Oil Pressure Testing 77 2.7

[strictly]

I bought a car sight unseen (hey at least it turned up!)

On the first turn of the key the oil cooler spewed its oil. I replaced the seals and restarted it. It stopped leaking, but I noticed The oil pressure guage on the dashboard was straight to 5 bar (75 psi) from zero, at idle with the engine cold (seems way to high)

Now before I start pulling relief valves to check, I wanted to start by connecting an oil pressure tester to confirm the guage pressure.

Can I connect this tester inline to a camline near the fan? Or do I need to do this at the very back of the engine where the oil pressure switch/sender is? The problem with this is access looks impossiable!

also ive noticed tbe oil pressure sender is right at the back (near the CSV) my last sc engine it was at the front, can I move it to the front, and change the rear sender for a switch for the idiot light?

when did they move senders from the back to the front was it 77/78 or before?

Thanks in advance

[74-911]

The sending unit back behind the CIS is for the idiot light. the oil pressure gauge sending unit is still up front. Sounds like someone has switched yours around or ??

[strictly]

Originally Posted by 74-911

The sending unit back behind the CIS is for the idiot light. the oil pressure gauge sending unit is still up front. Sounds like someone has switched yours around or ??

Ah intresting, that is exactly what I thought. Ive posted a picture below, that confirms the suspect wiring.

I will fit an oil pressure sender in the correct place. I presume, I can also test oil pressure in place of the sensor here? to confirm my guage pressure is accurate

If so Is it safe to disconnect the cam oil line, I presume that when the engine is off, there is no oil pressure to the tensioners anyway (3.2 oil fed tensioners fitted).

to change the one at the back to an oil pressure switch - do you think i can do it with a partial engine drop? (3" off the mounts), or is this realistically going to be engine out. In which case, i'll do it once ive checked the clutch, gearbox (havent driven it yet!)

thanks for your help

[Flat6pac]

The biggest problem is getting the pressure sender off the top of the block. I would just leave it there and get the parts you need by the fan. The other thing is, a 77 uses a 10 bar sender and gauge. If you have a 10 bar sender and 5 bar gauge your readings are wrong, especially right above the oil pump would be showing lower pressure.
You'll need a different hose for cam oil line as the one you have is too long.
Bruce

[boyt911sc]

Strictly,

The oil line connection shown in your picture seems to be different from the 3.0/3.2 engines configuration. Bruce A. should be able to tell more if there is a difference. And this is how I test the oil pressure during a cold start-up using an engine test stand.

Oil pressure sender installed:


Oil pressure gauge installed in lieu of OEM oil sender:


Tony

[strictly]

Thanks for the info chaps

A quick question before I order a new sender (i'll explain that in a minute). The sender changes from 77 to 78. My car was built 6/77 so very late 77MY, i have the 5 bar oil pressure guage, so I guess i need to order the 78 sender? From what you mentioned above, 10 bar was the 74 to 77 guage. Am I right?

----

I went for it, and removed the sender from the back of the engine. A pig of a job but I did it. I also found a leak in my airbox underneath at a pipe/plug (near #6), so i can fix that too. I went for a partial engine drop and alot of swearing!

I figured out why the sender was at the back. The hole at the front is suppossed to be m12 x 1, but someone must have stripped it, and tapped it out to m14 x 1.5, I've ordered all the bits to put it right, and am going to make a bush (m12 to m14 bush from brass) so i can connect it all as pictured above (special screw/bolt + housing for the oil sender + oil pressure switch adapter).

I also figured out i can test the oil pressure by removing the oil temperature sensor, which is M14 x 1.5 Its a tight fit for a oil gauge line here, so ive ordered a m14 x 1.5 banjo fitting, which i can attach to my guage and finally test my oil pressure.

Big job in all, but I would rather have the oil pressure guage and switch right, its too important not too! Thanks for the help so far, and i'll post my oil pressure results

[Flat6pac]

5 atm gauge, remember you might peg it
Bruce

[strictly]

Hi Bruce,

Thanks for the help bud. Okay thats what ive ordered. Ive tested the pressure mechaically, like you said i might peg it, it hits 6 bar when cold (95psi), but settles to say 5 bar (75psi) when warm and being reved, I can see the relief valve working, as not matter what the reves are it wont go over 5 Bar.

I can see know that im probally better with the 10 bar guage and sender, but thats okay i'll see how the 5 bar one goes first.

Im mostly just relieved that the oil pressure seems okay, and the relief valve seems to be working, at hot idle its the usual 0.5 - 1.5 bar

thanks for your help it was appreciated =)

Luke