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1998 Passat, Oil Pressure Light When Hovering at 1600 RPM

I have a 1998 Passat GLX with the 2.8 V6 and a 5-speed trans. It has 83K miles and has had all regular and preventive maintenance performed religiously.

Recently, I've had the oil light come on (seemingly) intermittently... usually when coming off the freeway and then slowing down. It's been into my regular shop (maintaining this car and other Passats) and the dealer at least three separate times. I've checked/done all the following:

Oil Level - good Oil weight and change history - good... I've been running the VW/dealer recommended since I owned the car. Previous owner was fanatical and he works in the office next door. I have all of his maintenance records. Oil and filter - changed each of the three times Oil sensor switch - replaced. Pressure checked mechanically at, above, and below 2000 rpm.

No mechanic has been able to duplicate the problem although the acknowledge it exists because I've been on the phone with them when the light/beep has occurred.

I learned something interesting last night on my commute home and I can now duplicate the problem... although I have no idea about the cause.

If I hover at 1600 RPM for 2-3 seconds, I get the oil pressure warning... EVERY time. If I'm just passing 1600 (up or down, fast or slow) I don't get the light. It also seems I don't get the light in the first few minutes of driving -- even when hovering at 1600 for longer thant the 2-3 seconds. But, as soon as the engine/oil is warm, I get the light at 1600.

I'm scheduled to go back to the dealer early next week. Until then, I'd really appreciate any insight.

Until now, I've shut the engine down immediately every time it occurred. I've even had it towed to the shop twice. Now, I just avoid hovering at 1600 and I never get the light. Should I be concerned about driving it if I'm not getting the light (but, obviously there is some problem)?

Reply to
cbdunn via CarKB.com
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Could be your oil pump going out. Hopefully, that's all it is. Worn bearings should not be occurring at only 83K miles.

Reply to
Papa

What is the oil pressure at 2000rpm with hot engine. I mean run the engine for about 45minutes and then check it.

Reply to
Lost In Space/Woodchuck

Some engines (I seem to remember an Audi I had once that did) have two oil pressure sensors--one for low engine speeds and one for high engine speeds. At a pre-set engine RPM (guess what speed?) the system would switch from the low to high sensor.

If the hot oil pressure is marginal then it is possible to have enough pressure to keep the low speed side happy, and the high speed happy when somewhat above the switch over point, but still have low enough to trigger the sensor right at the swtich point.

Keep in mind, I don't knwo if this is applicable to your vehicle!

Reply to
PeterD

I know I have one sensor, but I don't know if it has a dual aspect to it. I'll discuss with the mechanic.

Thanks!

PeterD wrote:

Reply to
cbdunn via CarKB.com

I've had two independent shops (one the dealer) check the pressure above, at, and below 2000. All pressures checked out fine on both occaisions.

Lost >What is the oil pressure at 2000rpm with hot engine. I mean run the engine

Reply to
cbdunn via CarKB.com

I thought about that, and discussed with the mechs... but if it was the oil pump, wouldn't I see fluctuations in oil pressure at variable RPMs... especially higher RPMs when the pressure needs are greater?

I get it EVERY time I hover at 1600. I've hovered at every 100 increments between 1000 and 2200 and I never get it at anything but 1600.

It's so odd...

Papa wrote:

Reply to
cbdunn via CarKB.com

Then perhaps your oil pressure sender and/or your oil pressure gauge (including the wiring to/from these devices) are defective. Did the shop do a comparison between their gauges and the car's gauges? Is your tachometer accurate? Could it be sticking?

Reply to
Papa

ones sensor, one wire. make sure it has the correct sensor in it.

Reply to
Lost again

Reply to
none2u

I have basically the same problem with my '94 Jetta. The only difference is that mine beeps at 1950 rpm. I hope somebody out there knows the answer for this.

Jim

Reply to
Jim Pineau

"But since the light comes on at 1600 only, I'd want the pressure checked at

1600. " The shop is checking this as I write this. I drove with the mechanic this am to ensure he knows how to duplicate the problem. He will hook up the gauge and get back to me.

"A no load 1600rpm oil light could indicate worn bearings. The motors barely moving enough to provide pressure. And no load floats everything in the bearings."

I'm assuming you mean engine bearings? That might be a silly question, but I'm not a mechanic. Assuming it is engine bearings, why would it only be at

1600? I saw what you wrote about the oil pump cam bearings, but I want to ensure I understand correctly; it could be either oil pump bearings or engine bearings?

The shop is also theorizing about the sludge/pickup problem at the oil pickup that is common with 4-cyl engines. I can't stop thinking that if it is a sludge pickup problem, I would see the pressure problem at lower RPMs... like idle... and at a variety of RPMs... not just at 1600 on ONLY at 1600 (hovering there).

Thanks a lot for your thoughts. It has been very helpful... even though the mystery isn't solved yet. I'll make sure I follow-up with the group when (if) I get the solution.

Reply to
cbdunn via CarKB.com

Jim,

Have you gotten anywhere with this? I'm still troubleshoot>I have basically the same problem with my '94 Jetta. The only difference is >that mine

Reply to
cbdunn via CarKB.com

You can get the oil pan removed for 2 hours tops to check the pickup if it's a 2.8l V6

Reply to
Lost In Space/Woodchuck

My 95 Jetta has a similar problem. I searched it on the internet. Someone mentioned that this problem is mentioned in the car manual. However I do not have one with me. Can someone help to verify it. Meanwhile I just ingnore the beeping and keep driving.

Lost > You can get the oil pan removed for 2 hours tops to check the pickup if it's > a 2.8l V6

Reply to
liminocean

I've gotten a little further on this, but still with no solution.

The wiring has been traced all the way back to the board. They did find one crimped section and spliced in new wire... no change. Problem still occurs.

They have driven the car and pressure checked at 1600 with and without the warning. They've recorded the pressures at the various RPMs as recommended by VW and all are within spec.

They are still speculating about oil pickup, oil pump, possibly engine bearings... but why would they seen guage pressures within spec?

The next recommendation is to switch out the sensor again. Apparently there are two different type sensors approved for this installation. I have the OEM original type. There is another that they state has "more tolerance."

They did learn that the sensor starts checking pressure at 1500. So, I'm getting the light at 1600-1650... right at the bottom edge of the sensor range.

I will check the owner's manual today again. All it says (from what I've seen) is that you are supposed to immediately stop the engine when the light occurs.

It's getting really annoying... and I think it's happening more frequently... like it's easier for it to occur.

Reply to
cbdunn via CarKB.com

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