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i have a 98 air nautique with efi gt40..........just dewinterized hooked up to water hose and ran for first time............the engine grumbles and roars like i think it should............but there is a constant knocking sound..............knock is the only word i can use to describe it.....its a slow constant knock at idle.....and when i rev the motor up to a higher rpm range the knock speeds up with the engine.............. this is my first boat and i am not sure if this sounds is normal or if i have a serious problem........i am by no means a mechanic...i do not know if this sound is normal or not....please help............it seems to be coming from the top inside of the motor on the tranny side......i couldnt pinpoint the source
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Knock Sensor
When you put the knock sensor back in the drain hole did you put Teflon tape or sealant on it? if so it will not work properly. I'm surprised it would allow you to rev the engine. That sensor is what the computer uses to advance and retard the spark to keep the engine from knocking. The sensor could also be bad.If that is not it it could be a rod knock. That would be much more serious.Nautiqueless in San Diego -
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i love when people reply with remarks that are no help at all...............if i wanted to take it to a mechanic first, why even post anythingComment
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I called the doctor and told him I had a sharp pain in my chest. Then I asked what it could be . He said he couldnt tell untill he checked me out.
Like Hollywood said bring it to a mechanic it is totally impossible to diagnose things like this over the phone or on line. I will say I wouldn't run it untill you know what is causing the knock.Comment
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if we cant hear the noise we cant tell u what it might be but hows the oil pressure was the noise there before u winterized and if its a rod nock try this while running engine pull spark plug wire off one at a time and if u pull one off and the knock goes away thats the bad cyl use a pair of spark plug wire pliers or rubber gloves or have your friend do itOriginally posted by g33b0 View PostComment
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i am not trying to show any disrespect to anyone...........i am just asking for a number of scenarios with troubleshooting, before i actually have to take it to a mechanic.....i understand ya cant hear it............lets start over, and...how about listing a number of things that could cause a ticking or knocking sound.......spun bearings, rods, lifters........can anything with the fuel injection system cause a knocking sound... if it made the sound before winterization, i didnt hear it........Comment
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theres really no way to troubleshoot a noise without hearing it but try the spark plug wire test its pretty easy and dont take long usally when u spin a bearing u lose some oil pressure but when you find out what it is post it I would like to know if you didnt live so far away i wouldnt mind checking it outOriginally posted by g33b0 View PostComment
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knocking
could it be coming from the exhaust manifolds where they bolt to the heads ? an exhaust leak can sound like an engine knocking. with the engine running feel around for air leaking.Comment
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exhaust leak was what i am going to check for next...as soon as it warms up this morning.........i was also told it might be the lifters..is it expensive or hard to replace lifters................. gonna make a recording for yall this morning as well, hopefully the sound quality will be sufficient enoughComment
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image quality not good.......but any insight on what this sounds like.......please helpengine..wmvLast edited by g33b0; 04-09-2010, 12:27 PM.Comment
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engine knockComment
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run some seafoam through the throttle plate or a vaccum line to clean the top end.Comment
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100% engine knock. That's not an exhaust leak so don't waste time there. An exhaust leak to sound like that would be a hole big enough to put your fist in. That's really loud knock, not a tick.
Could be a valve or bearing. Has that engine overheated? When was the oil changed last? Could be many things, the audio doesn't really give a good idea of where the sound is coming from. How's the oil pressure? Could be simple engine knock caused by detonantion. Could be something major. Find a mechanic.Last edited by steve-o; 04-09-2010, 01:25 PM.Comment
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sounds to loud to be a lifter and not deep enough to be a rod sounds louder at back of engine maybe could be a cracked dampener plate but its hard to tell but does it change if you put it in the water and put it in gear give it a load on the dampener plate do that see if noise goes away or changes i seen flex plates crack and make the same noise maybe you can pull the starter and look in there with a mirror and turn the engine over with a wrench back in forth it dont sound like a exust leakComment
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