Instrument cluster oil light staying on

[CM400T]

Hello,

The last couple of times I've driven my car the oil light has stayed on for 5-10 seconds after startup. I mean when I turn the key to "on", all the instrument cluster lights come on. After I start the car, all the lights go out, but the oil light comes back on.

Yesterday when I drove it, the oil light stayed on for 10-15 seconds. When I got home, I parked on level ground and I checked the oil 20 minutes later. The amount was fine. Right now the car has 155,811 miles on it.

When I drove it tonight, the oil light stayed on for probably 45-60 seconds. I was so worried, I turned the car around and pulled back into my driveway. At some point, I revved the engine up over 2000 RPM, and the light went out and stayed out (if lack of lubrication was going to change the sound of the engine, I wanted to know right away). So I figured it was safe to drive to a restaurant. When I exited after dinner an hour later, the oil light stayed on for like 3 seconds before going out.

(When the serpentine belt pulley ran out of lubrication and had to be changed, the pulley mounting bolt hole broke, so I installed a new timing chain and cover-casting, resulting in this thread. I started that repair on 02-21-20 and I finished it on 08-21-21. And since this was major engine work, I also replaced the oil and filter at this time, and the valve stem seals and valve cover gasket. Thus the car sat with 154,011 miles on it for 18 months. Strange but true.)

My timing chain cover does not leak, so I did the repair well. The Fel-Pro o-rings were installed properly. The oil pump and chain tensioner really should be working fine.

Is there a problem the sending unit? They can fail -- my parents had one fail on their old 79 Mercury Monarch 4-door with the 250 cubic inch inline 6 + Ford C-4 automatic years ago (*_cough_* MALAISE ERA *_cough_*).

Any idea how to check these things? Where is the sending unit even located on my 3rd-gen engine?

[fdryer]

You'll find the majority of past threads about the oil pressure light is about the oil sending unit wearing out and not the oil pump. The oil pressure sending unit is a single wire sensor calibrated mechanically to switch ground at the lowest pressure, ignition on time. Switched off as soon as pressure is generated, above a few psi. Look up parts in rockauto to see what yours like so you'll be able to find it on the engine. You can always configure a pressure gauge to fit after removing the oil sending unit to satisfy any curiosity of actual pressures but you'll habe to know pipe fitting dimensions and how to connect a pressure gauge to it.

And beware, the oil pressure light is just that. Monitoring oil pressure, not oil level.

[onlinebilerv2.0]

It sounds like you may have gotten a bit of schmutz - possibly a small piece of the timing chain tensioner plastic in the pump relief valve.

Were it me - I would pull the sending unit and put a test pressure gauge and verify thevactual pressure

If the pressure is good - replace the sending unit and go from there...

[CM400T]

Interesting -- Before removing the old oil pressure sensor from the back of the engine, I removed the wire from the sensor and started it up (while still up on jack stands). After the key returned to the "run" position, the light went out and stayed out. This makes me think the ECM is using some unknown guidelines or "fuzzy logic" to decide when to turn the oil light on.

When at rest, both the old sensor and the new sensor show pretty much zero ohms between both pins. They both show pretty much zero ohms between either pin and the body of the sensor that screws into the block.

Richpin06a had a great video on this, as usual.

Sadly, after I installed the new sensor and returned the car to the ground, I started it up and the oil light came back on for 20 seconds or so.

When I replaced the timing chain cover, I used the name brand timing chain kit (MAHLE I think) which included two new plastic guides and a new hydraulic tensioner. AFAIK I did the repair perfectly with the inch-pound torque wrench.

Is the light coming on because pressure is too high? Is there anything else I can do without pulling the timing chain cover again? (I can't drive my green 2001 as it is being repaired.)

The light only comes on at startup, and once it goes out does not come back on. Will I harm the car by driving it this way for a short time?

[fdryer]

I may have posted a wiring diagram of S-series oil sending units. If I'm not mistaken, the simple oil pressure sensor is a mechanical switch calibrated to close when a specified pressure is reached when the engine runs. With engine off, ignition on, this switch is normally closed, connecting ground to the instrument panel light or signal to pcm, turning on the low oil pressure light. When oil pressure develops, the switch opens, turning off the low oil pressure light.

When you disconnected the single wire to the sensor, this is the same as opening the ground path to engine block ground, disabling the light.

Unfortunately, you're options are either a different oil pressure sending unit or connecting a pressure gauge to the port to monitor actual pressures.

[CM400T]

Harbor Freight has a gauge I can use for $30, which is much cheaper than a new engine. I'll buy it when they open shortly.

When I eventually fix the problem, I can still use the brand-new sending unit, with a new crush washer, right?

(I remember the steel bolts that corroded in the aluminum intake manifold, power steering pump bracket and thermostat housing on the old 1983 "Iron Duke" Cutlass Ciera and all I can say is NEVER AGAIN.)

What crush-washer would be good for this? The inside diameter of the washer on the original Spring Hill sending unit is 1/2 inch. Can I use either copper or aluminum? Copper is compatible with brake calipers, which I think are aluminum. Harbor Freight has some 1/2 inch copper washers, would they be a good choice?

