Oil pressure gauge registering over 60 when running, around 40 at idle

What might be the problem that gauge is reading so high? Series II FHC

Is this a mechanical gauge, or an electric one? The first step would be to determine the real oil pressure by use of a mechanical gauge.

60psi running and 40 at idle seems pretty normal to me for a healthy XK engine. Mine will be over 75 on a cold start on the choke, around 45 at hot idle, and about 70 at speed. I run a mechanical gauge, btw.

My 150 engine, running on 20/50w, is about the same.

My engine indicates about 50/60 at cold start, around 40 at warm 2500 rpm and 15 at warm idle. When really hot it goes down to nearly 30 and 10 respectively.
I mounted a mechanical gauge because I was scared by my electrical gauge.
The electric gauge that I left on the dashboard indicates sub-zero at hot idle, hahaha!

I guess that my engine is certainly a bit tired, but from what I have read, the oil pressure as read by the mechanical gauge is still acceptable.

David,

Those numbers may be fine, but we need more information to make appropriate comments:

  1. Are these measurements when the engine is cold, or after a warming up for 30+ minutes driving?

  2. Are the measurements from the OEM electrical gauge/sender (notoriously unreliable), or from a mechanical gauge (tends to be more accurate)?

  3. Have these measurements changed recently, in which case, did anything precipitate them (eg change of oil, filter, new gauge/sender…)?

-David

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Thank you for all the help, answers to David’s questions,

  1. when cold reads around 40, when warm 60 plus
  2. electrical gauge
  3. no recent change

Your thoughts?

Maybe enjoy driving the car?
Tom

Don’t worry…drive happy!

And, I’d plumb in a mechanical gauge, to more accurately determine baseline pressures.

Plenty on how-to, in the archives.

It’s strange that the pressure increases as the oil warms up - one would have to suspect the sender/gauge. I’d plumb in a mechanical gauge and take comparative reading under a range of circumstances (engine temperature, engine revs). Lots of guidance in the archives about adding a mechanical gauge - there is a fitting from Merlin Motor Sports in the UK that makes this pretty straightforward.

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Thank you for the help, will do

My current gauge reads over 60 when cold and 60 at 2000rpm when hot, 40 at idle. Nothing wrong with the gauge head, it’s the sender. I know it overstates the actual pressure by about 50%. I don’t care. I check the pressure readings only to see if it is different from what I am expecting. Only then will I panic.

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Here is what my test set-up looks like with the tee piece from Merlin Motorsports in the UK. I am not near my car right now so cannot give you the exact part number I got. Took about a week to ship to the USA and at least a few years ago shipping was not too high. I got several of their copper crush washers also.

David
68 E-type FHC

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My 69 S2, built Aug. of 69 would run 40 at speed and 20 at idle when fully warmed. Since that was on 10W30 break in oil from eng rebuild, I have moved back to 20W50 and the pressures that you are reporting are in range for that car and that weight oil. What changed since the last time you saw the lower oil pressures? Where is your oil level on the dipstick? Using the same brand of oil? Has the engine ever been rebuilt? If so, what pressure were you noting after the rebuild? Running the risk of another endless debate, I will say that I run Valvoline VR1 conventional racing oil. Blends of conventional/synthetic/full synthetic may bring about different readings. It’s good to been concerned about this, because if there is an issue, damage can be pricey to repair. The mechanical gauge check is a good one.

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I installed an auxiliary mechanical gauge under my dash that I can just barely see when driving while at the same time replacing the sending unit. At first there was agreement between the two readings but over time the dash gauge now reads lower than the mechanical.

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That’s starting to look like an oil well Christmas Tree. :grin: :+1:

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