1991 Mercury 40hp Classic 4cyl 2-Stroke
Hello all
Had a bit of an engine day on Friday with the boat sat on the swinging mooring
Had stalling issues due to idle speed being too low, adjusted it up and all good
Even got my shift linkage adjusted so no pre-tension in any direction on the mechanism when in any gear F-N-R
Must have had the engine running on and off for up to an hour. Turned it off, trimmed it right up and tidied up the tools and was just about to jump in the dinghy and row to shore when I noticed oil/fuel dripping into the water from the lower unit water intake.
Caught some in my hand and gave it a sniff
Thin browny black translucent substance , i would have said petrol/gas but am very aware that oil from the water intake is most likely due to gear oil contaminating the coolant water via a lower driveshaft seal (under the water pump base).
I read that others also say the large o-ring seal on the water pump base can also be a culprit but in my opinion if the o-ring is compromised then this would effectively allow water ingress into the lower unit and/or gear oil into the mid section water jacket i.e. (outside the water pump chamber) and not inside it so would therefore not show up at the water intake?
I also hear shift shaft seals mentioned as a cause, but again that’s introducing gear oil into the mid section water jacket and not into the water pump housing which wouldn’t show up in the water intake?
Please correct me if I’m wrong
I’m confused as to what the oil is? Smells like gas, seems really thin like gas/petrol but I guess warm gear oil emulsified with water might appear/smell similar?
Have ordered water pump seal kit
26-79831A 1
and a new water pump base 46-77177A1
(I envision issues prying this out intact)
Planning on pulling the lower unit (while at sea) if I can get the dinghy under it
Take it ashore and pull the pump hosing off and replace all I can with the seal kit above
I’m expecting the lower drive shaft seal to be the culprit. Am I being too simplistic and hopeful? Any ideas anyone? Could I be way off here? Could gas/petrol or even unburned 2S oil be somehow entering the water pump housing from the mid section via drive shaft slinger seal, either by running down the driveshaft or having come down the inside or outside of the exhaust tube?
All input greatly appreciated.
Hello all
Had a bit of an engine day on Friday with the boat sat on the swinging mooring
Had stalling issues due to idle speed being too low, adjusted it up and all good
Even got my shift linkage adjusted so no pre-tension in any direction on the mechanism when in any gear F-N-R
Must have had the engine running on and off for up to an hour. Turned it off, trimmed it right up and tidied up the tools and was just about to jump in the dinghy and row to shore when I noticed oil/fuel dripping into the water from the lower unit water intake.
Caught some in my hand and gave it a sniff
Thin browny black translucent substance , i would have said petrol/gas but am very aware that oil from the water intake is most likely due to gear oil contaminating the coolant water via a lower driveshaft seal (under the water pump base).
I read that others also say the large o-ring seal on the water pump base can also be a culprit but in my opinion if the o-ring is compromised then this would effectively allow water ingress into the lower unit and/or gear oil into the mid section water jacket i.e. (outside the water pump chamber) and not inside it so would therefore not show up at the water intake?
I also hear shift shaft seals mentioned as a cause, but again that’s introducing gear oil into the mid section water jacket and not into the water pump housing which wouldn’t show up in the water intake?
Please correct me if I’m wrong
I’m confused as to what the oil is? Smells like gas, seems really thin like gas/petrol but I guess warm gear oil emulsified with water might appear/smell similar?
Have ordered water pump seal kit
26-79831A 1
and a new water pump base 46-77177A1
(I envision issues prying this out intact)
Planning on pulling the lower unit (while at sea) if I can get the dinghy under it
Take it ashore and pull the pump hosing off and replace all I can with the seal kit above
I’m expecting the lower drive shaft seal to be the culprit. Am I being too simplistic and hopeful? Any ideas anyone? Could I be way off here? Could gas/petrol or even unburned 2S oil be somehow entering the water pump housing from the mid section via drive shaft slinger seal, either by running down the driveshaft or having come down the inside or outside of the exhaust tube?
All input greatly appreciated.
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