Low Oil Pressure

[davevr6car]

Have very low readings on my Oil Pressure gauge.

Just above the red when cold and nearly no reading when car is warm.

I'm not sure if its a faulty gauge or maybe the sender unit.

Anybody got any ideas or have had the same problem?

[Techspy]

I have had the same issue. I had a decently high reading on cold, but just barely above red when idling warm. Driving at normal rpm's was ok, probably about at the half way mark. I replaced the gauge with another one from another Esprit. Same thing. I replaced the sender unit with a brand new sender from vdo. Same thing. I connected another sender and gauge and it showed fine oil pressure. There may be a ground issue in the dash that is causing this, but I think it is just the sensativity level of the vdo equipment. I also had a leak down test done and that came up fine, so with this and the other gauge test, I am confident that I don't have a problem. What I did was unhook the warning light wire on the sender (it has a sender for the gauge reading and a sender for the warning light) so it doesnt flash when I am idleing. Another issue to consider is that I am running synthetic oil. This along with general oil improvement/changes over the years can mean that the oil isn't as thick.

So, in short, check the readings with a new sender and gauge, and do a leak down test. It is a fairly cheap and sure way to see if there is a problem.

[davevr6car]

Will a leak down test only tell you if your pistion rings and liners are ok.

Worn Main & Big end bearings or a worn oil pump will result in low oil pressure.

I might try an aftermarket oil pressure kit.

Also with tinner oil it will result in low pressure and will cause extra wear?

[esprithk]

I am the same..

but don't worry.....

you will get used to it..

[Techspy]

Yes thinner oil will cause lower pressure, but doesn't mean it will be less protection. The thinking goes that modern oil is better at protecting than oil designed years and years ago. Just think about the technology and oil that was around when this engine was engineered. Synthetic oil was surely not being used in the engines then. Another thing to consider is that newer oil is designed to be more fuel efficient. Meaning, the less friction it causes (the thinner and more "slippery" it is), the less fuel the engine will use. I bought a new oil pump some time ago and when I purchased it, the parts co was suprised. Apparantly they don't sell many because they don't need replacing very often. I still haven't installed it, but got it just in case. Another consideration is that lower oil pressure doesn't mean less flow neccessarilly. If you had a blocked passageway somewhere, you would almost certainly see a rise in oil pressure, but there would be a component that wasn't getting the oil it should.

I know what you are going through because I chased my low oil pressure reading for months. Basically what I was told was that these engines rarely have failures in the components that would be a problem that low oil prssure would indicate. Of course the service history is a factor. I am confident in my previous owners maintainace etc, a modern sender and gauge showed good readings, and I have no other worn engine indications. I finally stopped worrying about the readings. I guess another option would be to send the gauge and sender to a vdo repair shop and have it calibrated.

PS: You are right about the leak down test. I had that done primarily to help troubleshoot some oil burning which turned out to be coming from the turbo. But, it was a good indicator of the general engine health.

[fmxa]

I had the exact same symptoms with my S4s - fool proof method is to measure the pressure with a mechanical oil pressure gauge - remove the oil pressure sender and screw in the mechanical unit and check. Checked mine and pressure was excellent dispite what the dash gauge said. I ended up replacing the gauge and sender, which seems to have fixed the issue.

[esprithk]

I had the exact same symptoms with my S4s - fool proof method is to measure the pressure with a mechanical oil pressure gauge - remove the oil pressure sender and screw in the mechanical unit and check.  Checked mine and pressure was excellent dispite what the dash gauge said.  I ended up replacing the gauge and sender, which seems to have fixed the issue.

<{POST_SNAPBACK}>

wow..interesting...

can you give more information on your merchanical oil pressure gauge??

so I can install this gauge and take out the old one (and the sender), right?

[fmxa]

Instead of an electrical sender, you actually send the oil via a pipe (which screws into the sender hole) or hose into the gauage which reads the pressure thus eliminating any doubt over the electrical sender or gauge accuracy. I don't think you'd want one in the Esprit as you'd have hot oil flowing from the engine into the cabin and to the gauge. I just used it to confirm my pressure was good.

P

wow..interesting...

can you give more information on your merchanical oil pressure gauge??

so I can install this gauge and take out the old one (and the sender), right?

<{POST_SNAPBACK}>

[esprithk]

Instead of an electrical sender, you actually send the oil via a pipe (which screws into the sender hole) or hose into the gauage which reads the pressure thus eliminating any doubt over the electrical sender or gauge accuracy.  I don't think you'd want one in the Esprit as you'd have hot oil flowing from the engine into the cabin and to the gauge.  I just used it to confirm my pressure was good.

P

<{POST_SNAPBACK}>

oh..I see, thx!

[Paul93Lotus]

I just want to share a story about mechanical oil pressure gauges...

