Low Engine oil light on idle only

[Che]

Well, never had this problem before when I live in snowy cold New England USA. This year I moved to the Blistering heat sunshine state Florida. I have this low engine oil light during idle only. The idle rpm is ok (a little over 1000 rpm)

I still have the original oil when I shipped the car to Florida. I don't remember the oil weight that was currently in the engine. My guess its 10/30 mobil 1. I ran out of idea except I plan to replace the oil using 15/50 Mobil and hoping

to cure this issue. My guess was, the oil is too thin or too hot and the sensor turning the oil light on. My engine oil showing ok in the dipstick. I hope I don't have a worn oil pump.

I have a few questions:

Is the V8 has  low oil valve? If there is, where is it located and what is the function?

What does oil tranducer's function?

Where is the oil sensor located?

I want to put a Tee and put an oil gauge and check if im getting 1.4 bar during idle. I can't tell until I put an oil gauge.

Thank you and appreciate any help

 

 

[mike_sekinger]

Hi Che,

I would move to a 10/50 oil as a first step, along with installing an oil pressure gauge.

The V8 has a Pressure Relief Valve (PRV) which in theory could be stuck open, although I really doubt that. Unfortunately, you will have to remove the sump in order to get access to the PRV, with is located in the front cover/oil pump.

The pressure switch is located low down on the left hand side of the block - ahead of the oil filter housing.

For the oil pressure sender - depending on the age of your Esprit, on the oil filter housing, you may have a blanking stud on the right hand side of the casting - this was originally for the oil pressure sender on the earlier car.  Later filter housing did not have the casting machined for this.

[DosTurbos]

"on the oil filter housing, you may have a blanking stud on the right hand side of the casting - this was originally for the oil pressure sender on the earlier car. "

Mike, first of all thank you for the feedback. I appreciate it very much.

If I have the a blanking stud that you were talking about, I assumed I can put an extra oil gauge.

Changing to a heavy weight oil is the first thing I will do and I will try to hook up a oil gauge too.

Thank you again 

[Espritv8black]

Definetly change to a heavier weight oil.  I would recommend 15/50 Mobil1 Synthetic and a Mobil 1 Filter Mi 204 I believe. Sometimes Autozone or Advance Auto Parts will have a special on the oil and you get a free filter.  You need about 8 quarts ish. I cut a Mobil1 Filter open and it looked very robust.  VDO makes a sender that will screw in as I did it and it has a provision for the Idiot light in the dash and  a hook up at the sender for the guage itself.  I think I took the original brown wire, which was attached to the original oil pressure sensor located above the filter and used the factory wire on my new sender.  I did have to extend the wire a bit.  The new sender was hooked up lower by the filter and is a VDO unit.  I still need to figure out where to run the wire to the oild pressure gauge and also where to put the guage.  The guage is small but larger diameter than the cubby by the shifter.  I will take a picture of what I have so you can see as my car is on my lift currently.

 

Thanks Mark

[Espritv8black]

Here are a few pictures of the blamking plug that was talked about.  I ordered the oil pressure sender and guage from Summit Racing here in the United States .  I think that the screw in is M10, but I will look upo the VDO guage and Oild Pressure sender part number for you.  Here are the pictures of my setup.

The brown wire I had to extend, which is the original wire that goes to the original sender , so it will operate the dash light for low oil pressure.

[Espritv8black]

The original sender is above the oil filter and once the oil filter is removed you can see the brown wire and the original sender.

[Che]

Thank You EspritV8black,

I had a chance to change the oil and filter yesterday. I used 15/50 mobil 1 and M1-204 mobil 1oil filter and the result was the same.

The oil light was flickering and on during idle only. The next move is to change the oil sensor switch and hoping it will solve my problem.

I saw  where I can connect an oil gauge. The hole is 10mm  with 1.00 pitch. I also saw the oil sensor switch (could be a bitch to replace it). On the top

of the oil switch, I also saw the oil pressure relief valve.

May I ask what the oil pressure relief valve does or function?  Will pressure relief valve can cause low oil pressure if the spring is bad?

Also, I researched for cross reference for the oil pressure switch and I didn't find any. I guess I have no choice except buy the Lotus.

Edited July 29, 2018 by Che

[mike_sekinger]

The PRV has a plunger that moves inside a sleeve with a drilling on the outside.  When the plunger is forced up inside the sleeve by the oil pressure, the tip of the plunger passes the drilling and the pressure is released back into the sump.

The spring is pretty meaty, I would be surprised if it is not providing sufficient resistance.  If the plunger is somehow becoming wedged and cannot smoothly return to position then you might see low pressure.  Get a gauge on the filter housing, so that you can monitor precisely what pressure you are experiencing.

