15-20 psi Oil Pressure too low for 87 GM 454 Magnum?

[jck3120]

I have an 87 Wellcraft 23' Nova with a 454 big block, and when the oil is hot and you bring it down to idle speed, the oil pressure drops to between 15-20 psi. When running cruising speed it varies between 40-60 psi. I just purchased the boat back in May, and it was the same way. Has about 40 psi at idle on first start-up when the engine is cold. So I changed the oil with a higher end 10W-30, to see if it was a problem with the oil and it didn't seem make a difference. This seems a little low to me, what do you guys with big blocks typically see for oil pressure? Any suggestions/advice? Thanks!

 

[dr_bowtie]

Re: 15-20 psi Oil Pressure too low for 87 GM 454 Magnum?

thats fine...

whats happening is when the motor gets warm the clearances are greater and you lose a little pressure couple that with oil thinning down due to heat...

add some lucas that will help protect where the oil leaves off...

 

[jtybt]

Re: 15-20 psi Oil Pressure too low for 87 GM 454 Magnum?

Running up to plane after warm-up I'm at 85 PSI. During good run pressure is down to 70PSI and drops to 20 PSI coming to no-wake speed.

If it drops during run...STOP!

 

[Bt Doctur]

Re: 15-20 psi Oil Pressure too low for 87 GM 454 Magnum?

25W-40 Merc oil is better, dosent thin out as much.

 

[cr2k]

Re: 15-20 psi Oil Pressure too low for 87 GM 454 Magnum?

For the oil viscosity you are running your pressure is fine. But you should run a slightly higher viscosity like 20-40 or 20-50 if it hot where you are.

 

[Bondo]

Re: 15-20 psi Oil Pressure too low for 87 GM 454 Magnum?

Ayuh,... It's well within the 10psi per 1000rpms rule of thumb... No Problem...

 

[JustJason]

Re: 15-20 psi Oil Pressure too low for 87 GM 454 Magnum?

Oil pressure is fine. When in doubt always check it with a mechanical gauge. Like others have said, 10-30W is a little light (but acceptable). a 15-40 or mercs 25-40 would be best.

Top of the morning to ya Bondo

 

[Fun Times]

Re: 15-20 psi Oil Pressure too low for 87 GM 454 Magnum?

Oil pressure is fine. When in doubt always check it with a mechanical gauge. Like others have said, 10-30W is a little light (but acceptable). a 15-40 or mercs 25-40 would be best.

Top of the morning to ya Bondo

Top of the morning to ya also jason. and by the way good info about the no spark post and using the meter like that. Just wanted to get my 300 post in. and say hi

 

[Bondo]

Re: 15-20 psi Oil Pressure too low for 87 GM 454 Magnum?

Top of the morning to ya Bondo

Ayuh,.... likewise Jason,.....

 

[jck3120]

Re: 15-20 psi Oil Pressure too low for 87 GM 454 Magnum?

Alright thanks guys! Only reason I used the Mobil 10-30 is because I had 2 gallon containers of it. Knew pressure would drop some but wasn't sure if that was too much and something else was wrong. Will run a little thicker oil next time I change it though. I'm in Michigan so it's not usually overly hot.

Thanks again!