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Thread: Hole in piston

  1. #1
    Join Date
    Nov 2008
    Location
    Long Beach, CA
    Posts
    186

    Default Hole in piston

    Hey guys I took my boat out for a power trial today and blew a hole in the #2 piston on the port side. Cause is unknown all other on that bank look fine. I was wondering if you guys could recommend an engine shop in the southern california region. I suspect rhis was an ongoing problem as this engine always had a low Compression cylinder (I was hoping it was a rusted valve).

    Any input as to my next moves are appreciated.

    Will

    1,586 hours by the way

  2. #2
    Join Date
    Oct 2011
    Location
    maplevalley WA
    Posts
    7,979

    Default Re: Hole in piston

    It sounds like it could be a couple of things it could have been running lean on that cylinder that will burn valves and pistons another possible is the dizzy was not advancing properly causing detonation most likely the cause. As long as the cylinders are good a new piston and re-ring and cross hatch the cylinder walls would be the cheaper way. Get the heads rebuilt and have the distributor gone through and set up with a marine advance curve. Pull the dizzy apart and see what the flyweights and springs look like. Any reputable engine shop will be able to do the engine work and a good electronic (pointless) dizzy would be a nice upgrade.

  3. #3
    Join Date
    Sep 2010
    Location
    Jersey Shore
    Posts
    3,197

    Default Re: Hole in piston

    Old fuel will burn a hole in your piston.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Let the insanity begin.

  4. #4
    Join Date
    Nov 2008
    Location
    Long Beach, CA
    Posts
    186

    Default Re: Hole in piston

    Hey guys thanks for the replies. The engine ran great otherwise awesome oil pressure and all other cyliners look good and had 120-130 compression. Im leaning toward buying a rebuild it and throwing it together.

    The fuel was really old but dilluted 50/50 with new. Other cylinders looked fine, no indications of a lean mix. I dill check the advance on the distributor or take it to a shop.

  5. #5

    Default Re: Hole in piston

    Too,hot of plug burns a hole in the piston.You just don't burn one.I'm sure you have more in line following as well.High Energy Ignition (HEI) distributor's are known for causing this as well.California region,I'm sure money's no object.Open the yellow pages and pick one.More money the better work.You get what you pay for.You'll be better off buying a New Short block in the long run.Less Money,Time & Man hours with a new short block.Plus,you will know what your getting as well a new block.Your engine must be pulled anyway,may as well drop a new short block in it and be done with it.
    The money & time your'll be spending rebuilding that block.Cheaper in the long run with a engine warranty.
    Let's face it,
    What's the condition of the valves now?If you burned a hole in the piston.Just think about the condition the valves must be.Right now we know you'll need a head job done.Did it get so hot to burn a hole in the piston and put a fine hair crack between the valves to crack the head.Maybe,who knows.
    I'm sure the engine was ran while the hole was in the piston,causing metal shavings in the oil pan to the main bearings to oil pump screen as well.
    Don't bother wasting your time & money rebuilding the block.Just buy a short block.

  6. #6
    Join Date
    Nov 2008
    Location
    Long Beach, CA
    Posts
    186

    Default Re: Hole in piston

    The plugs are what the factory call for. but that was a thought of mine also. Surprisingly the valves look okay. I will poor some solvent down the runners and see if they leak. While money is no object to some in southern California it s to me, Im only an E-4! thanks again. Still looking around will know more tomorrow after I call some places.

  7. #7
    Join Date
    Nov 2008
    Location
    Long Beach, CA
    Posts
    186

    Default Re: Hole in piston

    Oh ignition is still the factory points. (1973)

  8. #8
    Join Date
    Sep 2010
    Location
    Jersey Shore
    Posts
    3,197

    Default Re: Hole in piston

    Quote Originally Posted by buick430 View Post
    Hey guys thanks for the replies. The engine ran great otherwise awesome oil pressure and all other cyliners look good and had 120-130 compression. Im leaning toward buying a rebuild it and throwing it together.

