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tbd Sun Mar 07, 2021 4:35 pm

Sorry, had to edit, hit submit to soon. #-o

I have what seems to be a random low oil pressure light. I had searched the forum and found many threads about how/when the low pressure light turns on but the light is somewhat erratic. The light is never on steady, it just flickers. It only flickers when stopped with rpms below 1100, usually somewhere with my foot on the brake.

Conditions determined so far;
1. If the van is started, idles but is not moved, the light will start flickering when the van reaches normal operating temperature. It will go out at about 1100 rpm. If the van is immediately restarted the light will flicker.
2. The van can be driven around town for hours, the light never flickers. Today I even had a 15 minutes stretch at 40 MPH, no flicker.
3. If the van spends 5 minutes on the highway at about 60 MPH, the light flickers at each stop. This will stop if the van is turned off for about 10 minutes, then it is back to condition 2, no flicker.
I have had it in the shop, the oil pressure was just under the low operating pressure but that was idling in the shop, like condition 1. I had them do a fresh oil change with a Mann filter. The mechanic said there sounded like there was a noise coming from the passenger side of the engine but he was unable to determine what the noise was.

So any ideas? I would expect the see the oil light flicker at idle/braked in all cases not just 1 and 3. It really confuses me that after being in state 3 a simple restart after filling the tank causes the oil light to stay out. I have not tried a restart after condition 1.

BTW, I am going to be installing a full time oil pressure gauge.

Thanks, Tim

PS: 2.1 WBX in an 89 tin top.

?Waldo? Sun Mar 07, 2021 4:57 pm

Sounds like you have low oil pressure, plain and simple. There's nothing about what you have said that doesn't fit with that.

Around town driving is the condition where the cooling system is least stressed and where normal operating temperature oil pressure will be highest. There is plenty of airflow through the radiator for cooling, the water pump has higher rpms to move the coolant through the radiator, and the engine is not really stressed. At highway speeds the engine loads are higher, at idle the coolant flow and airflow through the radiator are greatly reduced.

Tobias Duncan Sun Mar 07, 2021 4:57 pm

You can install a new pressure switch and that might take care of it.
When you first start your engine and the oil is cold, that is when your pressure will be the highest at idle . Once warm, the oil thins and pressure dips.
Sometimes when oil pressure sending units in these get old they become too sensitive . Also , many auto parts stores are notorious for listing the wrong unit for our vans so someone may well have installed one that is not rated correctly at some point in the past.

dhaavers Sun Mar 07, 2021 4:58 pm

I'd say normal signs of an older engine, & not unheard of when new... :roll:

How many miles? OP gauge will tell the tale...keep in touch...

- Dave

mikemtnbike Sun Mar 07, 2021 5:16 pm

I know you said you read a bunch of oil pressure threads but making sure youíve read tencentlifeís post from this one in FAQs:

Bottom line you need a true high temp oil pressure test as your next step. To me this means getting to full temp on the gauge, then running wide open on the freeway for 10-15 minutes at 65-75 mph, or flooring it up some long freeway grades. Come to a stop safely as quickly as you can. Whatís your idle oil pressure?

As youíve read, the samba says low idle oil pressure can mean impending rod bolt failure in the 2.1. If it isnít in tencentís parameters, you have some decisions- that can be fun!

Good luck!

0to60in6min Sun Mar 07, 2021 5:35 pm

Given that both low and high pressure senders are good and their connectors in the engine bay are not corroded...

Then it's the instrument connector, the flat one with 14 pins and the pin #12 and #13 are not connecting well.

I just fix that same problem by repairing the pins†#12 and #13 on the blue foil.

Wildthings Sun Mar 07, 2021 8:06 pm

A flickering oil pressure warning light at hot idle can be the only warning you will get that you have a rod bolt getting ready to let go. I don't know of any way to diagnose this accurately without a teardown.

If a rod bolt goes, at a minimum you will be in for a crank regrind and a new rod and a piston, but if the rod goes through the block you will be looking for a replacement engine.

Going to a thicker oil might make the light stay out, but it will not lengthen the time between now and when the rod bolt fails.

jordauto Sun Mar 07, 2021 8:39 pm

What oil are you running in the engine? Iíve seen way too many shops do an oil change and put 5/30 in because they assume everything uses that. These engines were designed for heavier oil. 20/50 is good for most of the use our vans get in the warmer camping season. If you were going to use it for winter and in freezing temperatures I would suggest something like 10/40 or 5/40.

danfromsyr Sun Mar 07, 2021 9:17 pm

give the wire that goes over the back of the DS of the engine to from above to down to the oil pressure sender
I have seen it chaffed through when it rests on the engine case.
the combination of heat, vibration and aluminum oxide wears through the wire casing and slowly exposes the copper inside and creates a very mild short as it vibrates.

djkeev Sun Mar 07, 2021 9:29 pm


jimf909 Sun Mar 07, 2021 10:59 pm

^^^ That is the most ridiculously stupid owners manual ever.

