Typical Oil Pressure

[robupton]

What is a typical or acceptable range for oil pressure that people see?   This is on a 2.8 engine using 20 50 weight Valvoline non synthetic oil. On star t up  with a cold engine it goes more or less to the stop at 8 bar. When warm the idle is around 2 bar or slightly less which seems reasonable to me. However when increasing the revs it gets up to nearly 8 bar at 3,500 revs which seems excessive.
I have replaced the pressure regulator spring and also the pressure relief spring.
So firstly is the pressure too high? if so what could be causing it?
I will get a gauge to check the  gauge on the dash but my gut feeling, for what thats worth, is that its not the gauge. I am seeing more oil under the car  which I am concerned could be blowing by the main seal.
Any suggestions will be gratefully received.

[lancianut666]

I am not familiar with the working oil pressure on Flaminias as my engine is not running (yet!) but 30psi at tickover sounds high. Have you an owners handbook it might give typical oil pressures in there.
Clarkey

[lancianut666]

8 bar is 116psi. I think a mechanical oil pressure gauge is required. I think our Fulvia owners expect to see the oil pressure gauge at the mid point when cruising but according to your figures you would have 116psi at a cruising speed.
Clarkey

[Spider2]

Hi,
If the Flaminia has a similar pressure sender unit as the Fulvia then I would suspect that. It is rare to get a non lying sender unit on a Fulvia and, if one does have one, the chances are the sender is an 8 bar unit for a 6 bar gauge, or vice verse. How old is the engine? If new and tight I would sugest using a thinner oil. I have always used 10-40 semisynthetic. However, First step is to screw a pressure gauge into where the sender unit is and get a real and reliable reading and go from there.
Also in tracking down the cause of the problem ask yourself as to whether this is a sudden problem or slowly building up over time or maybe after a certain task had been performed. Do you have the correct dip stick? An overfilled sump can cause problems with oil seals etc. I had an Alfa 105 twin cam with high oil pressure and oil misting from the filler cap. The quotes to fix it were £5-10,000.  Fixed it by putting the correct dip stick in! Do you have an oil cooler? If so the thermostatic valve (if fitted) may be faulty so the oil is never warming up properly. I was advised to remove my oil cooler. Probably necessary in 1968 with old technology oil doing the Dakar Rally but not with modern oils tooling around Europe. Another thing not to go wrong!
Best of luck, be methodical and you will sort it; don't fear the worst.

[lancialulu]

8 bar is 116psi. I think a mechanical oil pressure gauge is required. I think our Fulvia owners expect to see the oil pressure gauge at the mid point when cruising but according to your figures you would have 116psi at a cruising speed.
Clarkey

the Fulvia test point is 4500 rpm when oil hot should be => 65% of gauge c 4.5bar

[robupton]

Thanks everyone for the suggestions.
 
I cant find anything in the literature I have re pressure. Oil temp should be around  80 -100 C which is what I have typically seen going a bit higher on a hot day running at 80mph + . The oil cooler was replaced by the previous owner  and the thermostat is opening. I don't know when or by whom he engine was rebuilt but it seems to be in good shape.

Some more history would be helpful. Everything seemed to be fine until a few months ago when it suddenly gave a high reading with revs and a low reading  at idle. I ordered a new pressure regulator spring and pressure relief spring which I have just fitted.

Upon removing the top plate above the filter the bushing for the relief valves that should be threaded in fell out.....   No bushing could explain the high / low pressure reading that I saw.
I put the bushing back in place and replaced the two springs  (the new relief spring is half an inch shorter than the old one but seems long enough to be under tension). The other thing I noticed was the oil in the filter casing was dirty whereas on the dip stick is clean. Presumably the oil had been short circuiting and going straight back to the engine and by passing the filter due to the absence of the bushing.

The problem now is high oil pressure, at warm idle it is just under 2 bar which I would think reasonable although at start up I get the almost 8 bar reading. So the changes have been 1. bushing fell  out and now replaced. 2. replaced the two springs. I think my next move is to replace the original  springs and see if that takes it back to normal. If I understand it correctly the relief spring should not  come into play unless the filter is blocked when oil by passes the filter to save the engine. So the pressure spring is the most likely culprit. This appears to be a very straightforward install, it just slides into the housing  but could I have screwed this up somehow? I will get hold of a pressure gauge as a  test but a I said before because it was a sudden change I doubt that is the problem. 

[Spider2]

You still have not ruled out the sender unit or the guage. I do not know the Flaminia engine; I am assuming it has an electrical sender unit not a direct pipe to the gauge. If so I would change that first.

[lancianut666]

Hi all
There is a pipe to the gauge from the block so it must be a mechanical one, I replaced the flexible pipe for this last week on my rebuild engine. My copy of the handbook just says the oil pressure gauge should indicate so it looks like you have found the problem with the loose bush.
Clarkey

[robupton]

Thanks guys!
I have a pressure gauge arriving tomorrow. I am not optimistic but a faulty gauge would be a great outcome. The flexible pipe feeds a short length of hard piping that runs to the sender unit on the bulkhead - all conveniently accessible. 
Meanwhile I replaced the pressure regulator spring with the original one. i did not revert to  the original relief valve spring which requires removal of the cannister etc  but if I understand this correctly  it would only operate in the rare event of a blocked filter. So this more or less replicates the  previous situation however with the stray bushing firmly back in place. The result is similar high and low readings to those I started with and the surprising conclusion that  bushing didnt make any difference.  Should that tell  me something i wonder?

[lancianut666]

The plot thickens...I assumed like the Appia the Flaminia had a pipe from the engine to the back of the oil pressure gauge on the dash via the flexible pipe but it looks like there is an electrical sender in there as well...where is the oil warning light pressure switch? and the oil temperature sender?

[lancianut666]

On examining my car a 1963 2.5 3B coupe it would seem the oil pipe just has the sender fitted into it and then goes through the bulkhead and into the car.

[robupton]

Over the holiday i secured a reasonably priced oil pressure gauge. This should give  a more accurate reading than the one on the dash  but the main advantage (surprise!) is that I could actually see the reading on the dial. At the high end - 4,000 rpm + - the pressure is 70-75 psi whereas trying to read the dash gauge it looked like nearly 8 bar or about 100psi. So I am happy with the actual pressure. Revving up to 4,500 it went to 80 for a second then flipped down  which I assume was the pressure regulator spring doing its job - good to know its working.
Thanks everyone for the input, much appreciated!
Lancianut - I am enjoying reading about your engine rebuild, a lot of work and a big challenge   but it sounds as though you are approaching the home stretch which must be very satisfying.
Robert