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-   -   High RPM oil pressure (https://www.offshoreonly.com/forums/general-q/192711-high-rpm-oil-pressure.html)

Griff 08-07-2008 03:53 PM


Originally Posted by Vicious22 (Post 2647591)
the filter housing has a sending unit port machined in it


If the sneding unit is not completely immersed in the flow of the oil, it will not read accurately.

What oil cooler and do you have a pic of where the sender is mounted???

You can also check oil temp with a laser IR temp gun and shoot it at the oil pan.

stevesxm 08-07-2008 04:01 PM

geeze... if we assume that the temp is wrong and its really 265 or something and thats the problem it seems to me that those motors would be creaking and pinging and smelling bad and you wouldn't need a temp gun to know there was something wrong but who knows.

either way... as mentioned earlier... a mechanical gage to confirm and if it really does this then you sure as hell better find out what it is before you have to put out a fire .

as for oil level... the pick up ought to be within a half inch of the bottom of the pan... it would have to be 6 quarts or more low to even think about sucking air... seems to me that while a quart low in an 10 quart pan is not likely to be the issue...

haven't read the thread recently but has anyone suggested just throwing a new filter at it ? maybe something bizzare going on in there...

Griff 08-08-2008 02:13 AM

Could be that the oil is too cool and the condensation is causing the paper element in the oil filter to swell. Try some Mobil 1 15-50 oil and a Mobil 1 filter. The use a synthetic filter media in the filter and the synthethic oil will hold up to higher temps better.

Bottom line is the actual temp of the oil needs to be verified mechanically. The oil can easily be getting to 260-290* without burning. It will just break down much faster and loose viscosity.

kvogt 08-08-2008 07:32 AM

Is it a stroker motor? Try running at a half to one qt low on the dip stick. This will help tell if you are frothing the oil.

What is your oil pump pickup to pan clearance? Might be to close and starving the pump at higher rpm.

Kris Vogt

kubcat 08-08-2008 08:08 AM


Originally Posted by Vicious22 (Post 2646245)
I'm running a 515ci BBC. On a long 5000 rpm run my oil pressure starts to slowly fall off. 3000 rpm it's at about 55psi. after about a minute at 5000 it starts down.

Stats: 10 qrt pan, Valvoline Racing 20w-50, mechanical gauge, Fram HP4 filter, Oil temp 195-205 (at filter before cooler).

If I stay on the throttle it'll drop to 30 psi.

I just changed the Oil. Found no metal in the filter.

Where do I start?

Do you have a high volume oil pump? Do a search on a thread comparing High Volume Oil Pumps to standard. Apparently they can sometimes suck an oil pan dry.

Though not sure why it would be getting worse over time.

Just taking a wild guess here.

Scarab28 08-08-2008 10:01 PM

If oil was whipping, how long would it take the pressure to return to normal after lowering rpms? Would it be immediate or take several minutes?


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