- "STOP AT ONCE" "Turn the engine off" if the oil light comes on.

- Umm, never mind, "that's no cause for concern".

Pure OG stupidity. Imagine the writers as they interviewed Hans und Franz and their ridiculous warning system when writing the manual. Hans: HALT! STOP AT ONCE!!! Franz: meh, nicht so viel...

Wildthings Mon Mar 08, 2021 3:58 am

jordauto wrote: What oil are you running in the engine? Iíve seen way too many shops do an oil change and put 5/30 in because they assume everything uses that. These engines were designed for heavier oil. 20/50 is good for most of the use our vans get in the warmer camping season. If you were going to use it for winter and in freezing temperatures I would suggest something like 10/40 or 5/40.

Every VW boxer engine I have ever had has run well running an xxW30 or straight 30wt oil. If the OP tries to cover up low oil pressure by running an overly thick oil he could well destroy his engine.

Abscate Mon Mar 08, 2021 4:33 am

Iíve owned and driven more air cooled VWs that flickered at idle than the membership of Dawn Wells Wanker Club

Drive with your senses on, consider mileage, and live life to the fullest

Check it at revs to assure yourself.

Steve M. Mon Mar 08, 2021 7:21 am

Wait a minute - how many miles on this engine?

jordauto Mon Mar 08, 2021 9:05 am

I wasnít suggesting running 4 litres of STP in his engine to try and mask immanent doom. I was simply suggesting what the VW engineers called for when they designed these engines. I canít count the number of times someone has come into the shop after a fresh oil change at a quick change place with complaints of oil light flickering only to find out they put bulk 5/30 or even worse a 0/20. Iíve seen it happen. Anyway the OP never said what oil he is running, or how many miles are on this engine. He also didnít say if he has had any engine work done recently. I have also seen shops install the oil pumps incorrectly, with the thick gasket under the pump causing a low oil pressure condition. The last one was on a newly ďrebuiltĒ engine.

The chart from my 1988 shows 20/50 as the all around oil unless itís being operated in Artic climates. Also the note that says no extended high speed driving with the thinner weights outside of Artic conditions.

MarkWard Mon Mar 08, 2021 9:11 am

From the ASE engine test. Car has an oil light on at idle.

Mechanic A states it the sensor.
Mechanic B states its the circuit board.

Who is right? A, B, both or neither? Trick question? I answered neither and added a comment at the end of the test.

The answer always is to verify the engine oil level and measure the actual oil pressure with a known good external gauge. I passed the test.

Guessing at oil pressure problems rarely ends well. As far as running thicker oil to cover a worn engine, is not really bad. The wear has already happened. When it becomes a problem is once the connecting rod leaves the crank shaft. At that point you don't even had a decent boat anchor.

jordauto Mon Mar 08, 2021 9:32 am

I guess I didnít say it well, but my point was that the engine needs the correct oil for the temperature range itís being operated in before checking oil pressure. The OP stated he had the shop check oil pressure but didnít share any specs with us. If it came into my shop, my first step would be to verify correct oil level and weight. Then install my master oil pressure gauge and compare it the specs in the Bentley. If the pressure is within specs then look at the oil pressure senders and warning system. If not in specs then itís time to figure out why.

ZsZ Mon Mar 08, 2021 9:44 am

info on the oil pressure switches

If the oil pressure is low - measured with gauge - then your sender is telling the truth.

DanHoug Mon Mar 08, 2021 9:46 am

with an oil pressure gauge on these WBX, does anyone know how much advance warning you get before the rod actually lets loose? is it a dropping pressure trend you observe over seconds, minutes, hours, days of engine running time?

i run oil pressure and temp gauges. i have an excellent base line of what is normal on my engine. just wondering the predictive timeline of a rod going out is once you start seeing a drop.

MarkWard Mon Mar 08, 2021 9:52 am

On race engine, the alert you get comes and goes quickly. You'll notice a drop in pressure then the rod bearing welds the crank oil supply shut and the pressure comes back. Next the rod departs the crankshaft.

I imagine the same is true for the 2.1.

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