    The fuel was really old but dilluted 50/50 with new. Other cylinders looked fine, no indications of a lean mix. I dill check the advance on the distributor or take it to a shop.
    If the fuel is old and the ethanol has separated out, adding new fuel to it does not do anything. You need to drain the fuel tank and put in fresh gas or you will burn a hole in a piston in your new engine.........Guaranteed.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Let the insanity begin.

  9. #9
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    7,308

    Default Re: Hole in piston

    I agree with the suggestions of old degraded fuel, and possible ignition advance issues. Either may cause detonation damage.
    The somewhat surprising thing to me is..... that you damaged only one piston.

    Ditto having the distributor tested, or better yet, replace it with new, and go with electronic triggering.


    .
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  10. #10
    Join Date
    Nov 2008
    Location
    Long Beach, CA
    Posts
    186

    Default Re: Hole in piston

    weather it was the old fuel (7 years) or a bad advance curve I still dont understand that it damaged only one piston. I found a great deal locally on a low hours so I am gonna go that route.

    Now I need to figure out how to get rid of 70 gallons of fuel!
    Test/replace the distributor.
    Turn boat in slip then remove and install the engines.

    thanks again guys,

    will

  11. #11
    Join Date
    Dec 2006
    Location
    Chaumont Bay, N.y., USA
    Posts
    4,223

    Default Re: Hole in piston

    Quote Originally Posted by buick430 View Post
    weather it was the old fuel (7 years) or a bad advance curve I still dont understand that it damaged only one piston. I found a great deal locally on a low hours so I am gonna go that route.

    Now I need to figure out how to get rid of 70 gallons of fuel!
    Test/replace the distributor.
    Turn boat in slip then remove and install the engines.

    thanks again guys,

    will
    Ayuh,.... No Doubt it was Bad gas,.... Detonation from lean conditions does that,....

    1 side of the carb is probably boogered up worst than the other,..?.
    That spark plug was indexed, just the right way,..?.
    That cylinder had more, or maybe less carbon build up,..?.

    I'd be doin' a Full system clean out, startin' at the tank, goin' to the carb.....

    Seven(7) year old gas,..??..?? What were ya Thinkin',..?? did ya do a Smell test,..??
    Any Grease is Better,... Than No grease at All....

  12. #12
    Join Date
    Sep 2010
    Location
    Jersey Shore
    Posts
    3,197

    Default Re: Hole in piston

    Quote Originally Posted by buick430 View Post
    weather it was the old fuel (7 years) or a bad advance curve I still dont understand that it damaged only one piston. I found a great deal locally on a low hours so I am gonna go that route.

    Now I need to figure out how to get rid of 70 gallons of fuel!
    Test/replace the distributor.
    Turn boat in slip then remove and install the engines.

    thanks again guys,

    will
    All of Bondo said,

    And the fact that there is always one cylinder that runs more lean then the rest. I have removed and replaced at least 5 engines in the last two years that had one burned piston with no damage to the rest. All from bad fuel.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Let the insanity begin.

  13. #13
    Join Date
    Nov 2008
    Location
    Long Beach, CA
    Posts
    186

    Default Re: Hole in piston

    I guess underestimated bad fuel. Hopefully no damage was done to the other engine!

  14. #14
    Join Date
    Sep 2010
    Location
    Jersey Shore
    Posts
    3,197

    Default Re: Hole in piston

    Quote Originally Posted by buick430 View Post
    I guess underestimated bad fuel. Hopefully no damage was done to the other engine!
    Get a bore scope and take a look.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Let the insanity begin.

  15. #15
    Join Date
    Nov 2008
    Location
    Long Beach, CA
    Posts
    186

    Default Re: Hole in piston

    Oh and the carbs are fresh rebuilds. Honestly I was being cheap and lazy by trying to run the old gas. It did smell quite bad.

