Oil in mercury 525 coolant tank
03-17-2018 | 08:44 AM
#1
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Oil in mercury 525 coolant tank
I test drove a boat with twin 525. The boat rode great. However when we got it on the trailer it was realized one of the motors had a very milky coolant in the reservoir tank. I checked the oil at the pan with the dipstick but no sign of anything milky at the pan. Don’t know if it’s an coincidence but the outdrive oil tank on that motor was empty also. I’m assuming the one motor with the milky coolant in the reservoir needs to be torn down or could it be minor in nature, I thought for sure the oil would be milky but it wasnt, no miss or anything on the test drive.
03-17-2018 | 10:20 AM
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the power steering on the boat wasn’t working the steering wheel was extremely hard to turn. However the power steering fluid in the reservoir on the motor was full.
03-17-2018 | 06:09 PM
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From: Ft. Worth TX
03-17-2018 | 09:55 PM
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Is that indicative of it being a cracked head, head gasket, leaking headers (nothing milky on the dipstick only milky coolant reservoir) or cracked block? On the 525 since those coolers are raw water called are they basically ruled out?
03-17-2018 | 11:55 PM
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From: Ft. Worth TX
I would want to know so we are on the same page here. Is this a OEM Stock Merc racing HP 525 ?
Thinking out loud and off the top of my head here. I do not have a HP 525 in currently actually not even yet for this year. Anyways raw water / sea water cooling side from start to finish.. The start --- water pick up however thru drive or pick up then thru the inlet of the water pump impeller side -- then out of the impeller housing to the fuel cooler --- then thru the engine oil cooler ---- then thru the pwr steering cooler --- then thru the inlet of the heat exchanger and then thru the outlets of the heat exchanger --- then to the exhaust headers distribution rails then thru the exhaust headers for the final exit.
The reason I am thinking about this is because AND DO NOT HOLD ME 100 percent here --- I think I had this same situation many many years ago. The owner thought since he had a closed cooled engine that nothing could ever freeze break and no winterization was needed. IF I recall correctly he had a cracked oil cooler and crack heat exchanger. But his oil level was always going low on the dip stick and the coolant reservoir would get some motor oil in it. Again I am trying to remember if thats what totally caused the motor oil in the coolant reservoir. Anyways that might be areas of concern if the boat was in freezing weather for even a couple days and not drained of water per those sides. Man it was a cold *****hhh this winter.
Thinking out loud and off the top of my head here. I do not have a HP 525 in currently actually not even yet for this year. Anyways raw water / sea water cooling side from start to finish.. The start --- water pick up however thru drive or pick up then thru the inlet of the water pump impeller side -- then out of the impeller housing to the fuel cooler --- then thru the engine oil cooler ---- then thru the pwr steering cooler --- then thru the inlet of the heat exchanger and then thru the outlets of the heat exchanger --- then to the exhaust headers distribution rails then thru the exhaust headers for the final exit.
The reason I am thinking about this is because AND DO NOT HOLD ME 100 percent here --- I think I had this same situation many many years ago. The owner thought since he had a closed cooled engine that nothing could ever freeze break and no winterization was needed. IF I recall correctly he had a cracked oil cooler and crack heat exchanger. But his oil level was always going low on the dip stick and the coolant reservoir would get some motor oil in it. Again I am trying to remember if thats what totally caused the motor oil in the coolant reservoir. Anyways that might be areas of concern if the boat was in freezing weather for even a couple days and not drained of water per those sides. Man it was a cold *****hhh this winter.
Last edited by BUP; 03-18-2018 at 12:04 AM.
03-18-2018 | 03:49 AM
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From: Germany
Normally it is very near that something wrong with Motorblock,heads or headgasket or intake is, as the other parts have no contact to the coolant liquid.
Sounds not good!Oilpressure is higher that the pressure in the freezecoolantside.So oil go the way in there.
regards
Michael
Sounds not good!Oilpressure is higher that the pressure in the freezecoolantside.So oil go the way in there.
regards
Michael
