Banging sound Alpha one drive

pyro225

Petty Officer 2nd Class
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Oct 1, 2014
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Just had my Regal 1800 1.7 mercuriser diesel delivered this week - I got it tested prior to buying and was told she was good, got here Wednesday went out for about 2hours and she was good. I then went out flat out this morning for an hour... all good... then we were going at about 10mph for about 4 hours and then went to speed up past 3000rpm and I could hear/feel a loud bang . slowed down she was fine but everytime I sped up same problem, I also had the same issue in reverse? the engine was purring nicely so maybe a drive issue - any ideas? hoping not serious as its meant be good! also the prop has abour 2mm play in itback and fourth is that a problem? any ideas?
 

alldodge

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Just had my Regal 1800 1.7 mercuriser diesel delivered this week - I got it tested prior to buying and was told she was good, got here Wednesday went out for about 2hours and she was good. I then went out flat out this morning for an hour... all good... then we were going at about 10mph for about 4 hours and then went to speed up past 3000rpm and I could hear/feel a loud bang . slowed down she was fine but everytime I sped up same problem, I also had the same issue in reverse? the engine was purring nicely so maybe a drive issue - any ideas? hoping not serious as its meant be good! also the prop has abour 2mm play in itback and fourth is that a problem? any ideas?

If you hear the noise only in gear then its in the lower section of the drive or the prop. The shaft should not have that much slop, 1mm would work but 2mm is high. Do you have any radial play?
 

pyro225

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Oct 1, 2014
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Right - here's the plan when the weather clears I will take sideways play and then I will rev it in neutral to confirm the banging doesn't occur. if it doesn't you are saying I have lower unit issues?
 

achris

More fish than mountain goat
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May 19, 2004
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27,468
Pull the top off the drive. Look for broken teeth. And yes, it may not happen out of gear...Had the same problem, same symptoms on my first drive. It was teeth coming off the driven gear in the top box...

Chris...
 

pyro225

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Oct 1, 2014
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update.. if I spend about 5 mins getting to full throttle its all fine its only if I do it quickly... someone is selling a lower unit for $300 would that fix my issues?
 

Watermann

Starmada Splash of the Year 2014
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Not if the problem is in the upper gears. Are they selling the entire outdrive or just the LU? You'll need an OD with the correct gear ratio for your diesel too.
 

alldodge

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update.. if I spend about 5 mins getting to full throttle its all fine its only if I do it quickly... someone is selling a lower unit for $300 would that fix my issues?

You need to find out what the problem is. There is currently differences in what the problem might be. If it is upper or lower section which is causing the problem, either way a tear down will be necessary. If anything is broke inside those pieces floating around will break other parts over time. Start with what Chris mentioned and remove the top cap, then pull the drain plug and see if the lube has any metal in it
 
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