  16. #16
    Join Date
    Oct 2011
    Location
    maplevalley WA
    Posts
    7,979

    Default Re: Hole in piston

    If it was detonation you would think more than one piston would be affected same as if it was the fuel I`m leaning toward maybe a vacuum leak on that port on the intake manifold or a intake valve not opening as far causing a too lean condition on that cylinder how did the valves look on that cylinder did you check for valve lash before you pulled the heads a worn lobe on the cam is another possibility. If you just gonna swap it out no need to determine the fault unless your gonna rebuild it. Do a thorough diagnostic on the other engine if it is weak also you would want to make them both the same and be good for a while. A couple short blocks rebuild the heads and have the dizzys reconditioned with matched curves that way your not fighting the wheel to keep it straight.

  17. #17
    Join Date
    Sep 2010
    Location
    Jersey Shore
    Posts
    3,197

    Default Re: Hole in piston

    Here is a Freshly rebuilt engine from a good builder. I installed the engine and ran it on a remote tank. I advised the boat owner to have his tank pumped out because of the fuel being 2-3 years old. Someone told him to add some fresh gas and all would be fine. So he did. This was the result. This engine did not make the ten hour mark.

    You can ask around until you get the opinion that you want to hear.

    In the end it will cost you. Just like this boat owner, Warranty Was Void. Just to save 70 gallons of fuel.

    Click image for larger version. 

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    Last edited by Docksidemarineservices; 08-01-2012 at 08:30 AM.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Let the insanity begin.

  18. #18
    Join Date
    Jul 2006
    Location
    Redmond, WA, USA
    Posts
    214

    Default Re: Hole in piston

    +1 on the old fuel, when I bought my boat it had 300 gallons of year old fuel and you could hear the engines ping at high power so I just limited the rpm to about 2000 rpm until I had used it up.

    Dan

  19. #19
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    Sep 2010
    Location
    Jersey Shore
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    Default Re: Hole in piston

    Quote Originally Posted by tolly_family View Post
    +1 on the old fuel, when I bought my boat it had 300 gallons of year old fuel and you could hear the engines ping at high power so I just limited the rpm to about 2000 rpm until I had used it up.

    Dan
    Running your engine at 2000 rpms puts more strain on it than running it WOT. The only place old fuel should go is to the recyclers.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Let the insanity begin.

  20. #20
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    12,597

    Default Re: Hole in piston

    ...."Running your engine at 2000 rpms puts more strain on it than running it WOT"

    Only if it's lugging at low speed. Obviously, your car/ truck motor will last longer cruising at 60 mph than flat out at 100!

    Jeff

  21. #21
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    Sep 2010
    Location
    Jersey Shore
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    Default Re: Hole in piston

    Quote Originally Posted by fastjeff View Post
    ...."Running your engine at 2000 rpms puts more strain on it than running it WOT"

    Only if it's lugging at low speed. Obviously, your car/ truck motor will last longer cruising at 60 mph than flat out at 100!

    Jeff
    Most old carbed boats are lugging between 2000 and 2500 RPMs. Under jetted for ethanol fuel.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Let the insanity begin.

  22. #22
    Join Date
    Feb 2011
    Location
    pocono's PA
    Posts
    64

    Default Re: Hole in piston

    Chris, great info I never realized the jetting issue with ethanol fuel!

  23. #23
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    12,597

    Default Re: Hole in piston

    Chris makes a really good point, for all of the OBs I mess with need their idle mixture screws opened a bit to again idle properly.

    I had to rejet one of the Edelbrocks on my boat when the plugs came out a bit too white for me (though that's what tends to happen with ethanol). My late buddy's drag car's plugs were stark white after a run on pure methanol. It takes an expert to read such plugs (which is what he was).

    Jeff

  24. #24
    Join Date
    Sep 2010
    Location
    Jersey Shore
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    3,197

    Default Re: Hole in piston

    FYI for all the inboard and I/O owners. With ethanol fuel I adjust the prop size so most engines will approach 5000 rpm at wot. Any engine that is spec-ed to run between 4600 and 4800 @ WOT

    Yes, a couple of hundred more RPMs at cruise speed but no damage from Ethanol fuel.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Let the insanity begin.