A friend of mine bought a 69 Corvette.... when I looked at the engine I noticed the small nylon tubing running from the engine into the firewall. I found it hard to believe that the car had a mechanical oil pressure gauge stock. I told him about the danger of having any type of mechanical gauge for oil or coolant going into his dashboard, and he kind of shrugged it off like I didn't know what I was talking about.....

Well two weeks later he was cruising around, and all of a sudden smoke started to come from his dashboard and he smelled something burning.

The oil line had cracked and sprayed oil all over the underside of his dashboard, over the back side of his gauges, on carpet, and all over the back of a new stereo he had just installed.

Needless to say the carpet was ruined, stereo destroyed, and complete clean-up was impossible.

He later just sold the car after he fixed the line. I got to deliver the big 'ol "I told you so."

Mechanical oil and coolant gauges are good only for testing, and in race cars. They are bad news for street driven cars.

Edited April 14, 2006 by Paul93Lotus

[x6gas]

I don't think you'd want one in the Esprit as you'd have hot oil flowing from the engine into the cabin and to the gauge.  I just used it to confirm my pressure was good.

P

<{POST_SNAPBACK}>

...although that's exactly what I have in my X180 which has aftermarket dials...

Made quite a mess when the o-ring on the back of guage didn't seal properly one time

[Paul93Lotus]

Something you might want to try on the pressure sensor before you trash it....

On my 300ZX Twin Turbo, the gauge would start reading low, and started to be very unresponsive. Sometimes, some sludge/engine particles/etc gets trapped within the orfice.

I got a pin and placed it within the hole being careful not to push to hard, and measured the depth. Then I grabbed a drill bit that was slightly larger than the factory orfice. I made sure to set the bit so I would not be able to drill beyond what I had measured with the pin (just a little less). I placed the sensor in a vice to hold it steady and drilled out the hole larger. Then sprayed carburettor cleaner / wd-40 / whatever into the orfice to clean out all residue that was left over. Did this thoroughly to be sure there was no metal particles left in there. Then reinstalled the sensor.

Fired up the car, and the sensor was twice as responsive as before, and fixed the sluggish reading. Been fine ever since.

Doesn't hurt to try if you're ready to pony up for a new sensor anyway, and may save yourself some money if it works.

[Paul93Lotus]

I think the reason why the orfice in the sensors are so small is that the factory wants the gauge slow to respond...i.e. no customers coming in saying they have low oil pressure complaints. They want the gauge to hang around in that "happy" area. But because of the small orfice, they are subceptible to clogging. So from the factory standpoint...they get less complaints on the sensor when it's working, and they sell a new sensor, when what the customer needed was just a cleaning of the sensor.

Edited April 23, 2006 by Paul93Lotus

[fjmuurling]

Just something to add about the orifice. The size of the hole determines how fast the sensor will react to pressure fluctuations, so a small orifice means that the sensor is less responsive to (small) pressure fluctuations and therefore the needle in the gauge is more steady. A bigger hole means a quiker reaction time but a less steady needle.

Freek

[DanR]

Does the oriface lead to a chamber before the sensor or is it the same size all the way to the sensor? If it's the same size, increasing the bore increases the area making it inaccurate and read more than what the pressure actually is.

[Paul93Lotus]

Does the oriface lead to a chamber before the sensor or is it the same size all the way to the sensor? If it's the same size, increasing the bore increases the area making it inaccurate and read more than what the pressure actually is.

<{POST_SNAPBACK}>

I have never opened one up, but the volume of oil is irrelevant. 50 psi of pressure will still be 50 psi whether it is going through a pipe 1" in diameter or .001" in diameter. The only result will be the gauge will be more sensitive to pressure change.

Edited April 23, 2006 by Paul93Lotus

[davevr6car]

Since posting the question about low oil pressure I've been talking to an independent Lotus specialist. He explained that not to worry that it is a commom fault with the seneder units to suffer with a weak spring resulting in low readings.

[DanR]

I have never opened one up, but the volume of oil is irrelevant. 50 psi of pressure will still be 50 psi whether it is going through a pipe 1" in diameter or .001" in diameter. The only result will be the gauge will be more sensitive to pressure change.

<{POST_SNAPBACK}>

Yep of course. I confused myself with testing the calibration accuracy of pressure guages when the applied test load/pressure is on other than a square inch.

Edited April 23, 2006 by DanR1201

[lince]

Does any of you know what the preassure should be I

[ChrisH]

I noticed today that my oil gauge started flutuating like mad after I had left it ticking over for quite some time but as soon as I revved it up it went back to normal, round about the 1/4 full mark then up to the half full mark at 2500 revs. did wonder however why it did'nt stay at the 1/4 full or was it becuse the oil pump was not under load so to speak