I was searching the forums but was unable to figure out what is going on with my 350. It was very cold the other day (like -20) I tried to start her up but she was turning slow. I threw the hood up and noticed she has pushed engine oil out around the filter from the cranking, oil was 10w-30. Since then, I changed to 5w-30 and my oil pressure is near zero at hot idle. As soon as I touch the gas it jumps up to about 40-45. It starts cold at about 50-55. When I rebuilt the engine, I used a Z-28 sping in the oil pump and have not plugged the oil filter adapter. I use the AC 35 filter. I installed a mechanical gauge thinking the old electric one was the problem, but the pressure is the same. I am leaning toward the relief valve in the filter adapter, any thoughts?
oil pressure issue
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I would say that this would be a norm with those temps. You could do better with some type of block heater for those temps. Plugged or stuck bypass spring or disc would also cause this. But main think I feel is the oil viscosity. The light weight oil would be good for seasonal use but you need to change back when warmer temps come around. I really would think of a block heater or and oil pan heat pad for very cold temps.
Thank you for the above comments, but I am thinking that by pushing this oil out, I caused, or it indicates some problem internally. if someone could explain exactly how the relief valve in the oil pump works, and if that could be stuck. I believe the valve in the oil filter adapter opens up and lets unfiltered oil return to the engine. I was thinking I would try plugging the filter adapter (just as a test) to see if it changes the oil pressure. I was advised to try some sea-foam in the oil to see if If it would free up a stuck valve in the oil pump. I don't think it would be wise to plug the adapter permanently with the cold temps I am starting.
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If you plug the adapter spring loaded hole , you will duplicate your problem. I also understand that your oil filter could be restricting also. Some of the guys here mentioned that a Napa Gold filter is the best one to use . I have never done it. With oil that cold, I would think you are trying to push oil with the consistency of molasses thru the filter and the bypass has to open up until the viscosity comes down. I am sure you are not filtering much oil at that rate. Rule of thumb in case you want to use the lighter oil. 10psi per 1000 rpm , so at idle you have about 5 psi until its reved up and hits 40 psi? I still think you need to have a block heater or oil pan heater at -20 degrees. Ask some of the guys in Canada what they do. Maybe Mark LW will pop in. Do check that bypass adapter anyway. You could be about to blow the filter can but the rubber will prolly pop first.
Your heater advice is good, but what worries me more than the infrequent -20 start ups is if this single incident caused an internal problem which has now caused this very low oil pressure at hot idle. Do you think the adapter relief could have been stuck shut thus forcing that cold oil into the filter and subsequently out in my case? or is it a problem with the oil pump? the AC brand filter is original equipment, so I would think that was engineered to work correctly. ps, I am about as close to Canada as you can get.
The oil filter bypass valve will open when the pressure drop across the filter is high. This would be because the filter is plugged, or in your case the cold oil will not flow freely through the filter media. This is likely what caused the pushing of the oil out around the filter. The NAPA gold filter may help, but at -20 the oil is so thick that nothing may help. Blocking the bypass will only aggrevate the leaking problem.
The pump relief valve limits the maximum pressure from the pump. The cold oil is so thick that the pump builds up pressure quickly and the relief valve is most likely open until the oil heats up some.
As mentioned 10 psi per 1000 rpm is a decent rule of thumb at operating temperature.
TTFN
Mat
The pump relief valve limits the maximum pressure from the pump. The cold oil is so thick that the pump builds up pressure quickly and the relief valve is most likely open until the oil heats up some.
As mentioned 10 psi per 1000 rpm is a decent rule of thumb at operating temperature.
TTFN
Mat
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