  25. #25
    Join Date
    Nov 2005
    Location
    Chi West, IL, USA
    Posts
    610

    Default Re: Hole in piston

    some info on plug reading here may be useful...............

    http://www.4secondsflat.com/Spark_plug_reading.html

  26. #26
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    7,308

    Default Re: Hole in piston

    Quote Originally Posted by Docksidemarineservices View Post
    Here is a Freshly rebuilt engine from a good builder. I installed the engine and ran it on a remote tank. I advised the boat owner to have his tank pumped out because of the fuel being 2-3 years old. Someone told him to add some fresh gas and all would be fine. So he did. This was the result. This engine did not make the ten hour mark.

    You can ask around until you get the opinion that you want to hear.

    In the end it will cost you. Just like this boat owner, Warranty Was Void. Just to save 70 gallons of fuel.

    Click image for larger version. 

Name:	Photo223.jpg 
Views:	61 
Size:	55.3 KB 
ID:	5200
    Chris, if I may...... I'll assume that this is a SBC. Part of the problem with detonation is this piston design.
    The full dished piston (with the SBC cylinder head chamber design) gives the gasses a place to hide from the flame front, and the results are often detonation when/if the ignition advance is too agressive.
    Good fuel/bad fuel, it sometimes makes little difference.

    No real point here, other than to point out this poor piston design.


    Quote Originally Posted by Docksidemarineservices View Post
    Quote Originally Posted by [B
    tolly_family][/B] +1 on the old fuel, when I bought my boat it had 300 gallons of year old fuel and you could hear the engines ping at high power so I just limited the rpm to about 2000 rpm until I had used it up.
    Dan
    Running your engine at 2000 rpms puts more strain on it than running it WOT. The only place old fuel should go is to the recyclers.
    Dan, I have to agree with Chris on this.............. 2k rpm is not a good rpm to sustain, IMO.
    Most of our hulls are not yet on step at/near this rpm range, which means that detonation potential is greater at/near this rpm.
    Plus, at this RPM, you're probably burning excessive fuel for the distance traveled.

    .
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  27. #27
    Join Date
    Jul 2006
    Location
    Redmond, WA, USA
    Posts
    214

    Default Re: Hole in piston

    Quote Originally Posted by Docksidemarineservices View Post
    Running your engine at 2000 rpms puts more strain on it than running it WOT. The only place old fuel should go is to the recyclers.
    I wasn't saying that 2000 rpm was a good cruising speed it was just a safe rpm where the engines wouldn't ping and I could use up the old fuel, that was 10 years ago.

    Now that fuel is so expensive I make my long distance cruises at 1700 rpm and 8 knots, this gives me almost 2 mpg compared to 1/2 mpg at 16 knots and 3000 rpm..

    Dan

  28. #28
    Join Date
    Nov 2008
    Location
    Long Beach, CA
    Posts
    186

    Default Re: Hole in piston

    Hey guys, Thanks for all the replies. I Have the block out of the boat and sitting at a machine shop. He said the heads/valves are in great shape. They already have hardened exhaust seats and have ben rebuilt recently. Upon disassembly he noted the crown of the #2 piston is irregularly worn (plus the whole). The cam checked fine along with the mains and rods. He could not come up with a good explanation for the damage to this piston alone, other than bad gas, vacuum leak on that port(ruled out with propane before disassembly) or lots of carbon. Either way a Master rebuild kit is on the way.
    Hopefully I have it running soon.
    thanks again, will

  29. #29
    Join Date
    Nov 2008
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    Long Beach, CA
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    186

    Default Re: Hole in piston

    oh and just for the record, the old fuel is being disposed of and the tanks are getting cleaned dockside.

  30. #30
    Join Date
    Oct 2011
    Location
    maplevalley WA
    Posts
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    Default Re: Hole in piston

    Did you ask about getting the dizzy up to snuff it sounds like the shop your at has their stuff together. Like my dad allways said it takes a nickle to go first class!

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