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View Full Version : Serpentine belt squeal mercruiser 5.7l 350 solved after months



Bob & Sue
02-08-2012, 10:11 AM
Thought I would post this with a searchable title.

Since we bought our boat last June I have been fighting a serpentine belt squeal I changed belts, idler pulleys and just about every remedy I found on line it would go away for sometimes a week then return. Finally I found an old recall notice from mercruiser for the alternator, power steering and oil filter bracket also included a recall on the sea water pump bracket. If you take a straight edge and check the pulley alignment to the crank pulley mine were off about 1/8" on the sea water pump about 1/4" on the alternator pulley. This recall covers a lot of engines built from the mid 90's to 2002 it expired in 2004 for mercruiser to pay for repairs my Sea Ray dealer did pay for the brackets if I did the labor.
Yesterday I finally put the new sea water pump and bracket on (will rebuild the old one for a spare) then replaced the alternator bracket that bracket was one real pain you need to remove half the front port side of the engine. I started at 9:00 am finished at about 3:00 pm launched the boat after running on muffs looking for any leaks before launching out for a test ride squeal is finally gone. The pulleys now are all in line.


A mercrcruiser mechanic with 20 years experience told me about it while he was doing some work on my boat after a coupler replacement. I did find a copy of the recall notice on the web months ago but it took a lot of searching. The design of the Mando alernator bracket was completely changed. In the photo you can see how much bend is in the bracket. We were out yesterday for 10 hours sounds like a new engine again.

http://www.marineengine.com/boat-forum/attachment.php?attachmentid=3491&stc=1&thumb=1&d=1321110524 (http://www.marineengine.com/boat-forum/attachment.php?attachmentid=3491&d=1321110524)

mikey43
02-13-2012, 10:42 PM
the pulley on mine was the power steering pump!! kept thrown belts put the new pulley on and works fine just thought i would throw that in happy boatn!!

johnm
02-14-2012, 01:39 PM
Bob or Sue,

I have a 1995 Chaparral with a Merc. 5.0 LX. I developed a squeal about 3-4 years ago. It only happens between 800 and 1200 RPM's. Two mechanics have said it could be the alternator. Do you think this could be the issue?

Bob & Sue
03-11-2012, 01:41 PM
Johnm

Sorry about not answering sooner if you have a V type belt I would buy a cheap shorter belt to eliminate the alternator run it to see if it goes away, if it's a serpentine belt try spraying wd40 on each pulley one at a time while it's squealing when or if it goes away that could be the component that's causing your problem. Another quick check is to flip the serpentine belt 180 degrees if the squeal goes away for a short time that could be a symptom of an out of aligned pulley check with a straight edge between crankshaft pulley face and all other pulleys there should be less than 1/8" difference. Between 800-1200 rpm is when both the alternator and if you have a belt driven sea water pump require more torque to get them going. Just my opinion not a certified mechanic.

Update have put about 25 hours on it still NO SQUEAL knock on gel coat

yachtie360
03-21-2012, 09:20 PM
Bob & Sue, I can't believe I found this post! I have been experiencing the same annoying squeal and could not solve the issue. Worse, I've gone through 2 belts in under 100 hours as the misalignment eventually shreds the belts. I can see that the alternator is bent inward and was going to have a mechanic come out as I could not figure out how to fix it myself. I called the dealer, but they can't find the recall notice. Any chance you could provide the service bulletin number / recall number? I've searched the net and can't find anything. I've got no problem doing the work myself (after replacing 4 cylinder heads..), I just don't want to spend a ton on replacing badly designed parts.

mikey43
03-22-2012, 11:19 PM
yachtie360 i had the same problem when i got new belt different # and had a powersteering pulley with it!!!! maybe this will help!!

Bob & Sue
04-14-2012, 11:46 AM
Bob & Sue, I can't believe I found this post! I have been experiencing the same annoying squeal and could not solve the issue. Worse, I've gone through 2 belts in under 100 hours as the misalignment eventually shreds the belts. I can see that the alternator is bent inward and was going to have a mechanic come out as I could not figure out how to fix it myself. I called the dealer, but they can't find the recall notice. Any chance you could provide the service bulletin number / recall number? I've searched the net and can't find anything. I've got no problem doing the work myself (after replacing 4 cylinder heads..), I just don't want to spend a ton on replacing badly designed parts.
Sent you a PM that recall notice has expired and is no longer on the internet ( I can't find it ) and didn't keep a copy, the new bracket has the same part number just redesigned. I have about 50 hours on it since replacing them without any squeal.