engine knock |
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kapla ![]() Grand Poobah ![]() ![]() Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148 |
![]() ![]() ![]() ![]() ![]() Posted: April-16-2012 at 5:12pm |
Last saturday I went out for a ride, did some barefooting, and then hanged in the river looking the city from the water. Then headed back to the marina... engine performed flawlesly as always, but from the last stop of it I started hearing a strange noise, like a blown exhaust gasket, so I lifted the doghouse while underways, and there it was this knock coming from the engine... WTF, boat idles fine no sound, I pumped the engine w/o gear up to 2500 rpm and no knock, only knock in gear starting to plane, around 1500-1800rpm and stays there. Engine starts fine without hesitation. No loss of power, no miss, no overheat...can´t say about oil pressure as the gauge broke a couple weeks ago, I grounded the sensor cable to the block and it didn´t peg. But after this I might think I had no pressure and maybe I toasted a rod bearing...oil pump was new when I rebuilt the engine. Other thing in play here, I started using fuel from a new gas station, this was my third outing using this fuel (put around 8 gallons in those fill ups)...so also made me wonder if this could be engine pinging due to bad quality fuel? advance is set to 10º. engine has only around 300 hours from rebuilt....so as you can imagine i´m really upset with this issue. I will go with my mechanic and friend who did the rebuilt to investigate some more, and let you know how this thing turns on... ![]() ![]() ![]() ![]() |
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<a href="">1992 ski nautique
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kapla ![]() Grand Poobah ![]() ![]() Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148 |
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So I limped back to the marina at idle speed, where it did no sound at all...
hope its the gas issue... |
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<a href="">1992 ski nautique
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JoeinNY ![]() Grand Poobah ![]() ![]() Joined: October-19-2005 Location: United States Status: Offline Points: 5697 |
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You need to KNOW if you have oil pressure before you run it again new fuel or not. I would also check compression before running it just because it is quick and easy and gives you a look at the plugs. IF you have good compression readings, good oil pressure, and your oil isnt full of metal filings then run it.
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kapla ![]() Grand Poobah ![]() ![]() Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148 |
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yup I plan on taking a mechanical oil pressure gauge and plug it in place of the oil sensor...
will do this on wednesday, as tomorrow the marina is closed... |
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<a href="">1992 ski nautique
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kapla ![]() Grand Poobah ![]() ![]() Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148 |
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I took a quick look at the oil that day, and seemed to be fine, I rubbed it between the fingers and no metals there..but you never know...
I´ll keeo you guys posted... |
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<a href="">1992 ski nautique
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Bri892001 ![]() Grand Poobah ![]() ![]() Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Exhaust manifold gasket maybe? A bad one will be louder under load and not necessarily noticeable when not.
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watrski ![]() Senior Member ![]() Joined: December-01-2010 Location: Chippewa Lake Status: Offline Points: 393 |
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How old is your distributor cap?
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kapla ![]() Grand Poobah ![]() ![]() Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148 |
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Its now 2 years old, as the dizzy, came new when i retrofited the protec ignition...
its a mallory |
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<a href="">1992 ski nautique
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watrski ![]() Senior Member ![]() Joined: December-01-2010 Location: Chippewa Lake Status: Offline Points: 393 |
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Take it off, look at it very closely. You might see a very faint mark where it is arcing between 2 cylinders. If you have a new cap....you can throw it on.
Happened to me...thought my motor was toast! |
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kapla ![]() Grand Poobah ![]() ![]() Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148 |
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Brian, I would be glad if this was the case, but this was no exhaust leak at all, this was coming from the guts of the engine...
actually i´m dealing with a exhaust leak on the vette, as 1 manifold bolt made its way out and its blowing there, totally different sound... |
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<a href="">1992 ski nautique
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NEDLUTZ ![]() Groupie ![]() Joined: November-26-2007 Location: Seekonk Ma. Status: Offline Points: 69 |
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Check your flex plate...
