Low oil pressure. What to check?

[maniac]

As topic says, I have problems with low oil pressure. The engine is recently started since a rebuild. New bearings, piston rings, arp head bolts etc, etc. The engine have´nt been properly warmed up due to the low pressure. The gauge shows around 2 bar when cold and under 1 bar when the oil gets warmer.
Changing oil and filter did´nt work. I have changed the oil pressure switch and sender on the block, the oilpump and the relief valve on the pump, and the pickup pipe is not clogged or something like that. Whats left to check? I´m starting to get really mad now

[Billman]

Good seal on the pickup pipe to the oil pump. If it sucks air then the oil is no coming up.

What main bolts did you use?

[pasbogdan]

Good seal on the pickup pipe to the oil pump. If it sucks air then the oil is no coming up.

good thinking of that
What clearances did you had at big end and main bearings?
New oilpump or used one?
The gear that spools the oilpump is fixed on crank?
Something is not ok.My engine had half of the bearings(big end and main) distroyed,they were yellow color,1 mm play and at cold start pres. was 4 bar...
Get a gauge in the place of presure sender to be shure the dash isn't wrong.

[maniac]

Thank you for your input guys!

It´s oem main bolts. Arp big end and to the cylinder head. The seal to the pickup pipe was replaced when the engine assembled but I did´nt bother to change it when I changed the pump. Perhaps that was stupid... The pump is new btw.
The pump is connected to the crank otherwise I should have zero pressure? Right?

And I think the bearing clearances was within the tolerance. I certainly hope it´s not the bearings...

Btw can the oilcooler be an issue? I have a bigger one where the aux rad used to be. Gonna try to lower it tomorrow and see if makes a difference. Also I´m gonna try to find another gauge to check the pressure.

[Error404]

Is this yet another build where the bearing clearances weren't checked on assembly? :yet:

you should definately use a proper pressure gauge not the dash gauge which is not accurate at all.
You should see 2+ bar cranking the car on the starter motor with the plugs out.

Did you pre-fill the oil cooler? How long did you run the engine for?

[caterpillar]

In the oilfilter housing you does hav a gasged, hav you checked this: and in the oilfilter housing, you does have the "bleedbackvalve".. its a umbrako, or torx 5-6mm valve in the oilfilterhousing; there come loose.. ( you need to take out the oilfilter housing, and the oilfiltercooler,the small sqare little box) to check this..
if this are ok: or you dont have more pressure; DONT use the engine.. have it out, and do the repair again....!

[maniac]

Is this yet another build where the bearing clearances weren't checked on assembly? :yet:

you should definately use a proper pressure gauge not the dash gauge which is not accurate at all.
You should see 2+ bar cranking the car on the starter motor with the plugs out.

Did you pre-fill the oil cooler? How long did you run the engine for?

I can´t say for certain because I did´nt build the bottom end. I am going to check with my friend who assembled the motor

Yes I did fill the oil cooler. I did loose the banjo bolts on top of the cooler and oil was coming out so it´s oil in the cooler.
I only run the engine until the low oil pressure warning light appeared, then I turned it off.

In the oilfilter housing you does hav a gasged, hav you checked this: and in the oilfilter housing, you does have the "bleedbackvalve".. its a umbrako, or torx 5-6mm valve in the oilfilterhousing; there come loose.. ( you need to take out the oilfilter housing, and the oilfiltercooler,the small sqare little box) to check this..
if this are ok: or you dont have more pressure; DONT use the engine.. have it out, and do the repair again....!

Good tip! Gonna check that also

I hope it don´t comes down to take the engine apart again

Thank you for your advice guys!

[V6quattro]

In the oilfilter housing you does hav a gasged, hav you checked this: and in the oilfilter housing, you does have the "bleedbackvalve".. its a umbrako, or torx 5-6mm valve in the oilfilterhousing; there come loose.. ( you need to take out the oilfilter housing, and the oilfiltercooler,the small sqare little box) to check this..
if this are ok: or you dont have more pressure; DONT use the engine.. have it out, and do the repair again....!

Are you sure there is a "bleedbackvalve" in the oil filter housing? Aren't you confused whit the oliecooler thermostat?

Roy

[caterpillar]

im very shure of this little devil, in the oilfilterhousing: you need to take the oilfilterhousing out...

[maniac]

I got hold of another filter housing, gonna change to that as soon I get a new gasket