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Serious looking problem b74 evinrude 70hp 70473M

H

halo786

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"please help guys...this looks

"please help guys...this looks exspensive..AAAaaaah!!! having run the motor on the boat, in the bay, for about 15 - 25 minutes out and back again i thought all was fine..she was running like a treat and performing well!! i can bakc and did a fresh water flush on the motor and didn't notice anything strange... the boat is now standing in my workshop while some patching and painting is done..and that is when i noticed an oily sludge leaking from the propshaft (which i presume is coming out the exhaust)..is this the head gasket which is gone..or a gear case oil seal or something.. i have attached some photo's of the sludge.. please advise.
374949.jpg
oil leak photo's "">
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374951.jpg
"
 
"I have twin 225's, 1990s.

"I have twin 225's, 1990s. The starboard engine does the same as yours, the port does not. Both seemed to run fine. I was totally convinced that it was a bad seal in the LU. Inpsected the LU. No water intrusion & held pressure during pressure test. Apparently, what VicS said is correct. My only clue is that my timing was way off. I will be curious to see if this engine still does this now that the timing has been corrected."
 
"thanks guys, you took the pre

"thanks guys, you took the pressure off!! i was sweating blood at the thought of major work!..any idea what the pressure on the cylinders should be ? i want to pressure test them...and how do i check the oil in the gear case...do i have to take it off..or is there an inspection plug.? much appreciated.."
 
and one more thing...what mix

and one more thing...what mix should i be running? i'm using 50/1 at the moment..could this be causing the oil leak?
 
"I'm not sure about a 1974

"I'm not sure about a 1974 engine, but most newer OMC's take a 50:1 fuel ratio. Normal way to look for water intrusion is to drain and replace the lower unit oil. Considered to be regular maintenance. The drain plugs on the OMC's I am familiar with are on the right hand side of the gearcase. The one at the top of the skeg area is the drain, the one towards the top of the cavitation plate is the level plug. Normal procedure: pan under LU, remove top plug, remove bottom plug. Oil usually looks pretty nasty and smells worse. Oil is replaced by using either a pump or squeeze bottle in lower hole. You have enough when it starts coming out the top hole. Put top plug in, then bottom. Please keep in mind that if your engine has electric shift, it uses a special LU fluid, and you must use the right kind. If drain plugs are stuck, made sure screwdriver is big enough, and fits well. Grind the end of the screwdriver if necessary to get a tight fit. Also, a couple of smacks with a hammer will help loosen the drain plugs too. Good luck!"
 
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