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kapla ![]() Grand Poobah ![]() ![]() Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148 |
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yes thats another place I wanted to check...
its pretty new though, replaced it when i rebuilt the engine... |
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<a href="">1992 ski nautique
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GlassSeeker ![]() Grand Poobah ![]() ![]() Joined: November-26-2008 Location: Elk Grove, CA. Status: Offline Points: 2421 |
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I'm hoping for the best outcome, after having 3 bad engines in a row I know the feeling all too well. Hopefully it turns out to be something minor.
take a long piece of pipe or a broom handle or long screw driver or a mechanics stethescope to listen and locate the source. Good luck. |
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This is the life
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kapla ![]() Grand Poobah ![]() ![]() Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148 |
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just came from the boat, I´m upset.
Hooked the oil pressure gauge, 60 idle upon start and raises when you hit the throtle. I have low compression on #2 cylinder. around 60-70. rest is in the upper 150´s... Plug on that cylinder was destroyed, the electrode gone, though I got a pictures but no. Strange is when I got that out, after inspecting it I found traces of water in the spark hole...and some drips in the engine mount that sit below there. But when cranking the engine, no water came from there. No water in oil. Rest are fine. Knock is there under load from 2000 rpm and keeps there. on neutral you can no noise... So will need to start tearing appart that head and see first valve problems or what... Seems the knock if from the upper engine, and not from below as i suspected.... Really don´t know what could have failed...only 250 hours from rebuilt, all oil changes on time, correct plugs.... Mechachic blames barefooting and the high engine speeds as culprits (joking of course), but I really don´t think so. Probably will start the tear down by next week... ![]() |
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<a href="">1992 ski nautique
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JoeinNY ![]() Grand Poobah ![]() ![]() Joined: October-19-2005 Location: United States Status: Offline Points: 5697 |
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Well we will know when we know but heat/detonation/bad gas type issues is my best guess. You could have stuck a valve, dropped a seat, or cracked/blew up or melted a piston. A little too much timing and/or less than ideal gas can cause/facilitate any of those things. They can happen pretty quick or overtime at barefoot speeds and loads.
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GlassSeeker ![]() Grand Poobah ![]() ![]() Joined: November-26-2008 Location: Elk Grove, CA. Status: Offline Points: 2421 |
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good that you have oil pressure, maybe you have caught this in time to keep repairs to a minimum---stuff happens. sorry that you are having engine issues. its a bummer but keep your chin up and take care of business. I don't think you can blame high engine speeds unless it was over reving. 4500-5000 rpms really is not high rpms in the big scheme of things, pulling 1 footer is not over loading anything. bad gas? maybe, bad component? maybe.
take a deep breath and tackle the problem. Once again very sorry, it sucks no matter what, it just sucks. ![]() |
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Waterdog ![]() Grand Poobah ![]() ![]() Joined: April-27-2006 Location: United States Status: Offline Points: 2020 |
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Knock under load, = rod bearing.
With low comp on #2 and bad plug, rip the haed off - fix what ya find. Hard to guess, but when you pull the head you'll know. Good luck, hope it don't cost too much! |
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crobi2 ![]() Senior Member ![]() ![]() Joined: April-05-2011 Location: Texas Status: Offline Points: 112 |
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Darn! I'm sorry. I remember watching your video on utube when you built that motor. That was before I even knew about this site.
Hope you get it fixed quick. |
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C-Rob
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kapla ![]() Grand Poobah ![]() ![]() Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148 |
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looks like my back deeps will be put on hold until this is solved...
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<a href="">1992 ski nautique
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kapla ![]() Grand Poobah ![]() ![]() Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148 |
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Engine ran sooo good, guess *************** happens...
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<a href="">1992 ski nautique
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kapla ![]() Grand Poobah ![]() ![]() Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148 |
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wow, auto bad words deleting!