Cheers,

Mike S

[Che]

Ok Thanks Mike,

At least I know how the PRV works now. Yes I will surely do two things. Change the oil pressure switch and put a gauge.

It's just to hot here in South Florida to even work inside my  garage. I can't wait a cooler days or winter to come [2 mos to go}.

[Che]

Oh by the way, do you happen to have a picture of the lotus oil pressure switch?

I LIKE TO SEE the part # that was stamped in the unit, also the brand name. I have a friend that works in the auto parts and he said he will try to cross reference.

Thank u

[Che]

I called one of the lotus part dealer and told me that the stock lotus oil pressure switch  is obsolete and discontinued. The replacement is the VDO switch. Anyone here knows which VDO oil pressure switch in the 4 links below ?

1.  https://www.vdo-gauges.com/sensors/pressure-sensors-switches/pressure-switch-14-5-psi-1-bar-contact-closes-as-pressure-rises-earth-ground-m10x1.html

2.  https://www.vdo-gauges.com/sensors/pressure-sensors-switches/pressure-switch-5-8-psi-4-bar-contact-closes-as-pressure-rises-earth-ground-m10x1.html

3.  https://www.vdo-gauges.com/sensors/pressure-sensors-switches/pressure-switch-36-25-psi-2-5-bar-contact-closes-as-pressure-rises-earth-ground-m10x1.html

4.  https://www.vdo-gauges.com/sensors/pressure-sensors-switches/pressure-switch-13-psi-9-bar-contact-opens-as-pressure-falls-earth-ground-m10x1.html

My guess is #4  ?

 

[Espritv8black]

I do not.  

 

Mark

[sailorbob]

The minimum oil pressure at idle is specified as 1.4 bar so the switch needs to operate a little below that pressure.

[Espritv8black]

So that would be 20.58 lbs of pressure in on the other side of the pond, so probably if you dont want it flickering if their is a 15lb switch it is what I would use.  I would probably use the highest switch that gets me closest to that approximate 21 lbs of pressure myself.

 

Jusat my opinion.  

Mark

[Che]

Thank you Mark

I will contact VDO

[Che]

"The minimum oil pressure at idle is specified as 1.4 bar so the switch needs to operate a little below that pressure."

 

I think this might work 1.2 bar at low oil pressure.

The thread also the same M10 x1.00

https://www.vdo-gauges.com/sensors/pressure-switch-17-4-psi-1-2-bar-contact-closes-as-pressure-falls-floating-ground-m10x1.html

[swindon_alan]

@Che, wow that's a great spot. I know the oil pressure switch is obsolete and I've been looking for cross references and alternatives for a while as mine is kaput. Did you get one and did it fix your problem?

[swindon_alan]

PS I've had another look at this and the VDO switch is pretty expensive. An alternative is the Bosch 0 986 344 053 (0.8 - 1.2 bar) which are around £15 on eBay UK. I will get one and check that it fits and works ok.

[Che]

I did not find the stock lotus Esprit oil switch. I found a 20 pound switch (20 low & 67 high) that i think will work, but the thread is not m10 x 1.0. I bought a small female to male adaptor with m10 x 1.0 thread. I also bought an analog oil gauge + the oil switch but the darn vendor was late on sending the item. I left for DUBAI & MANILA.  I will be back on the 30th and plan on installing both parts. So, no I was not able to install & test. 

I think I will buy the bosch you mentioned too. The one I bought and the bosch both dirt cheap, might as well have two to test. I will let you know when I get back from my trip. 

[MD355]

Since we are are talking about PRV (pressure release valve) , let me tell you from first experience that mine got stuck and now I am rebuilding the engine !!

I saw the low oil level flickering and immediately I started to hear metallic noise from the engine !!

i was doing about 3000 rpm and within 10-15 seconds I pulled over and stopped the car !!

Apparently the PRV got stuck open and the oil pump would not build enough oil pressure. The two pistons further away from the oil pump rotated their bearings on their conrods damaging the crankshaft !!

Now the crankshaft is at the machinist being fixed (metal is removed from crank to make it smooth). And we will use +0.25mm bearings !!

The oil pump was in bad shape two, so I am rebuilding it with new components!!

[v8GTmac1]

all this talk about the pressure sender, makes me jelous i dont have a threaded hole on my oil filter housing. 

I took the oil pressure reading from my 2nd oil filter setup. and I extended my existing Lotus pressure sender out to better access it in the future with some banjo bolts, AN fittings and 6" of SS braided line. 

But as an option, the cylinder heads have 3/8" plugs for the oil passages, these are directly connected to the entire oil system so I dont see why you cant get a pressure reading there?