Low Oil Pressure at Idle

[Omorgan 1 1 Cars]

Hello all,

 

I have completed building my XU9J4 MI16 engine and have run it in, changed the oil 4 times over the last 2000 miles, all good so far. I'm running 5W40 oil. I have recently noticed that my idle oil pressure has fallen from roughly 16PSI to about 8PSI when hot (95degrees).  I thought it was a cheap gauge fault so I replaced the sensor, and the issue was the same. I then bought and hooked up an analogue gauge to triple check which also agreed. 

 

I've installed the sprocket and chain mod for extra oil flow and a 6 bar spring, brand new OEM oil pump. I've since removed the sump, and baffle, inspected the pump and chain, everything looks good. 

 

When I built the engine, I replaced my old piston cooling squirters with used ones, that i blew through by mouth and tested that they stayed closed, which they did. 

 

All the research I have done tells me that 8PSI is too low. I'm wondering if I go up to 5W50 or I have something more going on that I have to be worried about.

 

I get 6Bar (85ishPSI) cold at idle.

         0.5Bar (8-10PSI) hot at idle

         5Bar at high RPM 

         3-4Bar at 40Mph in 3rd (I have no tacho, don't know RPM)

 

Any suggestions would be really appreciated.

 

Thanks,

Owen.

 

[welshpug 1,682]

did you check the bearing clearances with plastigauge?

 

 

where did the oil pump come from?

 

8psi would have the low oil pressure warning light on all the time, my fresh built 2.2 was running almost 6 bar cold on normal 10w40, 1.5 bar hot idle.

 

   5w40 is a bit thin for them, standard spec is 10w40, if its struggling with heat you could go 10w50.

Edited Monday at 08:40 PM by welshpug

[Omorgan 1 1 Cars]

Thanks for that mate, yeah I checked l clearences with plastigauge and they're all the same and in spec. The crank was oversized and the bearings were stamped 0.3 also. 

 

Oil pump was from PUG1OFF. 

 

I only went to 5w40 over 10w40 because of high cold oil pressure (6Bar). Perhaps I'll go for 10W50. However it feels like a bandage for a larger issue. I'm wondering if the valves in the oil squirters for the pistons have failed. 

 

 

[petert 616]

What clearance on:

mains?
con-rods?

 

How many teeth on the crank oil pump drive sprocket?

I would have chosen 10W-40.

[Omorgan 1 1 Cars]

Mains - 0.025

Big ends - 0.025

 

IIRC - I'll review my footage when I get home, and will double check oil pump drive. 

 

 

 

 

 

 

[petert 616]

0.025? What units?

[Omorgan 1 1 Cars]

MM - as per the Haynes 

 

 

[Omorgan 1 1 Cars]

Mains - Between 0.063 and 0.050 MM

Big ends - Between 0.050 and 0.038 MM

 

I have a 26T crack sprocket and 52 link chain.

 

 

[SRDT 203]

Did you buy the "XU10J4RS" pump?

[Omorgan 1 1 Cars]

No, just the XU9J4 pump. 

42 minutes ago, SRDT said:

Did you buy the "XU10J4RS" pump?

 

[Omorgan 1 1 Cars]

52 minutes ago, SRDT said:

Did you buy the "XU10J4RS" pump?

No, just the XU9J4 pump

[petert 616]

Is there a shim under the pump? I can’t see one.

 

I'm wondering if it's leaking between pump-shim-block?

Edited Wednesday at 12:11 AM by petert

[Omorgan 1 1 Cars]

Yeah I replaced it with a thicker one I made. I took it apart and checked it recently, and resealed it back together with no change. Still not ruled out though - thanks

[SRDT 203]

22 hours ago, Omorgan said:

No, just the XU9J4 pump

Looks more like the "XU10J4RS" one pictured on the PUG1OFF website. It just lacks the bolted baffle.

You can see the BG automotive logo, it must be LP0388 unless they started using the same pump body for LP2294 and didn't update the pictures.

 

How was it inside, was the piston even chamfered? LP0388 shoud also have a 6 bar spring with a guide pin but some manufacturers don't bother with internal parts compatibility.

[Omorgan 1 1 Cars]

I have a video of the teardown, which I have taken some screenshots of. Idk if this amoubnt of wear is typical for a 2000 mile pump?