HOWTO: Diagnose the Dynamic Oil Pressure Warning System

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Sat, 07 Aug 2010 12:36:14 +0100

Hey, nice write up. I've got an 84 diesel Jetta and the oil light and buzzer seem to have a mind of their own. The light will blink sometimes, the buzzer will go off, and off and off. If I wack the dashboard, or hit the horn it will often stop the buzzer. I've taken the instrument panel out thinking it may be an electrical issue in there. Any ideas what to look for? Hi Chris...thanks for your comments. Since mechanical change ie hammering the dash is leading to a change in the symptoms I'd certainly be inclined to suspect loose connections somewhere. After 35 years there may be some loose solder joints on the cluster or some corrosion between the cluster and the harness plug. A careful inspection of the cluster's circuit board with a magnifying glass might reveal a solder issue, and a can of electrical contact spray would be a good way to clean up any connector issues. If all else fails you could try swapping in a cluster from a junkyard... even a gasser cluster if you can find one... just to narrow it down a bit. cheers, Vince - chris

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Sat, 24 Jul 2010 15:35:07 +0100

Hi Vince, very good explanation, but I have another oil pressure indicator issue. Car is a Passat B4 TDI. Normal signalling of oil pressure system is working OK (i.e. indicator lights up with ignition turned, blinks and buzzes when wire from hi pressure switch is pulled), but during a normal driving the oil pressure indicator light (a red LED to be precise) very faintly glows, continously. Do you have any idea where to look? This happens both with a cold and a warm engine. Oil pressure verified OK with a pressure gauge. Please, any ideas? [i] Hi Mark: it takes very little current to make a LED glow... so it is likely a poor connection somewhere. Since it occurs at all RPMs it's probably on the low-pressure side... does the dim LED glow go out when you pull the wire off the low pressure sensor?? If so the sensor is defective. If not... you can trace the sensor wire along the harness... it may have rubbed bare somewhere and is grounding itself a bit. Another possibility is the cluster itself... swapping out a known-good cluster is the quickest way to isolate that problem. A bit of moisture on the circuit board can cause phantom current paths very easily. In the end, if you can convince yourself that you'l see a solid LED for both low and high pressure switches, you may decide to just ignore. Let us know what you find!! Vince [/i] - Mark

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Sun, 20 Jun 2010 10:54:03 +0100

Hi: Would you be able to clear up some conflicting info on your web site. My 1985-1992 VW Service Manual Section 3:41 says the lower oil pressure switch is on the filter flange and the higher one is on the end of the head. However, on 3:43 there is a picture which shows the high pressure switch at the filter flange. Which is correct?? Thanks Hi there... yes the Bentley is conflicting sometimes. The paragraph on page 41 of chapter 3 that reads "the low pressure switches are located on the oil filter flange (0.3 bar) and the end of the cylinder head (1.4 or 1.8 bar) is in error, in my opinion. On that same page figure 7.1 shows the higher pressure switch on the flange, and as you mention fig 7.6 on page 43 of that same chapter also shows the higher pressure switch flange. This has always been the case on any VW with dual sensors I've seem and also makes sense... I'd expect the most pressure to be at the flange just after the pump, with the least amount of pressure at the tail end of the head. It's also the case that previous engines with only one sensor had the 0.3 bar sensor at the head. All in all... I believe how the system is represented on my HOW-TO is accurate: higher pressure switch on the flange and lower pressure switch on the head. Vince - K. Stewart

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Sun, 13 Jun 2010 12:13:43 +0100

Hi recently i changed my oil and than i noticed when i drive over 2000 rpm the buzzer goes on what can i do to fix it im living in small island in thailand and the local mechanics don't know what the problem is after putting a new motor oil and checking the only oil sensors on oil filter , he gave up on me , do you have any suggestions thanks Hi Zia... if you follow the instructions in this HOW-TO step-by-step you should be able to figure it out... you will want to focus on the oil pressure at the high-pressure sensor on the oil filter flange, the sensor there, or the wiring to it. As per my instructions above, I'd start by getting a mechanical gauge hooked up to see what your oil pressure really is. Vince - zia

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Wed, 07 Apr 2010 21:28:46 +0100

I have 1.8 Golf and the Oil light comes on and the buzzer sounds at low RPM (engine warmed up)and they go out if I rev up the engine? No lights or buzzer while cold. It would seem to be a low pressure situation but with the high pressure warning? - Talon

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Thu, 01 Apr 2010 17:46:16 +0100

