3B Oil Pressure Readings (1 Viewer)

[YoYoHo]

I was doing a Turbo install on a 3B and as part of the process I take some oil pressure readings before and after just for peace of mind.

Anyway, I thought I would post a few pictures as they may help some one out if they are looking for 3B oil Pressures with Turbo etc.

The engine is a 3B with Rotary Fuel Pump running in a BJ46. It has 240 000 km on it

Compression is pretty much 475 across the board and I have drained the oil, removes the sump, inspected everything and then given it new Oil and Filters.

Oil is 15/40 T4

These readings where taken both cold and hot just to show the pressure and also the vagueness of the factory pressure gauge.

Cold Engine 2500 RPM

Cold Engine at Idle

Cold Engine 2500 RPM , 75PSI on the Gauge , Factory Gauge reading

Engine starting to warm, temp gauge just moving, 50 PSI on gauge, engine at idle

Warm Engine , at idle factory gauge makes you want to pull over 30 PSI on the gauge.

I will swap out the 15/40 for some 20/40 just to get it a little higher when warm but it goes to show that the factory gauge can give you a fright when really it is not that bad.

None of this cause the Fuel Cut off to Actuate.

 

[samwise]

Ive had similar readings, a bit higher but similar after I had mine rebuilt a year ago. When its really hot in the summer, like 95 outside running the AC on road trips it will drop to 14-20 at idle, but thats still fine according to fsm. Thats with 15/40 Delo.
That being said I have noticed my factory dash gauge is actually quite accurate, been watching both for a year, and the rough correlations between them are very consistent. Not saying another gauge isnt a good idea, just that mine has been good.

 

[gerg]

My buddies truck hot Idle was enough to shut the edic off so he bumped the rpms up. I'd say anything in the upper teens for hot Idle is doing pretty darn good.

 

[RufusTheDufus]

I usually run Rotella 15w40 T4 in the summer months and the Rotella 5w40 T6 in cold weather. I have a mechanical oil pressure gauge and my engine usually runs the same as YoHoHo's numbers in the first post.

I'm on a 10k mile trip to Baja California at the moment and decided to switch to Amsoil's Signature Series 15w40 for the trip. (longer oil change intervals) With the Amsoil I'm seeing 10 to 15 psi higher oil pressure readings over the entire RPM range when the engine is up to temp. And the engine is using much less oil, only 1 quart in 4k miles so far. With the Rotella 15w40 it was going through oil at least 2x faster.

 

[gerg]

Interesting

 

[mano002]

The oil pressure gauge on my BJ60 reads very low, I appreciate that you have measured this. I should do the same.

 

[GTSSportCoupe]

I've often wondered how much the piston oil coolers (squirters) drop oil pressure at low rpm....

Thanks for sharing this.

Somewhere on this forum someone opened up one of the OEM oil sender units and showed how they wear out over time. A new one would probably show higher oil pressure than your existing one does. Not that it matters; it's all relative as you've illustrated.

 

[Iszzyfj60]

I just replaced the turbo on my 3b, the previous turbo had a known oil leak on the compressor side and was pumping oil into my intake. Lots of black smoke. There's an aftermarket oil pressure gauge connected to the feed line going to the turbo. Before I swapped turbos I'd see 35-50 psi cold idle on the aftermarket gauge and right at the L on the factory gauge. Once warm the aftermarket gauge would read 5-10 psi at idle and 15psi at 2500rpms. Now the new turbo is on I'm seeing 50psi+ on cold starts and 20-35psi when warm at 2500rpm

 

[Greg_B]

You're good and healthy with those numbers as the FSM lists at operating temperature the oil should be: idle minimum 4.3psi or more and at 3000rpm 36psi-85 psi.

The 3B in my BJ42 has been around 7-10 psi at hot idle for all of my 2 decades of ownership. Though that's not saying much as it did not even get insured for road use in 2019! I was relived when I checked it with a mechanical gauge before I put in the full time mechanical gauge as after it warms up as the stock gauge shows hardly any pressure when driving and none when idling.

hth's
gb