. I added the engine to the shopping cart and it just indicated the engine price plus shipping and didn't show any core charge, but they have forms for core return, so who knows. Anyway, something a quick phone call during business hours should clear up. I'll post with more info from that place as I get it.
 

StevNimrod

Petty Officer 1st Class
Joined
Dec 13, 2008
Messages
343
Re: Worn Piston Ring on my Merc 4.3l TKS

You're about to spend a couple thousand on an engine - the real benefits (to me) would be how the internal parts used stack up against the purchase price; and I'd think these parts would be more important than sales tax or shipping in terms of knowing what you're getting.

$10 shipping for an item of this size is just "cost shifting". You will be paying more than $10 in shipping, but that cost is factored into the engine price. For whatever reason, consumers generally see the difference between $10 and $110 as greater than the difference between $2100 and $2200, so a company would expect to have more sales at $2200 + $10 than at $2100 + $110.

The best "deal" usually is going to be the local machine shop, provided he cares about his work (which is usually the case). Unless you know the specific recipe of parts for each engine supplier, how can you possibly shop by price? To quote John Ruskin, "there is nothing in the world that some man cannot make a little worse and sell a little cheaper, and he who considers price only is that man's lawful prey." Point being, price is only a valid consideration if you're comparing exactly the same thing; there are a bunch of different ways to build a stock 350.

If you don't have a contact locally who can recommend a shop, here is a good place to start looking. Call around, ask questions, visit a few shops and let them do the beauty contest routine. While I express no opinion about GM (or any production style place), I think a local machine shop would be less likely to do something like, say, decide they can't be bothered with checking piston-to-wall clearance.

And that doesn't even get us into talking about the paper (conspicuously marked "warranty") that some companies offer/sell/market. I haven't read them all, but if you go that route, read it very carefully. There is "out" language in all of them, even if that involves them refunding your money and not shipping you another engine. This is why it's important to fully troubleshoot and repair your fuel system, and rebuilding the carburetor - while a good place for you to start - is only the begining of the full procedure.
 

jdwarns

Seaman Apprentice
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Apr 5, 2009
Messages
34
Re: Worn Piston Ring on my Merc 4.3l TKS

Thank you for the link. That's very helpful given that it IS actually difficult to locate quality machine shops.
The rest of your advise was a bit condescending and akin to a typical father-son talk. Please don't correlate my "cadet" ranking here with my intelligence level. I know everyone here is just trying to help, and for that I do appreciate more than anything, but let's stay away from lectures on the importance of quality workmanship and parts. I'm a pretty intelligent guy and I bet you would have the same reaction I just had were I to post the above advice to you. Let's talk as knowledgeable adults here. Anyway, I digress...

A couple days ago I made my decision and went with Carolina Machine Engines in Johnston, SC to rebuild my engine. After many calls, they were the only shop that provided me with a sense of confidence in their business. They have a lot of experience and reassured me both through their website and over the phone as to the quality of their workmanship and the parts they use. Their customer service was also the most responsive, helpful, and knowledgeable of all the shops I called. Ironically enough, I just checked out of curiosity and they do indeed show up as an AERA member on the link that StevNimrod provided. That gives me even more peace of mind. They're going to fully re-manufacture my engine for $1,496 plus $195 round trip freight shipping from/to my door. They also spin test for compression as well as oil pressure and distribution before sending it back, which is another must for me.

I also ordered this carb rebuild kit:
http://www.allcarbs.com/detail.php?pid=908&mfgn=56&ctgn=6&stt=0&gb=2
I'll document my rebuild and post pics showing what I find.
 

jdwarns

Seaman Apprentice
Joined
Apr 5, 2009
Messages
34
Re: Worn Piston Ring on my Merc 4.3l TKS

I finally got around to rebuilding my carb. I started by taking the flame arrestor off and immediately made an interesting discovery...
One of the plastic standoffs from my flame arrestor had broken off and lodged itself in one of the barrels.
Could this have disrupted the fuel/air flow and mixture enough to cause detonation in my cylinder?
Carb1.JPGCarb2.JPGCarb3.JPG
 
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