tricky one for ya to scratch ure heads on

[daz]

this been happening for about a week now when starting from cold oil pressure goes to 6 bar runs ok for about a minute then funny noise comes from engine and oil pressure starts fluctuating....... car warms up and it stops oil pressure is fine again was running on mobil motorsport 15w 50 fully syn when oil level checked was about a quarter below full.... changed oil yesterday and put new filter on, started car this morning and the problem has gone completely. engine was fully re built about 6 months ago with a brand new gen oil pump, crank, big ends and mains and a con rod from nissan. just put normal 15w 40 oil in for now to try and give it a flush out...... any ideas as im stumped but obviously dont want the problem back. help or advice would be apprieciated.

daz

 

[daz]

stumped ya all then cause it has me if the oil pressure was fluctuating when making this noise ie a grinding/ not healthy noise then it has to be the oil pump it cant be anything else but why oh why would this dissappear when the oil was changed. :shock: :shock: if the pumps had it the no matter wat oil goes in then its gonna do the same thing surely ??

 

[Fast Guy]

What's the oil pressure doing now, with the new oil?
Maybe your old filter was blocked or the old oil was past it?

It certainly sounded like something mechanical. Noises and fluctuating oil pressure aren't good :shock:

Where was it rebuilt?

Keep an eye on it for now and let us know if anything else happens.

 

[daz]

oil pressure is not fluctuating now its as if its back to normal with no noise either :shock:

 

[Fast Guy]

What filter did you have on it?

 

[turblio]

If the noise is like a metallic gurgling then the pressure drops back to 4bar
when you first start it sounds like the pressure relief valve I have a theory
on this that when you first start there is air bubbles in the pump and thats
what makes the noise like a hydraulic pump that has air in it and changig the oil does stop this happening (for a while)
any other comments chaps?
Frank

 

[Fast Guy]

Oil strainer pick up letting air in then?

 

[turblio]

Now theres a good point Fast guy how to check it though easily?
Frank

 

[Fast Guy]

Only place I could see it getting in there, will be around the mating face o ring seal, unless it's loose. Unless the filter's loose, but that would leak oil. Maybe there's no air in there and it is/was something like the bearings dieing. :shock:

 

[daz]

bearings were brand new changed oil and no metal watsoever in the oil as i strained it . it also had a genuine nissan filter on it :?

 

[Fast Guy]

Don't rule out your oil pump, but it's unlikely

I fitted a new oil pump to a car before and it failed about 3 months later when an exhaust valve collet got in there and cracked a gear. Now where the hell that collet came from I don't know, cos I had all mine in place. :shock:

I'm still thinking there might have been a problem with the old filter. :?

 

[daz]

i now have an oil leak on the gearbox end ffs does this never end :shock: its going back to those who built it to have a look at it hope to god it aint the rear main else engine out again have new oil pump waiting at nissan mite fit that while its out just to be safe