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<a href="">1992 ski nautique
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8122pbrainard ![]() Grand Poobah ![]() ![]() Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Seb,
I'm sorry to hear about the problem - it sucks! Just keep moving forward. Get that head off and I know you will report back to us. |
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Waterdog ![]() Grand Poobah ![]() ![]() Joined: April-27-2006 Location: United States Status: Offline Points: 2020 |
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Hay Kap, The 30 seconds before it lets go is always the best it EVER ran. Keep your head up, ya know if we could wrench on it with you we would be there. Thats what makes this site that Keith created sooo cool. (Thanks for bringing us together Keith - get well soon!) The 4 wide nats at Z Max dragway was last weekend. Google "Mat Hegan explosion" hard to believe you could live through that!!! |
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Luchog ![]() Grand Poobah ![]() ![]() Joined: April-17-2007 Location: Argentina Status: Offline Points: 2135 |
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What we talked on the phone today I also suggested Seb to take the valve cover off and move the engine by hand to see the valves open and close see if one's stuck or there's a bent pushrod. We need to find out WHY the plug burnt, and then head to see what else broke and WHY so it doesnt happen again. Anyway the head must come off and most likely the engine as well. |
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GlassSeeker ![]() Grand Poobah ![]() ![]() Joined: November-26-2008 Location: Elk Grove, CA. Status: Offline Points: 2421 |
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That sounds like a good plan. That may tell more than just tearing into it. Just the fact that it is still rotating is a good thing.
We had a Mastercraft way back when and it was bought brand new, it had a 200 hour warranty, at 211 hours we blew a hole about 1 1/2 inches in the center of a piston, had to replace the piston and we got it back up and running again. The theory was a lean condition. Later the whole top deck worked the pop rivets loose and detached from the bottom/hull. That was real special. That was when we went to a BFN. When the BFN had somewhere near 3000 hours we rebuilt it, on teardown the piston skirts were detached/broken off and being held in place by the rings. Willies Malibu detonated at 5200 rpms at 800 hrs and had major damages, hole in block from the rod into the water jacket...when I pulled the head there was no piston left the rod looked like a hammer had beat it for hours. Roy was driving and he said the sound was something he would not forget. I've got my fingers crossed that yours will be a fairly minor repair, you may have caught it before the real bad stuff has happened. |
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This is the life
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kapla ![]() Grand Poobah ![]() ![]() Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148 |
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today I was looking at the ngk plugs I had on the engine prior to replacing them with the autolite 764 around 6-7 months ago...I mark them from whick cylinder they came out. By that time they where all looking good, so the problem arrised in this last outings, probalbly bad gas @ wot....
i can´t work on the boat during the week ends, not permited by the marina, so probably till next week until I´m able to start pulling the engine appart... Only 1 week from this problem and i´m starting to suffer boat withdrawal symptoms.... ![]() |
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<a href="">1992 ski nautique
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jimsport93 ![]() Platinum Member ![]() ![]() Joined: February-20-2008 Location: Alpharetta Ga Status: Offline Points: 1749 |
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Man! Kap you sure have had your share of problems this year. Cheer up..you will get it figured out. In the meantime I quess it is sun-bathing on the bow of your freinds cruiser. Seem to remember some good pics from past outings on the cruiser!
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storm34 ![]() Grand Poobah ![]() ![]() Joined: November-03-2008 Location: Dexter Iowa Status: Offline Points: 4492 |
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![]() Kao, hopefully it's something minor! Keep us updated and let us know what you find |
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gun-driver ![]() Grand Poobah ![]() Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4117 |
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Kap,
It could have been bad gas!! Last year I had the tips blown off 3 plugs from bad gas. Luckly my motor has a knock sensor and wouldn't let it go above I think it was 2,800 rpm. Long story short I would hate to think what would have happened if I was able to run it at full rpm. Oh by the way I was running Startron in the fuel at the time. I WON'T EVER BUY THAT CRAP AGAIN back to Stabil marine and no more problems. |
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lewy2001 ![]() Grand Poobah ![]() ![]() Joined: March-19-2008 Location: NSW Australia Status: Offline Points: 2234 |
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Kap that is bad news. At least you should have Bully there soon to help you with the spanner work.
What rpm's are you pulling footing? I would check your total ignition advance at those rpms and maybe wind it a back a few degrees for safety with varying fuel quality. |
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If you're going through hell, keep going
89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta |
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