I have just had my engine rebuilt and I am concerned about the oil pressure. With a cold start it is about 24 psi but as the enginr warms up it drops to about 7 psi ( at an idle ) is this normal?
yanmar yse oil pressure
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7 psi too low !
Oil Pressures vary between engines and will be higher when cold. Consistently low oil pressure suggests a worn engine. Many factors effect oil pressure especially oil grade, age, and temperature. As bearings wear and clearances increase the oil system has to work harder to maintain oil pressures. Therefore the oil pressure can give a very good indication of the general condition of an engine. Pressures are typically 40 - 60psi at idle on cold startup. Pressure must show on gauge within 15 seconds or shut down the engine and locate the problem. At high rpm these pressures should be maintained but will drop as the engine reaches operating temperatures. When returned to idle a hot engine may show pressures below 20psi. Low pressures throughout the operating range may indicate a well used engine, but check the oil system specification, and the gauge/sender, before taking any expensive action. Whoever rebuilt your engine should be able to provide detailed and specific information & advice.
Oil Pressures vary between engines and will be higher when cold. Consistently low oil pressure suggests a worn engine. Many factors effect oil pressure especially oil grade, age, and temperature. As bearings wear and clearances increase the oil system has to work harder to maintain oil pressures. Therefore the oil pressure can give a very good indication of the general condition of an engine. Pressures are typically 40 - 60psi at idle on cold startup. Pressure must show on gauge within 15 seconds or shut down the engine and locate the problem. At high rpm these pressures should be maintained but will drop as the engine reaches operating temperatures. When returned to idle a hot engine may show pressures below 20psi. Low pressures throughout the operating range may indicate a well used engine, but check the oil system specification, and the gauge/sender, before taking any expensive action. Whoever rebuilt your engine should be able to provide detailed and specific information & advice.
Oil Pressure
Gord's advice is good but think also about the following. Are you measuring the 7 psi directly from the analog guage on your panel. Analog guages, while sometimes extremely accurate, are mostly indicators of relative measurement of change---not at all exact. Often just measure a HI or A Low. To get the "exact" pst you will need a calibrated test guage to make these measurements. Also, when you see 7psi-- what is the "actual" engine idle speed? The tach is also a relative measurement and not and "exact measurement. Depending on the tach type it can be off as much as 10 or more per cent. Use a shaft tach to determine the real engine speed vs. manufacturers recommendation and a test oil psi guage to see how things really are. Then you will know where you actually are.
Gord's advice is good but think also about the following. Are you measuring the 7 psi directly from the analog guage on your panel. Analog guages, while sometimes extremely accurate, are mostly indicators of relative measurement of change---not at all exact. Often just measure a HI or A Low. To get the "exact" pst you will need a calibrated test guage to make these measurements. Also, when you see 7psi-- what is the "actual" engine idle speed? The tach is also a relative measurement and not and "exact measurement. Depending on the tach type it can be off as much as 10 or more per cent. Use a shaft tach to determine the real engine speed vs. manufacturers recommendation and a test oil psi guage to see how things really are. Then you will know where you actually are.
Rob,
assuming you owned the engine before it was rebuilt and assuming you had the same gauge, what where the corresponding readings before the rebuild? I would be concerned with the observed values no matter what speed or temperature.
assuming you owned the engine before it was rebuilt and assuming you had the same gauge, what where the corresponding readings before the rebuild? I would be concerned with the observed values no matter what speed or temperature.
Oil Pressure Problem
Rob, I assume that you have the Yanmar YSE-12 single. I had this diesel in our 1977 Catalina 30 until it died of "oil failure" (rod bearing seized) I managed to locate another YSE that had been rebuilt however it had only lasted about 25 hours after it's rebuild. Thought that I could maybe use it as a parts engine. Took the motors into the machine shop and soon learned of an apparent weakness with the YSE-12's and their oiling system. Seems that the reason my engine failed was due to low/no oil pressure as did the parts engine that I purchased. The oil pump that consists of two gears is located inside the aluminum cover at the front of the engine. There is a shaft that runs through a machined hole in this cover to run the gear. There is no bushing so it is steel against aluminum and over time and older age the machined hole starts to get worn and looks a bit egg shaped.(This was very noticable on mine) That is when the oil pressure starts to go south. The oil takes the path of least resistance which is back along the shaft and back into the crank case thus not providing the required oil pressure. Can it be fixed. Yes! However the cost of a new front aluminum oil pump case was quoted to me at approx. $1,500.00 Canadian. I had a great idea, why not just oversize the oil pump shaft hole and install an oversize brass bushing. Learned it had been tried before with fair to bad results. It had to be perfectly aligned to work and be dependable. I learned that there was a marine engine mechanical shop in England that has designed a jig that can do the job correctly at much less than purchasing a new part. As a matter of note another 1975 Catalina 30 at our marina also met a similiar fate this summer and again it was the worn oil pump shaft hole. This not to say this is your oil pressure problem however it is a YSE weakness. How did I cure the problem? Out with the old and replaced with a Yanmar 2GM. Cliff Carter PlusOne C-30, #598 Oak Bay, B.C.
Rob, I assume that you have the Yanmar YSE-12 single. I had this diesel in our 1977 Catalina 30 until it died of "oil failure" (rod bearing seized) I managed to locate another YSE that had been rebuilt however it had only lasted about 25 hours after it's rebuild. Thought that I could maybe use it as a parts engine. Took the motors into the machine shop and soon learned of an apparent weakness with the YSE-12's and their oiling system. Seems that the reason my engine failed was due to low/no oil pressure as did the parts engine that I purchased. The oil pump that consists of two gears is located inside the aluminum cover at the front of the engine. There is a shaft that runs through a machined hole in this cover to run the gear. There is no bushing so it is steel against aluminum and over time and older age the machined hole starts to get worn and looks a bit egg shaped.(This was very noticable on mine) That is when the oil pressure starts to go south. The oil takes the path of least resistance which is back along the shaft and back into the crank case thus not providing the required oil pressure. Can it be fixed. Yes! However the cost of a new front aluminum oil pump case was quoted to me at approx. $1,500.00 Canadian. I had a great idea, why not just oversize the oil pump shaft hole and install an oversize brass bushing. Learned it had been tried before with fair to bad results. It had to be perfectly aligned to work and be dependable. I learned that there was a marine engine mechanical shop in England that has designed a jig that can do the job correctly at much less than purchasing a new part. As a matter of note another 1975 Catalina 30 at our marina also met a similiar fate this summer and again it was the worn oil pump shaft hole. This not to say this is your oil pressure problem however it is a YSE weakness. How did I cure the problem? Out with the old and replaced with a Yanmar 2GM. Cliff Carter PlusOne C-30, #598 Oak Bay, B.C.
thanks
I took it out for my first sea trial in 20 min oil pressure had dropped to 30 psi ; engine died; restarted ( ENGINE NOT HOT ) 35 min engine died again ( this time hot -- cant restart)30 min later it had cooled enough to restart. I think Cliff has the answer -- I will have to work out the soloution. I have paid out over $5000 now so I have reached the point of no return. Wish me luck!!
I took it out for my first sea trial in 20 min oil pressure had dropped to 30 psi ; engine died; restarted ( ENGINE NOT HOT ) 35 min engine died again ( this time hot -- cant restart)30 min later it had cooled enough to restart. I think Cliff has the answer -- I will have to work out the soloution. I have paid out over $5000 now so I have reached the point of no return. Wish me luck!!
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