Oil pressure question

[wil7483]

Hey guys, what is the normal oil pressure reading range on a SBC 350 5.7 engine. I is a Rapido Marine rebuilt engine. Under way the pressure is steady at about 40 psi but at idle it is near the 60 psi range. is this normal? I know that the crankcase isn't over full because i just changed the oil and drained it completely and put exactly 5 quarts back in.

 

[HT32BSX115]

Re: Oil pressure question

Hi Dione,

Did you try a direct reading gage to verify the gage?

I'm thinking that you might have a sticky regulator in the pump that "releases" when you run up the engine.

Does it go from 40-60 when you throttle back or does it indicate 60 at cold idle and go to 40 when you run it up?

 

[wil7483]

Re: Oil pressure question

60 at cold idle and drops as you throttle up.

 

[Bondo]

Re: Oil pressure question

Ayuh,... I'd check it with a mechanical gauge,... Your's is working Backwards...

 

[wil7483]

Re: Oil pressure question

See, that is what I thought as well. I will go to autozone and buy an oil pressure gauge and get a correct reading. Thanks. Any idea what the correct reading should be.

 

[HT32BSX115]

Re: Oil pressure question

Use a direct reading gage too.....just get some fittings at the hardware store and hook up a gage from your air compressor or similar.

Any 0-100 psi gage will work.

 

[Varago]

Re: Oil pressure question

Your picture shows ~60psi under way 30mph at 150F, so what is wrong ? At idle cold it will also be about 60 and drop to 40 when hot at idle. Also I think its 5 qts when you change the filter otherwise 4 at the engines I have worked on.

Dave

 

[wil7483]

Re: Oil pressure question

Your picture shows ~60psi under way 30mph at 150F, so what is wrong ? At idle cold it will also be about 60 and drop to 40 when hot at idle. Also I think its 5 qts when you change the filter otherwise 4 at the engines I have worked on.

Dave

Yea, the filter was changed as well. It is now reading 60 psi at cold and goes down as you increase rpm's and put a load on the engine.

 

[wil7483]

Re: Oil pressure question

Use a direct reading gage too.....just get some fittings at the hardware store and hook up a gage from your air compressor or similar.

Any 0-100 psi gage will work.

Care to draw me a diagram Rick? So can I use my compression gauge?

 

[Don S]

Re: Oil pressure question

Don't mess up your compression gauge for what it was intended by getting oil in it. That oil makes a mell of a hess when you release the pressure on the compression gauge after doing a compression check.

 

[Bondo]

Re: Oil pressure question

That oil makes a mell of a hess when you release the pressure on the compression gauge after doing a compression check.

Ayuh,.... I Bet it does....
And, a mechanical gauge at Napa is What,...?? $10., $15, maybe....

 

[HT32BSX115]

Re: Oil pressure question

Yeah...any cheepy gage will work.....the little gage on a Harbor Freight regulator etc, will be fine (put a long enough hose on it and use the one from your air compressor)

Just get a small piece of hose and use a couple of brass hose bibs with clamps. You'll want to look at where the sender screws in. It's usually 1/8 or 1/4" NPT (National Pipe Thread) Home Depot will have the fittings....

(like they said) If you use your compression test gage you might accidentally push that little release button or bump it and fill the hose with oil!

 

[wil7483]

Re: Oil pressure question

Rick,

I'm not an engine guy so I need it spelled out a little better. Are you saying to get a gauge and some hose and I'm assuming a fitting that matches the hole that the sender is in and screw it in there and then start the engine and it will measure the pressure? What exactly is the gauge called so I will know exactly what to ask for when I go to O'Reilly's in the morning on my way to the bay?

 

[HT32BSX115]

Re: Oil pressure question

No problem D,

A gage like this one:

From the Surplus Center

http://www.surpluscenter.com/item.asp?UID=2009041700164626&item=21-1634-BB&catname=air


Would work just fine. Any similar gage is ok. Get some fittings from Home Depot (usually cheaper than the ones from an autoparts place) and use a piece of hose from any autoparts store (most autoparts stores have mechanical gages too)

The hose barb, like this one

work just fine for low pressure even without a clamp. I would use mini-clamps though...you do not want oil spewing all over!!

You can see those fittings at http://www.fittingsandadapters.com/

You just need to determine what size the hole in the block is. (just remove your oil press sender and compare the hose barb threads to it....) They come in all different size pipe threads.....most are 1/8" or 1/4 pipe....but if you have the sender in your hand you can match a hose-barb directly to it and a piece of hose.... ...




//R

 

[wil7483]

Re: Oil pressure question

I couldn't have asked for anything better than that Rick. Thanks. I will definitely get this done in the morning, probably while on the water. I have plenty of hose on the boat as well as hose clamps in the under seat storage areas. All I need is the gauge and fittings which I can get on the way to the bay.

 

[wil7483]

Re: Oil pressure question

Thanks Rick and everyone. I hooked up the mechanical gauge today and here are my results.

750 rpm idle - 53psi
2000 rpm - 63 psi

I hooked up the dash gauge afterwards and it is still showing 60 psi at idle and dropping to 45 psi as you increase rpm's. What is the cause of this? Is it the gauge itself or the sender?

Thanks again.

 

[wil7483]

Re: Oil pressure question

It just started doing it. I thought it was working backwards but I wasn't sure. I am going to order a new sender and see if that corrects the problem. It is the least expensive option. If it is still happening then I will invest in a new gauge.

 

[KJSmitty]

Re: Oil pressure question

For reference only,

My VP 350 idles at 550 rpm hot and gage reads 30psi. Anything over 2000 rpm its at 60 psi +. Max's out at around 70 psi.

Cheers