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Hi,

Noticed that my oil pressure was higher than what is was before. Just driving around town I noticed that I was running at about 80 Psi at 3000 rpm, before today it was around 65 Psl for those revolutions. Idle crept up as well, before 25 Psi when hot , now 45 Psi. I didn't change anything on the TR, oil level is where it should be. It got me a bit worried and puzzled. Any ideas anyone?

Thanks,

Yves

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I'd suspect a gauge problem. See if your local garage can put a calibrated gauge in the side of the block to see what it reads.

The relief valve won't cause this problem as it is closed except to relieve high pressure.

 

 

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It could be a sticky relief valve. Mine stuck open and I cured it with a new spring and clean. Details on this elsewhere on the forum. 
Keith

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33 minutes ago, Keith Wigglesworth said:

It could be a sticky relief valve. Mine stuck open

A relief valve stuck open will only result in low oil pressure Keith, as John explained above. A valve stuck shut might give high pressure at high revs but will have no effect at idle.

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10 hours ago, Keith Wigglesworth said:

It could be a sticky relief valve. Mine stuck open and I cured it with a new spring and clean. Details on this elsewhere on the forum. 
Keith

Problem is also visible with different oil filters. Notable paper to felt. I noted a drop in Oil pressure with felt type filters. From MGC applications. Who knows the flow resistance of the current batch of paper filters ?

Edited by BlueTR3A-5EKT
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Thanks for the reply/help all, will start with different gauge, and then go to filter and relief valve, will keep posted what I find!

Yves

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  • 2 weeks later...

Id bet my whole set of gauges that its the gauge! I rewired my 61TR3A - replaced wiring harness and as such completely took the dash apart. I was very careful with the gauges - not bash them around or shake them etc. I repainted the center dash. Once I got it all back together again I ended up with 2 items. The temp gauge runs about 10 degrees hotter than the coolant actually is and the oil pressure runs about 10 to 15 lbs higher than it did. I even took the oil gauge back out - cleaned it blew it out, etc and put it back - same thing. Nothing in my engine caused the oil pressure to go up 20 lbs. Its just the old original gauge and maybe the cork gasket on back, tube fitting, etc. Those things are a horrible bear to get back connected. I live it and the temp gauge knowing that its just off a bit. No harm no foul.

Now if I can just get a flasher unit that will STAY WORKING on the green dash light!!! The flasher units all work that I try, but within 1 to 2 weeks the green dash light quits flashing. Blinkers work great and flash great. But green dash light really bugs me - I want it to work as it should! Just my personal beef.    : )

 

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On 6/19/2022 at 10:09 PM, RobH said:

A relief valve stuck open will only result in low oil pressure Keith, as John explained above. A valve stuck shut might give high pressure at high revs but will have no effect at idle.

It could stick partially open giving low pressure at low revs and high pressure at high revs.

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29 minutes ago, Andy Moltu said:

It could stick partially open giving low pressure at low revs and high pressure at high revs.

Yes Andy but in his first post Yves states the the pressure at idle had increased also, so it couldn't be that.  

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Hi Guys,

Haven't found the time to swap out the gauge but whilst moving the car in the shop I noticed that pressure came up to 50 psi and stayed there on idle or throttle , so yup, gauge must be hooped. So what would be the reason? Dirt inside? Pressure parts getting "tired"? Would a clean inside fix this?

Thanks,

Yves

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As you probably know the pressure gauge is a Bourdon-tube type in which a C shaped tube tends to straighten as internal pressure increases. The free end of the tube has a mechanical linkage to the gauge needle.  It is most likely that this linkage has either worn or become faulty in some way, though you would perhaps expect it to result in the gauge reading low rather than high.  Maybe it is a simple as the needle having slipped on the spindle?

There is a picture of a typical mechanism here though it is from a dual oil and temperature gauge fitted to an MGA:

https://mgaguru.com/mgtech/dash/dt105.htm

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I agree.

I was just commenting that being stuck in a partially open state might affect high and low pressures. (Thus cannot be a reason to exclude a defective gauge.) perhaps should have made that clear.

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