You have helped me with the timing a year or so. Now I have a 90 diseal Jetta with no tack. I have a crashed car with a instrument pannel with one. Is it a easy thing to change the insterment pannel and hook up the tack and all the different gauges. Is the wiring harnes in the car with out the tack got the wirering in it? I have the generator from the crashed car and all the parts. If you could help It would be greatly appreacieted . Ian - Ian

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Sun, 07 Feb 2010 16:45:29 +0100

Ive had similar experiences and know several ways to get rid of that pesky buzzer, in a safe reliable fashion. first thing ive noticed is through all of my vw's, over the years the oil screen in the oil pan (one the bottom of the oil pump, clearly visible after it drips in your eye) that gets blocked up. take down the pump by three easy screws, buy replacement seal or wing it, and remove lower pump tube. its got two screws. use a can of brake cleaner and clean inside and out,scrubbing with an old toothbrush. the crap gets lodged inside the tube and you cant see very well from outside so dont be satisfied with a cursory inspection. at 180k (miles) i replaced my oil pump just because while these engines do last, a srop in oil pressure over time is expected and any losses are much more critical to an older engine. other problems include restrictions in oil travel, for which i only recommend BG products oil flush (in the red can). works a champ. i flushed my motor before cleaning the screen last, and replaced the pan gasket. problem solved. on another note if you have a loose connention to your oil pressure senders this will also trigger the warning buzzer but is rarely the cause. take care to unscrew them and spray clean the hole in the end, to allow proper readings. thank you! - Erik

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Wed, 20 Jan 2010 00:29:40 +0100

Hi - great article. I think I know, from what I've read, what my problem is but I want to double check. My 1.8 8v Mk2 GTI runs great, no smoke, no knocks, even idle, no overheating etc. When it warms up (oil at 90 deg and water at first marker - as high as it goes) the oil light flashes at idle, anything over 1000rpm and its off. It either flashes regularly or today flashed very quickly and intermittently, just stopping for a split second and rapidly flashing again. From cold it come on as you turn the ignition then straight off. Can you give me your opinion? many thanks, Ant - Ant Harvey

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Wed, 30 Dec 2009 17:52:10 +0100

I was able to change out the intermediate shaft bearings in my MKII Jetta by removing the front and rear motor mounts and tilting the belt-side of engine downwards. I then removed the intermediate shaft through the passenger side wheel well. - Rick

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Sat, 05 Dec 2009 04:20:20 +0100

Hey man,good article! Quick question.. I removed my mk2 1.8l 8v head recently because a water port corroded and caused the head gasket to fail. Had the head welded and skimmed and installed it again. Car runs nicely,engine sounds good,but since i installed the head,i'm suddenly getting the oil buzzer problem when i've driven the car hard for about 30miles,rev it,and it goes away.. I'm using the same 20w50 oil i've always used.. is there anything in the head that can cause the car to have low oil pressure since the repair? Thanks Hi Hennie... thanks for your comments. That's a strange one for sure. Since it's the buzzer and it's going away when you rev it has something to do with the hi pressure sensor circuit/sensor on the oil filter flange. I can't actually think of anything you could do to the head that would cause low oil pressure directly at the flange. As per my writeup I'd recommend getting a pressure gauge in there to see what's really going on... could simply be a sensor that decided to crap out at the same time as your repairs. thanks again for your comments, Vince - Hennie Stander

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Tue, 07 Jul 2009 04:34:32 +0100

WHOOOHAAAAAAAA!!! thanks for this... really a big help!!! :) - Ambet P

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Fri, 01 May 2009 14:35:21 +0100

In diesel quantums, the engine need not be removed to replace the intermediate shaft bearings. With the radiator out, the condenser rotated up and out of the way, the grill off, and the front engine support removed, you can jack the front of the engine up enough so that the center line of the intermediate shaft can be accessed via a slot in the front end. Via this slot, you can extend a threaded rod, and utilize the procedure for installing and removing both intermediate shaft bearings utilizing home made or custom crafted(recommended if you don't have a lathe)tooling as described in the "show us your custom tools" sticky thread over at the vwdieselparts.com/forum site. [i] Hey Josh... thanks for the useful suggestion... I've updated the HOW-TO to reflect your additional information. Vince [/i] - Josh

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Sun, 12 Apr 2009 22:31:00 +0100

Great article, friend. Thanks for helping us keep our cars in good shape. Long live the Mk2. - Cale