What is the upper oil pressure range of a Detroit 12v71TA ?

[Milacron]

I should know this but damned if I can remember since our last trip...plus we never went WOT. I ask as I need to order a new gauge and the current ones that have a range to 150 psi seems ridiculous. Range to 100 would be an improvement but thinking even less range than that might be more appropriate.

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(on edit) Occurred to me to look at the survey and during that trial run WOT (2250 rpm, 21 knots) oil pressure was 55.... so a 75 range would seem appropriate ? Only problem is I don't know which gauges the surveyor was going by to arrive at that 55 figure. The remote VDO gauges register a little lower than the direct engine room gauges.

 

[dsharp]

I've never seen one run over 40-45 pounds. At idle it can drop to 20 pounds or less depending on wear.

 

[captddis]

The regulator is set at 50psi.

 

[Steve Barz]

oil pressure from DD field service data book.
50-70# psi normal from 1800 rpm to 2300 rpm
30# minimum
200-250 Degree F temperature at pump pick up.

FYI these engines should always be run at 1800-2300 rpm underway.

 

[SKYCHENEY]

FYI these engines should always be run at 1800-2300 rpm underway.

I disagree. I run with a guy that runs his 12v71's at 1100 most of the time but always runs them up for at least 15 min(sometimes more) every 4hrs. I do the same with my 6v92s. 4200hrs and still running great.

 

[Milacron]

oil pressure from DD field service data book.
50-70# psi normal from 1800 rpm to 2300 rpm
30# minimum
200-250 Degree F temperature at pump pick up.

Thanks. Is the 30 psi minimum at idle (650 rpm in my case) or at 1800 rpm ?

 

[Regal2800]

29 psi is minimum operating pressure at 1800 rpm. but something is wrong if you have that pressure at cruise rpm.

 

[MikeP]

The DD service manual, dated OCT 1989, section 4.1.1 page 1 explains that in 6, 8, and 12V engines, if the oil pressure exceeds 50PSI, the oil pressure regulator valve lifts. So as CaptD pointed out, 50 PSI is the max you would expect to ever see. Obviously this could vary a few PSI either way based on relief valve spring variation.

Re Idle:

Section 13.1, page 2 states: " Start and run the engine at idle...A good indicator that all moving parts are getting lubrication is when the oil pressure gage registers pressure (10 psig - 69 kPa at idle speed)."

Further in the same section, page 4, the manual states that if the gauge does not show pressure 15 seconds after starting, to shut down the engine.

The above are the only specific oil pressure "specs" contained in the service manual regarding engine oil pressure in the galleries (where an oil pressure gauge/sender is connected.

So, per DD, all you are looking for is 10PSI at idle and 50PSI at WOT. Obviously, when cold, the idle pressure will be much higher until the engine/oil heats up.

 

[Milacron]

The DD service manual, dated OCT 1989, section 4.1.1 page 1 explains that in 6, 8, and 12V engines, if the oil pressure exceeds 50PSI, the oil pressure regulator valve lifts. So as CaptD pointed out, 50 PSI is the max you would expect to ever see. Obviously this could vary a few PSI either way based on relief valve spring variation.

Re Idle:

Section 13.1, page 2 states: " Start and run the engine at idle...A good indicator that all moving parts are getting lubrication is when the oil pressure gage registers pressure (10 psig - 69 kPa at idle speed)."

Further in the same section, page 4, the manual states that if the gauge does not show pressure 15 seconds after starting, to shut down the engine.

The above are the only specific oil pressure "specs" contained in the service manual regarding engine oil pressure in the galleries (where an oil pressure gauge/sender is connected.

So, per DD, all you are looking for is 10PSI at idle and 50PSI at WOT. Obviously, when cold, the idle pressure will be much higher until the engine/oil heats up.

Thanks....interesting info. Why Viking chose to use oil pressure gauges with 150 psi range is beyond me...makes it more difficult to tell exactly what the pressure is when the slightest needle move or angle of view can mean 5 lbs difference, and I would think would make the gauge itself less accurate when one needs only 1/3 of the scale.

 

[MikeP]

More FWIW info...I just looked in my DD 1996 V-series engine operators guide (NOT a service manual):

It LOWERS the minimum idle oil pressure from the 1989 service manual, stating that 5PSI at idle speed is OK. Yep, FIVE!!

There is also a statement that oil pressure should not fall below 28PSI at 1800RPM

 

[Milacron]

More FWIW info...I just looked in my DD 1996 V-series engine operators guide (NOT a service manual):

It LOWERS the minimum idle oil pressure from the 1989 service manual, stating that 5PSI at idle speed is OK. Yep, FIVE!!

There is also a statement that oil pressure should not fall below 28PSI at 1800RPM

Wow... 5 psi is scary low. I remember the surveyor thinking that 15 psi at idle was the minimum. According to survey my pressure at 1800 rpm was 40 psi.

At time of survey (May 5, 2015) , both engines had aprox 250 hours since major overhaul so should be like new in pressure department.