[fdryer]

Although I never had to address oil pressure issues, my understanding of them are that tapered pipe threads are used without need for Teflon pipe tape, sealant or washer. Crush washers are used in brake banjo fittings to crush copper washers, deforming to shape against the steel bolt and cast iron wheel cylinders or disc brake calipers. Crushing copper provides a seal against high pressure brake fluid from seeping out. I doubt Saturns use aluminum calipers. Aluminum corrodes so most high end vehicles anodize them with branding (Brembo is one example). Anodizing is chemically acid etching the surface with a permanent tint. If you see rust on calipers, cast iron.

Good eyes can see taper in pipe threads. As a fitting is tightened, the taper tightens against threads for a near perfect seal against oil pressure.

[fetchitfido]

I don't remember there being a crush washer with the OPS, but it's entirely possible it stuck to the sensors I swapped (though I'm pretty sure the sensor bottoms out in the hole so no where for a washer to go...). It's not pipe thread, it's normal bolt thread M14x1.5.

According to AllData the OPS is *closed* with low oil pressure (not specified but usually 7psi). Says 13psi at idle up to 36psi at 2000rpm when warmed up, not to be at or under 9psi idle or 29psi at 2000rpm. Cold, it's allowed to 80psi at 2500rpm...so you could probably test the sensor with a DMM and a blow gun on your air compressor regulated to under 80psi.

[CM400T]

After I put the new pressure switch in, the oil light stayed on for a couple of starts, but I have not had the problem since. So I returned the pressure gauge to Harbor Freight.

I may never know what happened.

A few weeks ago, someone changed lanes inappropriately and damaged the LF panel, the hood, and the front bumper. I was able to get all 3 from a Saturn that had only been in the junkyard for 3 days for less than the cost of my insurance deductible. It is silver, the same as the car that was damaged. Bolt on, no paint needed.

And after the collision, I RESUMED USING A DASH CAM AND RECOMMEND EVERYONE ELSE GET ONE AS WELL (I used one for about 8 years but quit using it about 6 months ago). This time I bought the Rove R2-4K and it seems like it's an excellent unit. My old unit (the iconic GW1-C) was warped by the sun, it was hard to use the buttons to reset the date when it forgot the date, which was often. The Rove R2-4K gets the date from GPS satellites or cell towers or whatever, usually before I've gone more than 50 yards from my driveway.

NOTE: Saturns are often crushed after only a short time at the JY, since there is little demand for parts anymore. You must monitor the junkyards close to you and be prepared to act quickly.

Another Saturn in that same JY has the same "variable assist" steering as I have on both of my Saturns (the "NV7" or "electronic variable orifice"), so I'm going to try to get both the rack and pinion and the pump, and rebuild them if possible so I have spares.

[fetchitfido]

"NV7" steering shouldn't be hard to find...it was on the SC/SC2/SL2/SW2 from '91-'02. Doesn't do much good anyhow, just turns off assist at 55mph. Also, the PCM has no feedback from the EVO valve so other than needing the bracket there's no reason not to use the SOHC pump.
The steering rack comes in 2 flavors...power and manual. No reason to wait for a DOHC car to get the power steering rack.

[CM400T]

Thank you, fetchitfido. Right now, RockAuto has a confusing listing for an AC Delco remanufactured rack and pinion unit. To quote:

Use With Tie Rod Ends Part# 21012398; Non-Variable Ratio Power Steering(N40)

"Variable ratio" sounds to me like the car changes the number of turns lock-to-lock while you're driving down the road, a really bad idea. And where is the corresponding listing for the "NV7"? And why does the tie rod matter? Tie rods have to be able to handle the force of pushing the tires back and forth with the weight of the car on the tires, and the R&P has to be able to deliver the pushing force. Same R&P? What you say makes sense when I think about it. This confusing listing made me think there were two different R&P steering mechanisms.

My "donor car" in the junkyard is a 2000 SOHC with auto transmission (it turns out NOT to have NV7). I was surprised. I really thought the relationship between the engine, tranny, cradle and unibody would be the same for all years. Boy was I wrong! There is much less space between firewall and rack and pinion on that 2000 (getting the pump out was also more difficult than on my DOHC). It looks like the automatic transmission takes up more space. But I should be able to get the R&P out on my next JY visit, rebuild it at home and have a spare.

I got one of the last NEW AC Delco PS pumps online, and have two JY pumps. The one that came off the car has some metal worn away from the shaft, I'm not going to try to rebuild that one. They 2 JY pumps may be rebuildable (but may have less life than a brand new unit, predictably). The one that AutoZone's online store sent me looks remanufactured (numbers and letters scrawled on some of the surfaces, and it clearly came from "BBB Industries" -- hint --> check RockAuto). I'll take that one back to AutoZone.

Does anyone have an exploded diagram of the EVO mechanism? I'm sorry to admit I'm not sure how it came apart......I could use some help here.

"NV7" steering shouldn't be hard to find...

And yet it is. At least 2 "S" series near Cincinnati airport do not have this. At least 2 of the 3 "S" series at the JY on Hall Road in St. Louis do NOT have NV7 PS pumps (yes, I drove that far). None of the "S" series currently at the JY near Louisville airport/UPS World Hub have the NV7 pumps.

Thanks, and I'll keep working away at it !

[CM400T]

And now something on pwrsteer dot com suggests GM developed a "bypass kit" that would bypass the EVO and resolve "inconsistent steering".

I'm not sure how I would "plug up" the spot where the EVO solenoid went, but I guess I'll have to buy the kit to find out.......