Noisy Lifters and Low Oil Pressure on 5.0 GXE-i with SAE 30 Synthetic

[Salty_Doug]

Hi, I am relatively new to this forum. My Boat, new to me, is a 2005 with no engine hour meter. I changed the oil and filter and used an OEM oil filter and Name Brand 10W-30 synthetic oil. (The owners manual recommends SAE 30 synthetic oil.) I checked the oil level after running the engine to fill the filter and check for leaks. When I took the boat out for a test run, the lifters would make a lot of noise and the oil pressure would drop when the engine was run above 3000 RPM. I drained the oil and put some SAE 30 oil in the engine. The next test run had the same symptoms. I drained the oil again and put "Racing" 15W-50 Synthetic oil in the engine. On the third run the oil pressure stayed up and the lifters were quiet up to 5,000 RPM.
My questions are:
1. Should I ignore the problem and keep putting 15W-50 oil in it?
2. Should I replace only the oil pump or replace the lifters too?
3. Can I buy the oil pump and lifters from Chevy/GM?

Thanks in advance.

 

[Scott Danforth]

have you verified the oil pressure with a mechanical gauge?

you may have an oil pump issue, you may have an oil pump pickup issue, you may have a cracked lifter valley issue, you may have an o-ring / distributor body issue (preventing oil from pressurizing the right bank) time to do some diagnostics

you can buy the oil pump from your local parts store, GM, or on-line. same goes with lifters. however if you starved the motor for oil, I would also look at bearing tolerances and probably a full tear down and rebuild.

I prefer to use Mehling oil pumps myself in my builds.

 

[jerryjerry05]

Maybe check the timing?

 

[jimmbo]

Volvo did recommend Synthetic 30 in their engines. I think they now included 15 - 40 in their spec.
So called 'Racing Oil's are not really a good choice. Racing oils are formulated for a short life cycle, a brutal one yes, but short. and therefore not blended for long duration use. A lot of automotive oils fall short for marine use too. In my opinion, Use a Volvo Oil or a Synthetic from Mercury in the proper viscosity.