MarineEngine.com - Your online store for all types of marine engines and boat parts.
PHONE ORDERS
Monday - Friday
9:00 AM - 5:00 PM EST
Click for TOLL-FREE Number
Online Checkout
Special $9.95 Flat Rate Shipping
(800) 209-9624 | Home | Contact | Shipping | Returns | Cart View your shopping cart.
Part Number Search
Shop by engine/drive part number.
Original & matching parts for sale.
Manuals & Accessories
Shop by description, item number
or manufacturer's model number.
Boat Repair Forum Boat Repair Forum   Boat Video Gallery Video Gallery
   
Get instant online access to repair manuals for your Mercury / Mariner outboard. Online Manuals
MercuryMariner
Order printed Mercury / Mariner service manuals — shipped to your door! Printed Manuals
MercuryMariner
Use engine diagrams to find & order parts for your Mercury / Mariner engine. Engine Diagrams
MercuryMariner
Find parts quickly with Mercury application guides. Quick Parts Guide
MercurySierraCDI
Results 1 to 6 of 6
  1. #1
    Join Date
    Jan 2012
    Location
    Los Angeles, California, United States
    Posts
    3

    Lightbulb 'Whirring' Noise - 1977 Mercury 75/7.5 hp, 2 cyl, 2-stroke

    Hello Everyone.

    I have a 1977 Mercury 75/7.5 hp, 2 cyl, 2-stroke. We call it "the engine that think it can!" She is a beautiful engine thats on our 13 ft Gregor...

    She works great. I cleaned the carb and tuned her up. Her idle isn't too rough.

    After about 1 to 2 hrs of continuous running time, she starts whirring... not in idle but when at 1000 rpms or higher in gear or not in gear. Its puzzling to me because I can't really start to take it apart when we are in the middle of the lake or behind the break wall.

    I do have a subscription for this engine to Seloc Online if needed.

    Any ideas on where to start trying to narrow it down?

    Thanks in advance!

    Q

  2. #2
    Join Date
    Sep 2010
    Location
    ontario
    Posts
    9,850

    Default Re: 'Whirring' Noise - 1977 Mercury 75/7.5 hp, 2 cyl, 2-stroke

    Without knowing the history of the motor ( was it ever sunk and not recovered properly etc )---It is hard to say.--------------I would start by looking at the lower unit oil.---Any water or metal bits present ??

  3. #3
    Join Date
    Jan 2012
    Location
    Los Angeles, California, United States
    Posts
    3

    Default Re: 'Whirring' Noise - 1977 Mercury 75/7.5 hp, 2 cyl, 2-stroke

    Quote Originally Posted by racerone View Post
    Without knowing the history of the motor ( was it ever sunk and not recovered properly etc )---It is hard to say.--------------I would start by looking at the lower unit oil.---Any water or metal bits present ??
    I took a look at the lower half... I was getting ready to pull it to see if there was water in the oil and i see the lower half leaking oil thats milky between the prop and the lower half body... I think you might be right.... Ill pull it and get back to you.

  4. #4
    Join Date
    Jan 2012
    Location
    Los Angeles, California, United States
    Posts
    3

    Default Re: 'Whirring' Noise - 1977 Mercury 75/7.5 hp, 2 cyl, 2-stroke

    Quote Originally Posted by racerone View Post
    Without knowing the history of the motor ( was it ever sunk and not recovered properly etc )---It is hard to say.--------------I would start by looking at the lower unit oil.---Any water or metal bits present ??
    ok... So i drained the oil. There wasn't any water in it... it wasn't super dark brown and it wasn't like a light coffee... I did notice a leak of milky oil from behind the prop. I think that seal needs to be replaced but I can't seem to figure out how to remove that spanner collar and get to that seal. I am going to replace the oil and if you guys have any idea how to replace that seal I will replace that too

    Thanks again!

  5. #5
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    12,656

    Default Re: 'Whirring' Noise - 1977 Mercury 75/7.5 hp, 2 cyl, 2-stroke

    The "collar" unscrews (lefthand thread). You might have a bad driveshaft bearing.

    Jeff

  6. #6
    Join Date
    May 2010
    Location
    Sebastian ,Fl
    Posts
    1,781

    Default Re: 'Whirring' Noise - 1977 Mercury 75/7.5 hp, 2 cyl, 2-stroke

    ???? Noises are the hardest to diagnose.Look under the hood and under the flywheel for metal shavings.
    Any color other than black or the original usually means water.
    There are several threads for a homemade pressure tester.Here or on other sites.
    i boats. com , Force Forum use the search function both sites.
    boats . net worst place to buy parts.
    Get towing insurance.Great investment.
    88 Bayliner with twin 85's

Similar Threads

  1. B-W 73C 'Whirring' Noise
    By k_m_thompson in forum Marine Transmissions and Reverse Gears
    Replies: 2
    Last Post: 12-05-2011, 10:30 AM
  2. 1977 mercury 4hp 2 stroke starts but cuts out
    By robmcc85 in forum Mercury Mariner Outboard Forum
    Replies: 3
    Last Post: 08-18-2011, 03:57 PM
  3. Mercury 115 EFI 4 Stroke Noise
    By MERC115EFI in forum Mercury Mariner Outboard Forum
    Replies: 0
    Last Post: 07-25-2011, 10:17 PM
  4. Replies: 3
    Last Post: 07-10-2011, 10:11 PM
  5. MJDE circa 1977 onan generator noise
    By gwalters in forum Detroit Diesel
    Replies: 1
    Last Post: 12-14-2008, 05:34 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •