Oil Pressure Issues L28

[rayaapp2]

Ive run across some interesting oil issues.

I finally got my hands on some nice tools so I can diagnose this. The car has been sitting for ages it seems.

 

I first installed this motor early this year with a F54 L28et bottom end and a E31 cylinder head. Im using a steal HKS head gasket. So the cam is externally oiled by the spray bar. I had 3 bad spray bars that had been giving me issues from the get go and I have an issue with the electrical system that has left me without an accurate oil pressure gauge. I replaced my spray bar with a nice billet aluminum one that has been mentioned here on this forum. The spray bar is awesome! I idled the car with the valve cover off to try and find a ticking in my valve train and I can see the flow and its directed nicely at the lobs and rockers! So I installed a nice pressure test gauge at the oil sending unit galley yesterday to find 10psi of pressure at idle and 80psi at 4000rpm. So I believe the ticking is from a lack of oil even though I can see flow at the oil spray bar. I had the oil pump apart not long ago and checked it over. It has wear, but I didnt think it was enough to cause this issue. Apparently it is. Ive checked the rest of the system. I preformed a full tare down and physically checked all the oil passages in the block and head. They are all clear. I even double checked the cam tower oil galleys. So before I totally condemn this oil pump I thought I would check and see if anyone had any thoughts of other possible causes, because I cannot think of any. As soon as I turn the engine off from running the pressure drops to zero so there is no residue pressure, but I dont believe I should be seeing residue pressure in an oiling system. I almost certain there are no oil pressure leaks.

 

The main reason for my concerns is that I had another oil pump on the car earlier this year with the same engine and it acted the same way(made the same tick). For reference I have replaced the following:

Rockers: Used

Lash pads: Used

Valve springs: New

Valves: refurbished

cylinder head: refurbished

Cam towers: Used

Spray bar: New

rocker Pivots: Used

Cams: Several Used ones that I have checked

the ticking gets louder in higher rpms and has been constant even with all the replacement parts including another oil pump.

 

I have a fresh Bosch oil filter and oil in the engine as well and have had several other filters on the engine during the diagnosis.

[Xnke]

Your oil pressure is fine.

 

10lbs at idle, plus 10PSI per 1000RPM is a general rule of thumb, and the stock oil pressure bypass valve tends to open up about 80PSI. Sounds like your ticking noise is a rocker out of adjustment. Go through and do a hot valve adjustment and I bet the ticking goes away. If it doesn't, then start looking for exhaust leaks at the head/manifold face.

 

I have two exhaust leaks on mine right now, from where I didn't get my manifold flange perfectly flat. Sounds just like a lifter tick, but eventually gets louder.

Edited November 18, 2011 by Xnke

[madkaw]

Hopefully as stated above it is an exhaust leak. When I took off my MSA header this last time I think I finally found my ticking noise. There was a divit on the flange and you could see where the exhaust was escaping. I couldn't see it on the car because it was pissing out the bottom right in the middle.

The more I read about oil pressures I think I might have too much and that is why it's squezzing by my rear main. The 10psi per 1000 doesn't always hold true for my engine.

it seems a lot of these L6's have some kind of 'noise personality', maybe yours a tick-but I know it would drive me nuts too!

[rayaapp2]

Your oil pressure is fine.

 

10lbs at idle, plus 10PSI per 1000RPM is a general rule of thumb, and the stock oil pressure bypass valve tends to open up about 80PSI. Sounds like your ticking noise is a rocker out of adjustment. Go through and do a hot valve adjustment and I bet the ticking goes away. If it doesn't, then start looking for exhaust leaks at the head/manifold face.

 

I have two exhaust leaks on mine right now, from where I didn't get my manifold flange perfectly flat. Sounds just like a lifter tick, but eventually gets louder.

 

Seems like all the other (Many other) L series engines Ive had ran 30psi 'ish at idle and tapped out around 65-70psi. I shimmed the current oil pump bypass valve for S&G mostly after I first assembled and noticed the tick. Obviously it didnt make a difference.

Ive done a hot valve adjust. In fact Ive checked and rechecked the hot valve adjust and even compared it to a cold reading. Its dead nuts. Im usually the first guy to call the valve adjustment on these things.

 

This is not an exhaust leak. The sound is coming from the center 4 cylinders top of the valve cover. I busted out a stethoscope on it. To give you an idea of the sound, it sounds like if I took all 8 center rocker adjustments and dropped them to full gap. The noise it makes when its wound up would make any Datsun folk cringe. The only other noise I have heard that is similar is a broken cam shaft, but thats not what has happened and Ive confirmed that. I wish I had another cylinder head laying around that was already setup just so I could slap it on there and see if the noise remains... lol

[Xnke]

Mine's a new nissan oil pump, runs 30lbs cold at idle, but 10lbs warmed up, and gains 10lbs per 1000RPM up till it hits 92lbs, which is where the slightly shimmed spring holds it.

 

I still don't think it's an oiling problem.

[rayaapp2]

I must have missed something when I built this head then. I will have to re-check the line bore on the cam towers. Ive seriously changed everything else already.