Mercruiser noises!!!

[philtheskipper]

My engine after running at high rpm makes a "whistle" sound. It kinda sounds like a tea pot whistle. I only can hear it when I run at low rpms. Any idea of what this could be? <br /><br />Also, the alternator makes a banging noise but when I apply a lot of presure on it the banging stops. Please help. This boat is broke down more than I use the darn thing!

 

[Walter]

Re: Mercruiser noises!!!

Hey Phil...<br /><br />I always tend to seek the most simple solution first. Get yourself a fine mist spray bottle of water and shoot it against all the drive belts while the engine is running while the noise you describe is present. Should it be something as simple as a squeeky belt, the water will lube it momentarily and hopefully kill the noise briefly. Focus on that belt and perhaps that will take care of it.<br /><br />You guys gotta think I'm a "Simple-ton" when I suggest solutions to your problems, but I gotta tell ya once again...so often what appears to be a major concern is really a simple fix. Check the easy stuff first! Maybe one day I'll tell why my 22 years "wrench" experience tells me this is so.<br /><br />Anyway, if that doesn't put you any closer to the problem, then check your intake for vacuum leaks. I'm trying to figure what would cause that high pitched whistle you describe. Too bad you aren't working on an inter-city transit coach...powered by a Cummins M-11 Celect... then maybe I could tell you exactly where to go! Nevertheless, always start with the obvious...most simple solutions first. <br /><br />Lemme know what you turn up....<br /><br />Walt<br /><br />I can only wish you the best and hope your problem isn't serious.

 

[Yepblaze]

Re: Mercruiser noises!!!

Get out the old siphon hose and while someone else is at the helm, put one end to your ear and with the other end probe around the engine area to isolate the source of the sound. <br /><br /><br />Watch out for belts and spinning parts. If it gets caught up in stuff, LET GO!

 

[fone_man]

Re: Mercruiser noises!!!

It is all that bangin around on Lake Erie!!!<br /><br />Need info:<br /><br />OK... MercCruiser<br /><br />4/6/8 ????<br /><br />Break it down... you want help/assistance... give me some info & I will try<br /><br />fone_man

 

[philtheskipper]

Re: Mercruiser noises!!!

It's a 1979 mercruiser 120, 153c/i, 4 cyl. Could it be air/fuel mixture intake on carb? Exhaust leak? Sounds like it's coming from the top of the engine somewhere. Around valve covers or something.

 

[fone_man]

Re: Mercruiser noises!!!

OK, Phil....<br /><br />..I have 3.0 140 4 cyl... same basics both GM Blocks, so here we go...<br /><br />...for starters, do me a favor remove spark arrestor on top of carb... see if carb is loose, not on base but carb loose... airhorn, etc... tell me if it is a rochester w/ mercury tag??? Vibration of these engines, will cause carb to loosen up & gasket between base of carb & middle part of carb will cause vac leak. If this is the case, pull carb, drain fuel into bucket, turn upside down, should be two phillips screws holding carb base(intake side) to middle part of carb... if these are loose you will need to rebuild carb & get carb kit from auto parts store... if this is rochester w/merc tag... look on side of carb & there will be numbers stamped in it... these are the ones you want... follow directions in kit, pick up brass float while at parts store as it will not absorb gas like old plastic/compostite orginal does. When replace screws in base... use locktite on threads... I use the color "blue" loctite... if you having any other questions, you can reach me at the address below...<br /><br />Next.....Alt... has two brackets... make sure they are both tight. Look at alt see if vibrating back & forth. Someone could have removed a bracket & engine vibrating makes it rattle... bracket bolts to block below & I believe around water pump area. Let me know.<br /><br />fone_man@bellsouth.net

 

[fone_man]

Re: Mercruiser noises!!!

Forgot...<br /><br />Grew up on Lake Erie... born & raised in Cleveland & Y-town... been in TN about 26 years now...So I know how the lakes are there... keep me posted on your findings.<br /><br />fone_man

 

[philtheskipper]

Re: Mercruiser noises!!!

Thanks for info, I'll let you know<br /><br />pdore@eriecoast.com

 

[fone_man]

Re: Mercruiser noises!!!

Phil:<br /><br />When I said 2 brackets... these are the adjusting brackets.<br />There should be 3 attachment areas, see below<br /><br />You have the one that goes through the Alt... @3/8 x @5"...<br /><br />Two... is on the front @5/16 x @1.5-2"... adjustment<br /><br />Three... a bracket attaching to the back @ 5/16 x @1"<br /><br />If one of these gets loose... it will cause it to shake & vibrate...<br /><br />Also, even if belt looks OK... it might be stretched way out & getting into position where a vibration occurs...<br /><br />Make sure belt is tight, tighten all adjusting bolts & MAKE SURE YOU TIGHTEN the long bolt tight... put your earmuffs on lower unit & fire it up and see if that got it!!! If belt is stretched, pull it off & pick one up at auto parts place (if you go to autozone or discount place... make sure you get a guy knowledgeable on belts).<br /><br />Keep me posted.<br /><br />fone_man

 

[philtheskipper]

Re: Mercruiser noises!!!

I tightened the alternator bolts and that seemed to do the trick. I just had to put some muscle into it. I just welded one of the brackets last year because it broke from vibration. <br /> The boat is docked so I'll have to let you know about the carb tomorrow(it got dark before I could do more). I know it's a rochester carb but I'll have to find out what model. Thanks.

 

[fone_man]

Re: Mercruiser noises!!!

Phil:<br /><br />Check belt... when was last time you changed belt????<br /><br />Remember this cause more problems than you realize!!!<br /><br />Thanks for keeping me posted... I look forward to your reply & if carb is loose like I said, just remove it... 1/2 or 9/16 nuts to intake, fuel line will be 1/2 or 9/16 plus adjustable wrench for fuel inlet... BINGO... carb in hand & just carry to parts store for kit!!!<br /><br />C-ya<br /><br />fone_man

 

[Walter]

Re: Mercruiser noises!!!

Phil...<br /><br />By tightening the alternator bolts you may have re-aligned the belt or snugged it up a bit. Or, perhaps the mounting components were loose, thus creating the noise? Either way...I hope that takes care of it. If so, then I feel vindicated with my simple-ton's approach. I'd definitely follow up on Fone's suggestion and check the condition of the belts... The more they wear the tighter they must be to prevent slippage. This places a lot of tension and stress on all the related components (alternator bearings, etc...). Cracked or glazed belts have no place on a boat engine. ....Walt

 

[philtheskipper]

Re: Mercruiser noises!!!

I believe all my problems are solved! Thanks fone_man and Walt! The alternater bolt was loose and I have a vacum leak in the carb. The belt was just replaced in the spring and is in good shape. Thanks again.