View Full Version : 471 GM

03-01-2009, 06:14 PM
my 471 marine motor is leaking black oil when under load into the pan. I cant see where its coming from possibly the small breather just above the oil pan - where should I check and why would it leak out of the breather

03-16-2009, 09:17 AM
What migh happen there it is that you have to much pressure in the engine you need to buy at valve cover that have a breather you can call at 305-545-5588 they be able to help you with that

03-16-2009, 09:50 PM
how can you tell your getting back oil the pan????

03-17-2009, 12:23 AM
"There is a stainless pan under the motor which we emptied, then after a run with the motor up to 1600 revs for an hour the pan had lots of black oil in it and the motor needed a similar amount
a litre or so

03-17-2009, 03:43 PM
"look for 1/4 tube on lower side of engine,comeing out of the block. run engine, should have air blowing out check if lots of oil also comeing out."

03-17-2009, 04:05 PM
I gather thats the tube pointing downward just above the sump on the left hand side at the back of the motor -looking forward. I think thats the tube leaking oil
will check to see if air is coming out as well
Thanks for your help

03-21-2009, 04:50 PM
the oil is definitely coming out of the air box breather.

03-23-2009, 09:02 PM
Black carbon oil blowing from the air box drain tube is a sign of worn cylinder kits. It may be time for an inframe overhaul!

03-26-2009, 06:32 PM
Is the air box with the breather a seperate chamber on its own or is it part of the crankcase?

03-30-2009, 09:33 PM
"air box is not part of crankcase system, its part of the blower syetem."

03-31-2009, 02:02 AM
thank you

04-09-2009, 09:38 AM
"Just to add to what Ronald said:

Bad blower seals could also cause oil to blow out of the air box tubes. So if your cylinder kits check out, I'd look at the blower."

04-23-2009, 08:32 PM
"I have a detroit diesel crusher on the engine the air breather is blowing out and muffler is sucking air in so, what could the problem be"

04-24-2009, 11:15 PM
"Anthony, have you just replaced your starter? Could have a starter with the wrong rotation, which is turning your engine backwards."