mariner40hp magnum power loss and rattle

[bill bean]

Hi please help, my mariner magnum 4 cylinder 40hp engine will start perfect when cold and will run on 3/4 throttle for approx 5 min's then slowly loose power and begin makeing a rattling noise then cut out and not want to restart.The water from the pee hole gets very hot and steamy when engine is run with mufflers and the 2 stroke oil level does not seem to be going down. The rattling noise is very loud and seems to be coming from the block?????

 

[carholme]

Re: mariner40hp magnum power loss and rattle

What is your engine s/n? Hard to interpret what rattle means but with the heating and being hard to re-start, I would start by examining each piston to see if there is any play indicating a rod problem. Are you comfortable tearing the engine apart if necessary and do you have the service manual?

Gerry

 

[bill bean]

Re: mariner40hp magnum power loss and rattle

What is your engine s/n? Hard to interpret what rattle means but with the heating and being hard to re-start, I would start by examining each piston to see if there is any play indicating a rod problem. Are you comfortable tearing the engine apart if necessary and do you have the service manual?

Gerry

Hi Gerry, thanks for your reply I am waiting for a workshop manual to arrive, as I said before it seems to use no oil from the tank? tha s/n is OC281526.the rattle is not there when engine is cold and only apeares when the engine is runnins hard and begins to loose power?

 

[carholme]

Re: mariner40hp magnum power loss and rattle

Your s/n comes up as:

MARINER - ( 40 H.P. (1990 ))
Serial No: 0C281526 Model No: 7040412SD

Parts List for model 7040412SD:

40 HP30 JET - Mercury, Mercruiser, Force, etc. Parts Lookup

It would be typical that the noise is not there when cold but as the temperature of the engine warms up and metals expand, it re-appears. If it is not using any oil from the tank, I certainly would not be running it anymore until I inspected the potential damage in the engine and then dealt with the oil problem. Could be anything from a bearing, rod assy, scuffed piston/cylinder etc.

I hope the manual you are getting is the Mercury manual and if not, send me a PM with an email address and I will send you a copy.

Gerry