How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
Type Your Boat Question Here...
Dominick is online now
A new question is answered every 9 seconds

Merc 75hp 4cyl not firing cyl 4, electrical system checks ok

Customer Question

merc 75hp 4cyl not firing cyl 4
JA: Sometimes things that you think will be really complicated end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so the Marine Mechanic can help you best.
Customer: electrical system checks ok on all four cylinders. cylinder four spark plug is suspiciously clean.
JA: Is there anything else important you think the Marine Mechanic should know?
Customer: there is a consistent whistle noise while going at speed. its not in time with the engine rpm. but it's very regular, approx. every 1-2 seconds.
Submitted: 1 month ago.
Category: Boat
Expert:  Tan replied 1 month ago.

Hello. My name is Tan.

Could I get the engine serial number please? Clean spark plug can be blown head gasket, no spark or no fuel.

Have you done a compression test?

Have you checked spark on all cylinders with a timing light under load?

Related Boat Questions